Neurology/Neurosurgery

Question 1

In what common situation is a lumbar puncture contraindicated and why?

Answer 1

When there are signs of intracranial hypertension (e.g., papilledema), or suspicion for subarachnoid hemorrhage; doing so may cause uncal herniation and death.

Do a lumbar tap only after you have a negative CT or MRI of the head in these settings.

Question 2

Describe the classic findings of cerebrospinal fluid (CSF) analysis in normal CSF in terms of

cells

glucose

protein

pressure

Answer 2

Cells: 0-3 lymphocytes/mL

Glucose: 50-100 mg/dL

Protein: 20-45 mg/dL

Pressure: 100-200 mmHg

Question 3

Describe the classic findings of cerebrospinal fluid (CSF) analysis in bacterial meningitis in terms of

cells

glucose

protein

pressure

Answer 3

Cells: >1000 PMN/mL (normal = 0-3 lymphocytes/mL)

Glucose: <50 mg/dL (normal = 50-100 mg/dL)

Protein: 100 mg/dL (normal = 20-45 mg/dL)

Pressure: >200 mmHg (normal = 100-200 mmHg)

Question 4

Describe the classic findings of cerebrospinal fluid (CSF) analysis in viral/aseptic meningitis in terms of

cells

glucose

protein

pressure

Answer 4

Cells: >100 lymphocytes/mL (normal = 0-3 lymphocytes/mL)

Glucose: normal mg/dL (normal = 50-100 mg/dL)

Protein: normal/slightly increased (normal = 20-45 mg/dL)

Pressure: Normal/slightly increased (normal = 100-200 mmHg)

Question 5

Describe the classic findings of cerebrospinal fluid (CSF) analysis in pseudotumor cerebri in terms of

cells

glucose

protein

pressure

Answer 5

Cells: normal (normal = 0-3 Leukocytes/mL)

Glucose: normal (normal = 50-100 mg/dL)

Protein: normal (normal = 20-45 mg/dL)

Pressure: >200 mmHg (normal = 100-200 mmHg)

Question 6

Describe the classic findings of cerebrospinal fluid (CSF) analysis in Guillain-Barre syndrome in terms of

cells

glucose

protein

pressure

Answer 6

Cells: 0-100 lymphocytes/mL (normal 0-3 lymphocytes/mL)

Glucose: normal (normal = 50-100 mg/dL)

Protein: >100 (normal = 20-45 mg/dL)

Pressure: normal (normal = 100-200 mmHg)

Question 7

Describe the classic findings of cerebrospinal fluid (CSF) analysis in cerebral hemorrhage in terms of

cells

glucose

protein

pressure

Answer 7

Cells: ++RBC (normal = 0-3 Leukocytes/mL)

Glucose: normal (normal = 50-100 mg/dL)

Protein: >45 (normal = 20-45 mg/dL)

Pressure: >200 (normal = 100-200 mmHg)

Question 8

Describe the classic findings of cerebrospinal fluid (CSF) analysis in multiple sclerosis in terms of

cells

glucose

protein

pressure

Answer 8

Cells: normal/slightly increased (normal = 0-3 Leukocytes/mL)

Glucose: normal (normal = 50-100 mg/dL)

Protein: normal/slightly increased (normal = 20-45 mg/dL)

Pressure: normal (normal = 100-200 mmHg)

Question 9

Give a classic case description of multiple sclerosis.

Answer 9

insidious onset in white women aged 20 - 40 yo with exacerbations and remissions; common presentations

• paresthesias and numbness
• weakness and clumsiness
• visual disturbances (decreased vision + pain caused by optic neuritis, diplopia as a result of cranial nerve involvement)
• gait disturbances
• incontinence and urgency
• vertigo
• emotional lability or other mental status changes
• Internuclear ophthalmoplegia (disconjugate gaze in which the affected eye shows impairment of adduction)
• scanning speech (spoken words are broken up into separate syllables separated by a noticeable pause and sometimes with stress on the wrong syllable)
• possible Babinski sign

Question 10

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

How is it treated?

How are acute exacerbations treated?

Answer 10

MRI - (most sensitive) - shows demyelination plaques

LP - IgG/oligoclonal bands and myelin basic protein in CSF

Treatment: interferon, glatiramer, mitoxantrone, natalizumab, cyclophosphamide, methotrexate.

Acute exacerbations: glucocorticoids

Question 11

What is Guillain-Barré syndrome?

What is the typical history a patient presents with?

How do these patients present?

How do you diagnose this?

Treatment?

Answer 11

GBS = postinfectious polyneuropathy.

History: history of mild infection (especially URI) or immunization roughly 1 week prior to onset of symptoms

Presentation:

• symmetric weakness/paralysis + loss of deep tendon reflexes + mild paresthesias that begin in the feet/legs
  
  • loss of motor function with intact/minimally impaired sensation *hallmark*
• As the ascending paralysis or weakness progresses, respiratory paralysis may occur.
• Spirometry is performed to follow inspiratory ability; Intubation may be required.

Diagnosis: made by clinical presentation, but supportive tests can confirm the diagnosis

• LP CSF is normal except for markedly increased protein
• Nerve conduction velocities are slowed.

Treatment: usually resolves spontaneously, but plasmapheresis (for adults) and IVIg (for children) reduce the severity and length of disease.

Question 12

What causes nerve conduction velocity to be slowed?

What are two potential causes of this?

Answer 12

Demyelination.

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

Question 13

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

Answer 13

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

Question 14

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

Answer 14

Intrinsic muscle disease such as the muscular dystrophies or inflammatory myopathies (e.g., polymyositis).

Question 15

What is the most common cause of syncope?

What other conditions should you consider?

Answer 15

• Vasovagal syncope - most common; classically is seen after stress or fear.
• Arrhythmias and orthostatic hypotension - also common.
• Hypoglycemia
• Cardiac problems (arrhythmias, hypertrophic cardiomyopathy, valvular disease, tamponade)
• Neurologic disorders (seizures, migraines, brain tumor)
• Vascular disease (TIA, carotid stenosis)
• Medications (anticholinergic agents, ß blockers, narcotics, vasodilators, alpha-agonists, antipsychotics).
• idiopathic

Question 16

localize the neurologic lesion for: Decreased or no reflexes, fasciculations, atrophy

Answer 16

Lower motor neuron disease (or possibly muscle problem)

Question 17

localize the neurologic lesion for: Hyperreflexia, clonus, increased muscle tone

Answer 17

Upper motor neuron lesion (cord or brain)

Question 18

localize the neurologic lesion for: Apathy, inattention, disinhibition, labile affect

Answer 18

Frontal lobes

Question 19

localize the neurologic lesion for: Broca (motor) aphasia

Answer 19

Dominant frontal lobe*

(*The left side is dominant in more than 95% of the population (99% of right-handed people and 60% to 70% of left-handed people)

Question 20

localize the neurologic lesion for: Wernicke (sensory) aphasia

Answer 20

Dominant temporal lobe*

(*The left side is dominant in more than 95% of the population (99% of right-handed people and 60% to 70% of left-handed people)

Question 21

localize the neurologic lesion for: Memory impairment, hyperaggression, hypersexuality

Answer 21

Temporal lobes

Question 22

localize the neurologic lesion for: Inability to read, write, name, or do math

Answer 22

Dominant parietal lobe*

(*The left side is dominant in more than 95% of the population (99% of right-handed people and 60% to 70% of left-handed people)

Question 23

localize the neurologic lesion for: Ignoring one side of body, trouble with dressing

Answer 23

Nondominant parietal lobe*

(*The left side is dominant in more than 95% of the population (99% of right-handed people and 60% to 70% of left-handed people)

Question 24

localize the neurologic lesion for: Visual hallucinations/illusions

Answer 24

Occipital lobes

Question 25

localize the neurologic lesion for: Cranial nerves III and IV

Answer 25

Midbrain

Question 26

Where do cranial nerves V, VI, VII, and VIII originate from?

Answer 26

Pons

Question 27

Where do Cranial nerves IX, X, XI, and XII originate from?

Answer 27

Medulla

Question 28

localize the neurologic lesion for: Ataxia, dysarthria, nystagmus, intention, tremor, dysmetria, scanning speech

Answer 28

Cerebellum

Question 29

For delirious or unconscious patients in the ED with no history of trauma, for what three common causes should you think about giving empirical treatment?

Answer 29

• Hypoglycemia (give glucose)
• Opioid overdose (give naloxone)
• Thiamine deficiency (give thiamine before giving glucose in a suspected alcoholic patient)
• Other common causes: alcohol, illicit drugs, prescription drugs, diabetic ketoacidosis, stroke, and epilepsy or postictal state.

Question 30

What are the classic differential points between delirium and dementia in terms of

onset

common causes

reversibility

attention

arousal level

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

Answer 30

Common:

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

Question 31

What is pseudodementia?

What is a common cause?

Answer 31

Depression can cause some clinical symptoms and signs of dementia, classically in older adults; reversible with treatment.

^{note: 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 32

What 2 major treatable causes of dementia must be ruled out?

Answer 32

B12 deficiency

hypothyroidism

Other

• hyperhomocysteinemia
• endocrine disorders (thyroid and parathyroid)
• uremia
• liver disease
• hypercalcemia
• syphilis
• Lyme disease
• brain tumors
• normal-pressure hydrocephalus
• Parkinsons

Question 33

Define Wernicke encephalopathy and Korsakoff syndrome.

What causes them?

How do you treat them?

Answer 33

Thiamine deficiency, classically in alcoholic patients

Causes Wernicke encephalopathy (acute delirium, ataxia, ophthalmoplegia, nystagmus, and confusion).

If untreated, it may progress to Korsakoff syndrome (memory loss, confabulation).

Always give thiamine before glucose in an alcoholic patient to prevent precipitating Wernicke encephalopathy.

Question 34

Differentiate among tension, cluster, and migraine headaches.

How is each treated?

Answer 34

Tension headaches - most common

• feeling of tightness or stiffness, usually frontal or occipital and bilateral
• Trmt: stress reduction NSAIDs

Cluster headaches

• unilateral, severe, and tender
• occur in clusters (e.g., three in 1 week, then none for 2 months)
• (+) autonomic symptoms such as ptosis, lacrimation, rhinorrhea, and nasal congestion.
• Trmt: O2 + sub-cu sumatriptan

Migraine headaches

• (+) aura
• photophobia
• nausea/vomiting
• (+) family history
• begin between the ages of 10 - 30 yo
• Acute trmt: NSAIDs, triptans, ergotamine, and antiemetics
• Prophylactic trmt: ß blockers, TCA, topiramate, valproic acid, and Ca channel blockers

Question 35

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

Answer 35

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: worse with a Valsalva maneuver, exertion, or sex.

Obtain a CT or MRI scan of the head.

Question 36

Define pseudotumor cerebri.

How do you differentiate it from an actual brain tumor?

What causes it?

How is it diagnosed and treated?

What is the main worrisome sequelae?

Answer 36

cause of intracranial HTN + papilledema + daily headaches that classically are worse in the morning and may be accompanied by N/V. Its presentation can mimic a tumor but the difference is that pseudotumor cerebri is usually found in young, obese females who are unlikely to have a brain tumor.

Causes: Large doses of vitamin A, tetracyclines, steroid withdrawal

Diagnosis: Negative CT and MRI scans rule out a tumor or mass.

Treatment: supportive; weight loss, and repeated LP or a CSF shunt may be needed to reduce ICP.

The main worrisome sequela is vision loss.

Question 37

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

Answer 37

• fever
• Brudzinski sign or Kernig sign
• (+) CSF findings (elevated WBC, decreased glucose, protein around 100 mg/dL, and increased opening pressure)
• Photophobia

Question 38

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

What are the common causes of this?

How do you diagnose this?

Answer 38

subarachnoid hemorrhage

common causes: ruptured congenital berry aneurysm or trauma

diagnosis: blood around the brain or within sulci on a CT or MRI scan, grossly bloody CSF on lumbar puncture

Trmt: supportive; aneurysms require surgical treatment to prevent rebleeding and death.

Question 39

What are the common extracranial causes of headache?

Answer 39

• 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 40

What does a lesion of the first cranial nerve (CN I) cause?

What exotic syndrome should you watch for clinically and what causes it?

Answer 40

CN I lesions cause anosmia (inability to smell).

Watch for Kallmann syndrome, which is anosmia + hypogonadism caused by GnRH deficiency.

Question 41

localize the lesion for a visual field defect of: Right anopsia (monocular blindness)

Answer 41

Right optic nerve

Question 42

localize the lesion for a visual field defect of: Bitemporal hemianopsia

Answer 42

Optic chiasm (classically caused by pituitary tumor)

Question 43

localize the lesion for a visual field defect of: Left homonymous hemianopsia

Answer 43

Right optic tract

Question 44

localize the lesion for a visual field defect of: Left upper quadrant anopsia

Answer 44

Right optic radiations in the right temporal lobe

Question 45

localize the lesion for a visual field defect of: Left lower quadrant anopsia

Answer 45

Right optic radiations in the right parietal lobe

Question 46

localize the lesion for a visual field defect of: Left homonymous hemianopsia with macular sparing

Answer 46

Right occipital lobe (from posterior cerebral artery occlusion)

Question 47

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

What are the treatments needed for each?

Answer 47

With benign causes (i.e., hypertension, diabetes), the pupil is normal in size and reactive

• Observation; 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.

With serious causes (i.e., aneurysm, tumor, uncal herniation), the pupil is dilated and nonreactive with additional neurological signs present

• Get CT or MRI scan of the head, stat

Question 48

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

Answer 48

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 49

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

Answer 49

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 50

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

Answer 50

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 51

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

Answer 51

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

Question 52

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

Answer 52

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 53

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

Answer 53

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 54

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

Answer 54

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, dyspha- gia, 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 55

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

Answer 55

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 56

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

Answer 56

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

Question 57

Which vitamin deficiencies may present with neurologic signs or symptoms?

Answer 57

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Question 58

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

Answer 58

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Question 59

Describe a simple partial seizure. How is it treated?

Answer 59

Simple partial (local or focal) seizures may be motor (e.g., Jacksonian march), sensory (e.g., hal- lucinations), 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 60

Describe complex partial seizures. How are they treated?

Answer 60

Complex partial (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 first- line agents for treatment are valproate, lamotrigine, and levetiracetam.

Question 61

Give the classic description of an absence seizure.

Answer 61

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 62

How do you recognize a tonic-clonic seizure?

Answer 62

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 63

Define febrile seizure.

Answer 63

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 ques- tion will give clues in the case description if you should pursue work-up for a serious condition.

Question 64

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

Answer 64

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Question 65

Define status epilepticus. How is it treated?

Answer 65

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 conscious- ness 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 66

True or false: Hypertension can cause seizures.

Answer 66

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

Question 67

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

Answer 67

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 68

What causes strokes? How common are they?

Answer 68

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 (atherothrom- botic 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 gan- glia, 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 69

How is an acute stroke treated?

Answer 69

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 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) 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 70

Define TIA. How is it managed?

Answer 70

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, hemiparesis, 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 71

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

Answer 71

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 dis- turbances. 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 72

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

Answer 72

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 73

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

Answer 73

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), mono- amine oxidase-B inhibitors (selegiline), COMT inhibitors (entacapone and tolcapone), anticholinergics (trihexyphenidyl and benztropine), and amantadine.

Question 74

What is the classic iatrogenic cause of parkinsonian signs and symptoms?

Answer 74

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 75

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

Answer 75

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, unilat- eral flailing of the limbs) is classically caused by a lesion in the subthalamic nucleus.

Question 76

What conditions other than Parkinson disease cause a resting tremor?

Answer 76

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 77

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

Answer 77

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Question 78

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

Answer 78

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

Question 79

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

Answer 79

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 sup- portive. Fifty percent of patients die within 3 years of disease onset.

Question 80

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

Answer 80

Genetic disorders, the most common of which is Werdnig-Hoffmann disease (WHD), and infant botu- lism. 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 pro- gressive 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 81

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

Answer 81

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Question 82

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

Answer 82

Nerve conduction velocity is slowed with a peripheral neuropathy.

Question 83

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

Answer 83

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 84

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

Answer 84

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 85

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

Answer 85

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 repeti- tive 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 86

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

Answer 86

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 87

List the five less common types of muscular dystrophies.

Answer 87

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 88

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

Answer 88

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.

Question 89

List the four major types of intracranial hemorrhage.

Answer 89

■ Subdural hematoma ■ Epidural hematoma ■ Subarachnoid hemorrhage ■ Intracerebral hemorrhage

Question 90

What causes a subdural hematoma? How do you recognize and treat it?

Answer 90

Subdural hematomas are caused by bleeding from veins that bridge the cortex and dural sinuses. On a computed tomography (CT) scan, the hematoma is crescent-shaped (Fig. 24-1). Subdural hema- tomas are common in alcoholic patients and victims of head trauma. They may present immediately after trauma or as long as 1 to 2 months later. If the patient has a history of head trauma, always consider the diagnosis of subdural hematoma. If large, expanding, or accompanied by neurologic deficits, treat with surgical evacuation.

Question 91

What causes an epidural hematoma? How do you recognize and treat it?

Answer 91

Epidural hematomas are caused by bleeding from meningeal arteries (classically, the middle menin- geal artery). On a CT scan, the hematoma is lenticular in shape (Fig. 24-2). At least 85% of epidural hematomas are associated with a skull fracture (classically, a temporal bone fracture), and many patients have an ipsilateral “blown” pupil (dilated, fixed, nonreactive pupil on the side of the hema- toma). The classic history includes head trauma with loss of consciousness, followed by a lucid inter- val of minutes to hours, then neurologic deterioration. Treatment usually includes surgical evacuation.

Question 92

Define subarachnoid hemorrhage. What causes it? How is it treated?

Answer 92

A subarachnoid hemorrhage is bleeding between the arachnoid and pia mater. The most common cause is trauma, followed by ruptured berry aneurysms. Blood can be seen in the cerebral ventricles and surround- ing the brain or brainstem on a CT scan. Classically, the patient describes the “worst headache of my life,” although many die or are unconscious before they reach the hospital. Patients who are awake have signs of meningitis (positive Kernig sign and Brudzinski sign). Remember the association between polycystic kidney disease and berry aneurysms. CT is the test of choice and should be performed before performing lumbar puncture (see question 12). A lumbar puncture shows grossly bloody cerebrospinal fluid (CSF). Treat with support of vital functions, anticonvulsants, and observation. Once the patient is stable, do a CT or magnetic resonance (MR) angiogram to look for aneurysms or arteriovenous malforma- tions, which may be treatable with surgical clipping or catheter-directed angiographic procedures.

Question 93

What causes an intracerebral hemorrhage? How do you recognize and treat it?

Answer 93

Intracerebral hemorrhage describes bleeding into the brain parenchyma (Fig. 24-3). The most com- mon cause is hypertension, but it may also be a result of other forms of stroke, trauma, arteriovenous malformations, coagulopathies, or tumors. Two thirds of intracerebral hemorrhages occur in the basal ganglia (especially with hypertension). The patient may come to the hospital with coma or, if awake, contralateral hemiplegia and hemisensory deficits. Blood (which appears white on a CT scan) can be seen in the brain parenchyma and may extend into the ventricles. Surgery is reserved for large, accessible hemorrhages, although usually it is not helpful.

Question 94

After a history of head trauma, what does a dilated, unreactive pupil on one side mean until proved otherwise?

Answer 94

In the setting of head trauma, a dilated, unreactive pupil on one side most likely represents impinge- ment of the ipsilateral third cranial nerve and impending uncal herniation caused by increased intracranial pressure. Of the different intracranial hemorrhages, this scenario is seen most commonly with epidural hemorrhages. Do not perform a lumbar puncture in any patient with a “blown” pupil because you may precipitate uncal herniation and death. Instead, order a CT or magnetic resonance imaging (MRI) scan of the head.

Question 95

List the four classic signs of a basilar skull fracture.

Answer 95

1. Periorbital ecchymosis (“raccoon eyes”) 2. Postauricular ecchymosis (Battle sign) 3. Hemotympanum (blood behind the eardrum) 4. CSF otorrhea or rhinorrhea (leakage of CSF, which is clear in appearance, from the ears or nose)

Question 96

What is the imaging test of choice for skull fractures of the calvarium? How are they managed?

Answer 96

Skull fractures of the calvarium (roof of the skull) are best seen on a CT scan (preferred over plain x-rays). Surgical indications include contamination (surgical cleaning and debridement), depression with impingement on brain parenchyma, or open fracture with CSF leak. Otherwise, such fractures can be observed and generally heal on their own.

Question 97

True or false: Severe, permanent neurologic deficits may occur after head trauma, even with a negative CT or MR scan of the head.

Answer 97

True. Head trauma can cause cerebral contusion or shear injury of the brain parenchyma, both of which may not show up on a CT or MR scan but may cause temporary or permanent neurologic deficits.

Question 98

What finding suggests increased intracranial pressure?

Answer 98

Increased intracranial pressure (intracranial hypertension) is highly suggested in the setting of bilaterally dilated and fixed pupils. Normal intracranial pressure is between 5 and 15 mm Hg. Less specific symptoms include headache, papilledema, nausea and vomiting, and mental status changes. Look also for the classic Cushing triad, which consists of increasing blood pressure, bradycardia, and respiratory irregularity.

Question 99

How should increased intracranial pressure be managed?

Answer 99

The first step is to intubate the patient in reverse Trendelenburg position (head up). Once intubated, the patient should be hyperventilated for rapid lowering of intracranial pressure through decreased intracranial blood volume (caused by cerebral vasoconstriction). For longer term treatment, mannitol diuresis may decrease cerebral edema. Furosemide is also used but is less effective. Ventriculostomy should be performed if hydrocephalus is identified. Barbiturate coma and decompressive craniotomy (burr holes) are last-ditch measures. Anticonvulsant therapy should be started if seizures are sus- pected; prophylactic anticonvulsants are controversial but may be warranted in some cases. Remember that cerebral perfusion pressure equals blood pressure minus intracranial pressure. In other words, do not treat hypertension initially in a patient with increased intracranial pressure because hypertension is the body’s way of trying to increase cerebral perfusion. Lowering blood pressure in this setting may worsen symptoms or even cause a stroke.

Question 100

True or false: Lumbar puncture is the first test that should be performed in a patient with increased intracranial pressure.

Answer 100

False. Never do a lumbar puncture in any patient with signs of increased intracranial pressure until a CT scan is done first. If the CT is totally negative, you can proceed to a lumbar puncture, if needed. If you do a lumbar puncture first, you may precipitate uncal herniation and death.

Question 101

How do patients with spinal cord trauma present? How are they managed?

Answer 101

Patients with spinal cord trauma often come to the hospital with “spinal shock” (loss of reflexes and motor function, hypotension). Order standard trauma radiographs (cervical spine, chest, pelvis) as well as additional spine radiographs or CT scans based on physical examination. Also give corticosteroids (proven to improve outcome). Moderate hypothermia is increasingly being used in the management of patients with spinal cord trauma. Surgery is performed for incomplete neurologic injury (some residual function maintained) with external compression (e.g., subluxation, bone chip). An MRI can show cord injury noninvasively.

Question 102

What causes spinal cord compression? How do patients present?

Answer 102

Spinal cord compression usually is defined as acute or subacute. Most cases of acute cord compres- sion result from trauma. Look for the appropriate history. Subacute compression is often caused by metastatic cancer but may also result from a primary neoplasm, subdural or epidural abscess (classically seen in diabetics and caused by Staphylococcus aureus), or hematoma (especially after a lumbar tap or epidural/spinal anesthesia in a patient with a bleeding disorder or a patient taking anticoagulation). Patients present with local spinal pain (especially with bone metastases) and neurologic deficits below the lesion (e.g., hyperreflexia, positive Babinski sign, weakness, sensory loss).

Question 103

How should patients with subacute spinal cord compression be diagnosed and treated?

Answer 103

The first step in the emergency department is to give high-dose corticosteroids and order an MRI scan (preferred over CT; Fig. 24-4). If the cause is cancer or tumor, give local radiation if the metas- tases are from a known primary tumor that is radiosensitive. Surgical decompression can be used if the tumor is not radiosensitive. For a hematoma or subdural/epidural abscess, surgery is indicated for decompression and drainage. Prognosis is related most closely to pretreatment function; the longer you wait to treat, the worse the prognosis.

Question 104

Define syringomyelia. What causes it? How does it usually present?

Answer 104

Syringomyelia is a central pathologic cavitation of the spinal cord, usually in the cervical or upper thoracic region. Most cases are idiopathic, but syringomyelia may also follow trauma or be related to congenital cranial base malformations (e.g., Arnold-Chiari malformation). The classic presentation, caused by involvement of the lateral spinothalamic tracts, is bilateral loss of pain and temperature sensation below the lesion in the distribution of a “cape.” The cavitation in the cord gradually widens to involve other tracts, causing motor and sensory deficits. MRI scan is the diagnostic imaging study of choice. The primary treatment available is surgical creation of a shunt.

Question 105

Define spina bifida. How can it be prevented?

Answer 105

Spina bifida is a congenital abnormality in which lack of fusion of the spinal column, specifically the posterior vertebral arches, allows protrusion of spinal membranes, with or without spinal cord. Spina bifida occulta, the mildest form of the disease (bone deficiency without dural membrane or cord protrusion), is often asymptomatic and should be suspected in patients with a triangular patch of hair over the lumbar spine. More serious defects are usually obvious and occur most often in the lumbosacral region. A meningocele is protrusion of the meninges outside the spinal canal, whereas a myelomeningocele is protrusion of meninges plus central nervous system (CNS) tissue outside the spinal canal. Patients with a myelomeningocele almost always have an associated Arnold-Chiari mal- formation. Giving folate supplementation to women contemplating pregnancy reduces the incidence of spina bifida and other neural tube defects.

Question 106

Define hydrocephalus. How is it recognized in children?

Answer 106

Hydrocephalus is excessive accumulation of CSF in the cerebral ventricles. In children, look for increasing head circumference, increased intracranial pressure, bulging fontanelle, scalp vein engorgement, and paralysis of upward gaze. The most common causes include congenital malforma- tions, tumors, and inflammation (e.g., hemorrhage, meningitis). Treat the underlying cause, if pos- sible; otherwise a surgical shunt is created to decompress the ventricles.

Question 107

In what setting does dural venous sinus thrombosis occur? How is it diagnosed and treated?

Answer 107

The risk factors are similar to those for deep venous thrombosis (DVT) in other areas, including hyper- coagulable state, trauma, dehydration, pregnancy, oral contraceptive use, infections (e.g., extension of sinusitis or mastoiditis intracranially), nephrotic syndrome, and local tumor invasion. The diagnostic test of choice is MRI (Fig. 24-5). Even though hemorrhagic infarcts are common with dural venous thrombosis, treatment with anticoagulation improves outcomes.