NEUROLOGICAL EMERGENCIES Flashcards
NEUROLOGICAL EMERGENCIES
- A 27-year-old man undergoes general anesthesia for a hernia repair.
As the anesthesia begins, his jaw muscles tense and he becomes generally
rigid. He becomes febrile, tachycardic, and tachypneic. Intravenous administration
of which agent may be lifesaving?
a. Suxamethonium
b. Nitrous oxide
c. Succinylcholine
d. Dantrolene
e. Phenobarbital
- The answer is d. (Victor, p 1563.) Malignant hyperthermia is characterized
by acute severe fever, tachypnea, tachycardia, and rigidity, and high
mortality rate if left untreated. It is typically precipitated by volatile anesthetics,
especially halothane, or muscle relaxants such as succinylcholine.
Patients may become severely acidotic and develop rhabdomyolysis. Pathology
shows diffuse segmental muscle necrosis. It appears to be a metabolic
myopathy in which there is abnormal release of calcium from the sarcoplasmic
reticulum (SR) and ineffectual uptake afterward. Genetic defects in the
ryanodine receptor, involved in calcium flux in the SR, are responsible for
about 10% of cases, although as yet unidentified abnormalities of this or
related proteins probably play a role in most cases. It is inherited in an autosomal
dominant fashion. Certain other myopathies, including Duchenne
muscular dystrophy and central core myopathy, are associated with this
condition as well. Treatment consists of discontinuation of anesthesia,
administration of dantrolene, which prevents release of calcium from the
SR, and supportive measures.
- A 66-year-old woman presents with fever and a generalized convulsion.
Neuroimaging and lumbar puncture are most consistent with a diagnosis
of herpes encephalitis. The most appropriate treatment for this patient
is which of the following?
a. Cyclophosphamide
b. Amphotericin B
c. Gamma globulin
d. Methotrexate
e. Acyclovir
- The answer is e. (Victor, pp 794–795.) The diagnosis of herpes
encephalitis is more controversial than the treatment. Many authorities
believe brain biopsy should be performed whenever the diagnosis is suspected,
but the availability of polymerase chain reaction (PCR) for herpes
simplex virus (HSV) in the CSF and MRI have made diagnosis easier. In the
appropriate clinical setting, these tests may obviate the need for brain
biopsy, although it still remains the definitive test. A high index of suspicion
must be maintained and treatment must be initiated quickly. Acyclovir
must be given intravenously for 10 days.
- A 6-month-old child who develops a febrile seizure should be investigated
with a spinal tap because
a. All febrile seizures justify spinal taps
b. Most febrile seizures are due to bacterial infections
c. Febrile seizures cause increased intracranial pressure that must be relieved by
withdrawing cerebrospinal fluid (CSF)
d. Intrathecal antiepileptics must be given
e. Children this age may have meningitis with no manifestations other than fever
and seizures
- The answer is e. (Swaiman, p 677.) Between birth and 1 year of age,
what appears to be a simple febrile seizure may actually be a seizure provoked
by a bacterial meningitis. The agents most likely to be responsible in
a 6-month-old child are Haemophilus influenzae, Streptococcus pneumoniae,
and Neisseria meningitidis. Since the introduction of vaccination against
H. influenzae, however, the incidence of meningitis due to this organism
has been drastically reduced. Below 3 months of age, group B streptococci,
Escherichia coli, and Listeria monocytogenes must also be considered. All
require rapid diagnosis and early treatment if the child is to survive. Even
though the child may not have substantial neck stiffness, the CSF will typically
reveal a glucose content less than two-thirds the serum level, elevated
WBC count, and increased protein content. The responsible organism may
be isolated and cultured, but treatment of the meningitis should begin
before the organism is identified. A delay of hours in treatment may be
lethal. Intravenous antibiotics should be started as soon as there is convincing
evidence that febrile seizures are secondary to a bacterial meningitis.
The drug chosen should be the one most effective against the most
probable organism. The child’s age, exposure, and symptomatology must
all be considered in deciding what organism is most likely responsible for
the infection.
- A 17-year-old girl presents with subacute mental status change and
left arm weakness. She had a viral illness 1 week ago and now a diagnosis
of acute disseminated encephalomyelitis (ADEM) is made. ADEM is a
white matter disease that is distinguishable from multiple sclerosis (MS) by
its being
a. Monophasic
b. Rapidly lethal
c. Associated with brainstem and spinal cord disease
d. Associated with magnetic resonance imaging (MRI) lesions, which may resolve
e. Associated with inflammatory changes in the brain
- The answer is a. (Rowland, pp 151–153.) Acute disseminated
encephalomyelitis is a demyelinating disease of the brain, brainstem, and
spinal cord that is indistinguishable from MS on MRI. It is, however,
monophasic, meaning that it occurs acutely on a single occasion, and not
in a recurrent fashion like MS. It usually develops within days or weeks of
a viral illness or an immunization. Childhood exanthems are especially
likely to precipitate ADEM, as are smallpox and rabies immunizations. As
in MS, the lesions associated with ADEM usually produce perivenous
demyelination with sparing of the nerve axons.
475. Acute herniation of an intervertebral disk will require emergency surgery if a. The disk is laterally herniated at C7 b. The disk is causing radicular pain c. The cauda equina is being crushed d. A thoracic disk is involved e. The filum terminale is displaced
- The answer is c. (Victor, p 217.) Surgery may eventually be necessary
with any intervertebral disk herniation, but with acute, massive cauda
equina injury, surgery must be performed before the deficits are irreversible.
Signs of cauda equina compression include loss of bladder and
bowel control and paraparesis or paraplegia. An acutely evolving focal
motor deficit in the legs, such as a footdrop, associated with sphincter dysfunction
is justification for emergency laminectomy and disk resection.
Preoperative studies should be obtained to be sure that the responsible
lesion is disk herniation, because metastatic cancers, such as prostate and
breast carcinoma, may imitate acute disk herniations. Establishing the
identity of the lesion is important because many tumors are better managed with high-dose corticosteroids and radiation therapy than with surgery.
Osteomyelitis of the vertebral body may also produce cauda equina compression;
a decompressive laminectomy is usually indicated with focal
infections of this sort to maximize the recovery achieved with antibiotic
therapy.
476. A 57-year-old man has been diagnosed with cluster headache. Ergotamine prophylaxis has been partially successful. The most effective means of aborting a cluster headache is a. Inhaled 100% oxygen b. Sublingual nitroglycerin c. Oral methysergide d. Oral propranolol e. Dihydroergotamine suppository
- The answer is a. (Victor, p 191.) Oxygen may terminate a cluster
headache within minutes. Some physicians recommend inhaling 4 L/min
of 100% oxygen by mask as soon as signs of an impending headache
develop. This has prompted many sufferers of cluster headache to keep a
cylinder of compressed oxygen at home during the season when they are
most likely to develop such headaches. Cluster headaches usually occur at
night when the patient is asleep, and so practical access to the oxygen tank
is possible. Methysergide is effective in preventing cluster headache for
many persons, but it does rarely cause the worrisome adverse effect of
fibrosis. Retroperitoneal, pulmonary, and endocardial fibroses are potential
adverse effects of methysergide. Sublingual nitroglycerin may in fact trigger
a headache and is not recommended for patients with migraine or cluster
headaches. Propranolol is a β-adrenergic blocking agent that is useful in
the prophylaxis of some vascular headaches, but it is of no value in aborting
a cluster headache. Dihydroergotamine suppositories may abort some
vascular headaches, but they do not have as obvious an effect in cluster as
in classic or common migraine syndromes.
Items 477–478
A 32-year-old woman with alcoholism and cocaine use dating back at
least 10 years comes to the emergency room after 48 h of recurrent vomiting
and hematemesis. She reports abdominal discomfort that preceded the
vomiting by a few days. For at least 36 h, she has been unable to keep
ethanol in her stomach. Intravenous fluid replacement is started while she
is being transported to the emergency room, and while in the emergency
room she complains of progressive blurring of vision. Over the course of
1 h, she becomes increasingly disoriented, ataxic, and dysarthric.
- The most likely explanation for her rapid deterioration is
a. Dehydration
b. Hypomagnesemia
c. Wernicke’s encephalopathy
d. Hypoglycemia
e. Cocaine overdose
- The answer is c. (Victor, pp 1206–1212.)Wernicke’s encephalopathy
is a potentially fatal consequence of thiamine deficiency, a problem for
which this woman was at risk by virtue of being an alcoholic. When she
came to the emergency room, intravenous fluids were started that probably
contained glucose. The stress of a large glucose load will abruptly deplete
the CNS of the little thiamine it has available and will precipitate the sort of
deterioration evident in this woman. Features characteristic of a Wernicke’s
encephalopathy include deteriorating level of consciousness, autonomic
disturbances, ocular motor problems, and gait difficulty. Autonomic disturbances
may include lethal hypotension or profound hypothermia. Hemorrhagic
necrosis in periventricular gray matter will be evident in this
woman’s brain if she dies. The mamillary bodies are especially likely to be
extensively damaged.
Items 477–478
A 32-year-old woman with alcoholism and cocaine use dating back at
least 10 years comes to the emergency room after 48 h of recurrent vomiting
and hematemesis. She reports abdominal discomfort that preceded the
vomiting by a few days. For at least 36 h, she has been unable to keep
ethanol in her stomach. Intravenous fluid replacement is started while she
is being transported to the emergency room, and while in the emergency
room she complains of progressive blurring of vision. Over the course of
1 h, she becomes increasingly disoriented, ataxic, and dysarthric.
478. Emergency administration of what medication is appropriate in this clinical setting? a. Glucose b. Magnesium sulfate c. Pyridoxine d. Cyanocobalamin e. Thiamine
- The answer is e. (Victor, pp 1206–1212.)Without rapid replacement
of thiamine stores, the patient with acute Wernicke’s encephalopathy may
die. Usually 50 to 100 mg of thiamine is given intravenously immediately.
This is followed over the course of a few days with supplementary thiamine
injections of 50 to 100 mg. Without thiamine, the patient will develop
periaqueductal and mamillary body lesions, which will be clinically apparent
as autonomic failure. With chronic thiamine deficiency, neuronal loss
occurs in alcoholic persons at least partly because of this relative vitamin
deficiency. Purkinje and other cells in the cerebellar vermis will be lost to
so dramatic an extent that gross atrophy of the superior cerebellar vermis
will be evident.
Items 479–480
A 57-year-old woman with a history of diabetes mellitus and hyperthyroidism
presents to the emergency room with a history of 2 days of vertical
and horizontal diplopia. There is moderate orbital pain. On examination,
her left eye is deviated downward and outward. It can be passively moved
medially and upward. The pupils both react normally.
479. This woman most likely has
a. Third-nerve palsy
b. Fourth-nerve palsy
c. Sixth-nerve palsy
d. Orbital fracture
e. Graves’ disease
- The answer is a. (Victor, pp 286–287.) The third cranial nerve (the
oculomotor nerve) controls several movements of the globe, including
upward and medial movements, through its control of the medial rectus,
superior rectus, and inferior oblique muscles. Its inactivity leads to displacement
of the eye down and out. Fourth-nerve palsy leads to weakness
of the superior oblique muscle, with resultant difficulty looking down and
medially; patients often complain of trouble walking down stairs. Sixthnerve
palsy produces weakness of the lateral rectus muscle, causing horizontal
diplopia. Fractures of the orbit can entrap individual muscles, but
there is no history of this here. Thyroid ophthalmopathy, or Graves’ disease,
can produce diplopia, but there is usually proptosis or lid retraction.
The inferior and medial recti are most frequently affected. Because this is
caused by infiltration of the muscles, there is usually limitation of passive
movement of the eyes (i.e., forced ductions).
Items 479–480
A 57-year-old woman with a history of diabetes mellitus and hyperthyroidism
presents to the emergency room with a history of 2 days of vertical
and horizontal diplopia. There is moderate orbital pain. On examination,
her left eye is deviated downward and outward. It can be passively moved
medially and upward. The pupils both react normally.
- The etiology of her diplopia is most likely
a. Hyperthyroidism
b. Diabetes mellitus
c. Cerebral aneurysm
d. Orbital pseudotumor
e. Orbital infection
- The answer is b. (Victor, pp 286–287.) Diabetes is a common cause
of third-nerve palsy (approximately 10% of cases). Usually, when diabetes
is the cause, there is sparing of the pupillomotor parasympathetic fibers,
which travel on the outside of the nerve. Diabetes causes third-nerve palsy
via nerve infarction, which affects the interior of the nerve but spares the
external fibers. Compressive lesions, however, can injure the surface fibers,
thereby causing pupillary dilation due to unopposed sympathetic activity.
- A 33-year-old operating room nurse accidentally has blood splashed
in her eyes during a procedure. The surgical resident who examines her
immediately afterward notices that she has 2-mm anisocoria and sends her
to the emergency room. She feels well, is alert and talkative, and has no
motor dysfunction. On examination, the emergency room physician recognizes
that the iris of the eye with the smaller pupil is pale blue, while that of
the other eye is brown. The etiology of the woman’s anisocoria is probably
a. Conjunctivitis
b. Traumatic third-nerve palsy
c. Carotid artery dissection
d. Pupillary sphincter injury
e. Congenital
- The answer is e. (Victor, p 296.) Sympathetic innervation of the iris
is required for the change in the color of the iris to occur after birth and
Neurological Emergencies Answers 327
infancy. Congenital Horner syndrome, which may be inherited as an autosomal
dominant trait, is characterized by failure of one eye to develop normal
iris color (heterochromia iridis). Any injury to the eye after this early
developmental period would not be expected to leave a difference in eye
color from one side to the other.
Items 482–486
A 26-year-old man is brought into the emergency room after a motorcycle
accident in which he was not wearing a helmet. Computed tomography
(CT) scan shows bifrontal hemorrhagic contusions. The Glasgow
Coma Scale (GCS) score is 6. He has no verbal response, opens his eyes to
painful stimulation only, and shows a flexion response to pinch of the
extremities.
482. This patient’s head injury may be classified as
a. Minimal
b. Mild
c. Moderate
d. Severe
e. Vegetative
- The answer is d. (Bradley, pp 45, 1057.) The GCS was introduced in
1974 by Teasdale and Jennett. It has three parts: best motor response (1 to
6 points), best verbal response (1 to 5 points), and eye opening (1 to 4
points). The total score ranges from 3 to 15 (normal). The presence of
coma is defined as GCS of 8 or less, which represents a patient who does
not follow commands, speak, or open the eyes. Head injuries may be
defined on the basis of the GCS: mild injury (GCS 14 to 15), moderate
injury (GCS 9 to 13), and severe injury (GCS ≤ 8). Although patients with
mild head injuries may receive a score of 15, the maximum on the GCS,
they may still have more subtle cognitive difficulties that are not reflected
by this easy-to-use and simple scale.
Items 482–486
A 26-year-old man is brought into the emergency room after a motorcycle
accident in which he was not wearing a helmet. Computed tomography
(CT) scan shows bifrontal hemorrhagic contusions. The Glasgow
Coma Scale (GCS) score is 6. He has no verbal response, opens his eyes to
painful stimulation only, and shows a flexion response to pinch of the
extremities.
483. The presence of periorbital ecchymosis in this patient should be considered a sign of a. Subdural hemorrhage b. Parenchymal hematoma c. Ocular injury d. Retinal detachment e. Basilar skull fracture
- The answer is e. (Bradley, p 1060.) The presence of periorbital
ecchymosis (raccoon eyes), ecchymosis over the mastoid region (Battle’s
sign), hemotympanum (blood behind the eardrum), or CSF rhinorrhea or
otorrhea should be considered evidence of a basilar skull fracture.
Items 482–486
A 26-year-old man is brought into the emergency room after a motorcycle
accident in which he was not wearing a helmet. Computed tomography
(CT) scan shows bifrontal hemorrhagic contusions. The Glasgow
Coma Scale (GCS) score is 6. He has no verbal response, opens his eyes to
painful stimulation only, and shows a flexion response to pinch of the
extremities.
484. Magnetic resonance imaging scan of this patient shows multiple foci of punctate hemorrhage in addition to the contusions indicated above. These are most likely indicative of a. Diffuse axonal injury (DAI) b. Uncontrolled hypertension c. Amyloid angiopathy d. Ischemic infarction e. Coagulopathy
- The answer is a. (Bradley, pp 1051, 1058.) Diffuse axonal injury is
the most common cause of coma in the head-injured patient without an
intracranial mass lesion. It is characterized pathologically by diffusely
spread axonal swellings affecting the white matter, corpus callosum, and
upper brainstem. These foci are usually hemorrhagic. The etiology is
thought to be due to shearing forces on axons in certain susceptible regions
of the brain, notably those that are particularly vulnerable to rotational
forces, such as the subcortical white matter, corpus callosum, and upper
brainstem. Uncontrolled hypertension may occur in patients with hypertension,
but would be unlikely to produce this pattern of injury. Amyloid
angiopathy causes multiple hemorrhages, but affects elderly patients. The
decreased cerebral perfusion pressure associated with brain swelling and
increased intracranial pressure could cause ischemic infarction, but this
would not be expected to give this appearance on MRI. Coagulopathies
also occur in up to 20% of patients.
Items 482–486
A 26-year-old man is brought into the emergency room after a motorcycle
accident in which he was not wearing a helmet. Computed tomography
(CT) scan shows bifrontal hemorrhagic contusions. The Glasgow
Coma Scale (GCS) score is 6. He has no verbal response, opens his eyes to
painful stimulation only, and shows a flexion response to pinch of the
extremities.
485. Which of the following treatments could be recommended to improve this patient’s long-term outcome? a. Corticosteroids b. Prophylactic hyperventilation c. Hyperthermia d. Hypothermia e. Prophylactic anticonvulsants
- The answer is d. (Bradley, p 1073.) Hypothermia has been shown to
reduce cerebral injury from ischemia both in experimental models and in
clinical studies of patients with traumatic brain injury. Hypothermia
decreases cerebral metabolism, reduces acidosis, attenuates changes in the
blood-brain barrier, and inhibits the release of excitatory neurotransmitters
that can be harmful. Corticosteroids, prophylactic hyperventilation, and
prophylactic anticonvulsants have not been shown to be of benefit in the
long-term prognosis of severely head-injured patients. Hyperthermia is
detrimental to such patients.
Items 482–486
A 26-year-old man is brought into the emergency room after a motorcycle
accident in which he was not wearing a helmet. Computed tomography
(CT) scan shows bifrontal hemorrhagic contusions. The Glasgow
Coma Scale (GCS) score is 6. He has no verbal response, opens his eyes to
painful stimulation only, and shows a flexion response to pinch of the
extremities
486. Which of the following factors, if present, predicts a worse long-term outcome for this patient? a. Apolipoprotein E4 genotype b. Apolipoprotein B level c. College education d. Right hemispheric injury e. Use of propofol treatment
- The answer is a. (Bradley, pp 1078–1080.) Genetic studies have
recently shown that patients with the apolipoprotein E4 genotype have an
increased risk of developing Alzheimer’s disease, posttraumatic encephalopathy
associated with boxing, and worse outcome after traumatic brain injury.
Other predictors of a poor outcome are increasing age, lower premorbid level
of education, substance abuse history, diffuse axonal injury, subarachnoid
hemorrhage, severity of the initial injury, and presence of other systemic
injuries. Propofol has been shown in recent studies to improve outcome after
injury.
Items 487–489
A 47-year-old woman begins to have difficulty swallowing food at dinner.
Over the following 3 h, she develops diplopia, dysarthria, and ultimately
anarthria. She has a history of hypothyroidism and is on thyroid hormone
replacement. There is no history of exposure to ticks or recent travel. On
exam, she nods her head appropriately to questions, and she can write.
Forced vital capacity is 500 mL, and she is intubated. She is afebrile, tachycardic,
and normotensive. Bilateral ptosis and ophthalmoparesis are present;
pupils are 6 mm in diameter and minimally reactive. Facial sensation is
intact. Bifacial paresis is present, and the tongue is weak. Extremity muscle
bulk and tone are normal, and proximal strength is 4/5 in her arms and legs.
Finger and toe movements are rapid and symmetric. Plantar responses are
flexor. Blood tests are normal. Motor nerve conduction studies show lowamplitude
compound muscle action potentials with normal velocities. Sensory
nerve action potentials are normal.
487. Which of the following organisms could be responsible for this woman’s syndrome? a. Cytomegalovirus (CMV) b. Treponema pallidum c. Chlamydia pneumoniae d. Clostridium botulinum e. Campylobacter jejuni
- The answer is d. (Victor, pp 1274–1275.) The rapid onset of bulbar
paresis is consistent with acute inflammatory demyelinating polyneuropathy
(AIDP, or Guillain-Barré syndrome), botulism, tick paralysis, and several
other conditions. The normal conduction velocities argue against
demyelinating neuropathy, which may be associated with C. jejuni.
Cytomegalovirus and T. pallidum may cause several different neurologic
syndromes, but acute bulbar paresis is not among them. C. pneumoniae is
under investigation as a cause of atherosclerosis, strokes, and MS, but it
does not cause acute motor weakness.
Items 487–489
A 47-year-old woman begins to have difficulty swallowing food at dinner.
Over the following 3 h, she develops diplopia, dysarthria, and ultimately
anarthria. She has a history of hypothyroidism and is on thyroid hormone
replacement. There is no history of exposure to ticks or recent travel. On
exam, she nods her head appropriately to questions, and she can write.
Forced vital capacity is 500 mL, and she is intubated. She is afebrile, tachycardic,
and normotensive. Bilateral ptosis and ophthalmoparesis are present;
pupils are 6 mm in diameter and minimally reactive. Facial sensation is
intact. Bifacial paresis is present, and the tongue is weak. Extremity muscle
bulk and tone are normal, and proximal strength is 4/5 in her arms and legs.
Finger and toe movements are rapid and symmetric. Plantar responses are
flexor. Blood tests are normal. Motor nerve conduction studies show lowamplitude
compound muscle action potentials with normal velocities. Sensory
nerve action potentials are normal.
- On further questioning, it is found that the patient made her own
jam several months before, and tasted a sample of it the previous evening
prior to discarding it because it smelled rancid. On further electrophysiologic
testing, which of the following abnormalities would be most characteristic
of this patient’s illness?
a. Abnormal visual evoked responses (VERs)
b. Abnormal brainstem auditory evoked potentials
c. Posttetanic potentiation of the compound muscle action potential
d. Conduction block
e. Fibrillation potentials
- The answer is c. (Victor, pp 286–287.) Botulism is a disorder of the
neuromuscular junction (NMJ). The characteristic findings are decremental
response of the muscles to repetitive stimulation of the nerve at a low frequency
(2 to 5 Hz) and incremental response to repetitive stimulation at high
frequency (20 to 50 Hz). Other disorders of the NMJ, such as myasthenia
gravis and Lambert-Eaton myasthenic syndrome (LEMS), also manifest with
decremental response to repetitive stimulation at low frequencies due to
depletion of acetylcholine in the synaptic cleft. Higher rates of stimulation
Neurological Emergencies Answers 329
lead to increased calcium in the presynaptic terminal, which allows more
acetylcholine to be released in presynaptic disorders such as botulism and
LEMS, thereby increasing the response of muscle. However, in myasthenia
gravis, which is characterized by loss of acetylcholine receptors postsynaptically,
there is no increase in response at higher rates of stimulation, because
there is already a maximal amount of acetylcholine present in the synaptic
cleft. Abnormal visual evoked and brainstem auditory evoked potentials
would be seen in disorders affecting central pathways, such as MS. Conduction
block occurs in demyelinating disorders affecting the nerves. Fibrillation
potentials are present in denervation and certain myopathic conditions; they
may occur in botulism, as well as in patients treated with botulinum toxin for
therapeutic purposes, but this is not diagnostic of clinical botulism.
Items 487–489
A 47-year-old woman begins to have difficulty swallowing food at dinner.
Over the following 3 h, she develops diplopia, dysarthria, and ultimately
anarthria. She has a history of hypothyroidism and is on thyroid hormone
replacement. There is no history of exposure to ticks or recent travel. On
exam, she nods her head appropriately to questions, and she can write.
Forced vital capacity is 500 mL, and she is intubated. She is afebrile, tachycardic,
and normotensive. Bilateral ptosis and ophthalmoparesis are present;
pupils are 6 mm in diameter and minimally reactive. Facial sensation is
intact. Bifacial paresis is present, and the tongue is weak. Extremity muscle
bulk and tone are normal, and proximal strength is 4/5 in her arms and legs.
Finger and toe movements are rapid and symmetric. Plantar responses are
flexor. Blood tests are normal. Motor nerve conduction studies show lowamplitude
compound muscle action potentials with normal velocities. Sensory
nerve action potentials are normal.
- The mechanism of disease in this case is due to which of the following?
a. Antibodies to the acetylcholine receptor
b. Antibodies to the calcium receptor
c. Depolarizing blockade of the potassium channel
d. Impaired formation of acetylcholine-laden vesicles
e. Toxic muscle necrosis
f. Demyelination
- The answer is d. (Victor, pp 286–287.) Botulinum toxin, a 150-kDa
polypeptide chain, is cleaved into two chains: a 100-kDa chain required for
neuronal binding, and a 50-kDa chain that destroys important proteins
required for neurotransmitter packaging. The toxin reduces the amount of
acetylcholine available for release when a motor neuron is depolarized.
Eight serotypes of botulism toxin are now recognized: A, B, C1, C2, D, E,
F, and G. Although the toxins cleave different proteins, they interfere with
the same step in vesicle formation.
Items 490–494
A 22-year-old woman presents to the emergency room with an episode
of acute painful loss of vision in the right eye. On examination, there is
right afferent pupillary defect and papillitis on funduscopic examination.
She has no history of neurologic symptoms. An MRI shows a few foci of T2
signal increase in a periventricular distribution.
490. Appropriate treatment for presumed optic neuritis in this patient would be a. Oral prednisone b. Intravenous methylprednisolone c. Cyclophosphamide d. Plasma exchange e. Intravenous gamma globulin
- The answer is b. (Bradley, p 1455.) Clinical trials have shown that
intravenous methylprednisolone for an attack of optic neuritis reduces the
likelihood of developing MS over 2 years from 16.7% to 7.5%. It also is
associated with a better outcome than oral prednisone. Intravenous
methylprednisolone is thus recommended by most experts as appropriate
therapy for acute exacerbations of MS involving more than sensory manifestations
alone.
Items 490–494
A 22-year-old woman presents to the emergency room with an episode
of acute painful loss of vision in the right eye. On examination, there is
right afferent pupillary defect and papillitis on funduscopic examination.
She has no history of neurologic symptoms. An MRI shows a few foci of T2
signal increase in a periventricular distribution.
491. This patient’s chances of eventually developing multiple sclerosis are approximately a. 0% b. 5% c. 25% d. 40% e. 75%
- The answer is e. (Victor, pp 962–963.) The risk of developing MS
after optic neuritis was 74% in women and 34% in men after 15 years of
follow-up in one study. Other studies have found similarly high rates. The
longer the follow-up period, and the more rigorously signs of MS are
sought, the more likely it is that MS will be found. Most patients develop
the MS within 5 years of the initial attack of optic neuritis. Magnetic resonance
imaging scanning of the brain at the time of optic neuritis is, in fact,
330 Neurology
abnormal in between 50% and 72% of patients, suggesting the presence of
subclinical MS.
Items 490–494
A 22-year-old woman presents to the emergency room with an episode
of acute painful loss of vision in the right eye. On examination, there is
right afferent pupillary defect and papillitis on funduscopic examination.
She has no history of neurologic symptoms. An MRI shows a few foci of T2
signal increase in a periventricular distribution.
- Six months later, the woman again presents to the emergency room
complaining of brief, sharp pain radiating into the left side of her face. The
vision in her right eye has largely recovered, and there is no evidence of
sensory loss on the right side of her face. She describes the pain as ice
pick–like and grimaces with each attack. She is most likely to have symptomatic
relief from her facial pain if she is managed with
a. Aspirin
b. Acetaminophen
c. Ibuprofen
d. Carbamazepine
e. Codeine
- The answer is d. (Victor, pp 196–198.) This woman has exhibited
two different complaints separated in time and space, a clinical pattern that
must raise the possibility of MS in a woman this age. The pattern of pain is
suggestive of trigeminal neuralgia (tic douloureux), an idiopathic facial
pain syndrome that often develops in persons with MS. Alternatives to carbamazepine
in the palliation of trigeminal neuralgia include phenytoin and
baclofen.
Items 490–494
A 22-year-old woman presents to the emergency room with an episode
of acute painful loss of vision in the right eye. On examination, there is
right afferent pupillary defect and papillitis on funduscopic examination.
She has no history of neurologic symptoms. An MRI shows a few foci of T2
signal increase in a periventricular distribution
493. On further questioning, the patient reveals that she has had recurrent episodes of bed wetting (enuresis) over the preceding month. This should decrease with the administration of a. Imipramine b. Phenytoin c. Carbamazepine d. Baclofen e. Methacholine
- The answer is a. (Bradley, pp 1453–1454.) Bladder dysfunction with
MS is usually a consequence of corticospinal tract disease. This lesion of
the upper motor neuron produces a spastic bladder. Tricyclic antidepressants
such as imipramine exert an anticholinergic effect and thereby inhibit
premature emptying of the bladder. Cholinergic drugs, such as methacholine,
are useful if the patient has a flaccid bladder, but that is much less
frequently the problem with MS.
Items 490–494
A 22-year-old woman presents to the emergency room with an episode
of acute painful loss of vision in the right eye. On examination, there is
right afferent pupillary defect and papillitis on funduscopic examination.
She has no history of neurologic symptoms. An MRI shows a few foci of T2
signal increase in a periventricular distribution
- Over the course of the next few months, she develops painful spasticity
in her left leg that interferes with flexion of her leg. The spasticity progresses
to the point of interfering with her sleep. She should now be treated
with
a. Imipramine
b. Phenytoin
c. Carbamazepine
d. Baclofen
e. Methacholine
- The answer is d. (Bradley, p 1453.) Baclofen affects spasticity
through an unknown mechanism and may cause considerable sedation.
Sedation is less a concern if spasticity is interfering with the patient’s ability
to sleep. The drug is usually given orally at a dose of 10 mg three or four
times daily, but most patients must start at a much lower dose and gradually
build up tolerance. Baclofen has been given intrathecally with an
implanted pump injector, but this highly invasive therapy is only appropriate
in patients with extreme spasticity. Candidates for intrathecal
treatment are functionally paraplegic and may recover considerable mobility
with elimination of the spasticity. Tizanidine is a centrally active
α2-adrenergic agonist that appears to relieve spasticity without affecting
strength.
Items 495–498
A 47-year-old man arrives at the emergency room in a coma. His wife
reports that he developed shaking movements and abnormal breathing
sounds in the middle of the night. His shaking and the sounds woke her,
but she was unable to wake him. He has been somewhat forgetful over the
prior 3 months, but has seemed well otherwise. Examination in the emergency
room reveals an unresponsive man who exhibits generalized convulsions
every 10 min. He is afebrile and incontinent of urine.
- The physician on call believes the patient is in status epilepticus, and
consequently immediately orders which of the following?
a. An intraventricular drain to monitor intracranial pressure
b. Lorazepam (Ativan) for intravenous administration
c. Carbamazepine (Tegretol) by nasogastric tube
d. Phenytoin (Dilantin) by nasogastric tube
e. Gabapentin (Neurontin) by nasogastric tube
- The answer is b. (Victor, pp 361–362.) There are several different
options in initiating the treatment of status epilepticus. Some clinicians
recommend intravenous diazepam (Valium) as the initial medication, but
this has a short-lived effect. Lorazepam (Ativan) is equally effective and has
a more persistent effect. Phenytoin should be used in conjunction with a
benzodiazepine to prevent relapse after the benzodiazepine’s effect abates,
Neurological Emergencies Answers 331
but it must be administered parenterally in the setting of status in order to
achieve rapid therapeutic levels. Although phenytoin cannot be given at
more than 50 mg/min because of the risk of cardiac depression associated
with more rapid infusion rates, the more recently available fosphenytoin
can be administered intramuscularly or intravenously at rates up to 150
mg/min. Carbamazepine (Tegretol) and gabapentin (Neurontin) are not
available as intravenous medications, and their absorption from the gastrointestinal
tract is unacceptably slow for the treatment of status epilepticus.
Intracranial pressure (ICP) will usually be increased during status
epilepticus, but that is of no immediate clinical consequence, and monitoring
of the ICP in status epilepticus is inappropriate in the absence of a
specific indication such as documented head trauma or other mass lesion.
Intracranial pressure is routinely monitored by neurosurgeons in cases
of severe head trauma to provide early warning of catastrophic changes
within the head.
Items 495–498
A 47-year-old man arrives at the emergency room in a coma. His wife
reports that he developed shaking movements and abnormal breathing
sounds in the middle of the night. His shaking and the sounds woke her,
but she was unable to wake him. He has been somewhat forgetful over the
prior 3 months, but has seemed well otherwise. Examination in the emergency
room reveals an unresponsive man who exhibits generalized convulsions
every 10 min. He is afebrile and incontinent of urine.
- During the initial treatment of his status epilepticus, a nurse reports
that the patient has just lost bladder control and that the urine appears
darker than normal. The responsible physician examines the bedsheets and
agrees with the nurse’s assessment. The physician should immediately
institute what measure?
a. Order placement of an indwelling urinary catheter
b. Order methacholine to regulate bladder emptying
c. Request a surgical consultation in anticipation of an exploratory laparotomy
d. Order placement of a condom catheter
e. Request a urologic consultation to assess the incontinence
- The answer is d. (Victor, pp 286–287.) Urinary incontinence is an
expected consequence of status epilepticus and consequently should not
arouse concern for abdominal or urologic disturbances. Keeping the
patient dry is important because of the risk of skin breakdown with any
comatose patient, but mechanical intervention is sufficient. An indwelling
catheter is unnecessary and introduces the risk of urinary tract infection. A
condom catheter will keep the patient dry, allow urine to be collected, and
enable the staff to more rigorously monitor fluid output. The urine is likely
to be darkened by myoglobin, a pigment that collects in the urine when
muscle breaks down after protracted seizure activity.
Items 495–498
A 47-year-old man arrives at the emergency room in a coma. His wife
reports that he developed shaking movements and abnormal breathing
sounds in the middle of the night. His shaking and the sounds woke her,
but she was unable to wake him. He has been somewhat forgetful over the
prior 3 months, but has seemed well otherwise. Examination in the emergency
room reveals an unresponsive man who exhibits generalized convulsions
every 10 min. He is afebrile and incontinent of urine.
- A precontrast CT of the brain reveals a hemorrhagic mass in the left
frontal lobe, but there is little apparent shift of brain structures and no ventricular
enlargement. Two hours after the patient’s seizures have stopped,
his blood pressure is still elevated at 180/100 mmHg and his pulse is slow
at 50/min. Although the patient is still unconscious, he appears to have
decreased tone on the right side of his body. The physician should request
which of the following interventions?
a. Intravenous clonidine (Catapres) to lower the blood pressure
b. Placement of a cardiac pacemaker to manage the bradyarrhythmia
c. Neurosurgical consult
d. Placement of a ventriculoperitoneal shunt
e. Intravenous tissue plasminogen activator (TPA)
- The answer is c. (Victor, pp 901–903.) An expanding intracranial
mass will produce an elevated blood pressure and a slow heart rate. This is
called the Cushing effect. This man may have a neoplasm in the brain or
amyloid bleed. The site of the hemorrhage is unlikely with chronic hypertension
or aneurysm. A biopsy of the mass would help identify the underlying
lesion, although it is not urgent. Metastatic neoplastic disease is a
possibility but is less likely than a glioblastoma multiforme at this age. The
administration of TPA is contraindicated because this drug will increase the
risk of rebleeding. Placement of a drain is not suggested by the clinical picture
because there was no evidence of obstruction to the flow of CSF.
Items 495–498
A 47-year-old man arrives at the emergency room in a coma. His wife
reports that he developed shaking movements and abnormal breathing
sounds in the middle of the night. His shaking and the sounds woke her,
but she was unable to wake him. He has been somewhat forgetful over the
prior 3 months, but has seemed well otherwise. Examination in the emergency
room reveals an unresponsive man who exhibits generalized convulsions
every 10 min. He is afebrile and incontinent of urine.
- A neurosurgical consultant decides to explore the site of the hemorrhage
and evacuate the mass that has collected there. He sends tissue from
the margin of the blood clot for a frozen section analysis by the pathologist.
The tissue is felt to be Kernohan grade IV astrocytoma. What postoperative
therapy is reasonable?
a. Cranial radiotherapy
b. Intravenous methotrexate
c. Intravenous fludarabine
d. Intravenous cyclophosphamide
e. Intravenous daunorubicin
- The answer is a. (Rowland, pp 321–325.) There are several different
grading schemes for astrocytoma, but Kernohan’s classification of grades
from I (least malignant) to IV (most malignant) is the one most widely
used. Glioblastoma multiforme is an older term for the grade IV astrocytoma
and is still in general use. This is a highly malignant tumor that develops
most often in the cerebral hemispheres. The most malignant tumors
usually exhibit areas of necrosis and have a poor prognosis. Survival with
glioblastoma multiforme is usually measured in months rather than years.
Treatment generally consists of gross total resection and radiation therapy.
Survival may be increased to 40 weeks after this combination of therapies,
whereas it is on average only 14 weeks after surgery alone. The intravenous
medications listed are antineoplastic agents, but they are not effective
against this type of tumor. The only chemotherapy generally regarded as
useful for this type of primary brain tumor is 1,3-bis (2-chloroethyl)-1-
nitrosourea (BCNU), which increases survival only marginally.
Items 499–500
A 56-year-old man is brought into the emergency room after having
collapsed at work 30 min ago. He has no medical history and takes no
medications. He is alert and speaking but has no awareness of any deficit.
He has a right gaze preference, dense left face and arm plegia, and mild left
leg weakness. When asked to raise his legs, he lifts only the right leg. He
has reduced blink to threat from the left side.
- The most appropriate initial diagnostic step is
a. Head CT
b. Cerebral angiogram
c. C-spine MRI
d. T2-weighted brain MRI
e. Skull x-rays
- The answer is a. (Shuaib, p 33.) The head CT scan is the mainstay
of emergency department management of acute stroke. It is crucial to
exclude intracranial hemorrhage prior to the potential administration of
intravenous thrombolytic agents. A cerebral angiogram may play a role in
the management of the acute stroke patient, particularly if there is evidence
of cerebral or subarachnoid hemorrhage, or if there exists a possibility of
performing intraarterial thrombolysis, but CT scan is required first. T2-
weighted MRI may also show ischemic and hemorrhagic injury, but infarction
may not appear this quickly on MRI and hemorrhage may also be
missed. MRI is also not as widely available as CT. In the absence of evidence
of trauma at the time of the patient’s fall, C-spine MRI and skull
x-rays play no role in management.
Items 499–500
A 56-year-old man is brought into the emergency room after having
collapsed at work 30 min ago. He has no medical history and takes no
medications. He is alert and speaking but has no awareness of any deficit.
He has a right gaze preference, dense left face and arm plegia, and mild left
leg weakness. When asked to raise his legs, he lifts only the right leg. He
has reduced blink to threat from the left side.
- A head CT scan shows no evidence of intracranial hemorrhage. The
most appropriate therapy at this point would be
a. Intravenous rTPA
b. Intravenous streptokinase
c. Oral aspirin
d. Intravenous heparin
e. Intravenous mannitol
- The answer is a. (Shuaib, pp 328–329.) In a large, multicenter randomized
trial sponsored by the NIH, thrombolytic therapy with intravenous
rTPA has been shown to be of benefit to patients with acute ischemic stroke
who can be treated early enough. The study demonstrated a statistically significant
benefit for the use of rTPA in the treatment of ischemic stroke
patients who can be treated within 3 h of symptom onset. A total of 624
patients arriving at the hospital within 3 h of symptom onset underwent CT
scan to exclude hemorrhagic stroke. Patients were randomized to receive
Neurological Emergencies Answers 333
either 0.9 mg/kg of rTPA or placebo. At 3 months, treated patients were at
least 30% more likely to have minimal or no disability on several disability
scales. Even with a symptomatic hemorrhage rate of 6.4% within 36 h
among the active treatment patients, the mortality and disability among
treated patients was less than that among placebo patients at 3 months. The
overall acute neurologic deterioration even after accounting for early hemorrhages
was the same in treated and placebo patients, indicating that the
increased risk of hemorrhage with rTPA therapy is offset by an increased risk
of neurologic deterioration from progressing stroke, cerebral edema, and
other causes in nontreated patients. The benefit of rTPA was not limited to
patients with cardioembolic or large-vessel strokes, but also benefited
patients with small-vessel strokes, who had a better prognosis.
