Neuro Exam Flashcards
1
Q
The history is critically important in Neurology. Many different signs and symptoms are highly informative and provide the initial basis by which you try to localize the lesion. Your first priority is not “what is it?” but “where is it?” Are you dealing with disease of the brain, spinal cord, peripheral nerve or muscle, or perhaps, there is no disease of the nervous system at all. The patient may be experiencing “functional” signs and symptoms due to psychiatric disease, as occurs, for example, in a “conversion reaction”. You will use the results of your neurological exam to confirm or reject what you suspect to be the anatomy of the lesion
A
Once you have a working hypothesis for the anatomy of the lesion, the next step is to determine its pathophysiology. Here you should think in broad categories. Do the history and physical exam suggest a vascular, neoplastic, infectious, paroxysmal, metabolic, neurodegenerative or some other process.
2
Q
You will learn more about each of these categories later but for now, you should realize that vascular usually means stroke characterized by a sudden loss of strength, sensation, vision, language or some other function.
A
Paroxysmal means something is of sudden onset but unlike stroke, there is often a gain of function. For example, involuntary jerking of the limbs during a seizure or visual aura in a migraine attack
3
Q
Neoplastic is usually insidious in onset, often producing pain due to tumor invading pain sensitive structures. There is a gradual loss of function and other organ systems may be involved.
Infectious causes usually produce fever, chills, stiff neck with meningitis and may involve other organ systems.
A
Neurodegenerative disorders, like Alzheimer disease, are insidious in onset, progressive, often painless, usually restricted to or predominant in the nervous system. So, your H&P should elicit information with a goal to make an anatomical diagnosis first and then to determine its pathophysiology. Only afterwards do you consider a differential diagnosis. This is called the Neurologic Method, and your lab testing, imaging and early treatment are typically better focused and more likely to be on target when you use the Neurologic Method.
4
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A
5
Q
What are the main parts of the neurologic exam?
A
Mental status, cranial nerves, motor function, sensory function, reflexes and gait. When you write down or present your exam to an attending, you should follow this format regardless of the order in which the information was collected.
6
Q
Neuro Exam tools
A
A hand held Rosenbaum card tests visual acuity.
The tuning fork is useful for testing vibration sense, and being metal and cold, it can also test for the sensation of temperature.
The tongue blade checks the gag reflex.
The cotton applicators with wooden sticks can be used in many ways, typically to test light touch and the corneal reflex, but also for testing cortical integration of sensory function such as texture, stereognosis and graphesthesia
7
Q
What is Stereognosis?
A
Stereognosis refers to your ability to identify objects through touch, for example, the feel of cotton in your fingers versus the stick.
8
Q
What is Graphesthesia?
A
refers to the ability to recognize numbers or letters written on the palm of your hand. This is done with the wooden part of the cotton applicator.
9
Q
The measuring tape is used to measure muscle bulk around a limb when atrophy is suspected and to check for optokinetic nystagmus. What is optokinetic nystagmus or OKN?
A
If you ever stood in a subway station and watched cars pass by, you may or may not have noticed that your eyes involuntarily jiggle due to OKN. The presence of optokinetic nystagmus indicates that the anatomical visual pathways from the eye to visual centers in the occipital cortex of the brain are all working properly.
10
Q
The mental status exam may be perceived as questioning the patient’s intelligence. That can be embarrassing to the patient and awkward for the physician, so mental status testing is often performed at the end of the neurologic exam
A
. It is helpful to include an explanation that the testing is routine and the patient is not being singled out. On the other hand, if the interview suggests an unreliable historian, then the mental status is tested first.
11
Q
How is mental status tested?
A
You note the level of consciousness. A patient is considered conscious if he opens his eyes to stimulation. In your typical clinic encounter, you check orientation, you ask the patient his name, his current place and the date
12
Q
With alterations in mental status due to any cause, knowing _____ is usually the first thing to go?
A
today’s date
13
Q
How can you test attention and concentration?
A
by asking the patient to spell WORLD forward, then backwards. You can also test “serial sevens”, that is ask him to subtract 7 from 100, 7 from 93, 7 from 86 and so on
14
Q
How should immediate recall and short-term memory be tested?
A
Ask the patient to repeat and then remember 3 objects for the next 5 minutes, while you distract him with other cognitive tasks. Patients with early Alzheimer disease often have difficulty laying down new memories and will forget 1, 2 or all 3 of the items. They will also have problems remembering what they had for breakfast or what they heard on the news recently.
15
Q
T or F. Long term memory is generally better preserved than recent memory.
A
T. To test, ask about the make and model of the first car bought or what color suit the patient wore at his wedding. Alzheimer patients with mild to moderate dementia will reminisce about the past with remarkable detail
16
Q
Disorders of language, so-called aphasias, will affect speech but they must be distinguished from ______ in which the mechanics of speech are affected to produce slurring of words.
A
dysarthria
17
Q
How should language be tested?
A
. Language is tested for fluency, comprehension, naming, reading and writing. You should ask how far the patient got in school and check general knowledge by asking him to name the Presidents starting with the current President and going backwards. Ask him to name the state capital, governor and mayor.
Check abstraction by asking him to interpret a proverb such as “people who live in glass houses shouldn’t throw stones” or “don’t cry over spilt milk” which is very simple. Ask him how a banana and orange are alike. They are fruit but a cognitively impaired patient typically will point out the differences instead.
Inquire about judgment by asking what he would do if he saw smoke in a crowded theater or found a stamped envelope on the pavement. Does the patient show insight into his own illness by asking appropriate questions or is he there to see the doctor because he got an appointment letter for reasons he does not know. Note if the patient appears depressed, unusually giddy or avoids eye contact because of sociopathic tendencies
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A
19
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A lesion in Broca’s area of the brain produces an expressive or Broca’s aphasia (they mean the same thing). What does this mean?
A
The patient has difficulty with word finding and getting words out, even though he knows exactly what he wants to say. He follows commands readily but is visibly frustrated that he can’t express his thoughts.
20
Q
How would a A lesion in Wernicke’s area present?
A
In a receptive or Wernicke’s aphasia (they mean the same thing). The patient speaks fluently and easily but has no insight that his words and sentences are devoid of meaning. He does not comprehend and cannot follow commands, whether spoken or written, but remarkably does not seem to be bothered by this lack of comprehension and inability to communicate.
21
Q
How would a lesion in the arcuate fasciculus that links the two language areas present?
A
results in a conductive aphasia. The patient can comprehend and speak fluently but has difficulty with repetition, especially with long sentences. Most aphasias can be characterized by asking the patient to name objects, to read, write and repeat sentences.
22
Q
How can dysarthria and aphasia be contrasted?
A
While speech in dysarthria may be hard to understand and suggest an aphasia, the dysarthric patient communicates normally through writing. A patient with aphasia, in contrast, will show the same abnormality in writing as in speaking.
23
Q
How do you test the sense of smell?
A
On the wards or in the clinic, go to the kitchenette and find some coffee, tea, lemon, soap or other odiferous substance.
Inspect the nares for obstruction or other pathology. Then use your cotton applicator to whisk some liquid soap, tea, coffee, whatever, and bring it to one nostril while the other is occluded by your finger. With eyes closed, ask the patient to identify the smell. Test the other nostril and ask if the smell differs on one side or the other. From a practical standpoint, smell is seldom tested unless the patient complains about its loss or experiences unusual smells.
24
Q
In testing smell, You want to avoid smelling salts, ammonia and alcohol that are irritating and activate nociceptive receptors in the nares. Why?
A
These are mediated by the trigeminal nerve as that would be testing a different cranial nerve.
25
When is smell commonly lost?
In head trauma because the fine nerve fibers from bipolar cells in the nasal mucosa are sheared as they pass through the cribiform plate of the skull and never reach the olfactory bulb.
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NOTE: Unusual smells, like rotten eggs or decaying meat, sometimes precede a temporal lobe seizure and constitute a seizure aura.
Olfactory information is sent along the olfactory tract to the uncus and entorhinal cortex in the temporal lobe where tumor or stroke or inflammation can distort processing of that information and produce unusual smells. You don’t have to worry about the limen insulae
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When compared to olfaction, vision is a far more important function. The eye and optic nerve, cranial nerve II, should be tested routinely. For the neuro-exam, fundoscopy allows direct inspection of the retina and optic disc. Visual acuity, color vision, visual fields and pupillary function are also tested.
You should become proficient with an ophthalmoscope. A few general principles include use of a dim lit room, not being afraid to get too close to the patient, being comfortably positioned, and reminding the patient not to move her eyes but keep looking at a distant object.
28
You should examine the optic disc to check that the edge is sharp and not swollen. This is where the optic nerve enters the eyeball along with retinal vessels. A swollen disc may be due to raised intracranial pressure from a brain tumor or other disease and is called papilledema.
Within the disc is a “cup”. Its size and depth should be checked since a small cup can strangle the vessels passing through and cause blindness in so-called anterior ischemic optic neuropathy. A deep cup should suggest elevated intra-ocular pressure due to glaucoma.
You should examine the blood vessels and any abnormalities of the retina. Some of the more common ones are small hemorrhages and exudates that accompany diabetes, severe hypertension and other diseases.
29
What does retinal venous pulsations upon fundoscopy suggest?
it means that the CSF pressure at that moment in time is normal. That excludes a large number of dangerous headaches that have raised intracranial pressure like brain tumor, abscess or brain hemorrhage.
30
Visual acuity can be tested with a hallway Snellen chart or a handheld Rosenbaum card. Make sure that conditions are optimal for vision, including use of glasses and adequate lighting. One eye is tested at a time. Read rows from top down and note where the first error is made. Visual acuity can be affected for many reasons, most commonly, by refractive error which you can correct with glasses or use of a so-called pin hole card.
Note that you rely on the central and most sensitive part of the retina, **the macula, which contains the fovea, for visual fixation, tracking moving targets and reading fine print.**
31
How shoud be confrontation testing be done?
For confrontation testing of visual fields, the examiner and patient should be facing each other more or less at the same eye level. The patient is asked to speak up as soon as she sees the white tip of a cotton applicator moving from her outer visual periphery toward her nose. All 4 quadrants of vision are tested. When an area of the visual field seems compromised, a stronger stimulus with wiggling fingers or finger counting is attempted. **Test one eye at a time.**
32
How does vision transmission occur?
1. The contralateral visual field projects onto the temporal or lateral portion of the retina. The ipsilateral visual field projects onto the nasal or medial portion of the retina
2. The optic nerve carries all info from the ipsilateral eye to the optic chiasm
3. Retinal fibers cross in the optic chiasm and combine with non-crossing fibers from the other eye to form a right and left optic tract
5. The optic fibers synapse in each lateral geniculate nuclei. The lateral geniculate then projects axons to the primary visual cortex in the occipital lobe
33
What would lesion of the optic nerve cause?
A lesion of the optic nerve would produce complete monocular visual loss with normal vision in the contralateral eye
This happens with inflammation of the optic nerve in multiple sclerosis and with obstructed blood flow or ischemia to the anterior optic nerve.
34
How would a lesion compressing the optic chiasm present?
It would destroy crossing optic nerve fibers and causes a bitemporal visual field deficit as shown below called a **bipolar hemianopia**
This occurs with enlarging pituitary tumors and giant internal carotid aneurysms that compress the chiasm
35
What is this type of lesion called? Causes?
Loss of the contralateral visual hemifield that is identical in each eye, a so-called **homonymous hemianopsia**
**Cause:** lesion or pressure on the right optic tract; lesion of the right occipital lobe
36
What is this lesion called and what causes it?
right nasal hemianopia due to lesion involving the right perichiasmal area
37
\_\_\_ desaturates before other colors with injury to the optic nerve.
Red.
Some people (10-15% males) are born color blind. **Ishihara plates** embed numbers among small colored dots and can be used to test color vision
38
A variety of neurologic disorders affect the pupils to make them smaller or larger and/or unreactive to light stimulation. .What are some common etiologies of a constricted pupil?
include glaucoma drops, opioid medication, and less commonly pontine hemorrhage that disrupts the central sympathetic tracts
39
When the pupil is enlarged this may indicate what?
oculomotor nerve compression by a so-called PCOM aneurysm or by early temporal lobe herniation due to a catastrophic expanding mass lesion. It might also reflect rubbing one’s eye after applying a scopalamine patch behind the ear in someone with nausea and vomiting.
40
Ptosis or drooping of the upper eyelid with a small pupil suggests what?
Horner’s syndrome The sympathetic tract can be damaged either by a central or by a peripheral lesion.
41
What is Miosis?
Miosis refers to a pupil that is small, typically 2 mm or smaller.
Mydriasis refers to an enlarged pupil, typically 5 mm or larger.
•Pupil size varies with ambient light, but averages 3-4 mm
42
Visual information in the retina is transmitted by neurons called what?
retinal ganglion cells
43
Where do retinal ganglion cell axons go?
About 85% of the retinal ganglion cell axons project via the optic nerve to the lateral geniculate body. Another 15% or so project to the midbrain superior colliculli and these fibers mediate the pupillary light reflex.
44
Note that light entering one eye reaches the superior colliculli on both sides and the superior colliculli in turn project to both Edinger-Westphal nuclei. What happens then?
The Edinger-Westphal nuclei project to the ciliary ganglia near the eye, which send cholinergic fibers to constrict the pupil. Thus shining a light in one eye activates both Edinger-Westphal nuclei and both pupils constrict equally and consensually.
45
What is the most informative bedside test in an unresponsive or comatose patient? Why?
The pupillary light reflex. It checks the integrity of the midbrain in the region where the **reticular activating system** is found. The reticular activating system is responsible for maintaining consciousness.
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To assess the pupillary light reflex properly, you should dim the light and ask the patient to stare on one spot in the distance. You shine the light obliquely so you don’t obstruct your view of the constricting pupil. Look for identical responses in both pupils.
Note that there is an afferent, that is a receiving part, of the light reflex that is mediated by the optic nerve (CN II) and an efferent, that is the effector part, that is mediated by the oculomotor nerve (CN III).
47
How is accommodation tested?
The pupils normally constrict as a reflex action when fixating vision from a distant object to a near object. To check accomodation, ask the patient to look at your finger as it approaches his nose. The pupils should constrict.
48
Pupils that fail to constrict to bright light but do constrict to accomodation are called what?
Argyll Robertson pupils and are seen with neurosyphilis
49
Cranial nerves III, IV and VI are responsible for the movement of the eyes called extraocular movement or EOM.
Check to see that the eyes remain conjugate, that is, aligned with each other, that they move smoothly and not in little jerks (saccades) and that the patient does not experience double vision, as might occur with a weakened eye muscle due to nerve injury. Check for nystagmus, that is, a rhythmic jiggling of the eyes during movement. This is very prominent in someone with vertigo due to inner ear disease.
Check to see if the patient can look from extreme lateral gaze to the center midline in a single smooth movement versus incoordinated zigzag-like movement due to cerebellar disease.
50
CN VI is aka \_\_\_\_\_. CN IV is aka \_\_\_\_\_
Abducens (innervates the lateral rectus)
Trochlear (innervates the superior oblique)
51
The trigeminal nerve is primarily a sensory nerve but does have a motor component for the muscles of mastication. There are three branches:
the ophthalmic, mandibular and maxillary branches.
52
How shoudl CN V be tested?
These are tested for sensation with a pin prick (pain sensation), a cold tuning fork (temperature) and a cotton applicator (touch). One tests all three divisions of the trigeminal nerve.
53
You should be aware that the most sensitive spot on your body is ______ which is innervated by the ophthalmic division, also known as V1 or the first division of the trigeminal nerve.
An important localizing sign is whether the angle of the jaw is affected by sensory loss or spared. The angle of the jaw receives separate sensory innervation from cervical root 2 of the spinal cord so the area should be spared in lesions of the trigeminal nerve. If the area is not spared and the sensory loss extends beyond the boundaries of the trigeminal nerve, then the lesion is likely to be a central lesion of CNS as occurs with stroke.
the cornea
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One uses cotton, including the cotton applicator, to lightly stroke the cornea and see if the patient blinks. Contact lenses may depress corneal sensation in which case the nasal hairs in the nares can be lightly stroked with a cotton wisp, a so-called nasal tickle to check for very sensitive light touch sensation.
The trigeminal nerve also innervates the muscles of mastication, the chewing, grinding muscles. These are best checked by asking the patient to open the jaw against resistance. If the pterygoid muscles on one side are weak, the jaw will deviate toward the side of weakness.
55
I am sure you are familiar with the tendon reflexes in the limbs but you may be less aware that there is a similar reflex in the jaw mediated by the trigeminal nerve. By lightly tapping the lower jaw, you can elicit a sudden closure of the mandible which may be unusually brisk, normal or reduced in amplitude. In someone with weakness of all 4 limbs, the jaw jerk provides very helpful localizing information.
A normal jaw jerk in the context of brisk reflexes in the limbs suggests compression of the spinal cord in the neck whereas a brisk jaw jerk would be compatible with an upper motor neuron lesion above the level of the neck such as occurs with cortical motor neuron involvement in ALS
56
The seventh cranial nerve, the Facial Nerve, innervates the muscles of facial expression. Inflammation of the nerve can paralyze these muscle on one side of the face to produce what?
Bell’s palsy.
However, the nerve has other functions as well, including sensation in the external auditory canal and a small area behind the ear.
Taste in the anterior two thirds of the tongue is mediated by the facial nerve.
Finally, the stapedius muscle that modulates sound transmission in the middle ear receives innervation through a branch of the facial nerve. Weakness of the muscle causes sounds in that ear be unpleasantly loud, so-called hyperacusis.
57
How should CN VII be tested?
To test the muscles of facial expression, ask the patient to furrow the brow, close the eyes against your efforts to open them, grit his teeth and puff out the cheeks. Look for any evidence of weakness, left versus right, upper face versus lower face, and generalized weakness from systemic disorders causing motor paralysis, for instance, botulism.
58
Facial paralysis on one side is common and the big question is whether this is due to a peripheral nerve lesion as in Bell’s palsy or due to a CNS lesion as in stroke. How can you tell?
As you know, the left cerebral hemisphere controls the right body and vice versa. That means that the facial motor nucleus receives input principally from the contralateral hemisphere for facial expression and that is very true for the lower face. **What is remarkable is that the upper face gets considerable ipsilateral innervation in contrast to the lower face.**
The upshot is that a central lesion will cause paralysis of the lower face but only mild weakness of the upper face. In contrast a peripheral lesion will produce equal weakness in the lower and upper face. The Bell's palsy patient, you discharge home from the emergency room. The stroke you admit and treat aggressively
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A further nuance on central lesions producing weakness of the contralateral lower face: If the lesion lies in the cortical motor areas and the deeper limbic structures are preserved, you will see the weakness when the patient is asked to make a grimace but it will disappear when the patient smiles.
If the deeper structures are affected by the lesion, the weakness will persist with the smile
You will learn later about the limbic system which mediates emotion and is important in memory and that it lies in the deeper parts of the cerebral hemisphere. The important thing to know now is that a central facial paresis may appear and disappear depending on where in the CNS the lesion lies.
60
There are five basic types of taste sensations:
salty, sweet, sour, bitter and that mediated by monosodium glutamate.
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How should you test taste in the anterior two-thirds of the tongue?
go to the hospital kitchenette and find some salt, sugar and lemon. Using water, make a solution of each in a small cup and dip a cotton applicator into one. Stroke one side of the tongue at a time and see if the patient can quickly identify salty, sweet or sour. Testing for bitter and MSG is more involved and best left to the ENT clinic.
Importantly don’t let the patient ponder to identify the taste since saliva will spread the substance over the entire tongue in a few seconds and the intact side will mask any deficit on the other side. Ask if taste seems the same on both sides since there may be partial preservation of taste when the injury is incomplete or recovering.
62
Cranial nerve VIII (auditory nerve) is comprised of what two parts:
an auditory and a vestibular component.
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How can you test the auditory component of CN VIII (vestibulocochlear nerve (auditory vestibular nerve))
To check the auditory component, ask if the patient can hear your finger rub at arm’s length with the other ear occluded by his finger. You can also whisper very softly at this distance and check if you are heard.
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What is a Rinne Test?
The Rinne test examines whether air conduction is greater than bone conduction to a vibrating tuning fork.
The tuning fork is placed on the mastoid process behind the ear and kept there until the patient no longer hears it vibrating Then it is brought just outside his ear. He should be able to hear it vibrating. **Air greater than bone is the normal finding** _but is also seen in so-called neural-sensory hearing loss with disease of the cochlea, auditory nerve or its connections._
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When would bone conduction be greater than air?
When disease does not involve neural structures, for example, excessive earwax in the ear canal, tympanic membrane rupture or otosclerosis of the ossicles.
66
What is a Weber test?
In the Weber test, the vibrating tuning fork is placed in the midline of the forehead, and the patient is asked if the vibration sounds louder in one ear or the other. **With conductive hearing loss, the vibration sounds louder in the affected ear**. If you ever forget, which side is which, give yourself a conductive hearing loss by sticking your finger in your ear and then start talking. You will notice your voice sounds louder on that side.
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How can you check the vestibular component of CN VIII?
you should check for nystagmus
It may be spontaneous or provoked by your extra-ocular movement testing.
68
How does the The head impulse test also known as “Head Thrust”, work?
It stimulates the vestibular system to keep the eyes on target with sudden head and neck turns.
There is an evolutionary highly conserved **vestibulo-ocular reflex, or VOR,** in which the brain permits visual tracking of an object of interest in one quick movement of the eyes to compensate for sudden movements of the head and body.
When there is vestibular disease, **the eye movements do not reach the target in a single swoop but require a so-called catch-up saccade.**
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The head impulse maneuver is very valuable in distinguishing what?
stroke and other CNS causes of acute vertigo from more benign peripheral nerve causes such as acute vestibular neuritis due to a viral illness. **The former have no catch-up saccades while the latter do.**
70
What is the Dix Hallpike test for?
tests the **posterior semi-circular canal for integrity**. This canal becomes blocked with calcium carbonate debris and that causes brief, recurrent episodes of vertigo whenever the canal is stimulated. **The disorder is called benign paroxysmal positional vertigo or BPPV** and is _one of the most common reasons people complain of dizziness_.
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BPPV can be cured by a sequence of head turns and movements called the _____ maneuver.
Epley
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the Dix Hallpike tests what?
The posterior semicircular canal for dysfunction
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horizontal end lateral gaze nystagmus is a common finding in who?
people on sedative medication, SSRIs, anticonvulsants or who drink alcohol to excess.
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Cranial nerves IX and X are usually tested together but you should know that **glossopharyngeal nerve is primarily a sensory nerve** and that the _vagus_ _nerve is primarily a motor nerve._ How should you test them?
To check their function, watch the upper palate move when a patient says “Aaaah”. Weakness on one side will cause the uvula to move toward the strong side. The patient may choke and cough on swallowing solids or fluids. The voice may be hoarse and/or hypophonic.
Cough will be muted.
Gag will be absent or reduced when the posterior pharynx is stroked on the affected side with a tongue blade.
Taste in the posterior 1/3 of the tongue is mediated by the glossopharyngeal and there are a few taste buds mediated by the vagus further down the throat, but their testing is difficult and not usually attempted.
75
How can the spinal accessory nerve (CN XI) be tested?
The spinal accessory nerve, cranial nerve XI, innervates the upper trapezius and the sternocleidomastoid muscle. Check to see if there is atrophy of the upper trapezius as shown by the arrow. See if a shoulder shrug is strong and symmetric against resistance.
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The sternocleidomastoid turns the head away in the opposite direction, in other words, **the right SCM turns the head to the left.**
By resisting that turn with your hand, you can see and feel the SCM. This muscle has special significance for localization.
Similarly to the upper face portion of the facial motor nucleus, this nucleus receives very prominent ipsilateral innervation. That means that when a right motor cortex epileptic discharge causes muscle twitching in the left body, it is the right SCM that convulses and turns the head to the left. With a right hemispheric stroke, the left body is paralyzed but so is the right SCM and the left intact SCM tonicaly turns the head to the right. **The patient lies in bed with his head turned to the right, away from his paralyzed side.**
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The 12th cranial nerve, the hypoglossal, innervates the tongue muscles. You should check that it lies in the midline at rest and stays midline on protrusion. Look for atrophy and for small wormlike movements called fasciculations that would indicate what?
denervation as is seen in hypoglossal nerve damage but also in motor neuron disease such as ALS.
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How should a motor exam be done?
For the motor exam, the patient should be in a hospital gown to permit adequate inspection of the limbs, torso, abdomen and back. A common practice is to examine the patient in their clothing but many neurological signs will be missed. You should look for musculoskeletal abnormalities, such as scoliosis, bone fractures or asymmetric body size and muscle wasting. You should check muscle tone by passively rotating the wrist, flexing/extending the elbow and flexing/extending the knee.
Check muscle strength and look for differences side to side, proximal limb versus distal limb and arms versus legs. **As examples, one side is characteristically weaker after a hemispheric stroke.**
Look for involuntary movements such as small muscle twitches (fasciculations), larger muscle twitches (myoclonus), tremor, chorea (flickering movements), athetosis (writhing movements), dystonia, rigidity, stiffness and muscle spasms. Compare the motor changes right versus left, proximal versus distal limb, and arms versus legs
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Reduced tone usually means there is so-called
lower motor neuron injury as seen with neuropathies but also with acute spinal cord injury affecting the anterior horn cell.
Increased tone is seen with upper motor neuron injury such as stroke or spinal cord injury that is not acute.
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T or F. Muscle disease tends to cause weakness predominantly in proximal muscles while peripheral neuropathies produce distal muscle weakness.
T.
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This is a summary slide of what to look for on your motor exam for lesions that are “upper motor neuron” or UMN and “lower motor neuron” or LMN.
What is a lower motor neuron lesion?
refer to disease of the peripheral nerve and its cell of origin, namely the anterior horn cell or neuron that gives rise to the motor axon.
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How does LMN disease present?
LMN disease will cause a muscle to be weak and become atrophic because the cell no longer is present to provide so-called neurotrophic factors to keep the innervated fiber muscle alive.
Muscle stretch reflexes are reduced because the motor fibers have disappeared and/or sensory fibers from the tendon have disappeared.
Muscle tone is reduced.
Because surviving nerve terminals sprout collaterals to innervate areas left denervated by dying axons, the motor unit increases in size and can produce tiny twitches visible to the eye as fasciculations.
83
How does UMN disease present?
With upper motor neuron lesions, the muscle is also weak but it does not atrophy because the anterior horn cell still provides the muscle with neurotrophic substances via axonal transport.
The vast majority of motor pathways descending from higher centers, namely UMN, are inhibitory so that the so-called “reflex arc” in the spinal cord becomes disinhibited with UMN damage and the reflexes are increased. Muscle tone is also increased and called spasticity when severe.
There are no fasciculations because there is no denervation by the LMN with UMN disease.
84
You should also check muscle strength by their innervated root levels. **Typically more than one root will innervate a muscle but for purposes of localization it is useful to be aware of the one root most closely associated with that muscle**.
Thus abducting the shoulders using the deltoids tests cervical root 5.
Flexing the elbow with the biceps is principally a C6 function and extending the elbow with the triceps is principally C7.
Handgrip is C8 and spreading the fingers apart, then bringing them together again, back and forth, is T1.
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Shoulder abduction is mediated principally by C5 and the axillary nerve.
Flexing the arm at the elbow is mediated mostly by C6 and the musculocutaneous nerve.
Extending the arm at the elbow is principally mediated by C7 and the radial nerve.
Handgrip is mediated by C8 and involves both the median and ulnar nerves.
Moving the hand intrinsic muscles involves **mostly T1 and the ulnar nerve.**
86
For the leg, raising the leg straight up from a lying position, that is flexing the hip, tests what nerve roots?
lumbar roots L1, L2 and L3 (iliopsoas muscle), via the femoral nerve
87
Pressing the knees together, hip adduction, tests what nerve root?
L2 (-L4, via the obturator nerve)
88
Extending the knee tests what nerve roots?
L3, L4 but principally L4. (quadricepts, femoral nerve)
89
L5 can be tested several ways. How?
by abducting the hip, that is opening the knees apart against resistance, but also by dorsiflexing the ankle, that is moving the foot upwards away from the floor, and by extending the big toe (extensor hallucis longus or EHL).
90
How can S1,2 be tested?
S1,S2 can be tested by foot flexion but because the gastrocnemius is so strong, there has to be severe weakness for the examiner to overcome the flexion with resistance. Hence it is better to have the patient stand on his toes or walk tip toe which provides a great deal more challenge to the gastrocnemius muscle.
91
Muscles controlling the anal sphincter and rectal tone are innervated by S3, S4, and S5. When a patient presents with ascending paralysis of the legs, this may be due to Guillain Barre syndrome affecting the peripheral nervous system or due to a spinal cord lesion. **With spinal cord lesions, anal sphincter tone is lost while with peripheral nerve lesions, as in Guillain Barre, it is typically spared even though paralysis may be severe.**
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The Medical Research Council in England developed a graded scale for measuring muscle strength. This scale has been universally adopted.
The dynamometric differences between the units are huge so the numbers describe strength by category and are not numerical units.
Five is assigned to someone with normal strength. Anything less than full strength is assigned a 4.
If weakness is such that the patient can move the limb against gravity but not against added resistance provided by the examiner, that merits a 3.
If there is movement at a joint but not against gravity, it’s a 2.
If there is no movement at the joint but you saw a muscle contract, it’s a 1.
Zero means absolute no muscle movement.
Testing against gravity means lifting a limb off a surface on which it is resting. You can probably see that there can be considerable variation in describing the same weakness by different people. Hence it becomes important to describe functional loss as well as assigning a number to the weakness, for example the patient can no longer hold a cup in his hands.
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Where does the pyramidal (corticospinal) tract originate?
in large neurons called Betz cells found in the 5th layer of the primary motor cortex.
This pathway is responsible for motor movements requiring dexterity and nimbleness such as in piano playing.
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One can selectively damage the pyramidal pathway in the brain, typically due to a small stroke, which leaves the patient with a normally strong arm and hand grip but **without the ability to perform fine finger manipulations**. How should you test?
One asks the patient to touch the thumb with each finger sequentially and quickly as if playing a piano. Alternatively, one asks the patient to rapidly tap the index finger against the thumb or a hard surface. Toe tapping tests the leg for pyramidal function but is not often done. You may not think of your toes as especially nimble or dexterous but individuals born without upper limbs can develop remarkable facility with their feet and toes, and **that is mediated by the pyramidal tract.**
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Examining cerebellar coordination includes what?
the finger to nose test. One looks to see if there is any side to side incoordination or ataxia that worsens as the finger approaches the target or if there is overshoot and the finger misses the target.
Sliding the heel along the shin from the knee cap to the ankle tests for similarly ataxic movements. Ask the patient to quickly place his hands palms up on his knees and then turn them over palms down as if playing patty cake.
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Cerebellar slowing and clumsiness of these rapid alternating movements is called what?
**dysdiadokinesia.**
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What happens when the midline portion of the cerebellum is affected?
the so-called **vermis**, commonly with alcoholism and also occasionally with stroke, _the patient develops an ataxic or drunken gait_. Mild versions of cerebellar ataxia are very common and tested by asking the patient to walk a straight line toe-heel tandem
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What are the primary sensory modalities?
Pain and temperature, light touch/pressure, vibration and proprioception which refers to joint position sense. These primary modalities are sent from the periphery to the brain for processing.
In the parietal cortex, this information is processed to make sense of the outside world and that cortical sensory capability is tested through graphesthesia, the ability to identify numbers or letters written on the palm of your hand while your eyes are closed, through stereognosis, the ability to identify objects by handling them with your fingers, and the detection that both sides of one’s body were touched simultaneously.
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Shown here are the sensory dermatomes.
Note C2 innervates the angle of the jaw. As mentioned earlier it should remain unaffected with damage to the trigeminal nerve causing facial sensory loss. Then note that C4 borders T2 anteriorly because a skip area is devoted to the arms. That is important to recognize when you are conducting a search for a spinal sensory level in this region with pin prick testing because you suspect spinal cord injury.
T4 is the nipple line. T10 is the belly button. L1 is the groin. L4 is the knee.
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One uses a safety pin to touch areas of the skin lightly with either the sharp end or the dull end. The patient should be able to identify which is which with his eyes closed or looking away. Check for the degree of sharpness felt in the peripheral extremities versus proximal parts of the limbs. **Neuropathy due to diabetes and many other conditions commonly presents with sensory loss in the periphery, the toes first and later the fingers**. March the pin up the dermatomes as shown in the previous figure to see if there is a sudden increase in sharpness. Finding a sensory level to pin prick and temperature (cold tuning fork) is a very important clue for spinal cord injury producing a neurological deficit in the limbs.
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An important thing to understand about the sensation of touch/pressure is that all the different sensory pathways participate in conveying this sensation to higher brain centers. What that means is that **touch has less localizing value than pain and temperature or vibration and position sense with spinal cord injury.**
Some physicians think that running one’s fingers up and down a person body to test for touch is an adequate screen that the spinal cord is not injured. **In fact a spinal cord level detectable by pin prick will be missed because touch will still be conveyed to the brain via the uninjured sensory pathways**. To test light touch, you can use your fingers or a cotton applicator. Ask the patient, whose eyes are closed, to identify where you touch and whether they recognize when you have touched them on both sides of the body.
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Many physicians place a vibrating tuning fork on a finger or toe, ask the patient if they feel it, and if they do, they are done. The proper way to test vibration sense is by placing the tuning fork **on the interphalangeal joint just below the finger tip or the big toe.** Put your finger underneath the joint and you should be able to feel the vibration through the joint. _Ask the patient when he no longer feels the vibration and hopefully you will lose the vibration at about the same time, assuming you have normal vibration sense_. **Patients with early neuropathy still have vibration sense and will feel it but they will stop feeling the vibration before you do when testing is done correctly, typically with a latency of a few seconds**
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To test position sense, steady the distal interphalangeal joint with your left hand and use your right to move the toe up and down. Hold the toe by the sides so that pressure applied is equal whether movement is up or down. If you grab the toe by the nailbed with one finger and the other side with your other finger, there will be pressure applied that is uneven and that pathway will be recruited to determine up and down movement rather than proprioception when the latter is damaged.
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What is a Romberg test?
**The Romberg tests the posterior columns in the spinal cord that carry position and vibration sensory information**. This is a valuable test in anyone who complains of unsteady gait especially in the dark.
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How is a Romberg test performed?
Ask the patient to stand with his feet close together and then to close his eyes. If there is swaying and a step to keep from falling, that suggests clinically relevant impairment of position sense.
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How would a pt with midline cerebellar lesions present on a Romberg tes?
They will show a drunken walk and will usually not be able to stand with their feet together. In that case, bring the feet apart just enough for them to stand without falling and eyes open. Then ask the patients to close their eyes. If they sway and almost fall, it indicates additional dysfunction of proprioception in the legs. As in the picture, be prepared to catch the patient if he suddenly starts to sway and fall.
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How can stereognosis be tested?
To check stereognosis, **the ability to identify objects and textures**, place a common item in the patient’s hand and ask him to identify it without looking at it. Keys, safety pins, coins are among the more common items used in testing.
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A stereognosis test tests what?
The integrity of the parietal lobe in processing sensory information.
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How is Graphesthesia tested?
By using a wooden cotton applicator to write numbers or letters on the palm of a patient’s hand and ask him to identify what is written without looking at it. The numbers should be written upright, not sideways, and the number of correct answers should be compared side to side. **Like sterognosis, this also tests cortical sensory processing.**
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The muscle stretch reflexes, formerly known as deep tendon reflexes, are tested with a reflex hammer. They can help localize a root level of injury when reduced. C6 for the biceps jerk, C7 for triceps, L4 for knee jerk, and S1 for the ankle jerk.
How are reflexes graded?
The reflexes are graded on a scale of 0 to 4. Zero means the reflex is completely absent, 1 is reduced, 2 is normal, 3 is brisk and 4 is so brisk that clonus can be induced.
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What is clonus?
Clonus refers to repetitive contractions when a tendon stretch is sustained. The best known is ankle clonus in which a stretch of the Achilles tendon by sudden ankle dorsiflexion will induce a repetitive ankle twitching
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What should be done if a reflex is absent?
If the reflex appears absent, one can employ a Jendrassik maneuver to augment the reflex response.
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How is Jendrassik maneuver done?
The patient is asked to clasp his hands and then pull them tightly apart. This action somehow increases the amount of inhibitory signal to the spinal cord reflex and causes the reflex to increase in size. It is similar to how a tense person might startle more if suddenly touched versus the same touch when that individual is calm. You can ask the patient to press the knees together and then check the reflexes in the upper limbs, again with the idea of exaggerating the muscle stretch reflex.
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What is a Babinski test?
The Babinski test is pathologic for **upper motor neuron disease when it elicits an extensor plantar response.**
The sole of the foot is stroked by the wooden end of that cotton applicator or another object that is somewhat sharp but not enough to injure the skin. Keys were once extensively used for this but that stopped due to concerns for transmitting HIV and Hepatitis C virus by inadvertent scraping that drew blood. Classically the little toes flare and the big one goes up. **The Babinski test is typically positive in instances of stroke, head trauma, spinal cord injury and anything that injures the CNS in a major way.**
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Gait is tested for posture and stance.
For example, you will hear about the stooped posture of Parkinson’s disease and wide based stance of cerebellar disease.
One checks for symmetry. for example a limping gait due to arthritic pain in one leg, dragging a leg due to stroke, foot drop due to peroneal nerve injury to mention some of the more common abnormalities. Steadiness of gait may be compromised due to Parkinson’s disease, muscle disease and many other conditions. Arm swing is typically still reduced on the side of weakness after stroke recovery. Turns may be “en block” that is stiff without fluid movement of the torso, head and neck, as seen in Parkinson’s disease. The usual screen for gait involves checking normal gait up and down the hall near the examining room, asking the patient to tiptoe, walk on his heels and perform toe-heel tandem gait
The length, speed and rhythm of steps are observed. With Parkinson’s disease as the example, the gait may be shuffling, show an initial “freezing” or “failure of ignition” and then be followed by festination, a sudden rapid series of small steps.
