Neurological Emergencies Flashcards
- 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
(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. Pathol- ogy shows diffuse segmental muscle necrosis. It appears to be a metabolic myopathy in which there is abnormal release of calcium from the sarcoplas- mic 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
(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 sus- pected, 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 suspi- cion 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 inves¬tigated 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
(E)
(Swaiman, p 677.) Between birth and 1 year of age, what appears to be a simple febrile seizure may actually be a seizure pro- voked 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 con- vincing evidence that febrile seizures are secondary to a bacterial meningi- tis. 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
(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.
- 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
(C)
(Victor, p 217.) Surgery may eventually be neces- sary with any intervertebral disk herniation, but with acute, massive cauda equina injury, surgery must be performed before the deficits are irre- versible. 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 com- pression; a decompressive laminectomy is usually indicated with focal infections of this sort to maximize the recovery achieved with antibiotic therapy.
- 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)
(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 abort- ing 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.
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 vomit¬ing 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
(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. Hem- orrhagic 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.
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 vomit¬ing 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.
- Emergency administration of what medication is appropriate in this clinical setting?
a. Glucose
b. Magnesium sulfate
c. Pyridoxine
d. Cyanocobalamin
e. Thiamine
(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.
A 57-year-old woman with a history of diabetes mellitus and hyperthy¬roidism 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.
- This woman most likely has
a. Third-nerve palsy
b. Fourth-nerve palsy
c. Sixth-nerve palsy
d. Orbital fracture
e. Graves’ disease
(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 dis- placement 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. Sixth- nerve 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’ dis- ease, 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).
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
(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 recog¬nizes 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
(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 infancy. Congenital Horner syndrome, which may be inherited as an auto- somal 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.
A 26-year-old man is brought into the emergency room after a motor¬cycle accident in which he was not wearing a helmet. Computed tomogra¬phy (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.
- This patient’s head injury may be classified as
a. Minimal
b. Mild
c. Moderate
d. Severe
e. Vegetative
(D)
Bradley,pp45,1057.)TheGCSwasintroducedin 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.
A 26-year-old man is brought into the emergency room after a motor¬cycle accident in which he was not wearing a helmet. Computed tomogra¬phy (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.
- The presence of periorbital ecchymosis in this patient should be con¬sidered a sign of
a. Subdural hemorrhage
b. Parenchymal hematoma
c. Ocular injury
d. Retinal detachment
e. Basilar skull fracture
(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.
A 26-year-old man is brought into the emergency room after a motor¬cycle accident in which he was not wearing a helmet. Computed tomogra¬phy (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.
- 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)
(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 hyper- tension, 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.
A 26-year-old man is brought into the emergency room after a motor¬cycle accident in which he was not wearing a helmet. Computed tomogra¬phy (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.
- 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
(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.
