Nervous System/Neurology Flashcards
A 78-year old woman presents to the emergency department with acute onset of left-sided ptosis and horizontal diplopia. On examination, there is dilated nonreactive pupil on left side and normal indirect light reflex of the left side. Which one of the following is the most likely diagnosis?
A. Optic nerve palsy.
B. Third cranial nerve palsy.
C. Fourth cranial nerve palsy.
D. Sixth cranial nerve palsy.
E. Seventh cranial nerve palsy.
B. Third cranial nerve palsy
Patients with acute acquired third nerve palsy usually experience sudden double vision (binocular horizontal, vertical, or oblique diplopia) and a droopy eyelid.
- Ptosis: Droopy eyelid
- Dilated pupil (midriasis)
- Paralysis of eye movements: Can’t move the eye inward (adduction), upward (elevation), or downward (depression)
- Eye position: The affected eye rests in an “abducted, slightly depressed, and intorted” position (down and out).
Note: Pupillary reflex is usually intact in third nerve palsies due to ischemia (e.g., diabetes, midbrain infarcts).
- Leads to monocular visual loss (affects one eye)
- Symptoms: Impaired pupil light reflex, central vision loss (scotoma), color blindness (dyschromatopsia)
- Causes binocular vertical diplopia and torsional diplopia
- Symptoms: Weakness in the superior oblique muscle, resulting in an upward deviation of the affected eye (ipsilateral hypertropia)
- Causes binocular horizontal diplopia that worsens when looking toward the side of the affected lateral rectus muscle
- Symptoms: Weakness in abduction, with the affected eye often deviated inward (medial deviation)
- Symptoms: Inability to close the eye, facial droop, inability to form forehead wrinkles, changes in taste sensation on the front two-thirds of the tongue
- Peripheral Lesion: Affects one entire side of the face (upper and lower)
- Central Lesion: Only the lower part of the contralateral face is affected; the forehead is spared because it receives input from both hemispheres of the brain.
Note: With an upper motor neuron lesion (central seven), the contralateral lower face is affected while the forehead remains unaffected. With a peripheral lesion, there is complete ipsilateral facial dysfunction (upper and lower face).
Patients with acute acquired third nerve palsy usually complain of the sudden onset of binocular horizontal, vertical, or oblique diplopia as well as a droopy eyelid.
On examination, patients with complete non-pupil-sparing third nerve palsy have ptosis, a midriatic (dilated) pupil, and paralysis of adduction, elevation, and depression of the eye on the affected side. The eye rests in a position of abduction, slight depression, and intorsion (down and out).
NOTE - pupillary reflex is often intact and unaffected in third nerve palsies due to ischemia such as in diabetes or midbrain infarcts.
Left third nerve palsy. The affected eye rests in ‘out and down’ position. Mild ptosis is noted. (see photo below)
Option A: An optic nerve lesion leads to monocular visual loss. Other features of optic neuropathy include:
-Impaired pupil light reflex (the afferent limb)
-Central vision loss (scotoma) on visual field testing
-Dyschromatopsia (color blindness) often out of proportion to acuity loss
Option C: Fourth nerve palsy may result in binocular (with both eyes open) vertical diplopia and subjective torsional diplopia. It causes paralysis of superior oblique muscle. On examination, an ipsilateral hypertropia is present (the involved eye is deviated upward) because the action of the superior oblique muscle (moving the eye down and inwards) is weak.
Option D: Patients with sixth nerve palsies typically complain of binocular (both eyes open) horizontal diplopia that worsens with gaze toward the paretic lateral rectus muscle. Lateral rectus muscle paralysis results in weakness of abduction of the affected eye with the affected eye often resting in medial deviation.
Option E: Seventh nerve palsy results in inability to close eye, facial droop, inability to form wrinkles on forehead and change in taste sensations in anterior two-thirds of the tongue. When one entire side of the face is weak, the lesion is usually peripheral. With a central lesion (such as stroke in one cerebral hemisphere), the forehead muscles are often spared because the part of the facial nerve nucleus supplying innervation to the forehead gets input from motor neurons of both cerebral hemispheres. The portion of the facial nerve nucleus innervating the lower face does not have the same bilateral input; its input is predominantly from the contralateral cortex.
NOTE - With upper motor neuron lesion of the facial nerve (also called central seven), the contralateral lower parts of the face are affected. The contralateral forehead remains unaffected. With peripheral lesions, complete ipsilateral dysfunction of the face muscles (upper and lower) occurs and the forehead is not spared.
Which one of the following conditions causes ptosis and dilated pupil?
A. Myasthenia gravis.
B. Mitochondrial myopathy.
C. Horner’ssyndrome.
D. Third cranial nerve palsy.
E. Sixth cranial nerve palsy.
D. Third cranial nerve palsy
Third cranial nerve (oculomotor) palsy can cause:
- Ptosis (droopy eyelid)
- Deviation of the eye downwards and outwards
- Dilated pupils
- Sluggish or absent light reflex
In cases of ischemic third nerve palsy (e.g., due to diabetes or midbrain infarcts), the pupils usually remain unaffected.
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Option A: Myasthenia Gravis
- Causes ptosis and double vision (diplopia)
- No pupil abnormalities
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Option B: Mitochondrial Myopathy
- Causes progressive eye muscle weakness and limb weakness with exercise
- No pupil involvement
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Option C: Horner’s Syndrome
- Causes ptosis, miosis (constricted pupils), and loss of sweating on one side
- No diplopia
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Option E: Sixth Cranial Nerve Palsy
- Causes impaired lateral eye movement
- No pupil abnormalities
Third cranial nerve (oculomotor) palsy can cause ptosis, deviation of the eye downwards and outwards, dilated pupils and sluggish or absent light reflex. In the third nerve paralysis due to ischemia (e.g. diabetic palsy or midbrain infarcts) pupils usually remain intact.
Option A: Myasthenia gravis can cause ptosis and diplopia with no pupil abnormality.
Option B: Mitochondrial myopathy is associated with progressive ophthalmoplegia and limb weakness induced by exercise. It does not involve pupils.
Option C: Horner’s syndrome is characterized by ptosis, miosis (constricted pupils) and ipsilateral loss of sweating. There is no diplopia.
Option E: Sixth cranial nerve palsy presents with impaired lateral eye movement without affecting the pupils.
An 79-year-old diabetic man presents with isolated third nerve palsy. Which one of the following findings, if present, suggests diabetes as the etiology?
A. Normal pupillary reflex.
B. Normal extra ocular movements.
C. Enophthalmos.
D. Involvement of the superior oblique muscle.
E. Absence of ptosis.
A. Normal pupillary reflex
- Most common causes: Diabetes mellitus, hypertension, and advanced age
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Symptoms:
- Ptosis (droopy eyelid)
- Eye deviated down and out
- Paralysis of superior rectus, inferior rectus, medial rectus, and inferior oblique muscles
- Normal pupillary reflex (pupils unaffected)
Note: If the pupil is involved, consider aneurysmal compression until proven otherwise.
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Option A: Normal Pupillary Reflex
- Common in ischemic third nerve palsy (e.g., diabetes)
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Option B: Paralysis of Eye Muscles
- All cases of third nerve palsy affect the superior rectus, inferior rectus, medial rectus, and inferior oblique muscles
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Option C: Enophthalmos
- Seen with orbital floor fractures from trauma, not due to nerve paralysis
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Option D: Superior Oblique Muscle
- Supplied by the fourth cranial nerve, not affected in third nerve palsy
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Option E: Ptosis
- Present in all cases of third nerve palsy, regardless of cause
Ischaemic third nerve palsies comprise the vast majority of third nerve palsies in adults. Diabetes mellitus is the most common cause, follwoed by hypertension and advanced age.
Isolated third nerve palsy with a normal pupillary reflex and completely paralysed extra-ocular muscles innervated by this nerve (superior rectus, inferior rectus, medial rectus and inferior oblique) are the most common presenting features in diabetic third nerve palsy.
NOTE - Pupil involvement in third nerve palsy should be assumed to be due to aneurysmal compression until proven otherwise.
Option B: With third nerve palsy the function of superior rectus, inferior rectus, medial rectus and inferior oblique muscles are impaired regardless of the etiology.
Option C: Enophthalmos can be seen in palsies occurred in trauma setting and is caused by orbital floor fractures not the paralysis of the nerve.
Option D: Superior oblique muscle is supplied by the fourth cranial nerve and its function remains intact in diabetic third nerve palsy.
Option E: Ptosis can be seen in all cases of third nerve palsy regardless of the underlying etiology.
A 32-year-old man presents with complaint of not being able to use his right arm as usual. On examination, shoulder abduction and elbow extension on the right side are diminished. Moreover, there is loss of sensation over the right deltoid area. Which one of the following could be the cause of his problem?
A. C5 nerve palsy.
B. Injury to the brachial plexus.
C. Carpal tunnel syndrome.
D. C7 nerve root injury.
E. C6-C7 nerve root injury.
B. Injury to the brachial plexus
The brachial plexus is crucial for the movement and sensation of the upper limb. It consists of nerve roots from C5 to T1, forming various nerves that innervate different muscles and areas.
- Diminished shoulder abduction and sensory loss over deltoid area: Suggests involvement of C5 and C6 nerve roots.
- Decreased elbow extension: Indicates radial nerve involvement (C5, C6, C7, C8, T1).
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Option A: C5 Nerve Palsy
- Can explain shoulder abduction weakness and deltoid sensory loss.
- Does not account for decreased elbow extension, which is radial nerve territory.
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Option C: Carpal Tunnel Syndrome
- Due to median nerve entrapment, affecting hand and wrist.
- Does not affect shoulder abduction, deltoid sensation, or elbow extension.
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Options D and E: C7 Nerve Injury
- Justifies weakened elbow extension (triceps weakness).
- Does not explain shoulder abduction weakness or deltoid sensory loss (supplied by axillary nerve, involving C5 and C6 roots).
- Likely Diagnosis: Injury to the brachial plexus involving multiple nerve roots (C5, C6, and possibly others).
- Clinical Features: Reflect deficits in shoulder abduction, deltoid sensation, and elbow extension, matching the distribution of affected nerves.
To answer this question, one should know the anatomy and distribution of brachial plexus which innervates almost all of the movements and sensation of the upper limb.
The following schematic diagram pictures the structure of the brachial plexus, the rami, trunks, divisions, cords and terminal branches and shows which spinal nerve roots contribute to formation of the nerves: - see photo below -
Diminished shoulder abduction and sensory loss over deltoid area suggest that C5 and C6 are affected. With decreased elbow extension, radial nerve (C5, C6, C7, C8 and T1) must be affected. With possible involvement of several roots, the injury to the brachial plexus is the most likely underlying cause to this man’s presentation.
Option A: C5 nerve palsy, can justify, to some extent, the loss of sensation of deltoid and shoulder abduction, but not the elbow extension which is innervated by the radial nerve.
Option C: Carpal tunnel syndrome is caused by entrapment of the median nerve in the flexor retinaculum. It does not affect elbow extension, shoulder abduction and sensory loss over the deltoid area.
Option D and E: C7 nerve injury can justify the weakened elbow extension but not the shoulder abduction and sensory loss over the deltoid area which is supplied by axillary nerve comprised of C5 and C6 nerve roots. This is through about C6-C7 nerve root deficits.
A 26-year-old woman sustains a closed head injury in a motor vehicle crash. She is unconscious on arrival at the emergency department. A head CT scan excluded skull fractures and hematomas. She regains consciousness after 25 minutes and now is complaining of double vision when she looks to the right. Vision ahead is normal, as is when either eye is covered. Which one of the following cranial nerves is more likely to have been injured?
A. Right third cranial nerve.
B. Right fourth cranial nerve.
C. Left fourth cranial nerve.
D. Left sixth cranial nerve.
E. Right sixth cranial nerve.
E. Right sixth cranial nerve
The sixth cranial nerve innervates the lateral rectus muscles; therefore, damage to the nerve produces binocular (when looked with both eyes) horizontal diplopia when the patient looks to the side of the injured nerve. This occurs because the lateral rectus muscle on the affected side fails to turn the eye to the affected side laterally, while the functioning medial rectus muscle of the contralateral eye turns it medially. The result of uncoordinated move of the two eyes produces two distinct picture on the retina and causes horizontal diplopia.
The sixth cranial nerve has a long course from the lower pons and reaches the lateral rectus muscle after emerging through the superior orbital fissure. The long course of this nerve makes it susceptible to injuries.
Option A: Typical presentation of the third cranial nerve palsy is ipsilateral ‘down and out’ gaze and fixed dilated pupil. With ischemic palsy of this nerve (e.g. diabetic palsy, midbrain stroke) the pupil reflex usually remains intact.
Option B and C: The fourth cranial nerve supplies the superior oblique muscle. The function of this muscle gives eye intorsion which is moving of the eye inwards and downwards. Damage to this nerve will lead to binocular diplopia on downward gaze.
Option D: With the left sixth cranial nerve injury, there will be binocular diplopia on looking to the left side (the affected side).
The sixth cranial nerve, also known as the abducens nerve, innervates the lateral rectus muscle of the eye. Damage to this nerve results in a specific set of symptoms:
- Function: It controls the lateral movement of the eye towards the side of the injury.
- Symptom: When the sixth cranial nerve is damaged on one side, the affected eye cannot move laterally towards the side of the injury. This leads to binocular horizontal diplopia (double vision when using both eyes together), particularly noticeable when looking towards the affected side.
- Mechanism: The intact medial rectus muscle of the contralateral eye pulls the eye inward (medially), while the paralyzed lateral rectus muscle on the affected side fails to move the eye outward (laterally). This mismatch causes each eye to perceive a different image, resulting in horizontal diplopia.
- Course and Susceptibility: The abducens nerve has a long course from the lower pons in the brainstem to the lateral rectus muscle, making it vulnerable to injuries along its path.
Comparison with Other Nerve Palsies:
- Third Cranial Nerve (Option A): Controls multiple eye muscles including the medial rectus. Damage leads to “down and out” gaze and a dilated pupil, often seen in conditions like diabetic neuropathy.
- Fourth Cranial Nerve (Options B and C): Supplies the superior oblique muscle, causing vertical diplopia specifically on downward gaze when damaged.
- Left Sixth Cranial Nerve (Option D): Specifically causes horizontal diplopia when looking towards the left side, reflecting the side of the nerve injury.
Understanding these specific symptoms and mechanisms helps in distinguishing between different cranial nerve palsies based on clinical presentations.
Aaron, 73 years old, is a diabetic patient of yours who has presented to the clinic with sudden onset of horizontal diplopia, better when he looks at a near object and worse when looking at distance. On examination, the left eye is deviated towards medial side. Which one of the following is the most likely diagnosis?
A. Left sixth cranial nerve palsy.
B. Right Sixth cranial nerve palsy.
C. Right third cranial nerve palsy.
D. Left third cranial nerve palsy.
E. Left fourth cranial nerve palsy.
A. Left sixth cranial nerve palsy
The sixth cranial nerve (CN-VI) palsy results in isolated weakness of abduction of the affected eye and horizontal binocular diplopia. On examination, there is an esotropia (inward deviation) that is worsened with gaze into the field of the affected lateral rectus muscle. Abduction is commonly limited on the side of the lesion. Poorly controlled diabetes is a predisposing factor.
Option B: In the right sixth cranial nerve palsy the right eye will be in an abnormal position (medially deviated), and the patient is diplopic on looking laterally to the right side.
Option C and D: The third cranial nerve supplies the levator palpebrae muscle of the eyelid and 4 extraocular muscles: the medial rectus, superior rectus, inferior rectus, and inferior oblique. These muscles adduct, depress, and elevate the eye. Patients with acute acquired third nerve palsy usually complain of the sudden onset of binocular horizontal, vertical, or oblique diplopia and a droopy eyelid. Pupil reflex remains intact in ischemic palsies (e.g. due to diabetes or midbrain infarcts).
Option E: A person with fourth nerve palsy may complain of binocular (both eyes open) vertical diplopia and/or subjective tilting of objects (torsional diplopia). The affected eye is usually extorted because the superior oblique muscle is responsible for intorsion of the eye. Objects viewed in primary position, especially in down-gaze may appear double when going down a flight of stairs so that the patient does not know which step to take first.
An 11-year-old boy is brought to your practice with progressive difficulty climbing stairs, walking, and running for the past few days. On examination, bilateral lower limb weakness is noted. All lower limb deep tendon reflexes (DTRs) are lost. The sensation however is intact. Which one of the following tests is most likely to confirm the diagnosis?
A. CSF analysis.
B. Forced vital capacity.
C. MRI.
D. Nerve conduction studies.
E. X-ray.
D. Nerve conduction studies
Asymmetrical lower limb weakness, areflexia and intact sensation, make acute inflammatory polyradiculoneuropathy (Guillain-Barre syndrome) the most likely diagnosis. Guillain-Barre syndrome (GBS) often presents acutely with rapidly progressive widespread weakness and sensory disturbances such as pain, often in the presence of a normal sensory examination. Weakness usually begins peripherally. Tendon reflexes are often lost or impaired. Some cases may have a preceding infectious disease such gastroenteritis with Campylobacter.
GBS occurs world-wide with an overall incidence of 1-2 per 100,000 per year. While all age groups can be affected, the incidence increases by approximately 20% with every 10-year increase in the age beyond the first decade of life.
The initial diagnosis of GBS is based on the clinical picture. The cardinal clinical features of GBS are progressive, mostly symmetric muscle weakness and absent or depressed deep tendon reflexes. The weakness can vary from mild difficulty walking to nearly complete paralysis of all extremities, facial, respiratory, and bulbar muscles.
The diagnosis of Guillain-Barre syndrome (GBS) is confirmed if cerebrospinal fluid (CSF) and clinical neurophysiology studies show the typical abnormalities. Therefore, lumbar puncture and clinical neurophysiology studies are performed in all patients with suspected GBS. Of these two, however, nerve conduction studies (NC) and needle electromyography (EMG) are more accurate. They are used not only for confirmation of diagnosis, but also for providing information regarding prognosis.
The typical CSF finding, known as albuminocytologic dissociation, starts approximately 48 hours after symptoms onset and is present in 50-66% of the patients in the first week, and over in 75% in the third week. Nerve conduction studies show a typical demyelinating pattern. NCV changes often lag behind those of CSF.
Patients with GBS should always be managed in an inpatient setting. Vital capacity should be monitored 4-hourly, using forced vital capacity (FVC), and if it falls to less than 20 ml/kg or is declining rapidly, the patient should be transferred to an intensive care unit. FVC monitoring is not diagnostic though. Cardiac monitoring is also recommended for such patients due to significant risk of cardiac arrhythmia.
Imaging studies (MRI, X-rays, etc.) are not of diagnostic value.
Guillain-Barre syndrome (GBS) is characterized by acute inflammatory polyradiculoneuropathy, typically presenting with rapidly progressive weakness in the limbs, areflexia (loss of reflexes), and intact sensation. It often follows an infectious illness like gastroenteritis caused by Campylobacter.
Diagnosis of GBS is primarily clinical, confirmed by findings such as progressive symmetric muscle weakness and absent or reduced deep tendon reflexes. Additional tests include cerebrospinal fluid (CSF) analysis and nerve conduction studies (NCV) with electromyography (EMG). NCV and EMG are particularly useful for confirming the diagnosis and assessing prognosis, showing characteristic demyelinating patterns.
CSF analysis may reveal albuminocytologic dissociation, a hallmark of GBS, which typically appears within 48 hours of symptom onset. This supports the clinical diagnosis.
Management of GBS involves close monitoring of vital capacity, as respiratory function can deteriorate rapidly. Patients are usually managed in an inpatient setting, with intensive care support if respiratory function declines significantly. Cardiac monitoring is also recommended due to the risk of arrhythmias associated with GBS.
Imaging studies like MRI or X-rays are generally not helpful for diagnosing GBS.
Understanding these clinical and diagnostic features is crucial for prompt recognition and appropriate management of Guillain-Barre syndrome.
A 22-year-old college student presents to your practice, complaining of recurrent episodes of drowsiness and feeling detached from the surrounding environment, mostly when she is in a shopping mall. Which one of the following would be the next best step in management?
A. CT scan of the head.
B. EEG.
C. Ask a witness about the episodes.
D. Polysomnography.
E. Advise relaxation techniques.
C. Ask a witness about the episodes
This patient has presented with episodes of transient alteration or absence of consciousness. Evaluation of such episodes is critical to diagnose epileptic seizures, parasomnias, organic enecphalopathies, psychogenic nonepileptic seizure, or sometimes a false account of the events for malingering.
A witness is a valuable source of information regarding the episode(s), and should be asked about the event if possible.
The following are examples of questions to ask:
- What did they see?
- Did the person become pale or confused before or during the attack?
- What does she/he looked like during the attack?
- How long does the episode last?
- How long did it take before consciousness returned to normal?
A thorough history in conjunction with an account of the event from a witness (if present) is always the very first step in stable patients who present with such episodes.
Option A, B and D: Investigations such as CT scan, EEG, or polysomnography can be selected for further evaluation of possible diagnoses based on history and physical exam findings.
Option E: Relaxation techniques are indicated if anxiety is found to be the underlying etiology.
Approach to the patient with transient alteration of consciousness
Medscape - 10 Steps Before You Refer for Syncope
One week after a knee surgery, a 24-year-old man presents with complaints of numbness and paresthesia of the right leg. On examination, there is foot drop and weakness of dorsiflexion and eversion of the right ankle. Sensation over the outer aspect of the right leg is also lost. Right ankle jerk is intact. Which one of the following nerves is most likely to have caused such presentation?
A. L4 nerve root.
B. L5 nerve root.
C. Common peroneal nerve.
D. Tibial nerve.
E. Sciatic nerve.
C. Common peroneal nerve
The clinical picture suggests damage to the common peroneal nerve as an adverse outcome of the knee surgery. Foot drop is the result of weakness of the ankle dorsiflexors (extensors) innervated by the deep peroneal nerve (with the exception of peroneous tertius, a weak ankle dorsiflexor located in the lateral compartment of the leg, and supplied by the superficial peroneal nerve). Sensation over the outer aspect of the leg is supplied by the common peroneal nerve and its superficial branch. These together make the common peroneal nerve injury the most likely explanation.
After branching off the sciatic nerve, the common peroneal nerve runs down laterally, wraps around the fibular head and enters the leg. The nerve is superficial in this region and susceptible to injuries during knee surgeries, with compression or in trauma.
Option D: Tibial nerve damage causes impaired ankle jerk, weak or absent plantar flexion and weak ankle inversion. Sensory impairment due to tibial nerve injury affects the back the leg and most parts of the sole of the foot.
Option E: Sciatic trunk (nerve) is above the knee, and unlikely to have been affected by the knee surgery. Moreover, sciatic damage affects the ankle and foot movements globally, and gives a clinical picture consistent with injuries of both common peroneal and tibial nerves at the same time.
L5 radiculopathy can mimic CPN injury**
A 45-year-old man with history of type II diabetes mellitus comes to the emergency department with diplopia and ptosis of his left eye. On examination, the left eye is deviated slightly out and down in straight-ahead gaze. Upward gaze is impaired. Pupils have normal reaction to light. Which one of the following would be the most likely underlying cause of this presentation?
A. Aneurysm of the posterior communicating artery.
B. Tumor.
C. TB meningitis.
D. Diabetes mellitus.
E. Trans-tentorial brain herniation.
D. Diabetes mellitus
The clinical features described are consistent with left oculomotor (3rd cranial nerve [CN-3]) palsy with sparing of the pupil.
The most common causes of third nerve palsy include:
1. Ischemia - Ischemic third nerve palsies, are the most common etiologic subset of third nerve palsies in adults. The pathogenesis is hypothesized to be microvascular.
2. Intracranial aneurysms - The most dreaded cause of a third nerve palsy is compression by an enlarging intracranial aneurysm. The most common site of an aneurysm causing a third nerve palsy is the posterior communicating artery; however, aneurysms involving the internal carotid artery and basilar artery are reported to produce third nerve palsies as well. In the setting of an acute third nerve palsy, the aneurysm is believed to be acutely enlarging and therefore at risk of imminent rupture. In this setting, subarachnoid hemorrhage can occur within hours or days of initial presentation of a third nerve palsy.
3. Trauma - Traumatic third nerve palsy usually arises only from severe blows to the head assoiciated with skull fracture and/or loss of consciousness. Thus, a third nerve palsy associated with mild head trauma should prompt evaluation for an associated pathology.
4. Migraine - Ophthalmoplegic migraine is a condition affecting children and young adults, and most commonly involves the third cranial nerve, sometimes with permanent deficits.
5. Other causes - Infections, tumors, vasculitis, and herniation are other less common causes of third nerve palsy.
NOTE - The most common causes of the oculomotor nerve palsy sparing the pupil reaction is ischemia of the nerve as a result of vascular compromise due to diabetes mellitus.
Third nerve involvement associated with impaired pupil light reaction can be caused with any of the following:
* Aneurysm of the posterior communicating artery – it can rarely spare the pupil light reaction
* Transtentorial brain herniation
* TB meningitis
3rd nerve palsy - when is light/pupillary reflexes impaired or normal?
A 34-year-old woman presents to the Emergency Department with complaint of sudden-onset severe unilateral headache on the left side. The pain is felt behind the orbit and is associated with nasal stiffness and conjunctival injection and lacrimation. She has the history of previous similar headaches. Which one of the following is the the treatment of choice to prevent further attacks?
A. Verapamil.
B. Oxygen100%.
C. Propranolol.
D. Sumatriptan.
E. Paracetamol.
A. Verapamil
The scenario describes a classic case of cluster headache, also known as migrainous neuralgia. Cluster headache is characterized by attacks of severe orbital, supraorbital, or temporal pain, accompanied by autonomic phenomena. The typical attacks may strike up to eight times a day and are relatively short-lived. Cluster headache is strictly unilateral, and the symptoms remain on the same side of the head during a single cluster attack. However, the symptoms can switch to the other side during a different cluster attack (side shift) in approximately 15%.
The pain is very severe and as opposed to migraine pain, patients with cluster headaches are restless and prefer to pace about or sit and rock back and forth. The attacks of cluster headache can be so severe and vicious that patients may commit suicide if the disease is not diagnosed or treated. Unlike migraine headache, cluster headache is NOT associated with nausea and vomiting.
Autonomic symptoms include ptosis, miosis, lacrimation, conjunctival injection, rhinorrhea, and nasal congestion. These symptoms are due to both sympathetic impairment and parasympathetic hyperactivity. In some patients, the signs of sympathetic paralysis (miosis and ptosis) persists indefinitely and increases during attacks.
The very first step in management of a cluster headache attack is oxygen 100% through a tightly-sealed face mask for 15 minutes. This treatment alleviates the headache in most patients. For those unresponsive to oxygen, the following could be tried with indefinite response:
-Sumatriptan (intramuscularly or intranasally)
-Dihydroergoramine (intramuscularly)
-Lidocaine (intranasally)
NOTE - Nasal congestion may render the intranasal route ineffective.
After cluster headache is diagnosed, preventive treatment should be started with verapamil (sustained released) as the first-line medication.
Methysergide, corticosteroids, or lithium have been used as alternatives, but not as first-line. Methysergide is associated with the serious complication of retroperitoneal, cardiac and/or pleural fibrosis.
A 65-year-old woman presents to the emergency department with complaint of difficulty walking for the past 24 hours. She also mentions that she has been experiencing progressive pins and needles in hands and feet for the past few days. On examination, she has a blood pressure of 130/80 mmHg, pulse rate of 90 bpm, respiratory rate of 14 breaths per minute and temperature of 37.5°C. On neurological examination, she is found to have brisk deep tendon reflexes (DTRs). There is an extensor plantar response. There is also a decrease in sensing pain, temperature, vibration and touch. Romberg test is positive. There is no visual sign or symptom. Which one of the following is the investigation of choice to reach a diagnosis?
A. Lumbar puncture.
B. Nerve conduction studies.
C. Serum vitamin B12 level.
D. Serum creatine kinase(CK).
E. MRI of the brain.
C. Serum vitamin B12 level
The simultaneous presence of clinical findings attributable to peripheral neuropathy and myelopathy are strong indicators of subacute combined spinal cord degeneration that occurs with vitamin B12 deficiency.
Patients with the condition complain of distal paresthesia and weakness of the extremities, followed by spastic paresis and ataxia (represented by a positive Romberg test here). On physical exam, there is a combined deficit of vibration and proprioception with pyramidal signs (plantar extension and hyperreflexia). Other sensory modalities can be affected as well.
Neuropsychiatric manifestations, such as recent memory loss with reduced attention span and otherwise normal cognition, depression, hypomania, paranoid psychosis with auditory or visual hallucinations (megaloblastic madness), violent behavior, personality changes, blunted affect, and emotional lability are possible presentations of the disease reported in some of the patients.
To establish the diagnosis, measuring the serum vitamin B12 level is the most important investigation. Treatment replacing vitamin B12.
(Extensor Plantar Response = positive Babinski reflex)
Vitamin B-12 Associated Neurological Diseases
Which one of the following statements is incorrect regarding Guillain-Barre syndrome?
A. Intravenous immunoglobulin (IVIG) Is the treatment of choice.
B. Plasma exchange is the first-line treatment.
C. Neuropathic pain is commonly seen during the illness.
D. Steroids have no role in treatment.
E. Neuropathic pain is responsive to tricyclic antidepressants.
B. Plasma exchange is the first-line treatment
Acute inflammatory polyradiculoneuropathy (Guillain-Barre syndrome) often presents acutely, with rapidly progressive widespread weakness and sensory disturbance, often in the absence of sensory signs that usually begins peripherally. Tendon reflexes are often lost or impaired. Many different clinical presentations are seen including Miller Fisher variant, manifested with extraocular paresis, ataxia and arefelxia. There is also an uncommon variant with bulbar presentation.
Some cases have an infectious trigger including Campylobacter infection.
Confirmatory tests include a cerebrospinal fluid (CSF) examination with typical finding of elevated CSF protein level with an absent or minimal cellular response and, a little while later in the course of the disease, slowing of nerve conduction on nerve conduction studies.
Patient should always be managed in an inpatient setting. Vital capacity should be monitored 4-hourly and if it falls to less than 20 ml/kg or is declining rapidly, the patient should be transferred to an intensive care unit. Cardiac monitoring is recommended for such patients due to significant risk of cardiac arrhythmia.
Intravenous immunoglobulin (IVIG) and plasma exchange are both proven treatments with similar efficacy. Both can be used as treatment options; however, plasma exchange is logistically more difficult and associated with greater potential complications making it less desirable as first-line treatment.
Option A: IVIG can be more readily available and can be used as the treatment of choice in most centers.
Option C and E: Neuropathic pain is a frequent complaint in patients with Guillain-Barre syndrome. The management is the same as for any neuropathic pain syndrome – adjuvant analgesia with a tricyclic antidepressant or antiepileptic drug, often administered conjointly with an opioid is used for pain control. Gabapentin is more effective than carbamazepine.
Option D: Steroids have no proven role in management of Guillain-Barre syndrome.
On neurological assessment of a patient, he is unable to copy a pentagon. Which one of the following is the site of the lesion?
A. Temporal lobe
B. Temporoparietal lobe
C. Frontal lobe
D. Dominant parietal lobe
E. Non dominant parietal lobe
E. Non dominant parietal lobe
Drawing intersecting pentagon assesses the ability patients in constructional praxis (ie a task require three-dimensional manipulation). This is a task of non dominant parietal lobe that leads to constructional apraxia.
TOPIC REVIEW
The Mini Mental State Examination (MMSE) is a tool that to systematically and thoroughly assess mental status. It is an 11-question measure that tests five areas of cognitive function: (1) orientation, (2) registration, (3) attention and calculation, (4) recall, and (5) language. The maximum score is 30. A score of 23 or lower is indicative of cognitive impairment. The MMSE takes only 5-10 minutes to administer, and is practical to use repeatedly and routinely.
*** Read example of MMSE on page 719
Failing to answer the questions or doing the tasks indicates dysfunction of a particular area of the cortex:
To perform a dilation and curettage on a woman, she is placed in lithotomy position, after which she is found to have developed a nerve injury. Which one of the muscles is most likely to be affected by this injury?
A. Extensor hallucis longus.
B. Flexor digitorum longus.
C. Tibialis posterior.
D. Soleus.
E. Quadriceps.
A. Extensor hallucis longus
The most commonly injured lower extremity nerve in patients undergoing surgery in lithotomy position is the common peroneal nerve. The injury is thought to be secondary to compression of the nerve between the lateral aspect the fibular head and the bar holding the leg, especially when candy cane stirrups are used (see below). Low weight, smoking and prolonged surgery are risk factors for this injury.
(See photo of nerves in lithotomy position below)
At the level of the popliteal fossa, the sciatic nerve bifurcates into tibial and common peroneal (fibular) nerves. Medial to the course of the biceps femoris muscle, common peroneal nerve runs laterally and inferiorly, wraps around the fibular head and enters the lateral compartment of the leg. It passes between the attachments of the fibularis longus muscle, where the nerve divides into the superficial and deep fibular (peroneal) nerves.
Injury to common peroneal nerve can cause dysfunction of both deep and superficial peroneal nerves that can present with the following:
- Loss of dorsiflexion and eversion of the foot (equinovarus deformity)
- Sensory manifestations along the anterolateral border of the leg and dorsum of the toes except those supplied by saphenous and sural nerves.
The following muscles of the leg are innervated by deep and superficial branches of the common peroneal nerve:
- Tibialis anterior
- Extensor digitorum longus
- Extensor hallucis longus
- Peroneous tertius
- Peroneous longus
- Peroneous brevis
Of the given options, only extensor hallucis longus can be affected as a result of common peroneal nerve injury in lithotomy position. In fact, inability to extend the greater toe is a common finding in patients with injured common peroneal nerve.
Option B, C and D Soleus (plantar flexor), tibilalis posterior (plantar flexor and ankle inverter), and flexor muscles of the foot, including flexor digitorum longus are innervated by tibial nerve; therefore, unaffected with common peroneal nerve injury.
Option E Quadriceps muscle is supplied by femoral nerve and unaffected by common peroneal injury.
NOTE : Lower leg manifestations of L5 radiculopathy can be exactly similar to the common peroneal nerve injury.
A 45-year-old man presents with loss of inversion, eversion, dorsiflexion and plantar flexion of his left foot. His left knee jerk is preserved, but left ankle reflex is weak. Which one of the following can be the cause of this presentation?
A. Sciatic nerve injury.
B. Common peroneal nerve injury.
C. Tibial nerve injury.
D. L4/L5 disc herniation.
E. Femoral nerve damage.
A. Sciatic nerve injury
Loss of ankle inversion in this man can be either due to dysfunction of deep peroneal nerve (a branch of common peroneal nerve), or tibial nerve that supply the two main ankle invertors: tibialis anterior and tibialis posterior.
Ankle eversion is the action of the muscles in the lateral compartment of the leg: peroneous (fibularis) longus, peroneous (fibularis) brevis and peroneous tertius. These muscles are supplied by the other main branch of the common peroneal nerve, superficial peroneal nerve.
Plantar flexion of the ankle is mediated mostly by the muscles in the posterior compartment of the leg, all of which are innervated by tibial nerve. On the other hand, ankle reflex in this patient is weak and suggests involvement of the S1 (and to a lesser extend S2).
In fact, the clinical picture is only justified if both common peroneal and tibial nerves are involved and affected. This can be explained by injury to sciatic nerve.
Tibial nerve and common peroneal (fibular) nerve exit from the pelvis together contained in a sheath of connective tissue to form the sciatic trunk (nerve). In fact, the sciatic nerve is the common peroneal nerve and tibial nerves running down together in the buttock and back of the thigh. In the distal thigh, these two nerves separate and run different paths.
Injury to sciatic nerve (trunk) can present with motor and sensory deficits attributable to both the tibial nerve and common peroneal nerve.
The clinical findings include:
1. Common peroneal nerve:
-Weak or absent ankle eversion
-Weak or absent ankle dorsiflexion (drop foot)
-Weak or absent toes extension
-Weak ankle inversion
-Paresthesia / impaired sensation over the lateral aspect of the leg and dorsum of the foot (except the areas supplied by saphenous and sural nerves)
- Tibial nerve:
-Weak or absent plantar flexion (the patient cannot stand on the ball of his foot on the affected side)
-Weak ankle inversion
-Weak or absent toes flexion
-Weak or absent ankle jerk reflex
-Paresthesia/impaired sensation over the posterior part of the leg and sole of the foot (except those areas supplied by saphenous and sural nerves)
In summary, injury to sciatic trunk causes weakness of ankle movements in all directions, impaired or absent ankle reflex and impaired sensation below the knee except the medial aspect of the leg and the outer part of the foot. Knee reflex usually remains intact.
Option B: Common peroneal nerve damage (in isolation) explains loss of sensation over the lateral leg, as well as weakened dorsiflexion, eversion and inversion, but not the weak plantar flexion.
Option C: Tibial nerve injury (in isolation) explains the absence of the ankle plantar flexion and impaired ankle jerk, but not the other clinical aspects.
Option D: Lateral L4/L5 disc herniation affects the L5 nerve root and results in L5 radiculopathy. L5 and common peroneal nerve injuries present similarly in the lower leg. L5 radiculopathy does not cause weak plantar flexion and impaired ankle reflex.
Option E: Femoral nerve supplies all the muscles in the anterior compartment of the thigh, as well as the sensation of the thigh except the posterior part (which is supplied by the sciatic trunk) and a small medial part (supplied by the obturator nerve), and through the saphenous branch, the medial aspect of the leg and outer part of the foot.
Which one of the following is caused by damage to the trigeminal nerve?
A. Forehead wrinkling.
B. Vision loss.
C. Double vision.
D. Loss of taste.
E. Difficulty in opening the mouth.
E. Difficulty in opening the mouth
Trigeminal Nerve (CN V) Overview:
-
Function:
- Sensory: Carries sensations (pain, temperature, touch) from the face, mucosa, teeth, and portions of the dura.
- Motor: Controls muscles of mastication (chewing).
-
Divisions:
-
Ophthalmic (Upper):
- Innervates: Forehead, upper eyelid, cornea, conjunctiva, dorsum of the nose.
- Path: Leaves through the superior orbital fissure, travels via the cavernous sinus.
-
Maxillary (Middle):
- Innervates: Upper lip, lateral/posterior nose, upper cheek, temple, nasal mucosa, upper jaw/teeth, roof of the mouth.
- Path: Leaves through the foramen rotundum, travels via the inferior cavernous sinus.
-
Mandibular (Lower):
- Innervates: Lower lip, chin, posterior cheek, temple, external ear, lower mouth mucosa, anterior 2/3 of the tongue.
- Path: Leaves through the foramen ovale.
-
Ophthalmic (Upper):
-
Motor Division:
- Supplies muscles of mastication: Masseter, temporal, pterygoid, mylohyoid, digastric.
- Function: Controls jaw movements (elevation, depression, protrusion, retraction, side-to-side).
Key Points:
- Difficulty Opening Mouth:
- A lesion in the motor part of the trigeminal nerve affects the muscles of mastication, making it hard to open the mouth and chew.
- Unilateral Paralysis: Jaw deviates to the paralyzed side when opening.
- Bilateral Paralysis: Jaw droops, no movement possible.
-
Jaw Jerk Reflex:
- Normal: Brisk contraction when mandible is tapped.
- Abnormal (UMN Lesion): Hyperactive or clonus.
- Absent (Nuclear/Infranuclear Lesion): No reflex.
Other Functions (Non-Trigeminal Nerve):
- Forehead Wrinkling: Facial nerve (CN VII).
- Vision: Optic nerve (CN II).
- Diplopia (Double Vision): Extraocular muscles (CN III, IV, VI).
- Taste: Facial (CN VII), Glossopharyngeal (CN IX), Vagus (CN X).
Important Reminder:
- Trigeminal Nerve (CN V): Provides general sensation to the tongue but not taste.
Example Question:
- Scenario: Difficulty in opening the mouth, no other cranial nerve symptoms.
- Answer: Lesion in the trigeminal nerve (CN V), specifically affecting the motor division.
Easy Memory Tip:
- Three Divisions: Think “O-M-M” (Ophthalmic, Maxillary, Mandibular).
- Muscles of Mastication: “My Time Produces Delicious Meals” (Masseter, Temporal, Pterygoid, Digastric, Mylohyoid).
- Jaw Jerk Reflex: Normal is a “quick jerk,” abnormal is “hyper or absent.”
Trigeminal nerve (NC V) has three divisions that carry pain, temperature and touch modalities from the skin of the face, the mucosa of sinuses, nose, mouth, the teeth, and portions of the dura. They also carry proprioceptive sensation from the teeth, hard palate, temporomandibular joint, and muscles of mastication. Motor fibers are included in the maxillary division of the trigeminal nerve.
The three divisions of this nerve are:
1. Ophthalmic (upper) division - Innervates forehead, upper eyelid, cornea (thus the corneal reflex - different from pupilary reflex), conjunctiva, dorsum of the nose, and the dura of some of the anterior cranial fossa.
This division leaves orbit through the superior orbital fissure. It then proceeds through the lateral wall of the cavernous sinus in close relation to the CN III, CN IV and CN VI and joins the other two divisions to form the trigeminal (semilunar, Gasserian) ganglion.
- Maxillary (middle) division – Innervates the upper lip, lateral and posterior portions of nose, upper cheek, anterior temple, mucosa of the nose, upper jaw, upper teeth, the roof of the mouth, and the dura of part of the middle cranial fossa. The nerve leaves the pterygopalatine fossa, passes through the foramen rotundum, traverses the inferior part of the cavernous sinus, and enters the trigeminal ganglion.
- Mandibular (lower) division – Supplies the lower lip, chin, posterior cheek, temple, external ear, mucosa of the lower part of mouth, anterior two-thirds of the tongue, and portions of the dura of anterior and middle cranial fossae. Proprioceptive impulses are carried largely in the motor nerve, which is incorporated into the mandibular division. It enters the cranium through the foramen ovale and goes to the trigeminal ganglion.
Sympathetic and parasympathetic fibers join the three divisions and are distributed to the pupil, to the nasal mucosa causing mucus secretion, to the lacrimal, submaxillary, and sublingual glands, and to the arterioles of the face.
The motor division of the nerve (incorporated in the mandibular division) supplies the muscles of mastication including:
-Masseter
-Temporal
-Pterygoid
-Mylohyoid
-Digastric.
These muscles produce elevation, depression, protrusion, retraction, and the side-to-side movements of the mandible; therefore, lesions of motor portion of this nerve lead to dysfunction of these muscles and difficulties in opening the mouth and chewing, and impairment of various mandible (jaw) movements. The motor division also supplies the tensor tympani and tensor palati muscles.
When there is unilateral paralysis of the masticatory muscles, on mouth opening, the mandible deviates toward the paralyzed side. This direction of the mandible is due to the action of normal pterygoids on the opposite side. The mandible droops, and no jaw movement is possible with bilateral paralysis. The involved muscles undergo atrophy in nuclear or infranuclear lesions.
The jaw jerk is one of the deep tendon or stretch reflexes. When it is normal, tapping the mandible produces a brisk contraction. When abnormal, with upper motor neuron lesions, there is a hyperactive or repeating reflex (clonus). With nuclear or infranuclear lesions, the reflex is absent.
Option A Forehead wrinkling is an action of the 7th cranial nerve (facial nerve).
Option B Carrying visual stimuli is a function of 2nd cranial nerve (optic nerve).
Option C Diplopia (squint) is mostly caused by dysfunction of extraocular muscles innervated by CN III, CN IV and CN VI.
Option D Sense of taste is mediated by three cranial nerves:
1. Facial nerve (CN VII)
2. Glossopharyngeal nerve (CN IX)
3. Vagus nerve (CN X)
Facial nerve (chorda tympani and the greater petrosal branch nerves) provides the sense of taste in the anterior 2/3 of the tongue. Glossopharyngeal nerve provides that of the posterior 1/3 of the tongue. The superior laryngeal branch of vagus (CN X) innervates taste buds in the laryngeal surface of the epiglottis. The trigeminal nerve provides the general sensation of the tongue not the taste sense; therefore, CN V lesions do not result in taste loss.
See Page 732 for photo of Tongue Nerves
One week after a knee surgery, a 24-year-old man presents with complaints of numbness and paresthesia of the right leg. On examination, there is foot drop and weakness of dorsiflexion and eversion of the right ankle. Sensation over the outer aspect of the right leg is also lost. Right ankle jerk is intact. Which one of the following nerves is most likely to have caused such presentation?
A. L4 nerve root.
B. L5 nerve root.
C. Common peroneal nerve.
D. Tibial nerve.
E. Sciatic nerve.
C. Common peroneal nerve
The clinical picture suggests damage to the common peroneal nerve as an adverse outcome of the knee surgery. Foot drop is the result of weakness of the ankle dorsiflexors (extensors) innervated by the deep peroneal nerve (with the exception of peroneous tertius, a weak ankle dorsiflexor located in the lateral compartment of the leg, and supplied by the superficial peroneal nerve). Sensation over the outer aspect of the leg is supplied by the common peroneal nerve and its superficial branch. These together make the common peroneal nerve injury the most likely explanation.
After branching off the sciatic nerve, the common peroneal nerve runs down laterally, wraps around the fibular head and enters the leg. The nerve is superficial in this region and susceptible to injuries during knee surgeries, with compression or in trauma.
Option A L4 nerve root is in the lumbar area. L4 radiculopathy can cause weakened knee reflex and partially impaired ankle inversion, but does not explain other manifestations.
Option B L5 nerve root damage has a very similar clinical presentation in lower leg to that of the common peroneal nerve injury; however, the history of knee surgery makes the latter more likely.
Option D Tibial nerve damage causes impaired ankle jerk, weak or absent plantar flexion and weak ankle inversion. Sensory impairment due to tibial nerve injury affects the back the leg and most parts of the sole of the foot.
Option E Sciatic trunk (nerve) is above the knee, and unlikely to have been affected by the knee surgery. Moreover, sciatic damage affects the ankle and foot movements globally, and gives a clinical picture consistent with injuries of both common peroneal and tibial nerves at the same time.
A 75-year-old woman underwent total left hip replacement surgery yesterday. Today, she has developed weakness and numbness of her left foot. On examination, there is weakness of all the left ankle movements including dorsiflexion, plantar flexion, eversion and inversion, and numbness over the dorsum and sole of her foot and lateral aspect of her leg. The left ankle jerk is absent. Which one of the following is the most likely site of the lesion?
A. Left common peroneal nerve.
B. Left femoral nerve.
C. Left obturator nerve.
D. Left sciatic nerve.
E. Left tibial nerve.
D. Left sciatic nerve
Ankle dorsiflexion and eversion are actions of the deep peroneal and superficial peroneal nerves, respectively. Inversion is supplied by deep peroneal nerve (anterior tibialis muscle) and tibialis nerve (posterior tibialis muscle). Plantar flexion and ankle reflex are supplied by the tibial nerve. The efferent limb of the ankle jerk reflex is innervated by S1 and to lesser extend S2 fibers within this nerve. The pattern of the sensory impairment indicates that both nerves are affected.
As a matter of fact, this woman has a clinical presentation consistent with both common peroneal and tibial nerves injuries. When such clinical presentation is encountered, injury to the sciatic nerve is the most likely explanation. This can be the most likely diagnosis given the history of hip surgery.
The sciatic nerve is derived from lumbosacral plexus. Once formed, it leaves the pelvis and enters the gluteal region via greater sciatic foramen. It emerges inferiorly to the piriformis muscle, and enters the posterior thigh by passing deep to the long head of the biceps femoris, and descends in an inferolateral direction. Within the posterior thigh, the nerve gives off branches to the hamstring muscles and adductor magnus. When the sciatic nerve reaches the apex of the popliteal fossa, it terminates by bifurcating into the tibial and common fibular (peroneal) nerves.
NOTE - The sciatic nerve can be described as two individual nerves bundled together in a sheath of connective tissue. These two nerves are the tibial and common peroneal nerves. These two nerves usually separate at the apex of the popliteal fossa, however in a minority or persons, they separate as they leave the pelvis.
Sciatic nerve injury can occur during hip surgeries. Stretch, compression, ischemia, and direct damage are primary mechanisms. The lithotomy, frog leg, and sitting positions have been implicated in perioperative injury to this nerve. Regional anesthetic techniques and hip arthroplasty may also cause injury. The common peroneal component is more common to be affected because it is more superficial compared with the tibial component.
Sciatic nerve Injury manifests as paralysis of the hamstring muscles (knee flexion weakness) and all the muscles below the knee. All sensation below the knee is affected with the exception of the sensation of the medial aspect of the leg and lateral aspect of the foot, which remains intact because these two areas are supplied by saphenous nerve (a sensory branch of the femoral nerve) and sural nerve, respectively.
OPTION A : Left common peroneal nerve injury results in foot drop (loss of ankle dorsiflexion), weak inversion and inability of the patient to evert the ankle. Sensory impairment occurs over the lateral aspect of the leg and dorsum of the left foot (except the lateral margin of left foot).
OPTION B : Left femoral nerve injury causes global weakness of all muscles in the anterior compartment of the thigh, impaired knee jerk and sensory disturbances of the lateral, and anteromedial surfaces of the thigh, as well as the medial aspect of the leg.
OPTION C : Obturator nerve consists of L2, L3, and L4 nerve roots. It innervates the muscles adductor longus, adductor brevis, adductor magnus, gracilis, and obturator externus. It provides, along with the femoral nerve, the sensation of the medial aspect of the thigh. Obturator nerve injury presents with medial thigh or groin pain, weakness of leg adduction and sensory loss in the medial thigh.
OPTION E : Tibial nerve damage results in weak plantar flexion. Impaired ankle jerk and sensory disturbances over the posterior aspect of the leg and sole of the foot are other manifestations.
A 26-year-old-man develops weakness of foot plantar flexion and inversion. Which nerve is most likely to have been damaged?
A. Common peroneal nerve.
B. Tibial nerve.
C. Sciatic nerve.
D. Lumbosacral plexus.
E. Lumbar nerve roots.
B. Tibial nerve
Plantar flexion is provided by the ankle flexor muscles in the posterior compartment of the leg, all of which are innervated by the tibial nerve. Ankle inversion is the action of two muscles: tibialis anterior and tibialis posterior Tibialis anterior is supplied by deep peroneal nerve, while tibialis posterior in the posterior leg compartment is innervated by tibial nerve. This movement can be affected with injuries to the tibial or deep peroneal nerves.
OPTION A : With involvement of the common peroneal nerve, foot drop (caused by weakness of the ankle extensors) and sensory disturbances over the outer surface of the leg is expected. Ankle jerk reflex remains intact.
OPTION C : With sciatic nerve injury, global weakness of all ankle and foot movements occurs. Ankle reflex is also affected. Weakness of the knee flexion may be noticed as well.
OPTION D : Lumbosacral plexus problems have various presentations depending on the affected nerve root. S1 radiculopathy presents with similar manifestation seen in tibial nerve injury; however, back pain radiating from low back and the buttock down to the posterior aspect of the leg into the foot is a feature not mentioned here. It makes lumbosacral plexus involvement less likely.
OPTION E : Lumbar nerve root problems cause deficits in the movements and sensation of the hip, thigh and knee extension and reflex.
*http://www.medscape.com/viewarticle/758724_7
*http://www.orthobullets.com/anatomy/10115/sciatic-
*http://www.orthobullets.com/anatomy/10116/tibial-n
*http://ceaccp.oxfordjournals.org/content/early/201
*http://www.uptodate.com/contents/acute-lumbosacral
A 26-year-old man develops weakness of foot dorsiflexion and eversion. Which nerve is most likely to have been damaged?
A. Common peroneal nerve.
B. Tibial nerve.
C. Sciatic nerve.
D. Lumbosacral plexus.
E. Lumbar nerve roots.
A. Common peroneal nerve
Ankle eversion is an action of three muscles in the lateral compartment of the leg, including:
-Peroneous (fibularis) longus
-Peroneous (fibularis) brevis
-Peroneous tertius
These muscles are innervated by the superficial peroneal nerve which is one of the two main branches of the common peroneal nerve.
Ankle dorsiflexion is the action of the following:
-Tibialis anterior
-Extensor hallucis longus
-Extensor digitorum longus
-Peroneous (fibularis) tertius
Peroneous tertius is innervated by the superficial peroneal nerve. The other three are supplied by deep peroneal nerve, the other main branch of the common peroneal nerve. With both ankle dorsiflexion and eversion affected, the common peroneal nerve is most likely to be involved.
OPTION B: Tibial nerve innervates the posterior compartment of the leg. Muscles in this compartment are mostly ankle plantar flexors.
With tibial nerve injury plantar flexion and ankle jerk will be affected.
OPTION C : With sciatic nerve involvement, global weakness and impairment of all ankle and foot movements is expected. Ankle reflex will be affected as well. Weakness of the knee flexion could also be problem.
OPTION D : Clinical findings associated with lumbosacral plexus problems vary depending on the affected nerve root. S1 radiculopathy presents similar to tibial nerve injury with impaired plantar flexion, ankle jerk and sensory disturbances in the back of the leg and most parts of the sole of the foot.
OPTION E : Lumbar nerve root problems cause deficits in the movements and sensation of the hip, thigh and knee extension and deep tendon reflex.
Which one of the following can be a presentation associated with L5/S1 disc prolapse?
A. Absent knee reflex.
B. Absent ankle reflex.
C. Impaired ankle dorsiflexion.
D. Impaired ankle eversion.
E. Impaired sensation over the lateral aspect of the leg.
B. Absent ankle reflex
In L5/S1 disc prolapse, which often occurs laterally, the herniated disc compresses the S1 nerve root causing S1 radiculopathy. S1 radiculopathy presents with pain radiating down the posterior aspect of the leg into the foot from the back.
On examination, weakness of plantar flexion is specific. Weakness of leg extension (gluteus maximus) and toe flexion are other possible features. Sensation is generally reduced on the posterior aspect of the leg and the lateral edge of the foot. Loss of the ankle reflex is typical.
OPTION A : Knee reflex is an action of L3 and L4 nerve roots.
OPTION C, D and E : Ankle dorsiflexion, eversion, and sensation over the lateral aspect of the leg are innervated by L5 that can be affected in L4/L5 disc prolapse.
Which one of the following is most suggestive of sciatic nerve injury?
A. Absent ankle reflex.
B. Foot drop.
C. Inability to flex the hip.
D. Decreased sensation over the anterior thigh and medial leg.
E. Intervertebral disc prolapse at L2/L3 level.
A. Absent ankle reflex
The sciatic nerve is derived from the lumbosacral plexus. Once formed, it leaves the pelvis and enters the gluteal region via greater sciatic foramen. It emerges inferiorly to the piriformis muscle, and enters the posterior thigh by passing deep to the long head of the biceps femoris, and descends in an inferolateral (down and out) direction. Within the posterior thigh, the nerve gives off branches to the hamstring muscles and adductor magnus. When the sciatic nerve reaches the apex of the popliteal fossa, it terminates by bifurcating into the tibial and common fibular nerves.
The sciatic nerve can be described as tibial and common peroneal nerves bundled together in a sheath of connective tissue.
Sciatic nerve Injury manifests as paralysis of the hamstring muscles (knee flexion weakness) and all the muscles below the knee. All sensation of the leg except the medial aspect is impaired. Absent or weak ankle reflex is most specific to sciatic nerve injury among other options.
OPTION B : Foot drop is seen in sciatic as well as common peroneal nerve injuries and is not specific to sciatic nerve injury.
OPTION C : Hip flexion is the action of L1-L2 nerve roots. Hip flexion is not an action of the sciatic nerve which is formed by L4, L5, S1, S2, and S3 nerve roots.
OPTION D : Decreased sensation over the anterior thigh and medial leg is caused by femoral nerve injuries.
OPTION E : Intervertebral disc lesion at L2/L3 compromises the action of L3 nerve root, which does not contribute to the formation of the sciatic nerve.
A 65-year-old man is being seen in the Emergency Department because of severe headache starting two hours ago. On a scale of 1 to 10, the patient scores the pain as 10 in intensity. There is no history of similar headaches in the past. Relatives accompanying the patient inform you that he lost consciousness 30 minutes after the headache started but he was lucid again few minutes later. Which one of the following could be the most likely cause of the headache?
A. Subdural hematoma.
B. Epidural hematoma.
C. Cerebral abscess.
D. Subarachnoid hemorrhage.
E. Migraine.
D. Subarachnoid hemorrhage
Of the options, subarachnoid hemorrhage (SAH) is most consistent with the clinical scenario. Symptoms of SAH typically begin abruptly. The most common and premier symptom is a sudden, severe headache occurring in 97% of patients. Patients often describe the headache as the “worst headache of my life.” The onset of the headache may be associated with a brief loss of consciousness, seizure, nausea, or vomiting. Signs of meningeal irritation may be present but may not develop until several hours after the bleed, because it is caused by the breakdown of blood products within the CSF and the consequent aseptic meningitis.
Meningismus can be elicited by a positive Kernig’s sign (extending the patient’s knee while the hip is flexed at 90° causes pain) and/or Brudzinski’s sing (flexing the patient’s head while the chest is restrained with the physician’s other hand causes flexion of the hip and the knees). Neurological deficits such as hemiplegia, third cranial nerve palsy, etc. may be found on physical examination as well.
A non-contrast CT scan is the initial investigation of choice and should be performed as soon as possible to confirm the diagnosis.
OPTION A : Subdural hematoma is due to a venous bleed between the dura and the arachnoid. It follows injuries that may be trivial, especially in the elderly. It can be acute (less than two days), subacute (2-14 days), or chronic (more than 14 days).
Subdural hematoma should be considered if a person presents with the following:
-Personality changes
-Slowness and unsteadiness of movements
-Headache
-Irritability
-Fluctuating level of consciousness
CT scan of the head is the confirmatory diagnostic tool of choice for subdural hematoma.
OPTION B : Epidural hematoma is a life-threatening head injury that is caused by arterial bleeding between the skull bone and dura mater. The typical clinical scenario is loss of consciousness following trauma to the head which is usually followed by a short lucid interval before consciousness deteriorates further. The patient with epidural hematoma is usually restless, confused, irritable, and may develop severe headache, seizures, ipsilateral pupil dilatation and facial weakness. Lumbar puncture is contraindicated in this situation. CT scan of the head is used to confirm the diagnosis.
OPTION C : In cerebral abscess, symptoms are more insidious and usually develop over two weeks or so. Presentation is usually with fever, confusion and decreased responsiveness.
OPTION E : Classic features of migraine include headache (frontal or temporal) radiating to retro-orbital and/or occipital area. The pain is aggravated by tension and relieved by rest particularly in a dark silent environment. Loss of consciousness is not a feature.
A 52-year-old man presents to your clinic for evaluation of spasticity and weakness in his left lower limb. The condition has progressively worsened over the past three months and made walking difficult for him. On examination, fasciculation in the left deltoid muscle and small muscles of the hand are noted; however, the muscle power, reflexes and sensation of the upper limbs are within the normal range. In the lower limb, bilateral extensor plantar reflexes, left-sided foot drop and muscle weakness and spasticity are noted. Lower limb sensation is intact. Which one of the following investigations is the most appropriate one to reach a diagnosis?
A. CT scan of the brain.
B. MRI of the cervical spine.
C. Electromyography.
D. Lumbar puncture (LP).
E. MRI of the brain.
C. Electromyography
While fasciculation of the deltoid and small muscles of the hand and the foot drop in this patient suggest a lower motor neuron (LMN) problem, increased muscle tone (spasticity) and extensor plantar reflex are pointers toward an upper motor neuron lesion. The combination of LMN and UMN findings in the same area of the body as well as the intact sensation puts amyotrophic lateral sclerosis (ALS), the most common motor neuron disorder, at the top of the differential diagnoses list.
Motor neuron disorders (MNDs) are a clinically and pathologically heterogeneous group of neurologic diseases characterized by progressive degeneration of motor neurons. Either or both of the following two sets of motor neurons can be affected:
1. Upper motor neurons (UMNs) – These neurons originate from the primary motor cortex of the cerebrum (precentral gyrus). These neurons have long axons that form corticospinal and corticobulbar tracts.
2. Lower motor neurons (LMNs) – These neurons originate from the brainstem (cranial nerve [CN] motor nuclei) and spinal cord (anterior horn cells) and directly innervate skeletal muscles.
MNDs can be classified into those affecting primarily the UMNs, those affecting primarily the LMNs, and those affecting both. The patient’s symptoms vary, depending on which set of motor neurons is involved.
Motor neuron disorders include:
-Amyotrophic lateral sclerosis (ALS)
-Primary lateral sclerosis (PLS)
-Hereditary spastic paraparesis (HP)
-Progressive bulbar palsy (PBP).
-Spinal muscular atrophy.
-X-linked spinobulbar muscular atrophy.
-Post-polio syndrome
ALS, the most common neurodegenerative disease of adult onset, is a fatal disorder and is characterized by progressive skeletal muscle weakness and wasting or atrophy (i.e., amyotrophy), spasticity, and fasciculations as a result of degeneration of both the UMNs and LMNs. ALS eventually results in respiratory paralysis. Both LMN and UMN abnormalities should be observed in a single area before ALS could be considered a highly likely diagnoses. ALS is sporadic in 90-95% of cases and hereditary in only 5-10% of affected individuals.
ALS should be suspected as a diagnosis when there is insidious loss of function or gradual, slowly progressive, painless weakness in one or more regions of the body, without changes in sensation, and there is no other explanation for to this presentation. With time, patients with ALS develop manifestations of both LMN and UMN involvement.
Findings indicating UMN involvement include the following:
-Stiffness (spasticity)
-Brisk tendon reflexes (hyperreflexia) – but maybe diminished if there is concurrent LMN
-Presence of abnormal reflexes (e.g., Babinski, Chaddock, or Hoffman signs)
-Loss of dexterity in the presence of normal strength
-Muscle spasms
Findings indicating LMN dysfunction include the following:
-Twitching muscles (fasciculations) – this can be an early manifestation most commonly seen in the tongue and limbs
-Reduction of muscle bulk (atrophy)
-Foot drop (or wrist drop in case of upper limb involvement)
-Depressed reflexes
-Breathing difficulties
The diagnosis of ALS is primarily clinical. When the disease has progressed far in its course and involves many parts of the body, the patient’s appearance and neurologic examination findings often provide sufficient evidence for the diagnosis. However, if the patient presents early in the course of the disease, the diagnosis is not straightforward, and often exclusion of other possible causes is required before a diagnosis of ALS is made because there is no pathognomonic test for ALS (or other motor neuron disorders) and the symptoms are initially nonspecific. Often, several months (average 14 months) are needed before a definite diagnosis of ALS is made.
Of the investigations currently in use for workup and assessment of ALS (and other motor neuron disorders), electromyography (EMG) and nerve conduction studies (NCS) are most useful for confirming the diagnosis of ALS and for exclusion of peripheral conditions that resemble ALS. The role of EMG/NCS in diagnosis of ALS is so crucial that some consider it as an extension to physical examination.
Imaging studies such as CT scan (option A) or MRI (option B and E) may be primarly used in some patients for assessment of other conditions, such as multiple sclerosis (MS), spinal canal stenosis or other spinal lesions that can mimic initial presentations of ALS. Imaging studies are usually normal in patients with ALS, and not diagnostic for the condition.
OPTION D : LP and examination of the CSF is not necessary unless the patient has a pure UMN or pure LMN presentation, in which case it can be of diagnostic value in ruling out inflammatory conditions, neoplastic infiltrations, or infection. With a combination of both UMN and LMN manifestations, this patient will not benefit from LP as a diagnostic tool.
Alan, 45 years, is a new patient to your clinic. He has presented with complaint of frequent tripping of his right foot for the past few months, which has increased in frequency in the past month. On examination, interosseous muscles wasting of the right foot is noted. Plantar reflex is equivocal on the right but extensor on the left. Lower limb deep tendon reflexes are normal. There is foot drop on the right side. Which one of the following tests is most likely to make a diagnosis?
A. MRI of the head and cervical spine.
B. Acetylcholine receptor antibodies.
C. CT scan of the head and cervical spine.
D. Lumbar puncture (LP).
E. Electromyography (EMG).
E. Electromyography (EMG)
Alan has signs of both lower motor neuron (LMN) and upper motor neuron (UMN) involvement in different parts of his body. He has foot drop and muscle wasting in his right foot (LMN signs), while his left foot shows an upward plantar reflex (Positive Babinski sign, an UMN sign). His right plantar reflex is unclear, making it hard to determine if the right foot issues are due to LMN or UMN problems. Overall, he has symptoms of both LMN and UMN lesions in different places.
The most likely diagnosis for Alan is amyotrophic lateral sclerosis (ALS), a type of motor neuron disease (MND). ALS typically presents with painless motor problems and normal sensations. Over time, it shows features of both LMN (e.g., muscle twitching, cramps, atrophy, foot drop) and UMN (e.g., spasticity, hyperreflexia, abnormal reflexes) involvement.
ALS usually starts in the limbs, with 75-80% of cases showing limb involvement first. Lower limb onset may cause tripping, stumbling, or foot drop, while upper limb onset can lead to reduced finger dexterity and hand weakness. Bulbar involvement (20-25% of cases) affects speech and swallowing.
Diagnosis often relies on clinical examination, with electromyography (EMG) and nerve conduction studies (NCS) being crucial for confirming ALS and excluding similar conditions.
Other tests, such as checking for acetylcholine antibodies (for myasthenia gravis) or lumbar puncture (for inflammatory conditions or infections), are not as relevant here given Alan’s combination of LMN and UMN symptoms. Imaging studies typically appear normal in ALS.
In summary, ALS is the most likely diagnosis given Alan’s mix of LMN and UMN signs, painless progression, and the pattern of neurological deficits.
Alan has signs of lower motor neuron (LMN) involvement of his right foot including the foot drop and muscle wasting. While his left foot has an upward plantar reflex (Positive Babinski) indicating upper motor neuron lesion, the right plantar reflex is equivocal making it hard to tell if the right foot signs and symptoms are LMN or UMN in origin. However, in general he has clinical findings suggesting both LMN and UMN lesions at different sites.
Among the differential diagnoses justifying such presentation, a motor neuron disorder (MND) is the most likely diagnosis. Spinal canal stenosis can be a differential diagnosis but is far less likely in this scenario because firstly chronic pain is the most common presenting symptom in spinal canal stenosis which is absent here. Secondly, stenotic lesions cause UMN manifestations at the level of stenosis and LMN features below that. The pattern of neurological deficits here does not match that of a stenotic spinal canal.
Given the pattern of clinical findings, amyotrophic lateral sclerosis (ALS) as the most common MND could be the most likely diagnosis in this case. ALS often presents with insidious onset of painless motor neurological deficits and intact sensations. With time, features of both LMN and UMN will be present in the affected area. While LMN involvement manifests with fasciculations (twitching muscles), muscle cramps, muscle atrophy, foot drop (or wrist drop) and depressed reflexes, features of UMN include spasticity (stiffness), hyperreflexia, presence of abnormal reflexes (such as Babinski, Chaddock, or Hoffman signs), loss of dexterity in the presence of normal muscle strength and muscle spasms.
In ALS, symptoms begin with limb involvement in 75-80% of cases and bulbar symptoms in 20-25%. Individuals with upper limb onset may experience reduced finger dexterity, cramping, stiffness, and weakness or wasting of intrinsic hand muscles. This may lead to difficulty with actions such as buttoning clothes, picking up small objects, or turning a key. Wrist drop may develop.
There is equal likelihood for presentation in either lower extremity. Patients who have lower limb onset initially may complain of tripping, stumbling, or awkwardness when running. Foot drop is common, and patients may report a “slapping” gait.
Bulbar involvement presents with slurred speech, hoarseness, or decreased volume of speech, or aspiration or choking during a meal. Hypernasality of the voice and eventually loss of speech, swallowing difficulty (usually starting with liquids), and drooling occurs later in the course of the disease. Women have a greater frequency of bulbar (speech dysfunction) onset than men.
Neurologic examination often provides sufficient evidence for the diagnosis.
Of the investigations currently in use for workup and assessment of ALS (and other motor neuron disorders), electromyography (EMG) and nerve conduction studies (NCS) are confirmatory for ALS and for exclusion of peripheral conditions that resemble ALS. The role of EMG/NCS in diagnosis of ALS is so crucial that some consider it as an extension to physical examination.
OPTION B : Assessment of acetylcholine antibodies is used when myasthenia gravis is suspected as a diagnosis. This disease typically affects the extraocular, bulbar, or proximal limb muscles. Droopy eyelids or double vision is the most common symptom at initial presentation (more than 75%). These symptoms progress from mild to more severe over weeks to months. Difficulty in swallowing, slurred or nasal speech, difficulty chewing, and facial, neck, and extremity weakness often follow.
Imaging studies are usually normal in patients with ALS.
OPTION D : LP and examination of the CSF is not necessary unless the patient has a pure UMN or pure LMN presentation, in which case it can be of diagnostic value in ruling out inflammatory conditions, neoplastic infiltrations, or infection. With a combination of both UMN and LMN manifestations, this patient will not benefit from LP as a diagnostic tool.
NOTE - For patients with a new focal presentation, the differential diagnoses by region include the following:
1. Upper motor neuron (UMN) bulbar signs - Brainstem lesions including syrinx, mass, stroke, and demyelinating forms of other degenerative diseases
2. Lower motor neuron (LMN) bulbar signs - Cranial nerve palsies
3. Limb UMN signs - Cervical myelopathy, cord tumor, hereditary spastic paraparesis, transverse myelopathy, HIV-related myelopathy, syrinx
4. Limb LMN signs - Radiculopathy, plexopathy, neuropathy
Differential diagnoses for patients with more advanced disease most commonly include the following:
i) UMN signs - Compressive myelopathy, syrinx
ii) LMN signs - Chronic inflammatory demyelinating polyradiculoneuropathy; multifocal motor, toxic, or metabolic neuropathies or myopathies such as inclusion body myositis or polymyositis
The following table summarizes the most important differential diagnoses of MNDs and their diagnostic tests:
(Table in page 744)
A 68-year-old woman presents with left hemiplegia. A CT scan of the brain is obtained and is shown in the following photograph. Past medical history is significant for a melanoma that was excised 3 years ago. Which one of the following could be the most likely diagnosis?
A. Metastasis from the melanoma.
B. Glioma.
C. Cerebral hemorrhage.
D. Cerebral abscess.
E. Meningioma.
A. Metastasis from the melanoma
The CT scan shows a round hyperattenuated lesion in the right hemisphere. These features are suggestive of either an abscess or a tumor. Since the patient is afebrile, abscess is less likely as the diagnosis, and a brain tumor will top the differential diagnoses list.
With history of melanoma, a metastatic brain tumor from the melanoma could be the most likely diagnosis.
Although, most cases of malignant melanoma are diagnosed at an early stage, when surgical excision can be curative, a few patients have metastatic disease at presentation, or develop metastases after the initial definitive surgical excision. Melanoma can metastasise to distant sites. Brain and lung are the most common sites of metastasis.
Melanoma is one of the three most common malignancies metastasising to the brain. The other two are breast cancer and lung cancer.
The following factors are associated with increased risk of systemic metastasis (including brain metastasis):
-Male gender
-Melanomas arising on mucosal surfaces or the skin of the trunk, head, or neck
-Wide, thick, deeply invasive, or ulcerated primary lesions
-Acral lentiginous or nodular lesions on histologic examination
-Involvement of more than three regional lymph nodes, either at diagnosis or relapse
If amenable, surgical resection of the metastatic brain tumors is the best appropriate treatment option; however, it is not the case often.
Lindsay, 35 years of age, presents to your practice with a 48-hours history of facial weakness. She has no remarkable past medical history, is on no medications currently, and has been fit and well to date. On examination, she is asked to smile. Her appearance while smiling is shown in the accompanying photograph. She has no tinnitus, vertigo, or hearing loss. Otoscopic exam is normal. Which one of the following options can be the most likely diagnosis?
A. Acoustic neuroma.
B. Bell’s palsy.
C. Central facial nerve lesion.
D. A parotid glad tumor.
E. Ramsay – Hunt syndrome.
B. Bell’s palsy
In the photograph, the forehead lines and nasolabial fold on the right side are lost on smiling. Also, the right mouth corner has failed to be elevated while she is smiling. These features suggest the complete right-sided facial palsy. With no clue on exam pointing toward a specific underlying cause, as well as the absence of vertigo or hearing problems, Bell’s palsy (idiopathic facial nerve palsy) is the most likely diagnosis.
Bell’s palsy is the most common cause of unilateral facial paralysis. This idiopathic condition, is one of the most common neurologic disorders of the cranial nerves. In most patients, Bell palsy gradually resolves over time.
Signs and symptoms of Bell palsy include the following:
-Acute onset of unilateral upper and lower facial paralysis (over a 48-hour period)
-Posterior auricular pain
-Decreased tearing
-Hyperacusis (increased hearing sensitivity)
-Taste disturbances (anterior 2/3 of the tongue is innervated by the facial nerve)
-Otalgia (ear pain)
-Weakness of the facial muscles
-Poor eyelid closure
-Aching of the ear or mastoid
-Tingling or numbness of the cheek/mouth
-Excessive watering of the eye
-Ocular pain
-Blurred vision
-Flattening of forehead and nasolabial fold on the side affected by palsy
-When patient raises eyebrows, palsy-affected side of forehead remains flat
-When patient smiles, face becomes distorted and lateralizes to side opposite the palsy
OPTION A : Acoustic neuroma presents with hearing loss, tinnitus and vertigo, none of which Lindsay has. Acoustic neuromas, however, can cause facial paralysis due to pressure on the facial nerve. This occurs later in the course of the disease. It is very unlikely that facial nerve palsy is the first presentation of an acoustic neuroma.
OPTION C : A central lesion of the facial nerve, e.g. caused by a lacunar stroke, spares the forehead due to bilateral motor neuron innervation. With an affected forehead, the palsy is always peripheral.
OPTION D : Malignant parotid tumors can invade the facial nerve in its course through the superficial and deep layers of the affected parotid gland and cause paralysis of the facial nerve. A painless enlarging mass is the typical initial presentation, the absence of which makes a parotid tumor as the cause a less likely diagnosis.
OPTION E : Ramsay – Hunt syndrome (herpes zoster infection of the facial nerve) is caused by the reactivation of dormant varicella zoster virus in the geniculate ganglion. It typically presents with peripheral facial palsy, ear pain, loss of taste, dry eyes and a vesicular rash. Although Ramsay- Hunt syndrome shares many clinical features with Bell’s palsy, the absence of vesicular rash in the ear canal (the otoscopic exam is normal) makes it a less likely diagnosis.
Peter, 48 years old, is on your office concerned about facial weakness, unpleasantly increased perception in the left ear, and that everything tastes bland. His symptoms have developed and progressed since yesterday. He denies hearing loss and tinnitus. He is an accountant and otherwise healthy with no previous health problems but an upper respiratory viral infection 10 days ago. He does not take any medications except supplemental vitamins. On examination, there is right-sided facial weakness. The following photograph illustrates his facial expression when he is asked to smile. Neurological examination is otherwise unremarkable. Hearing is unaffected. An otoscopic examination reveals normal ear canal and tympanic membrane. Which one of the following diagnostic investigations should be considered for him at this stage?
A. Nerve conduction studies (NCS).
B. CT scan of the head.
C. MRI of the head.
D. Swallowing test by a speech pathologist.
E. No investigation is required at this stage.
E. No investigation is required at this stage
Features evident in the photograph are loss of forehead wrinkles, failure of the right mouth corner to rise, absence of laugh lines, and failure of the eye to tighten up, all on the right side. These features suggest peripheral (lower motor neuron) right facial nerve palsy (in upper motor neuron palsy the forehead is spared due two dual innervation). Additional features of Hyperacusis and loss of taste are also confirmatory findings. Peter’s physical findings are otherwise normal and there is no significant past medical history to point towards any specific underlying etiology. These make idiopathic facial nerve palsy (Bell palsy) the most likely diagnosis.
Bell palsy is the most common cause of unilateral facial paralysis. Bell palsy gradually resolves over time. The cause is unknown; however, herpes simplex type 1 virus and herpes zoster virus have been implicated by some authors.
Clinical features of Bell palsy include:
-Acute onset of unilateral upper and lower facial paralysis (over a 48-hour period)
-Posterior auricular pain
-Decreased tearing
-Hyperacusis (increased hearing sensitivity)
-Taste disturbances (anterior 2/3 of the tongue is innervated by the facial nerve)
-Otalgia (ear pain)
-Weakness of the facial muscles
-Poor eyelid closure
-Aching of the ear or mastoid
-Tingling or numbness of the cheek/mouth
-Excessive watering of the eye
-Ocular pain
-Blurred vision
-Flattening of forehead and nasolabial fold on the side affected by palsy
-When patient raises eyebrows, palsy-affected side of forehead remains flat
-When patient smiles, face becomes distorted and lateralizes to side opposite the palsy
In many cases, the history and physical examination establish the diagnosis of Bell palsy, and no further investigation including imaging studies, laboratory tests and nerve conduction studies are required because most patients recover within 6- 8 weeks. Investigations are only indicated if the diagnosis is uncertain or the paralysis last longer 6-8 weeks.
OPTION A : NCS and electromyography (EMG) have prognostic value in Bell palsy but are most useful if performed 3-10 days after the onset of paralysis. Generally speaking, NCS/EMG is a tool used for research rather than diagnosis in Bell palsy.
NOTE - Most NCS/EMG studies do not show an abnormality for 3 weeks following a peripheral nerve injury.
OPTION B : Ct scan of the head is indicated if there are other associated physical findings or if the paresis is progressive and unremitting. CT scan is used for assessment of the temporal bone architecture, and, if used with contrast enhancement, for detection of tumors compressing the facial nerve (MRI is a better option for this purpose).
OPTION C : In patients with Bell palsy, MRI may show enhancement of the facial nerve at or near the geniculate ganglion. MRI, however, is not indicated unless the diagnosis is in doubt, symptoms do not resolve within 6-8 weeks, or symptoms are progressive. MRI is the preferred imaging modality for assessment of cerebellopontine angle, or if, based on the history and/or clinical findings, a tumor compressing the facial nerve is suspected. Such tumors include acoustic neuroma (Shcwannoma), hemangioma, meningioma, and sclerosing hemangioma. Acoustic neuroma is the most common tumor associated with facial nerve palsy.
OPTION D : Facial nerve has not a significant role in swallowing and swallowing remains mostly unaffected. Therefore, swallowing tests for assessment of dysphagia in patients with facial nerve palsy are not indicated.
A 58-year-old man presents with complaint of progressive difficulty in walking for the past few months. He denies any pain or pins and needles. On examinations, he drags his left foot on walking. On the left side, ankle tendon reflexes are exaggerated and the strength of plantar flexion and dorsiflexion are decreased to 4/5. Sensation is intact. The right foot is completely normal. Plantar reflexes are equivocal bilaterally. The rest of the physical examination including neurologic exam of the face and upper extremities are unremarkable. Lesions of which one of the following parts could be the mostly likely cause to this presentation?
A. Common peroneal nerve.
B. L5/S1nerve root.
C. Cervical spine.
D. Brainstem.
E. Cerebral cortex.
E. Cerebral cortex
One of important points to consider in dealing with patients who have presented with motor neurological deficits, such as this patient, is the possible origin(s) of such presentation. Distinguishing lower motor neuron lesions from those of upper motor neuron is of paramount importance.
Upper motor neurons (UMNs) neurons originate from the primary motor cortex of the cerebrum (precentral gyrus). These neurons have long axons that form corticospinal and corticobulbar tracts.
Lesions of UMN presents with:
-Stiffness (spasticity)
-Brisk tendon reflexes (hyperreflexia)
-Presence of abnormal reflexes (e.g., Babinski, Chaddock, or Hoffman signs)
-Loss of dexterity in the presence of normal strength
-Muscle spasms
Lower motor neuron (LMNs), on the other hand, originate from the brainstem (cranial nerve [CN] motor nuclei) and spinal cord (anterior horn cells) and directly innervate skeletal muscles.
Findings consistent with LMNs lesions include:
-Fasciculations (twitching muscles)
-Reduction of muscle bulk (atrophy)
-Decreased muscle strength
-Depressed deep tendon reflexes
While the weakness of muscles responsible for weak ankle flexion and dorsiflexion indicates an LMN lesion, the increased ankle tendon reflexes on the same side reflects an UMN problem. Therefore, this patient has both LMN and UMN disorders at the same time. Additionally, he has no sensory impairment. This constellation of findings makes a motor neuron disease (MND), more specifically, amyotrophic lateral sclerosis, the most likely diagnosis. Of the given options, only lesions of cerebral cortex can give rise to this scenario.
Injuries to the common peroneal nerve (option A) can weaken the ankle dorsiflexion and disturbed sensation over the anterolateral aspect of the leg and lateral aspect of the foot. However, such lesions are associated with a depressed ankle reflex. Moreover, with such injuries, sensation of the lateral aspect of the lower leg and foot that are innervated by the superficial branch of this nerve would be impaired.
Lesions of the L5/S1 nerve root (option B) can cause weak ankle dorsiflexion and drop foot (L5) and decreased plantar flexion (S1). Atrophy of muscles innervated by these nerve roots is another feature, but since the lesions are of lower motor origin, decreased reflexes would be expected. This patient has also features consistent with UMN deficits that makes this diagnosis unlikely.
Cervical spine lesions (option C ) caused by conditions such as multiple sclerosis (MS), or spinal canal stenosis/compression can cause signs and symptoms consistent with UMN lesions. But with cervical spine involvement, neurological deficits are expected to be more pronounced in upper extremities than the lower extremities. Normal neurologic exam findings in the face and arms make cervical spine lesions a less likely diagnosis.
OPTION D : UMN lesions of the brainstem origin is almost an unlikely diagnosis in this scenario due to lack of signs and symptoms suggestive of bulbar involvement such as slurred speech and oropharyngeal dysphagia, especially for liquids, or facial involvement.
A 56-year-old man presents to the emergency department with complaint of diplopia. On examination, he has right-sided ptosis. His visual acuity and visual fields are unaffected. His right eye is depressed inferiorly and laterally and he is not able to look at to the left side. The pupillary light reflex of the right eye is sluggish. The neurological examination is otherwise unremarkable. Which one of the following can be the most likely cause to this presentation?
A. Midbrain infarct.
B. Right 6th nervepalsy.
C. Posterior communicating artery aneurysm.
D. Right 4th nerve palsy.
E. A lesion in the occipital cortex.
C. Posterior communicating artery aneurysm
This patient has the classic presentation of a third cranial nerve palsy. The third cranial nerve supplies the levator muscles of the eyelid and four extraoccular muscles: (1) the medial rectus (eye adduction), (2) superior rectus (eye elevation), (3)
inferior rectus (eye depression), (4) and inferior oblique (eye elevation).
Additionally, the third cranial nerve constricts the pupil through its parasympathetic fibers that supply the smooth muscles of the ciliary body and the sphincter of the iris. The third nerve begins as a nucleus in the midbrain that consists of several subnuclei innervating the individual extraoccular muscles, the eyelids, and the pupils.
The etiology of the third cranial nerve palsy is vast and includes conditions such as:
- Ischemia (e.g. diabetes and midbrain infarcts)
- Compressive effects of aneurysms such as those of the posterior communicating artery, internal carotid artery and basilar artery.
- Trauma
- Infections
- Infiltrative diseases (e.g. neoplasms)
- Demyelination
- Space occupying tumors
- Meningitis
- Herniation
- Inflammatory diseases
Of the given options, only a posterior communicating aneurysm can cause a third nerve palsy that involves the pupilary reflex. Compression of the third nerve by an enlarging intracranial aneurysm is the most dreaded etiology. The most common site of an aneurysm causing a third nerve palsy is the posterior communicating artery.
OPTION A : Midbrain infarcts can cause third cranial nerve palsy. However, since the etiology is ischemic (such as in diabetes) the pupillary light reflex is expected to be unaffected most of the time. Furthermore, with a midbrain infarct, an isolated third nerve palsy as the sole presenting symptom is very unlikely and other signs and symptoms related to a midbrain infarct are expected.
OPTION B : Right 6th nerve palsy presents with horizontal binocular diplopia upon looking laterally to the affected side. Furthermore, lesions of the sixth cranial nerve do not cause ptosis.
OPTION D : The fourth cranial nerve palsy presents with binocular vertical diplopia. Ptosis is not a feature.
OPTION E : Lesions of occipital cortex are associated with impaired vision and visual fields deficits, none of which are present here. Furthermore, ptosis is not a feature.
Which one of the following is the most likely sensory disturbance associated with the following x-ray?
A. Paresthesia over the deltoid.
B. Decreased sensation of the ulnar aspect of the forearm and hand.
C. Decreased strength of handgrip.
D. Decreased sensation over dorsum of the hand.
E. Decreased sensation over the 2/3 radial side of the palm.
D. Decreased sensation over dorsum of the hand
The X-ray shows a fracture in the mid-shaft of the left humerus. Radial nerve injury and palsy associated with fracture of the shaft of the humerus is the most common nerve injury complicating fractures of long bones. Rarely, median or ulnar nerves can be affected. Injury to the axillary nerve is seen in the fractures of humeral neck.
The primary motor function of the radial nerve is to innervate the muscles responsible for wrist and metacarpophalangeal (MCP) joints extensors, and abduction and extension of the thumb; therefore, proximal radial nerve injuries results in wrist drop.
Radial nerve also provides the sensation of dorsum of the hand and fingers at the 2/3 radial portion (thumb, index, middle and half of the ring fingers), the web space between the thumb and index fingers, most parts of the posterior aspect of the forearm. Depending on the anatomical site of the injury, sensory disturbances over these areas can be noted.
Of the options, decreased sensation over dorsum of the hand can be caused by radial nerve injury.
OPTION A : Paresthesia over the deltoid area is a sign of damage to the axillary nerve. Axillary nerve damage can be an associated injury in fractures of the humeral neck, not the shaft.
OPTION B : Decreased sensation over the ulnar aspect of the forearm and hand is associated with ulnar nerve injuries. Compared to the radial nerve injuries, ulnar nerve injuries are rare in humeral shaft fractures.
OPTION C : The strength of grip is the action of flexor muscles of the wrist and fingers. These muscles are innervated by median (mostly) and ulnar nerves.
OPTION E : Decreased sensation over the 2/3 radial side of the palm can be caused by injuries of the median nerve.
Which one of the following could the most likely finding in a patient with mid-shaft humerus fractures?
A. Numbness of the little finger.
B. Inability to extend the thumb.
C. Numbness of the ventral aspect of the thumb.
D. Decreased grip strength.
E. Decreased wrist flexion.
B. Inability to extend the thumb
Radial nerve injury and palsy associated with fracture of the shaft of the humerus is the most common nerve injury complicating fractures of long bones. Rarely, median or ulnar nerves can be affected. Injury to the axillary nerve is seen in the fractures of humeral neck.
The primary motor function of the radial nerve is to innervate the muscles responsible for wrist and metacarpophalangeal (MCP) joints extensors, and abduction and extension of the thumb; therefore, proximal radial nerve injuries results in wrist drop or the decreased or absent thumb extension and abduction.
OPTION A : The sensation of the little finger and half of the ring fingers are supplied by terminal braches of the ulnar nerve which is very less like to be damaged in humeral mid-shaft fracture compared to the radial nerve.
OPTION C : The sensation of the ventral aspect of the thumb is provided by the terminal branches of the median nerve. Compared to the radial nerve, the median nerve is less likely to be affected in a mid-shaft humeral fracture.
OPTION D and E : The motor innervation of hand grip and wrist flexion is supplied by the median nerve.
A 71-year-old man, who has been diagnosed with bilateral osteoarthritis of his knees few years ago, presents to the GP clinic you work at with complaint of paresthesia and numbness of the lateral aspect of his right leg. The condition is worse at night and improves after walking for about 10 minutes. Which one of the following is the most important physical exam finding to consider in this patient?
A. Positive straight leg raise test.
B. Any tenderness over the right lateral condyle.
C. Any loss of sensation over the lateral side of the right leg.
D. Weakened dorsiflexion of the right foot.
E. Weak distal pulses of the right leg.
D. Weakened dorsiflexion of the right foot
The chief complaint of this man is paresthesia and numbness below the knee over the lateral side of the right leg. This presentation can be caused by common peroneal nerve injury (CPN). CPN is one of the two main nerves comprising the sciatic nerve. Along with the tibial nerve, CPN runs down from the buttock down the posterior part of the thigh to the apex of the popliteal fossa where it changes its path lateral to reach the knee. After wrapping around the fibular head, CPN enters the lateral compartment of the leg. There, this nerve divides in ‘deep peroneal’ and ‘superficial peroneal’ nerves. The proximal lateral aspect of the leg is innervated by CPN, while the distal part is innervated by superficial peroneal nerve.
(See photo below)
CPN through its branches supplies the muscles of ankle dorsiflexion, eversion and inversion in the anterior and lateral compartments of the leg. CPN nerve injury can cause weak ankle dorsiflexion (extension) resulting in foot drop and ankle and foot eversion, as well as toes extension.
This patient has presented with sensory deficits without any obvious motor weakness. He has osteoarthritis and bony processes (osteophytes) can compress the CPN in the lateral aspect of the knee, resulting in nerve irritation and damage. It should be noted that motor weakness, if subtle, might not be always appreciated by the patient. Therefore, a thorough physical examination is required to reveal any motor deficits that have remained unnoticed by the patient. In this case, weakened dorsiflexion of the right foot makes the diagnosis almost certain. Weakened dorsiflexion is the characteristic feature of CPN nerve injury as well as L5 radiculopathy.
OPTION A : Lesions of L5 nerve root and CPN nerve in the leg present similarly. However, these two can be differentiated by other historical and clinical findings. L5 radiculopathy is often associated with low back pain as a prominent feature. The pain radiates down from the lateral aspect of the thigh, is aggravated by walking (especially uphill) and bending, and is relived by recumbency and lying down. Pain relieved by walking and aggravated during sleep in unusual for L5 nerve root lesions. If in doubt, tests such as straight leg raise (SLR) or slump test can reproduce the symptoms in L5 radiculopathy, but not in CPN lesions.
OPTION B : While tenderness over the lateral condyle may be caused by compressing an injured CPN, it could also be just due to osteoarthritis itself, and is not a distinguishing feature.
OPTION C : With this presentation, loss of sensation over the lateral aspect of the leg is very likely as the main complaint is paresthesia and numbness of this area. Such finding adds no significant diagnostic benefit.
OPTION E : Weak distal pulses of the leg can be an important finding pointing towards vascular problems as a concomitant condition. It does not justify or adds any diagnostic clue to the presentation.
- Medscape - Peroneal Mononeuropathy
A 68-year-old man presents with a history of headache for the past several months. The headache is worse on waking up, coughing, sneezing and bending forward. He also mentions that he has been suffering from cough for the past 3 months. His history is significant for smoking of 45 cigarettes a day for the past 45 years. Significant finding on examination is left hemiparesis. A chest X-ray reveals an opacity of 3x2 cm in size in the left lung field. A contrast CT scan of the head is obtained which is shown in the following picture. Which one of the following could be the most likely diagnosis?
A. Primary brain tumor.
B. Metastatic brain tumor.
C. Brain abscess.
D. Cerebral hemorrhage.
E. Ischemic stroke.
B. Metastatic brain tumor
The clinical picture of headache worse in the morning, and by sneezing, coughing and bending forward is suggestive of a space-occupying lesion in the brain that can be either a tumor or abscess. Considering the age of the patient, history of heavy smoking and the cough, this patient has lung cancer with high certainty.
Lung cancer is one of the three primary cancers that tend to metastasize to the brain (21%). The other two are melanomas (40%) and breast cancer (9%).
With this history and chest X-ray findings, the lesion is most likely to be a metastatic brain lesion from a primary lung cancer.
Metastatic brain tumors are the most common form of brain tumors. Of all brain tumors, more than a half are metastatic.
OPTION A : With the high probability of an underlying lung cancer in this patient, this tumor is more likely to be metastatic than primary.
OPTION C : Brain abscess has similar appearance on contrast CT scan (ring enhancement); however, with absence of fever and considering the history, a brain abscess is not a likely diagnosis.
OPTION D and E : The appearance of the lesion as well as the insidious onset and progression of the symptoms make cerebral hemorrhage and ischemic stroke unlikely diagnoses.
A 12-year-old boy is brought to your office after accidentally cutting his left wrist with a pocketknife. On examination, there is a deep 2-cm laceration at the base of the thenar eminence. To test the motor injury to the median nerve you would have the patient:
A. Extend the thumb and fingers.
B. Oppose the thumb and little finger.
C. Flex the wrist.
D. Abduct the thumb and index finger.
E. Adduct the thumb and index finger.
B. Oppose the thumb and little finger
The scenario describes a cut in the thenar area of this child.
There are three muscles in the thenar eminence:
1. abductor pollicis brevis
2. flexor pollicis brevis
3. opponens pollicis.
Median nerve injury at wrist level results in the dysfunction of these three muscles (as well as the lumbrical muscles of the digits 2 and 3).
The first two muscles are conjoined with fibers from their counterparts originating from forearm, namely abductor pollicis longus and flexor pollicis longus. While median nerve injury at wrist level causes the dysfunction of thenar region muscles, thumb abduction and flexion remain preserved due to compensatory action of abductor pollicis longus and flexor pollicis longus muscles. However, thumb opposition becomes severely impaired due to denervation of the opponens pollicis muscle. Isolated impairment of thumb opposition is the most likely finding in median nerve injuries at wrist level.
OPTION A : Extension of the thumb and fingers is an action of radial nerve and is not affected by median nerve injuries.
OPTION C : Wrist flexion is mainly the action of flexor carpi radialis and flexor carpi ulnaris muscles, innervated by the median and ulnar nerves, respectively, in the forearm. Median and ulnar nerve injuries in the wrist will not affect wrist flexion; therefore, this movement will be unaffected in this patient.
OPTION D : While median nerve injury at wrist can impair the function of abductor pollicis brevis in the thenar eminence, thumb abduction is preserved to a great extend, because the fibers of abductor pollicis longus are innervated in the forearm by the anterior interosseous nerve (a branch of median nerve) and unaffected by injury to the median nerve at wrist level. Therefore, this action is preserved. Abduction of other fingers than the thumb are provided by dorsal interosseous muscles and abductor digiti minimi, all supplied by the ulnar nerve; hence unaffected in this patient.
OPTION E : Thumb adduction is mainly provided by the muscle adductor pollicis that is innervated by the deep branch of the ulnar nerve. Median nerve injury at wrist level is unlikely to significantly affect this movement. Adduction of the other fingers other than the thumb are the action of palmar interosseous muscles all innervated by ulnar nerve and is not expected to be impaired in this patient.
A 35-year old woman presents to your practice with complaint of decreased ability to hold small objects between his right thumb and index finger. He noticed it few months ago when he was unable to properly hold the door or car keys. Which one of the following conditions could have led to this presentation?
A. Radial nerve injury.
B. Carpal tunnel syndrome.
C. Anterior interosseous nerve injury.
D. Ulnar nerve injury.
E. Posterior interosseous nerve injury.
D. Ulnar nerve injury
Types of Pinching:
-
Tip-to-Tip Pinch:
- Thumb tip touches the tip of the index or middle finger.
- Used for holding small objects.
-
Pad-to-Pad Pinch:
- Pad of the thumb touches the pad of the index or middle finger.
- Used for holding larger objects needing more stability.
-
Three-Jaw-Chuck Pinch:
- Thumb touches the tips of the index and middle fingers.
- Used for holding larger or heavier objects, like a piece of chalk or a pencil.
-
Lateral/Key Pinch:
- Thumb pulp touches the side of the index finger.
- Used for actions like turning a key in a lock.
Key Muscles in Pinching:
- Adductor Pollicis and Dorsal Interosseous Muscle of the index finger.
- Both are supplied by the ulnar nerve and provide strength for pinching.
Common Nerve Injuries Affecting Pinching:
-
Ulnar Nerve Injury:
- Symptoms: Difficulty with pinch strength, especially with the lateral/key pinch.
- Froment’s Sign: When asked to hold a piece of paper, the thumb flexes at the distal joint to compensate for weak adductor pollicis, creating a “clamp” grip instead of the normal “tongs” grip.
-
Radial Nerve Injury:
- Symptoms: Affects the extensor muscles of the forearm, wrist, and fingers.
- Note: Does not cause weakness in pinching between the thumb and index finger.
-
Anterior Interosseous Nerve (AIN) Syndrome:
- Symptoms: Inability to make an “O.K.” sign due to impaired flexion of the thumb and index finger.
- Pinch Test: Cannot pinch a sheet of paper properly, resulting in a “tongs” appearance instead of a “clamp.”
- Affected Muscles: Flexor pollicis longus (thumb), flexor digitorum profundus (index/middle fingers), and pronator quadratus.
-
Carpal Tunnel Syndrome:
- Symptoms: Sensory disturbances in the palmar side of the thumb, index finger, middle finger, and half of the ring finger, and weakness of the thenar muscles.
- Note: While thumb opposition is affected, pinching between thumb and index finger is not significantly impaired since key muscles (flexor pollicis longus and flexor digitorum profundus) are innervated by AIN, which is not affected by carpal tunnel syndrome.
- Ulnar Nerve Injury: Affects pinch strength, particularly the lateral/key pinch, with signs like Froment’s sign.
- Radial Nerve Injury: Does not significantly impact pinching ability.
- AIN Syndrome: Impairs the ability to make an “O.K.” sign and perform effective pinching, but does not cause sensory symptoms.
- Carpal Tunnel Syndrome: Affects sensation and thumb opposition but does not majorly impair pinching.
Understanding these nerve injuries and their impact on pinching helps in diagnosing and managing conditions effectively.
In order to understand clearly the nerve injury associated with this presentation, it is essentinal to know the pinching and its types.
Four types of pinching have been described:
(PICTURES OF TYPES PINCHES in PAGE 762-764)
-
Tip-to-tip pinch
Tip to tip pinch (pulp of the thumb against that of the index/middle finger) – this type of pinch is used for holding and positioning of small objects -
Pad-to-pad pinch
Pad to pad pinch (pad of the thumb against index / middle finger) – this type of pinch is used for larger objects or objects that need more stabilization -
Three-jaw-Chalk pinch
Three jaw chalk pinch (thumb against tips of index and middle fingers) – it is used for larger or heavier objects e.g., holding a piece of chalk while writing on the blackboard or holding a pencil -
Lateral/key pinch
Lateral / key pinch (pulp of thumb against radial/lateral aspect of the index finger) – object is aligned with forearm and with supination/pronation the object is moved through the space (using a key to open a door)
Different muscles work together to provide precise alignment and power of different types of pinch (pincer grip); however, the two key muscles providing the strength of a grip are adductor pollicis and dorsal interosseous muscle of the index finger, both of which are supplied by the ulnar nerve. With decreased power of pinching, an ulnar nerve injury is more likely to be the underlying cause of this presentation.
If a patient with ulnar nerve injury is asked to grasp a piece of paper between the thumb and lateral aspect of the index finger, loss of power to adductor pollicis muscle will cause flexion of the distal thumb as the flexor pollicis longus compensates. Patient makes a “clamp” instead of the naturally-occurring “tongs” to hold the paper (Froment’s sign).
OPTION A - Radial nerve and its branch - the posterior interosseous supply the extensor muscles of the forearm, wrist and fingers. Radial nerve lesions do not cause weakness of pinching between the thumb and index finger.
OPTION C - For tip-to-tip approximation during pinching between the thumb and index finger (thumb-index finger pincer grip) the two key muscles involved are flexor pollicis longus (flexing the interphalangeal joint of the thumb) and flexor digitorum profundus (flexing the distal interphalangeal joint of the index finger). Both flexor pollicis longus and the flexor digitorum profundus muscles of fingers II and III are innervated by anterior interosseous nerve (AIN), a motor branch of the median nerve. Patients with AIN lesions typically fail to make an “O.K.” sign, because flexion of the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger are impaired. Another sensitive test is the pinch test: a patient with AIN lesions will also not be able to pinch a sheet of paper between his thumb and index finger, instead they hold the sheet between his extended thumb and index fingers, giving an appearance similar to a “tong” rather than a “clamp”. The anterior interosseous nerve, however, does not contribute as significantly to the power of the pincer grip as do adductor pollicis and dorsal interosseous muscle.
NOTE - Anterior interosseous nerve innervates the following muscles:
a) Flexor pollicis longus – main flexor of the thumb
b) Flexor digitorum profundus of digits II and III (index and middle fingers) – flexor of the distal interphalangeal joints of forefinger and middle finger
c) Pronator quadratus – along with the pronator teres, and while the elbow is flexed to a right angle, turns the hand so that the palm of the hand faces the floor.
OPTION B and E : Carpal tunnel syndrome is caused by compression of the median nerve in the carpal tunnel, and presents with sensory disturbances in palmar aspect of the thumb, index finger, middle finger and half of the ring (4th) finger. It also causes the weakness of the thenar muscles the abductor pollicis brevis, flexor pollicis brevis and opponens pollicis. While thumb opposition can be significantly affected in patients with carpal tunnel syndrome, pinching between thumb and index fingers are NOT markedly impaired because the key muscles to the action, which are flexor pollicis longus and flexor digitorum profundus muscle of the index finger are supplied by AIN that does not run in the carpal tunnel; therefore, unaffected in carpal tunnel syndrome.
Which one of the following nerves supplies the interosseous muscles of the hand?
A. Radial nerve.
B. Median nerve.
C. Ulnar nerve.
D. Anterior interosseous nerve.
E. Posterior interosseous nerve.
C. Ulnar nerve
Interosseous muscles are intrinsic hand muscles that abduct (dorsal interosseous muscles) and adduct (palmar interosseous muscles) the fingers. These muscles are innervated by deep branch of the ulnar nerve.
- Orthobullets - Dorsal interossei
- Orthobullets - Palmar interossei
A 30-year-old woman presents to your GP clinic with complaint of headaches 3 to 5 days before her periods. The headache often starts from the back of her head (occipital area) and radiates to her left temple, and is aggravated by walking or other types of physical activity. She denies visual, auditory, or taste disturbances, but mentions that during attacks she cannot tolerate noisy or crowded places. According to her, every episode of headache lasts from two to several hours. Physical examination, including a full neurological exam is inconclusive. Which one of the following could be the most likely diagnosis?
A. Migraine with aura.
B. Migraine without aura.
C. Tension vascular headache.
D. Cerebral tumor.
E. Premenstrual tension headache.
B. Migraine without aura
The description of headache in the patient’s words implies a unilateral nature for the pain (from occipital area radiating to the left temple). The headache is aggravated by walking and physical activity and the patient is intolerant of noise and crowded places. These, collectively, make migraine the most likely diagnosis. She also denies visual, taste, or auditory disturbances (aura). So she is very likely to be suffering from migraine without aura. Relation to menstruation (hormonal changes as a trigger) is also another supporting evidence for such diagnosis.
Over 50% of women with migraine report an association between migraine and menstruation. Such association has been hypothesized to be due to hormonal changes around menstruation.
OPTION A : Absence of visual, taste or auditory disturbances makes migraine with aura (classic migraine) an unlikely diagnosis.
OPTION C : Tension-vascular headache is a term used for headaches that cannot be categorized as tension-type headache or migraine headache due to overlapping symptoms. In such patients both migraine and tension headaches are present. Findings in this woman are nearly classic for migraine without aura.
The following tables outline differences between tension headache and migraine:
(TABLE IN PAGE 776)
OPTION D : Headache caused by space-occupying brain lesions such as cerebral tumors characteristically occur early in the morning and are associated with forceful (projectile) vomiting and focal neurological findings, absence of which in the scenario make a space-occupying lesion as the cause of the headaches less likely. Also, headache associated with such lesions do not occur just prior to menstruation and in a cyclic fashion.
OPTION E : Although this woman has headaches before menstruation, the features of headache are more consistent with migraine rather than tension headache.
A 56-year-old man is brought to the Emergency Department with presenting complaint of vertigo. He describes that he had mild dizziness and nausea before he hears a popping sound in his right ear. The dizziness intensified afterwards, and he felt a severe spinning sensation associated with nausea and two episodes of vomiting. On examination, he has a blood pressure of 145/105 mmHg, pulse rate of 100 bpm, respiratory rate of 18 breaths per minute, and a temperature of 36.7°C. He also has right-sided Horner’s syndrome, complete sensorineural deafness of the right ear and nystagmus. There is paresthesia of the left upper and lower limbs. Which one of the following would be the most likely cause of this clinical presentation?
A. Meniere’s disease.
B. Acoustic neuroma.
C. Acute labyrinthitis.
D. Vertebrobasilar insufficiency.
E. Vestibular neuronitis.
D. Vertebrobasilar insufficiency
This patient’s symptoms—vertigo, Horner’s syndrome, sensorineural deafness, and nystagmus on the right side, along with left-sided sensory impairment—suggest a problem in the brainstem, specifically related to blood flow issues in the vertebrobasilar artery.
-
What’s Happening:
- The vertebrobasilar arteries supply blood to important parts of the brain like the brainstem and cerebellum. When blood flow is disrupted (vertebrobasilar insufficiency), it can cause a stroke or similar symptoms.
-
Why These Symptoms?:
- Vertigo, Nystagmus, Nausea, Vomiting: These are caused by involvement of the vestibular system in the brainstem, which controls balance and eye movements.
- Horner’s Syndrome: A sign of damage in the brainstem, leading to drooping eyelid, small pupil, and reduced sweating on one side of the face.
- Sensorineural Deafness: Hearing loss on the right side due to involvement of the auditory pathways.
- Contralateral Sensory Impairment: Sensory loss on the opposite side of the body (left side) because the brainstem pathways cross over.
-
Most Likely Diagnosis:
- This pattern suggests occlusion (blockage) of the left inferior cerebellar artery (PICA), leading to a condition known as lateral medullary syndrome (Wallenberg syndrome).
- Meniere’s Disease: Causes vertigo, tinnitus, and hearing loss but doesn’t involve neurological symptoms like Horner’s syndrome or sensory loss in the body.
- Acoustic Neuroma: Usually causes gradual hearing loss, not sudden onset vertigo or sensory changes on the opposite side of the body.
- Acute Labyrinthitis: Causes vertigo and hearing loss, often after a viral infection, but doesn’t involve Horner’s syndrome or sensory changes in the body.
- Vestibular Neuronitis: Involves vertigo and imbalance without hearing loss or neurological symptoms like Horner’s syndrome.
This patient’s symptoms are best explained by a blockage in a blood vessel (PICA) that supplies the brainstem, leading to a lateral medullary stroke. This condition causes a mix of symptoms on the same side of the body as the stroke (like vertigo and Horner’s syndrome) and the opposite side (like sensory loss). Other conditions, like Meniere’s disease or acoustic neuroma, don’t match because they don’t cause this specific pattern of symptoms.
With vertigo, Horner’s syndrome and sensorineural deafness and nystagmus on the right side after a popping sound in the ear (which indicates sudden onset tinnitus), a central cause for this presentation should be thought of first. Considering the fact that this patient has also contralateral (left-sided) sensory impairment, vertebrobasilar insufficiency is the most likely explanation.
The vertebrobasilar arterial system provides blood supply to the medulla, cerebellum, pons, midbrain, thalamus, and occipital cortex.
Characteristic features of vertebrobasilar insufficiency/ stroke include the following:
-Vertigo, nausea, and vomiting, along with nystagmus, represent involvement of the vestibular system, and are seen in vertebrobasilar strokes.
-Unilateral Horner syndrome occurs with brainstem lesions.
-Cerebellar signs (e.g., dysmetria, ataxia) are frequently observed.
-Dysarthria and dysphagia are typically present.
-When cranial nerves or their nuclei are involved, the corresponding clinical signs are ipsilateral to the lesion and the corticospinal signs are crossed, involving the opposite arm and leg.
-Involvement of the ascending sensory pathways may affect the spinothalamic pathway or the medial lemniscus (dorsal column), resulting in dissociated sensory loss, which is loss of one sensory modality on one side and preservation of other sensory modalities in the opposite limbs (dissociative sensory loss).
-Occipital lobe lesions result in visual field loss or visuospatial deficits.
-Cortical deficits, such as aphasia and cognitive impairments, are absent.
In the absence of visual problems, this patient is more likely to have developed occlusion of the left inferior cerebellar artery (PICA) occlusion. The following diagram depicts the vertebrobasilar circulation: see anatomy of circle of willis below.
PICA is the largest branch of the vertebral artery and is one of the three main arteries that supply the cerebellum (the other two are superior cerebellar artery and anterior inferior cerebellar artery). Occlusion of PICA (A) results in a clinical syndrome called lateral medullary syndrome, Wallenberg syndrome or PICA syndrome.
This syndrome is characterized by sensory deficits that affect the trunk and extremities contralaterally (opposite to the lesion), and sensory deficits of the face and cranial nerves ipsilaterally (same side as the lesion).
The cross body finding is the chief symptom leading to PICA syndrome as the diagnosis.
Other possible symptoms include:
1. Difficulty walking or maintaining balance (ataxia) or difference in temperature sensation between left and right sides of the body
2. Attacks of vertigo and nystagmus
3. Difficulty swallowing (dysphagia) caused by the involvement of the nucleus ambiguus (this nucleus supplies the vagus and glossopharyngeal nerves).
4. Dysarthria and dysphonia
5. Ataxia (imbalance on walking) due to damage to the cerebellum or the inferior cerebellar peduncle
6. Horner’s syndrome caused by damage to hypothalamospinal fibers and disruption of sympathetic nervous system
7. Palatal myoclonus
8. Hoarseness
9. Nausea and vomiting
10. Bradycardia and dysregulation of blood pressure (due to injuries of nucleus ambiguous)
OPTION A : Meniere’s disease is caused by abnormal accumulation of endolymph in the labyrinth, and presents with vertigo, tinnitus and hearing loss lasting for hours each time. Patients often mention a sensation of fullness in the ear. There is often a positive family history. In Meniere’s disease, the pathology is contained within the labyrinth, and there is no neurological abnormalities such as Horner’s syndrome or sensory deficits of the body otherwise.
OPTION B : Acoustic neuromas are intracranial tumors arising from the Schwann cell sheath of either the vestibular or cochlear nerve. As acoustic neuromas increase in size, they eventually occupy a large portion of the cerebellopontine angle. Acoustic neuromas account for approximately 80% of tumors found within the cerebellopontine angle. The remaining 20% are principally meningiomas.
Unilateral hearing loss is the most common symptom present at the time of diagnosis and is generally the symptom that leads to diagnosis. The tumor can produce hearing loss through at least two mechanisms: (1) direct injury to the cochlear nerve or (2) interruption of cochlear blood supply. Progressive injury to cochlear fibers probably accounts for slow progressive neurosensory hearing loss observed in majority of patients with acoustic neuromas. Sudden and fluctuating hearing loss is seen in 5-15% of patients, probably due to disruption of cochlear blood supply by the tumor.
Other symptoms of acoustic neuroma include headaches (50-60% of patients at the time of diagnosis, but in less than 10% as the presenting symptom) and facial numbness (in 25% of patients but in less than 1% as the presenting symptom).
Vertigo and disequilibrium are uncommon presenting symptoms among patients with acoustic tumors. Overall, approximately 40-50% of patients with an acoustic neuroma might have some balance disturbance. However, balance disturbance is the presenting symptom in less than 10% of patients. This is due to the fact that destruction of vestibular fibers by the tumor is slow and allows for compensation.
Sudden onset of vertigo and hearing loss and contralateral sensory disturbances are strongly against acoustic neuroma as the diagnosis. In majority of patients with acoustic neuroma, the presenting symptom is progressive unilateral hearing loss.
OPTION C : Acute labyrinthitis presents with acute vertigo often followed by nausea and vomiting, tinnitus, and hearing loss. There is often a history of preceding viral upper respiratory tract infection. Change in head position provokes vertigo. Each episode of vertigo lasts from few seconds to minutes. Although there are similar symptoms of vertigo and hearing loss between labyrinthitis and vertebrobasilar insufficiency, the former is not associate with Horner’s syndrome and abnormal neurological findings such as sensory impairment.
OPTION E : Vestibular neuronitis is the inflammation of the vestibular nerve, often by a viral infection. Patients may have a preceding viral upper respiratory infection or herpes zoster. Vertigo and imbalance are the prominent features of vestibular neuronitis and there is no hearing loss or tinnitus. Loss of balance is more prominent in vestibular neuronitis compared to other causes of vertigo, and patient commonly presents with vertigo and falls. Similar to benign paroxysmal positional vertigo (BPPV), symptoms in vestibular neuronitis are aggravated by change in the position of the head. Neurological examination in patients with vestibular neuronitis is otherwise normal and there is no Horner’s syndrome.
A 30-year-old woman presents to your general practice with complaint of blurred vision and pain in the right eye for the past 3 days. She is otherwise healthy and has not had any major medical or surgical history. On examination, her visual acuity of the right and left eyes are 6/12 and 6/6, respectively. She cannot read the numbers in Ishihara chart and confuses red and green. Other significant finding on examination is worsening of the right eye pain with eye movements that are normal and symmetric in all directions with no diplopia. Which one of the following could be the most likely diagnosis?
A. Intracranial hemorrhage.
B. Orbital tumor.
C. Optic neuritis.
D. Temporal arteritis.
E. Retinal detachment.
C. Optic neuritis
Sudden onset of decreased vision and retro-orbital pain in a young female is highly suggestive of optic neuritis as the most likely diagnosis.
Optic neuritis (ON) is a demyelinating inflammation of the optic nerve that often occurs in association with multiple sclerosis (MS) and neuromyelitis optica (NMO). A gradual recovery of visual acuity with time is characteristic of ON; however, permanent residual deficits in color vision and contrast and brightness sensitivity are common.
Typically, patients with first time acute optic neuritis (ON) are otherwise healthy young adults, who experience rapidly developing impairment of vision in one eye or, less commonly, both eyes during an acute attack. Dyschromatopsia (change in color perception) in the affected eye occasionally may be more prominent than the decreased vision. Decreased color vision is tested with Ishihara chart shown in the following picture. Patients with impaired color vision cannot read the numbers in the chart due to color blindness.
In almost all cases, the visual changes are associated with a retro-orbital or ocular pain, usually aggravated by eye movement. The pain may precede the visual loss.
Patients may complain of vision loss exacerbated by heat or exercise (Uhthoff phenomenon). Objects moving in a straight line may appear to have a curved trajectory (Pulfrich phenomenon), presumably due to asymmetrical conduction between the optic nerves.
Physical examination findings in patient with ON may include:
-Decreased visual acuity
-Decreased color vision
-Presence of relative afferent pupillary defect
-Reduction in subjective brightness
-Visual field defect
-Abnormal contrast sensitivity
-Certain appearances of the optic nerve (swelling, peripapillary hemorrhage or pallor)
OPTION A : Intracranial hemorrhage is not likely to present with isolated findings of reduced vision and retro-orbital pain worsening on eye movement. In patients with intracranial hemorrhage, more significant motor and/or sensory disturbances would be expected.
OPTION B : An orbital tumor presents differently with probable findings of eye bulging, decreased vision, impaired visual fields, and manifestations of raised intraocular pressure. It is less likely that an intraorbital tumor is missed on funduscopic examination in experienced hands. Vision loss and retro-orbital pain are unlikely to be the sole manifestations of an eye tumor.
NOTE - Uveal melanoma is the most common intraocular malignancy in adult.
OPTION D : Temporal arteritis is a vasculitis of large vessels of middle-age onset and characterized by a variety of symptoms including headache, scalp tenderness, jaw claudication and vision loss. Polymyalgia rheurmatica can be an association. Neither the patient’s age, nor the clinical presentation is consistent with temporal arteritis as the diagnosis.
OPTION E: Although retinal detachment is associated with vision loss, absence of other features like flashes and floaters in the visual fields and the presence of pain makes such diagnosis unlikely.
