NEUROLOGICAL EMERGENCIES Flashcards
NEUROLOGICAL EMERGENCIES
1
Q
- 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
A
- 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.
2
Q
- 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
A
- 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.
3
Q
- 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
A
- 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.
4
Q
- 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
A
- 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.
5
Q
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
A
- 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.
6
Q
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
A
- 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.
7
Q
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
A
- 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.
8
Q
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
A
- 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.
9
Q
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
A
- 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).
10
Q
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
A
- 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.
11
Q
- 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
A
- 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.
12
Q
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
A
- 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.
13
Q
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
A
- 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.
14
Q
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
A
- 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.
15
Q
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
A
- 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.
