Neurology

Question 1

In what common situation is a lumbar puncture contraindicated?

Answer 1

In the setting of acute head trauma, signs of intracranial hypertension (e.g., papilledema), or suspicion for subarachnoid hemorrhage. Do a lumbar tap only after you have a negative computed tomography (CT) or magnetic resonance imaging (MRI) scan of the head in these settings. Otherwise, you may cause uncal herniation and death

Question 2

What would you find in CSF analysis for a pt with bacterial meningitis? particularly cells, glucose, protein and pressure.

Answer 2

Cells >1000 (PMN) (normal 3), glucose <50 (normal is 50 - 100) Pressure >200mm Hg (normal 100 - 200mm Hg) Protein is >100 (normal 20 - 45) Note: Tuberculous and fungal meningitis have low cells(100), which are predominantly lymphocytes. In patients with fungal meningitis, a positive India ink preparation equals Cryptococcus neoformans.

Question 3

For a pt with viral meningitis what would you expect to find in CSF analysis. Particularly cells, glucose, protein and pressure.

Answer 3

Cells >100 Lymphocytes (normal 0-3), Glucose - normal (normal is 50 - 100 mg/dL), protein normal or slightly increased (20 - 45 mg/dL), pressure is normal or slightly increased. Note: Tuberculous and fungal meningitis have low glucose (100), which are predominantly lymphocytes. In patients with fungal meningitis, a positive India ink preparation equals Cryptococcus neoformans.

Question 4

For a patient with pseudotumor cerebi (idiopathic intracranial hypertension) what would you expect to find in analysis of their CSF cells, glucose, protein, pressure.

Answer 4

Cells normal (3mg/dL) glucose normal (50-100 mg/dL) protein normal (20-45 mg/dL) pressure >200 (100 - 200 mm Hg)

Question 5

For a patient with Guillain-Barré syndrome what would you expect to find in analysis of their CSF cells, glucose, protein, pressure.

Answer 5

Cells 100 lymphocytes (normal 3), glucose normal (50 - 100mg/dL) protein >100 (normal 20 - 45 mg/dL) pressure is normal (100 - 200 mm Hg)

Question 6

For a patient with cerebral haemorrhage what would you expect to find in analysis of their CSF cells, glucose, protein, pressure.

Answer 6

Cells - bloody (RBC) glucose normal (50 - 100 mg/dL) protein >45 mg/dL (normal 20 - 45 mg/dL) pressure >200 mm Hg.

Question 7

Give a classic case description of multiple sclerosis

Answer 7

Multiple sclerosis classically presents with an insidious onset of neurologic symptoms in white women aged 20 to 40 years with exacerbations and remissions. Common presentations include paresthesias and numbness, weakness and clumsiness, visual disturbances (decreased vision and pain caused by optic neuritis, diplopia as a result of cranial nerve involvement), gait disturbances, incontinence and urgency, and vertigo. Also look for emotional lability or other mental status changes. Internuclear ophthalmoplegia (a disorder of conjugate gaze in which the affected eye shows impairment of adduction) and scanning speech (spoken words are broken up into separate syllables separated by a noticeable pause and sometimes with stress on the wrong syllable) are classic; the patient may have a positive Babinski sign.

Question 8

What is the most sensitive test for diagnosis of multiple sclerosis? How is it treated?

Answer 8

MRI is the most sensitive diagnostic tool and shows demyelination plaques. Also look for increased IgG/oligoclonal bands and possibly myelin basic protein in the CSF. Treatment is not highly effective but includes interferon, glatiramer, mitoxantrone, natalizumab, cyclophosphamide, and methotrexate. Acute exacerbations are treated with glucocorticoids

Question 9

Define Guillain-Barré syndrome.

Answer 9

Guillain-Barré syndrome is a postinfectious polyneuropathy. Look for a history of mild infection (especially upper respiratory infection) or immunization roughly 1 week before onset of symmetric, distal weakness or paralysis with mild paresthesias that start in the feet and legs with loss of deep tendon reflexes in affected areas. The hallmark of the disease is that motor function is often affected with intact or only minimally impaired sensation. As the ascending paralysis or weakness progresses, respiratory paralysis may occur. Watch carefully; usually spirometry is performed to follow inspiratory ability. Intubation may be required. Diagnosis is by clinical presentation. CSF is usually normal except for markedly increased protein. Nerve conduction velocities are slowed. The disease usually resolves spontaneously. Plasmapheresis (for adults) and intravenous immune globulin (for children) reduce the severity and length of disease. Do not use steroids; they no longer have a role in the treatment of Guillain-Barré syndrome

Question 10

What causes nerve conduction velocity to be slowed?

Answer 10

Demyelination. Watch for Guillain-Barré syndrome and multiple sclerosis as causes

Question 11

What causes an electromyography (EMG) study to show fasciculations or fibrillations at rest?

Answer 11

A lower motor neuron lesion (i.e., a peripheral nerve problem).

Question 12

What causes an EMG study with no muscle activity at rest and decreased amplitude of muscle contraction upon stimulation

Answer 12

Intrinsic muscle disease such as the muscular dystrophies or inflammatory myopathies (e.g., polymyositis). You now know enough about EMG for the USMLE

Question 13

What is the most common cause of syncope? What other conditions should you consider?

Answer 13

Vasovagal syncope is the most common cause and classically is seen after stress or fear. Arrhythmias and orthostatic hypotension are also common. Consider hypoglycemia as a cause. The other main categories include: n Cardiac problems (arrhythmias, hypertrophic cardiomyopathy, valvular disease, tamponade). Always check an electrocardiogram (ECG). Further testing with echocardiography or treadmill stress testing can be performed based on the ECG findings and degree of suspicion. n Neurologic disorders (e.g., seizures, migraine headache, brain tumor). Consider an electroencephalogram or CT/MRI scan if history suggests seizures or intracranial lesion. n Vascular disease (consider transient ischemic attacks (TIAs) or carotid stenosis, which can be ruled out with carotid artery ultrasound/duplex scanning, although this is not a common cause of syncope). n Medication effects (e.g., anticholinergic agents, beta blockers, narcotics, vasodilators, alphaagonists, antipsychotics). As many as half of patients have syncope of unknown cause after a standard diagnostic evaluation

Question 14

For signs and symptoms of decreased or no reflexes, fasciculations, atrophy what area is most likely affected?

Answer 14

Lower motor neuron disease (or possibly muscle problem)

Question 15

For signs and symptoms of Hyperreflexia, clonus, increased muscle tone what area/areas are most likely affected?

Answer 15

Upper motor neuron lesion (cord or brain)

Question 16

For signs and symptoms of Apathy, inattention, disinhibition, labile affect what area is most likely to be affected?

Answer 16

Frontal lobes

Question 17

For signs and symptoms of Broca (motor) aphasia what area is most likely to be affected?

Answer 17

Dominant frontal lobe*

Question 18

For signs and symptoms of Wernicke (sensory) aphasia what area is most likely to be affected?

Answer 18

Dominant temporal lobe*

Question 19

For signs and symptoms of Memory impairment, hyperaggression, hypersexuality what areas are most likely to be affected?

Answer 19

Temporal lobes

Question 20

For Inability to read, write, name, or do math what area of the CNS is most likely affected?

Answer 20

Dominant parietal lobe*

Question 21

For Ignoring one side of body, trouble with dressing what are of the CNS is most likely affected?

Answer 21

Nondominant parietal lobe*

Question 22

For Visual hallucinations/illusions what area of the CNS is most likely affected?

Answer 22

Occipital lobes

Question 23

Lesions of which part of the brain can cause dysfunction to Cranial nerves III and IV

Answer 23

Midbrain

Question 24

Lesions of which part of the brain can cause dysfunction to Cranial nerves V, VI, VII, and VIII

Answer 24

Pons

Question 25

Lesions of which part of the brain can cause dysfunction to Cranial nerves IX, X, XI, and XII

Answer 25

Medulla

Question 26

Ataxia, dysarthria, nystagmus, intention, tremor, dysmetria, scanning speech can be caused by lesion of which part of the brain?

Answer 26

Cerebellum

Question 27

What are the classic differential points between delirium and dementia?

Answer 27

DELIRIUM DEMENTIA
Onset - Acute and dramatic - Chronic and insidious
Common causes -Illness, toxin, withdrawal -Alzheimer disease, multi-infarct
dementia, HIV/AIDS

Reversible - usually -usualy not
Attention - Poor -Usually unaffected
Arousal level -Fluctuates -Normal

Question 28

What symptoms and signs do delirium and dementia have in common?

Answer 28

Both may have hallucinations, illusions, delusions, memory impairment (usually global in delirium,
whereas remote memory is spared in early dementia), orientation difficulties (unawareness of time,
place, person), and “sundowning” (worse at night).

Question 29

Define pseudodementia.

Answer 29

Depression can cause some clinical symptoms and signs of dementia, classically in older adults.
This type of “dementia” is reversible with treatment. Step 2 questions will address other signs and
symptoms of depression (e.g., sadness, loss of loved one, weight or appetite loss, suicidal ideation,
poor sleep, feelings of worthlessness).

Question 30

What treatable causes of dementia must be ruled out?

Answer 30

The American Academy of Neurology recommends screening for B12 deficiency and hypothyroidism.
Other treatable causes of dementia that you might consider screening for but which do not have
clear data to support or refute screening in all patients with dementia include hyperhomocysteinemia,
endocrine disorders (thyroid and parathyroid), uremia, liver disease, hypercalcemia, syphilis, Lyme
disease, brain tumors, and normal-pressure hydrocephalus. Treatment of Parkinson disease may
reverse dementia if it is present.

Question 31

Define Wernicke encephalopathy and Korsakoff syndrome. What causes them?

Answer 31

Thiamine deficiency, classically in alcoholic patients, causes the acute delirium of Wernicke
encephalopathy, which results in ataxia, ophthalmoplegia, nystagmus, and confusion. If untreated,
this acute encephalopathy may progress to Korsakoff syndrome, which is characterized by memory
loss with confabulation; because patients cannot remember, they make things up. Korsakoff syndrome
usually is irreversible. Always give thiamine before glucose in an alcoholic patient to prevent
precipitating Wernicke encephalopathy.

Question 32

Differentiate among tension, cluster, and migraine headaches. How is each
treated?

Answer 32

Tension headaches are the most common; look for a long history of headaches and stress, plus a
feeling of tightness or stiffness, usually frontal or occipital and bilateral. Treat with stress reduction
and acetaminophen/nonsteroidal antiinflammatory drugs (NSAIDs).
Cluster headaches are unilateral, severe, and tender; they occur in clusters (e.g., three in 1 week,
then none for 2 months) and are usually accompanied by autonomic symptoms such as ptosis, lacrimation,
rhinorrhea, and nasal congestion. Supplemental oxygen and subcutaneous sumatriptan are first-line
therapy for acute attacks.
Migraine headaches classically are associated with an aura (a peculiar sensation, such as a
noise or a flash of light, that lets the patient know that an attack is about to start). Often signs and
symptoms include photophobia, nausea/vomiting, and a positive family history. Occasionally neurologic
symptoms are seen during attacks. Migraines usually begin between the ages of 10 and 30
years. Medications used for the acute treatment of migraines include NSAIDs, triptans, ergotamine,
and antiemetics. Prophylaxis can be achieved with beta blockers, tricyclic antidepressants, topiramate,
valproic acid, and calcium channel blockers.
18.

Question 33

How do you recognize a headache secondary to brain tumor or intracranial
mass?

Answer 33

By the presence of associated neurologic symptoms and signs of intracranial hypertension (papilledema;
nausea/vomiting, which may be projectile; and mental status changes or ataxia). The classic headache
occurs every day and is worse in the morning. Watch for a headache that wakes the patient from sleep.
Headaches from an intracranial mass get worse with a Valsalva maneuver, exertion, or sex. Obtain a CT
or MRI scan of the head.

Question 34

Define pseudotumor cerebri. How is it diagnosed and treated?

Answer 34

Pseudotumor cerebri is a fairly benign condition that can mimic a tumor because both cause intracranial
hypertension with papilledema and daily headaches that classically are worse in the morning and may
be accompanied by nausea and vomiting. The difference, however, is that pseudotumor cerebri usually is
found in young, obese females who are unlikely to have a brain tumor. Negative CT and MRI scans rule
out a tumor or mass. The main worrisome sequela is vision loss. Treatment is supportive; weight loss
usually helps, and repeated lumbar punctures or a CSF shunt may be needed. Large doses of vitamin A,
tetracyclines, and withdrawal from corticosteroids are possible causes of pseudotumor cerebri.

Question 35

How do you recognize a headache as a result of meningitis?

Answer 35

The adult patient has a fever,

Brudzinski sign [The classic Brudzinski sign refers to spontaneous flexion of the hips during attempted passive flexion of the neck]

or Kernig sign (The Kernig sign refers to the inability or reluctance to allow full extension of the knee when the hip is flexed 90 degrees. The Kernig test is usually performed in the supine position, but it can be tested in the seated patient.),

and positive CSF findings (the classic findings in bacterial meningitis are significantly elevated white blood cells, decreased glucose, protein around 100 mg/dL, and increased opening pressure) if a lumbar tap is done. Photophobia is also common.

Question 36

What causes the “worst headache” of a patient’s life?

Answer 36

This is a classic description for a subarachnoid hemorrhage. The most common causes are ruptured
congenital berry aneurysm or trauma. Look for blood around the brain or within sulci on a CT or MRI
scan or grossly bloody CSF on lumbar puncture. Treatment is supportive. Aneurysms require surgical
treatment to prevent rebleeding and death

Question 37

What are the common extracranial causes of headache?

Answer 37

Eye pain (optic neuritis, eye strain from refractive errors, iritis, glaucoma)
Middle ear pain (otitis media, mastoiditis)
Sinus pain (sinusitis)
Oral cavity pain (toothache)
Herpes zoster infection with cranial nerve involvement
Nonspecific headache (malaise from any illness, studying for the Step 2 examination)

Question 38

What does a lesion of the first cranial nerve (CN I) cause? What exotic
syndrome should you watch for clinically?

Answer 38

CN I lesions cause anosmia (inability to smell). Watch for Kallmann syndrome, which is anosmia plus hypogonadism caused by gonadotropin-releasing hormone deficiency.

Question 39

True or false: Brain lesions can be localized based on the visual field
defect.

Answer 39

True. Remember this stuff from basic science? Review it again for at least one easy point on the USMLE Step 2 (Fig. 23-1). If you really hate this stuff, at least remember bitemporal hemianopsia caused by an optic chiasm lesion, usually caused by a pituitary tumor.
VISUAL FIELD DEFECT LOCATION OF LESION

Right anopsia (monocular blindness) Right optic nerve

Bitemporal hemianopsia Optic chiasm classically caused by pituitary tumor

Left homonymous hemianopsia Right optic tract

Left upper quadrant anopsia Right optic radiations in the right temporal lobe

Left lower quadrant anopsia Right optic radiations in the right parietal lobe

Left homonymous hemianopsia with macular sparing is caused by right occipital lobe (from posterior cerebral artery
occlusion)

Question 40

How do you distinguish between a benign and serious cause of CN III deficit?

Answer 40

With benign causes (i.e., hypertension, diabetes) of a CN III palsy, the pupil is normal in size and reactive; no treatment is needed. With serious causes (i.e., aneurysm, tumor, uncal herniation), the pupil is dilated and nonreactive (“blown”). Urgent diagnosis and treatment are required. Additional neurologic symptoms also indicate a serious cause. The first step in serious cases is to obtain a CT or MRI scan of the head. Careful observation is preferred in benign cases. If the patient does not improve within a few months or does not have hypertension or diabetes, order a CT or MRI scan of the head to be sure.

Question 41

What does CN V (trigeminal nerve) innervate? What classic peripheral nerve
disorder affects its function?

Answer 41

CN V innervates the muscles of mastication and facial sensation, including the afferent limb of the corneal reflex. Watch for trigeminal neuralgia (tic douloureux), which classically is described as unilateral shooting pains in the face in older adults and often triggered by activity (e.g., brushing the teeth). This condition is best treated with antiepilepsy medications (e.g., carbamazepine). If the patient is younger and female or the symptoms are bilateral, consider multiple sclerosis and rule out
other causes, such as tumor or stroke.

Question 42

What structures does CN VII innervate? What is the difference between an
upper and lower motor neuron lesion of the facial nerve?

Answer 42

CN VII (facial nerve) innervates the muscles of facial expression, taste in the anterior two thirds of the tongue, skin of the external ear, lacrimal and salivary glands (except the parotid gland), and stapedius muscle. With an upper motor neuron lesion of CN VII, the forehead is spared on the affected side, and the cause is usually a stroke or tumor. With a lower motor neuron lesion, the forehead is involved on the affected side, and the cause is usually Bell palsy or tumor.

Question 43

What rare tumor is a classic cause of lower motor neuron lesions of CN VII and
CN VIII?

Answer 43

Cerebellopontine angle tumors (e.g., acoustic neuroma, classically seen in patients with neurofibromatosis).

Question 44

What problems other than facial droop affect patients with a CN VII lesion?

Answer 44

Patients may be unable to close their eyes. Give artificial tears to prevent corneal ulceration. Also watch for hyperacusis (quiet noises sound extremely loud) in Bell palsy as a result of stapedius muscle paralysis.

Question 45

Describe the function of the vestibulocochlear nerve (CN VIII). What symptoms
do lesions cause?

Answer 45

CN VIII is needed for hearing and balance. Lesions can cause deafness, tinnitus, and/or vertigo. In children, think of meningitis as a cause. In adults, symptoms may be caused by a toxin or medication (e.g., aspirin, aminoglycosides, loop diuretics, cisplatin), infection (labyrinthitis), tumor, or stroke

Question 46

What does the glossopharyngeal nerve (CN IX) innervate? What physical
findings are associated with a lesion?

Answer 46

CN IX innervates the pharyngeal muscles and mucous membranes (afferent limb of gag reflex), parotid gland, taste in the posterior third of the tongue, skin of the external ear, and the carotid body/sinus. With lesions (cause by stroke or tumor) look for loss of gag reflex and loss of taste in the posterior third of the tongue.

Question 47

Describe the function of the vagus nerve (CN X). Specify the physical findings
and causes of lesions.

Answer 47

CN X innervates muscles of the palate, pharynx, and larynx (efferent limb of gag reflex); taste buds in the base of the tongue; abdominal viscera; and skin of the external ear. Look for hoarseness, dysphagia, and loss of gag or cough reflex. Lesions are commonly a result of stroke, but do not forget aortic aneurysms or tumors (especially apical/Pancoast lung tumors) as a cause of recurrent laryngeal
nerve palsy and hoarseness.

Question 48

What muscles does the spinal accessory nerve (CN XI) innervate? How do you
know on which side the lesion is located?

Answer 48

CN XI innervates the sternocleidomastoid and trapezius muscles. Patients with CN XI lesions have trouble turning their heads to the side opposite the lesion and have ipsilateral shoulder droop

Question 49

What does a lesion of the hypoglossal nerve (CN XII) cause?

Answer 49

CN XII innervates the muscles of the tongue. A protruded tongue deviates to the same side as the lesion.

Question 50

Which vitamin deficiencies may present with neurologic signs or symptoms?

Answer 50

Vitamin B12: Dementia, peripheral neuropathy, loss of vibration sense in lower extremities, loss of position sense, ataxia, spasticity, hyperactive reflexes, and positive Babinski sign.

Thiamine: Peripheral neuropathy, confusion, ophthalmoplegia, nystagmus, ataxia, confusion, delirium, dementia.

Vitamin E: Loss of proprioception/vibratory sensation, areflexia, ataxia, and gaze palsy.

Vitamin A: Vision loss.

Vitamin B6: Peripheral sensory neuropathy (watch for isoniazid as a cause, and give prophylactic B6 to patients taking isoniazid, if given the choice).

Question 51

What are the six general types of seizures that you should be able to
recognize?

Answer 51

Simple partial (focal seizures with retained awareness)
Complex partial (focal seizures with lose of awareness)
Absence (petit mal)
Tonic-clonic
Febrile
Secondary

Question 52

Describe a simple partial seizure (focal seizure with no lose of consciousness) . How is it treated?

Answer 52

Simple partial (local or focal) seizures may be motor (e.g., Jacksonian march), sensory (e.g., hallucinations), or psychic (cognitive or affective symptoms). The key point is that consciousness is not impaired. The first-line agents for treatment are carbamazepine, lamotrigine, oxcarbazepine, and levetiracetam.

Question 53

Describe complex partial seizures. How are they treated?

Answer 53

Complex partial, focal seizure with lose of consciousness (psychomotor) seizures are any simple partial seizure followed by impairment of consciousness. Patients perform purposeless movements and may become aggressive if restraint is attempted (however, people who get in fights or kill other people are not having a seizure). The firstline agents for treatment are valproate, lamotrigine, and levetiracetam

Question 54

Give the classic description of an absence seizure.

Answer 54

Absence (petit mal) seizures do not begin after the age of 20 years. They are brief (10 to 30 seconds in duration), generalized seizures in which the main manifestation is loss of consciousness, often with eye or muscle fluttering. The classic description is a child in a classroom who stares into space in the middle of a sentence, then 20 seconds later resumes the sentence where he left off. The child is not daydreaming; he or she is having a seizure. There is no postictal state (an important differential
point). The first-line treatment agents are ethosuximide and valproate

Question 55

How do you recognize a tonic-clonic seizure?

Answer 55

Tonic-clonic (grand mal) seizures are the classic seizures that we knew about before we went to medical school. They may be associated with an aura. Tonic muscle contraction is followed by clonic contractions, usually lasting 2 to 5 minutes. Associated symptoms may include incontinence and tongue lacerations. The postictal state is characterized by drowsiness, confusion, headache, and muscle soreness. The first-line agents for treatment are valproate, lamotrigine, or levetiracetam.

Question 56

Define febrile seizure.

Answer 56

Children between the ages of 6 months and 5 years may have a seizure caused by fever. Always assume another cause outside this age range. The seizure is usually of the tonic-clonic, generalized type. No specific seizure treatment is required, but you should treat the underlying cause of the fever, if possible, and give acetaminophen to reduce fever. Such children do not have epilepsy, and the
chances of their developing it are just barely higher than in the general population. Make sure that the child does not have meningitis, tumor, or another serious cause of the seizure. The Step 2 question will give clues in the case description if you should pursue work-up for a serious condition.

Question 57

What are the common causes of secondary seizures? How are they treated?

Answer 57

Mass effect (tumor [Fig. 23-2], hemorrhage)
Metabolic disorder (hypoglycemia, hypoxia, phenylketonuria, hyponatremia)
Toxins (lead, cocaine, carbon monoxide poisoning)
Drug withdrawal (alcohol, barbiturates, benzodiazepines, withdrawing anticonvulsants too rapidly)
Cerebral edema (severe or malignant hypertension; also watch for pheochromocytoma and eclampsia)
Central nervous system (CNS) infections (meningitis, encephalitis, toxoplasmosis
Trauma
Stroke

Treat the underlying disorder and use a benzodiazepine (lorazepam or diazepam) and/or phenytoin or
fosphenytoin acutely to control seizures. For all seizures (primary or secondary), secure the airway,
and, if possible, roll the patient onto his or her side to prevent aspiration.

Question 58

Define status epilepticus. How is it treated?

Answer 58

Status epilepticus is defined as a seizure that lasts for a sufficient length of time (usually 30 minutes or longer) or is repeated frequently enough that the individual does not regain consciousness between seizures. Status epilepticus may occur spontaneously or result from withdrawing anticonvulsants too rapidly. Treat with intravenous lorazepam. Give fosphenytoin if the seizures persist. As with all seizures, remember your ABCs (airway, breathing, circulation). Protect the airway. Intubate if necessary, and roll the patient on his or her side to prevent aspiration.

Question 59

True or false: Hypertension can cause seizures

Answer 59

True. Remember hypertension as a cause of seizures or convulsions, headache, confusion, stupor, and mental status changes

Question 60

What do you need to remember when giving anticonvulsants to women?

Answer 60

All anticonvulsants are teratogenic, and women of reproductive age need counseling about the risks of pregnancy. Do a pregnancy test before starting an anticonvulsant and offer birth control. Valproic acid is a major contributor to the risk. Polypharmacy increases the risk. There is limited human information of the risks to the fetus with the newer antiepileptic medications.

Question 61

What causes strokes? How common are they?

Answer 61

Cerebrovascular disease (stroke) is the most common cause of neurologic disability in the United States—and the third leading cause of death. Ischemia as a result of atherosclerosis (atherothrombotic ischemia) is by far the most common type of stroke (more than 85% of cases). Hypertension is another cause of stroke and typically causes hemorrhagic stroke, most commonly in the basal ganglia, thalamus, or cerebellum. With this in mind, be aware of more exotic causes of stroke, such as
atrial fibrillation with resultant clot formation and emboli to the brain, septic emboli from endocarditis, and sickle cell disease.

Question 62

How is an acute stroke treated?

Answer 62

Treatment for an acute stroke in evolution is supportive (e.g., airway, oxygen, intravenous fluids). The first step is to obtain a CT scan of the head without contrast to evaluate for bleeding or mass (Fig. 23-4). If no blood is seen on the CT scan, aspirin or clopidogrel is usually the medication of choice. Heparin is not recommended for the treatment of acute ischemic stroke and should be avoided as a choice
on the USMLE. Chapter 39 (“Vascular Surgery”) discusses the role of carotid endarterectomy, which is not done emergently. Thrombolysis with tPA (tissue plasminogen activator e.g. Alteplase) can be attempted if patients come to the hospital within 3 hours (up to 4.5 hours in certain circumstances) and meet strict criteria for its use.

Question 63

Define TIA. How is it managed?

Answer 63

TIA is a brief episode of neurologic dysfunction resulting from temporary cerebral ischemia not associated with cerebral infarction. This newer definition is tissue-based rather than time-based. TIA is often a precursor to stroke and is caused by ischemia. The classic presentation is ipsilateral blindness (amaurosis fugax) and/or unilateral hemiplegia (paralyses), hemiparesis (weakness), weakness, or clumsiness that lasts less than 5 minutes. Order a carotid duplex scan to look for carotid stenosis. The correct choice for long-term therapy is aspirin and antiplatelet medications. Choose carotid endarterectomy over aspirin if the degree of carotid stenosis is 70% to 99%.

Question 65

Describe the signs and symptoms of Huntington disease. How is it acquired?
What is the classic CT finding?

Answer 65

Huntington disease is an autosomal dominant condition that usually presents between the ages of 35 and 50 years. Look for choreiform movements (irregular, spasmodic, involuntary movements of the limbs or facial muscles) and progressive intellectual deterioration, dementia, or psychiatric disturbances. Atrophy of the caudate nuclei may be seen on CT or MRI scan. Treatment is supportive; tetrabenazine or atypical neuroleptics (olanzapine, risperidone, or aripiprazole) may help with the chorea and agitation/psychosis.

Question 66

# Define Parkinson disease. How do you recognize it on the Step 2
examination?

Answer 66

Parkinson disease has a classic tetrad of (1) slowness or poverty of movement, (2) muscular (“lead pipe” and “cog-wheel”) rigidity, (3) “pill-rolling” tremor at rest (which disappears with movement and sleep), and (4) postural instability (manifested by the classic shuffling gait and festination). Patients may also have dementia and depression. The mean age of onset is around 60 years.

Question 67

Describe the pathophysiology of Parkinson disease. How is it treated
pharmacologically?

Answer 67

The cause is thought to be a loss of dopaminergic neurons, especially in the substantia nigra, which project to the basal ganglia. The result is decreased dopamine in the basal ganglia. Drug therapy, which aims to increase dopamine, includes dopamine precursors (levodopa with carbidopa), dopamine agonists (bromocriptine, apomorphine, pergolide, pramipexole, and ropinirole), monoamine oxidase-B inhibitors (selegiline), COMT inhibitors (entacapone and tolcapone), anticholinergics
(trihexyphenidyl and benztropine), and amantadine

Question 68

What is the classic iatrogenic cause of parkinsonian signs and symptoms

Answer 68

Antipsychotics may cause parkinsonian symptoms in schizophrenic patients. This is a favorite Step 2 question. Treat this side effect of antipsychotic medication with anticholinergics (benztropine, trihexyphenidyl) or antihistamines (diphenhydramine).

Question 69

What brain lesions cause a resting tremor and an intention tremor? What
about hemiballismus?

Answer 69

A resting tremor, if caused by a brain lesion, is generally a sign of basal ganglia disease, as is chorea. An intention tremor is usually a result of cerebellar disease. Hemiballismus (random, violent, unilateral flailing of the limbs) is classically caused by a lesion in the subthalamic nucleus.

Question 70

What conditions other than Parkinson disease cause a resting tremor?

Answer 70

A resting tremor may be caused by hyperthyroidism, anxiety, drug withdrawal or intoxication, or benign (essential) hereditary tremor. Benign hereditary tremor is usually autosomal dominant; look for a positive family history and use beta blockers to reduce the tremor. Also watch for Wilson disease (hepatolenticular degeneration), which can cause chorea-like movements; asterixis (slow, involuntary flapping of outstretched hands) may be seen in patients with liver failure.

Question 71

What diseases should come to mind in children with cerebellar findings?

Answer 71

Brain tumor (cerebellar astrocytoma, medulloblastomas)

Hydrocephalus (enlarging head in an infant younger than age 6 months, Arnold-Chiari or Dandy-Walker malformations)

Friedreich ataxia (starts between ages 5 and 15 years; autosomal recessive; look for areflexia, loss of vibration/position sense, and cardiomyopathy)

Ataxia-telangiectasia (progressive cerebellar ataxia, oculocutaneous telangiectasias, and immune deficiency)

Question 72

What diseases should come to mind in adults with cerebellar findings?

Answer 72

Alcoholism, brain tumor, ischemia or hemorrhage, and multiple sclerosis

Question 73

How do you recognize amyotrophic lateral sclerosis (ALS) on the Step 2
examination?

Answer 73

ALS (Lou Gehrig disease) is the only condition that you are likely to be asked about that causes both upper and lower motor neuron lesion signs and symptoms. This idiopathic neurodegenerative disease is more common in men, and the mean age at onset is 55 years. The key is to notice a combination of upper motor neuron lesion signs (spasticity, hyperreflexia, positive Babinski sign) and lower motor neuron lesion signs (fasciculations, atrophy, flaccidity) present at the same time. Treatment is supportive. Fifty percent of patients die within 3 years of disease onset.

Question 74

What are the two classic causes of a “floppy” (flaccid) baby? How do you
differentiate the two?

Answer 74

Genetic disorders, the most common of which is Werdnig-Hoffmann disease (WHD), and infant botulism. History easily differentiates the two. WHD is an autosomal recessive degeneration of anterior horn cells in the spinal cord and brainstem (lower motor neuron disease). Most infants are hypotonic
at birth, and all are affected by 6 months. Look for a positive family history and a long, slowly progressive disease course. Treatment is supportive only.
Infant botulism is caused by a Clostridium botulinum toxin. Look for sudden onset and a history of ingesting honey or other home-canned foods. Diagnosis is made by finding C. botulinum toxin or organisms in the feces. Treatment involves inpatient monitoring and support with a close watch of respiratory status. The child may need intubation for respiratory muscle paralysis. Spontaneous recovery usually occurs within 1 week, and supportive care is all that is needed.

Question 75

List the causative categories of peripheral neuropathy and give examples of
each.

Answer 75

Metabolic/endocrine: Diabetes mellitus (autonomic and sensory neuropathy), uremia, hypothyroidism.

Nutritional: Deficiencies of vitamin B12, vitamin B6 (look for history of isoniazid), thiamine (“dry” beriberi), and vitamin E.

Toxins/medications: Lead (the classic symptom is wrist drop or foot drop; look for coexisting CNS or abdominal symptoms) or other heavy metals, isoniazid, vincristine, ethambutol (optic neuritis), aminoglycosides (especially CN VIII).

Immunization and autoimmune disorders: Guillain-Barré syndrome, lupus erythematosus, polyarteritis nodosa, scleroderma, sarcoidosis, amyloidosis.

Trauma: Carpal tunnel syndrome (entrapment of the median nerve at the wrist; usually caused by repetitive physical activity but may be a presentation of acromegaly or hypothyroidism; look for positive Tinel and Phalen signs), pressure paralysis (radial nerve palsy in alcoholics), fractures (causing nerve compression).

Infectious: Lyme disease, diphtheria, HIV, leprosy.

Question 76

What test can be used to prove the presence of a peripheral neuropathy,
regardless of etiology?

Answer 76

Nerve conduction velocity is slowed with a peripheral neuropathy

Question 77

Describe the pathophysiology of myasthenia gravis (MG). Who is affected?
What are the classic physical findings?

Answer 77

MG is an autoimmune disease that destroys acetylcholine receptors. Most patients have antibodies to acetylcholine receptors in their serum. The disease usually presents in women between the ages of 20 and 40 years. Look for ptosis, diplopia, and general muscle fatigability, especially toward the end of the day or with repetitive use.

Question 78

How is MG diagnosed? What tumor is associated with it?

Answer 78

Diagnosis is made with the Tensilon test. After injection of edrophonium (Tensilon), a short-acting anticholinesterase inhibitor, muscle weakness improves. Nerve stimulation studies can also be used. Watch for associated thymomas (a tumor of the thymus). Thymectomy is generally recommended for patients younger than age 60 years without thymoma. Long-term medical treatment consists of long-acting anticholinesterase inhibitors (pyridostigmine) and immunotherapy (glucocorticoids,
mycophenolate, azathioprine, and cyclosporine).

Question 79

What three conditions may cause an MG-like clinical picture?

Answer 79

1. Eaton-Lambert syndrome is a paraneoplastic syndrome (classically seen with small cell lung cancer) associated with muscle weakness. The extraocular muscles are spared, whereas MG almost always is characterized by prominent involvement of extraocular muscles. Eaton-Lambert syndrome has a different mechanism of action (impaired release of acetylcholine from nerves) and a differential response to repetitive nerve stimulation. The weakness in MG worsens with repetitive
   use or stimulation, whereas the weakness in Eaton-Lambert syndrome improves.
2. Organophosphate poisoning also causes MG-like muscle weakness. Poisoning usually is caused by agricultural exposure. Look for symptoms of parasympathetic excess (e.g., miosis, excessive bronchial secretions, urinary urgency, diarrhea). Edrophonium causes worsening of the muscular weakness. Treat with atropine and pralidoxime.
3. Aminoglycosides in high doses may cause MG-like muscular weakness and/or prolong the effects of muscular blockade after anesthesia

Question 80

What is the most common type of muscular dystrophy? How is it inherited?
What are the classic findings?

Answer 80

The most common type is Duchenne muscular dystrophy, an X-linked recessive disorder of dystrophin that usually presents in boys between the ages of age 3 and 7. Look for muscle weakness, markedly elevated levels of creatine phosphokinase, pseudohypertrophy of the calves (caused by fatty and fibrous infiltration of the degenerating muscle), and often a lower-than-normal IQ. Gower sign is also classic:
the patient “walks” his hands and feet toward each other to rise from a prone position (Fig. 23-5). Muscle biopsy establishes the diagnosis. Treatment is supportive. Most patients die by age 20.

Question 81

List the five less common types of muscular dystrophies

Answer 81

1. Becker muscular dystrophy: Also an X-linked recessive dystrophin disorder but milder.
2. Facioscapulohumeral dystrophy: An autosomal dominant disorder that affects the areas in the name (face, shoulder girdle). Symptoms begin between the age of 7 and 20 years. Life expectancy is normal.
3. Limb-girdle dystrophy: Affects pelvic and shoulder muscles; begins in adulthood.
4. Mitochondrial myopathies: Of interest because they are inherited mitochondrial defects (passed only from mother to offspring; cannot be transmitted by men). The key phrase is “ragged red fibers” on biopsy specimen. Ophthalmoplegia is usually present.
5. Myotonic dystrophy: An autosomal dominant disorder that presents between the ages of 20 and 30 years. Myotonia (inability to relax muscles) classically presents as an inability to relax the grip or release a handshake. Look for coexisting mental retardation, baldness, and testicular or ovarian atrophy. Treatment is supportive, including genetic counseling. The diagnosis is clinical.

Question 82

What class of inherited metabolic disorders affects muscle and may resemble
muscular dystrophy?

Answer 82

The rare glycogen storage diseases (autosomal recessive inheritance) can cause muscular weakness, especially McArdle disease, a deficiency in glycogen phosphorylase that is relatively mild and presents with weakness and cramping after exercise as a result of lactic acid build-up.