Block 1: Neuro Board Review: Q & A
1. A 15-year-old girl presents to the emergency department with a 4-week history of nasaldrainage and face pain and a 2-week history of frontal headaches and fatigue. Her mothercomplains that her daughter has an "attitude" and has not been respectful or seemed to careabout anything for the past 2 weeks. The daughter awoke this morning with a headache andvomited. On physical examination, the adolescent is afebrile and has normal vital signs. Sheresponds slowly to questions and is not oriented to the date. She complains of pain to palpationof her cheeks and forehead. She has no nuchal rigidity and no focal weakness. The remainderof the physical examination findings are normal.
Of the following, the BEST initial diagnostic procedure is
A. computed tomography scan of the head with intravenous contrast
B. emergent electroencephalography to rule out nonconvulsive status epilepticus
C. lumbar puncture to rule out meningitis
D. nasal swab for bacterial culture
E. urine drug screen for barbiturates, amphetamines, and cocaine
Preferred Response: A
The subacute onset of mental status changes described for the adolescent in the vignettewarrants an emergency evaluation. In most cases, neuroimaging is indicated, along withappropriate laboratory testing. The relatively nonspecific pain and what her mother perceives as common emotionalproblems (apathy in a teenager) probably represent early frontal lobe symptoms. The headacheon awakening and vomiting are concerning for increased intracranial pressure (ICP).
Confusionand psychomotor retardation on the mental status examination indicate involvement of thecentral nervous system. A focal, ischemic, ictal, infectious/inflammatory, or toxic/metabolicprocess must be identified urgently. A brain abscess is suggested by the prominent facial pain inthis setting; the sinuses are a common source of brain abscesses. Brain abscessesoften present only with nonspecific pain and not with fever.
Head computed tomography (CT) scan is preferred for this patient because theconstellation of pain, confusion, and morning vomiting makes a focal intracranial mass apossibility. Increased ICP is associated with morning vomiting because ICP is highest in themorning. Contrast is recommended because of the insidious onset, which could indicate either aneoplasm or infectious process. Intravenous contrast is not needed for all neuroimagingprocedures. However, it increases the diagnostic yield of imaging studies where either neoplasmor infection is suspected because both typically involve some degradation of the blood-brainbarrier or hypervascularity, resulting in contrast enhancement at the site of the lesion.
Magneticresonance imaging (MRI) with contrast also is a good choice. The advantage of MRI is higherspatial and soft-tissue resolution. Disadvantages of MRI compared with CT include: 1) lessavailability for emergency department studies; 2) need for pharmacologic sedation in agitatedpatients because sedation affects mental status, thereby masking disease-related mentalstatus; 3) longer time in the scanner, which could delay treatment decisions; and 4) cost. Thus,in most cases, a head CT scan with contrast is preferred as the initial study in the emergencydepartment.
Electroencephalography (EEG) is an important test for assessment of a patient who hasencephalopathy of unclear cause to rule out nonconvulsive status epilepticus (NCSE),particularly if the patient is known to have epilepsy. If an EEG cannot be obtained rapidly,intravenous administration of 0.1 mg/kg lorazepam can treat NCSE immediately, although thiswould not clear confusion about other causes. For this adolescent, the facial pain makes thediagnosis of NCSE less likely than a brain abscess. A lumbar puncture may be needed to rule out meningitis or encephalitis, but the pain andmorning vomiting more strongly suggest the possibility of an intracranial mass. Lumbar punctureprior to head CT is not advised in this case because it could reduce pressure below the foramenmagnum and result in herniation from the supratentorial mass. Toxicology screening and nasalswabs are reasonable but not the preferred initial diagnostic tests because they will not affectemergency management of the increased intracranial pressure.
2. A 14-year-old boy presents to your office because the side of his face is drooping. His motherstates that he complained yesterday of decreased food taste. Today, while at school, he couldnot use the microscope in science class because he couldn't close his left eye, and his teachernoted that his smile was crooked. Physical examination reveals no abnormalities and no vesiclesin his ears. Mental status on neurologic examination is normal, pupil responses are normal,extraocular movements are full, and there is no nystagmus or reported double vision. He isunable to close his left eye or raise his left eyebrow, has decreased left-side nasolabial folds,and cannot close his mouth to puff out his cheeks (Item Q22). His palate and tongue movementsare normal. Motor examination reveals normal proximal and distal strength in both arms andnormal regular and tandem gait.
Of the following, the MOST appropriate initial diagnostic procedure is
A. blood test for antistreptococcal antibodies
B. brain magnetic resonance imaging
C. edrophonium (Tensilon®) test
D. no further testing
E. noncontrast head computed tomography scan
Preferred Response: D
Acute focal or generalized weakness is a medical emergency requiring a systematic historyand neurologic examination to localize the problem. For acute focal weakness, the problem canlocalize to the brain, brainstem, spinal cord, anterior horn cell, root, nerve, junction, or muscle.Often, the physical examination can localize the problem to one of these levels.
In the case ofacute unilateral facial weakness, as described for the boy in the vignette, the typical differentialdiagnosis is acute facial nerve palsy (ie, Bell palsy) or a more rostral disease process of thebrainstem or brain (cerebrum, motor cortex) such as a stroke. The key diagnostic point for facialweakness is whether the weakness involves the entire side of the face or the face below theforehead. A 7th nerve palsy affects all the innervated muscles, weakening or paralyzing theentire hemi-face from forehead to chin. A lesion above the facial nerve nucleus typicallyweakens the face below the forehead.
The boy described in the vignette has full left-sided facial weakness, including the musclesin his forehead. Such findings localize to the facial nerve, and in this clinical setting,neuroimaging is not revealing. Accordingly, no further testing is required. When the examinationlocalizes a problem involving facial weakness to the brain or brainstem, brain magneticresonance imaging (MRI) or, if MRI is not available quickly, noncontrast head computedtomography should be obtained.
Facial weakness due to an acute brain process, such as a left middle cerebral artery stroke,usually presents with involvement of both the contralateral right face and the right hand. Thebrainstem, specifically the pons, is the source of the facial nerve, and brainstem diseases canproduce full hemi-facial weakness. However, due to the close proximity of other brainstemnuclei, a brainstem lesion affecting the left face also should affect other functions, including theleft 6th nerve, which abducts the left eye. Often, sensory and motor findings on the oppositeside of the body, the so-called "crossed signs," indicate brainstem disease.
The edrophonium/Tensilon® test involves administration of this acetylcholinesterase inhibitorto increase acetylcholine at the neuromuscular junction and reverse weakness. The test is usedfor diagnosis of myasthenia gravis. Myasthenia gravis typically produces bilateral fatiguingweakness, particularly ptosis, as well as weakness in other cranial nerves or generalizedweakness.
Facial nerve palsy can be caused by a variety of infectious agents, but no specificdiagnostic testing is indicated in most cases. However, in regions where Lyme disease isendemic or exposure is possible, testing for Lyme disease may be indicated. Assessment ofantistreptococcal antibodies is not helpful because streptococci do not cause facial nerve palsy. The American Academy of Neurology practice parameter states that oral steroids probablyare beneficial and acyclovir possibly is beneficial for treatment of facial nerve palsy. Pediatricstudies and reviews have concluded that evidence is insufficient to recommend steroids forchildren. However, many clinicians recommend administering a short course of oral prednisonefor Bell palsy.
3. At 8 am, your nurse urgently calls you to see a child in the waiting room. You come out andobserve a 5-year-old boy whose eyes are glassy and staring off to the right. He is makingchewing movements and has urinated. He is not responding to his mother calls or touch. Hethen blinks several times and begins to respond, but is clearly confused. His mother explainsthat her son has been diagnosed with epilepsy, but she ran out of medication 2 days ago.
Of the following, the MOST appropriate maintenance antiseizure medication for this child is
A. carbamazepine
B. diazepam
C. ethosuximide
D. phenobarbital
E. phenytoin
Preferred Response: A
The child described in the vignette has had a classic complex partial seizure. The seizure onsetis likely in a nonmotor area, such as a temporal lobe, which caused the staring andnonresponsiveness. The chewing movements are automatisms. The confusion is typical for apostictal period. The cause of the seizure is the child’s epilepsy and probably the parent’smedical mismanagement. The reason for “running out” of medication needs to be explored withthis parent so that she understands that abruptly discontinuing seizure medication places herchild at risk of harm.
Selection of medications for the treatment of epilepsy depends on the type of epilepsy. Themost basic distinction is whether the epilepsy is partial or generalized. Clinical data from acareful history are critical. For example, if the seizure begins with an aura (a smell, a particularsensation), a stare, or focal motor movements, it is likely to be a partial seizure. Partial seizurealso may be characterized by asymmetric findings on the neurologic examination or thepresence of focal weakness after the seizure. If a staring seizure is followed by immediatereturn to normal awareness, focal onset is much less likely and the child may have generalizedonset, primary absence epilepsy. If the clinical history is unavailable or inconclusive as to theseizure type, but the clinician judges prior events to be highly likely to be seizures,electroencephalography may be helpful in defining epilepsy type and choosing appropriatemedication.
Carbamazepine is effective for partial seizures, as experienced by the child in the vignette,and has a superior safety profile to phenobarbital or phenytoin. Diazepam is usedprimarily for cluster or prolonged breakthrough seizures. Ethosuximide is the drug of choice forprimary absence epilepsy.
4. A 10-year-old boy has double vision and drooping eyelids. On physical examination, he isafebrile and has normal mentation. Pupillary responses are normal, but he has bilateral ptosis. He cannot fully adduct his right eye. You note that his ptosis increases with sustained upward gaze. Bedside forced vital capacity is normal.
Of the following, the test MOST likely to confirm the diagnosis is
A. brainstem auditory evoked potentials
B. cold caloric testing
C. edrophonium test
D. lumbar puncture
E. visual evoked potentials
Preferred Response: C
The child described in the vignette presents with progressive fatigable weakness affecting hisocular muscles and bilateral eyelids. Fatigable weakness means that at the onset of a voluntarymovement, or after a period of rest, muscle strength is normal. However, after a period ofsustained use, muscle strength diminishes. Such a pattern is characteristic of weakness due topathology at the neuromuscular junction.
New-onset weakness mandates urgent evaluation and consideration of problems involvingairway protection and respiratory insufficiency, particularly if there is evidence on physicalexamination of generalized weakness. If the pharyngeal muscles are affected, speech soundshyponasal. Negative inspiratory force or forced vital capacity should be documented promptlybecause these findings determine whether the child should be transferred to an intensive careunit for ventilatory monitoring and support.
The first step in the diagnostic process is to localize the problem to the proper level of thenervous system: brain, brainstem/cerebellum, spinal cord, nerve, junction, or muscle. Such adetermination not only allows for urgent appropriate diagnosis and treatment but can reduceunnecessary discomfort, risks, and costs of inappropriate diagnostic testing. Consultation with aneurologist can be useful before ordering testing.
In this case, bilateral weakness in the eyelidsand normal mentation make a cerebral or midbrain cause unlikely. Lateral gaze palsy from apontine lesion also should affect the full face (as occurs in Bell palsy), which is not present. Amultifocal cranial neuropathy is rare and unlikely. The ocular fatigability suggests aneuromuscular junction problem such as myasthenia gravis.
The diagnosis of myasthenia gravis can be confirmed with the edrophonium test ("Tensilon®test"), a specialized assessment using the acetylcholinesterase inhibitor edrophonium. Becausethe test can pose a risk of life-threatening bradycardia, it should be undertaken by anexperienced physician with atropine at the bedside. Neurologic examination before and afteradministration ideally should be documented on video.
Lumbar puncture is the appropriate test for suspected Guillain-Barré syndrome (GBS), anacute inflammatory demyelinating polyneuropathy. Typically, affected children present withweakness beginning in the proximal legs, pain, and absent reflexes. A variant of GBS caninvolve predominantly the brainstem and cerebellum, but usually weakness is more extensivethan described for this child, and the weakness is not fatigable. Further, at this early stage, thecharacteristic cerebrospinal fluid findings in GBS, normal cells and high protein, often have notemerged. Therefore, lumbar puncture is not the preferred study in this setting. Cold calorictesting evaluates vestibular function. This patient has no nystagmus and does not require thisuncomfortable test. Neurophysiologic testing with auditory or visual evoked potentials is notneeded when no clinical evidence suggests that these systems are affected.
Treatment of myasthenia gravis is complex and is managed best by an experiencedneurologist. Treatment may include immunomodulation (eg, intravenous immunoglobulin orplasmapheresis) and acetylcholinesterase inhibitors.Imaging to assess for the presence of athymoma also is standard practice in a child. The patient and family also should be educatedabout disease management and early recognition of impending myasthenic crisis.
5. A 4-year-old boy presents to the emergency department with balance problems. He had beenpreviously healthy, but his walking has worsened progressively for the past 2 days, with staggering and lurching. On physical examination, the boy is cooperative and alert. His musclesare not tender, and his joints are not red, swollen, or tender. His vision seems functionallynormal, but there is end-gaze nystagmus in all directions. When sitting independently, his headand trunk bob. His strength appears normal, and his reflexes are normal. When asked to standwith his hands outstretched, a symmetric tremor is evident and worsens as he approaches thetarget on finger-to-nose testing. His gait is broad-based. A urine toxicology screen revealsnormal results. Brain magnetic resonance imaging shows no tumors or other gray or whitematter lesions. Lumbar puncture shows 3 white blood cells, 2 red blood cells, protein of 20.0g/dL, and glucose of 50.0 mg/dL (2.8 mmol/L).
Of the following, you are MOST likely to advise the child’s mother that
A. intravenous steroids significantly reduce recurrence risk
B. neuroblastoma is a common cause of these symptoms
C. repeat lumbar puncture is needed in 2 days
D. symptoms may resolve in weeks to months
E. symptoms usually resolve after antibiotic treatment
Preferred Response: D
A child who experiences subacute-onset gait or balance problems should be evaluatedthoroughly in the emergency department based initially on localization obtained through carefulexamination. The differential diagnosis includes structural and immunologically mediateddiseases that can be life-threatening or cause permanent neurologic injury. The bilateralsymptoms with completely normal mental status and no somnolence described for the boy in thevignette makes a cerebral cause less likely. The lateral end-gaze nystagmus, tremor on handactivation and finger-to-nose testing, trunk bobbing (titubation), and broad-based gait localize theproblem to the cerebellum. The subacute onset of such symptoms strongly suggestsacute cerebellar ataxia, which usually is acquired after infection or immunization. Because this isa self-limited, monophasic illness, the mother can be advised that the symptoms should resolvein weeks to months.
A repeat lumbar puncture in a few days is not likely to clarify the diagnosis. Otitis mediadoes not cause nystagmus and ataxia, and antibiotics are not indicated (unless there is aconcurrent bacterial infection). The recurrence risk for acute cerebellar ataxia is low, and it isunknown whether steroids reduce the risk further. Although clinical trials are not available toguide management, due in part to the low incidence of this condition, many clinicians empiricallytreat with a short course of high-dose steroids to reduce the duration of illness.
Although the time course makes a structural cerebellar or brainstem lesion unlikely for thispatient, ordering the magnetic resonance imaging is reasonable because children in this agegroup may present with cerebellar and brainstem neoplasms such as astrocytomas, pontinegliomas, primitive neuroectodermal tumors (medulloblastomas), or ependymomas. Rarely, such apresentation may be associated with Guillain-Barré syndrome. Therefore, specialty consultationis advised.
For children presenting with acute ataxia, the clinician should be especially vigilant for thepossibility of neuroblastoma presenting as opsoclonus myoclonus ataxia syndrome. Case serieshave shown that children who have opsoclonus myoclonus often are misdiagnosed initially ashaving acute cerebellar ataxia. Because distinguishing these diagnoses clinically is challenging,specialty consultation is advisable.
6. A 10-year-old boy presents with leg weakness that has progressed over 24 hours, bladder andbowel incontinence, and back pain. There is no history of trauma. On physical examination, legreflexes are diminished, and there is numbness in the legs and lower trunk. Rectal examinationdemonstrates decreased tone. Sensory examination shows absent pinprick sensation below T6.
Of the following, the MOST appropriate initial diagnostic test is
A. brain magnetic resonance imaging with contrast
B. electromyography of the legs