15Neurology
D Agenesis of the corpus callosum
Agenesis of the corpus callosum is seen along with mental retardation, epilepsy, and patches of retinal pigmentation in Aicardi syndrome. The syndrome is inherited in an X-linked dominant fashion and is lethal in most males. (A) Absence of the septum pellucidum has many etiologies and is seen in Morsier syndrome (septo-optic dysplasia). (B) A Dandy-Walker malformation is a partial or complete absence of the cerebellar vermis. (C) Fusion of any two of the cervical vertebrae is associated with Klippel-Feil syndrome. (E) A Chiari type 3 malformation is characterized by an occipital encephalocele containing neuroectodermal tissues from the posterior fossa and is associated with hydrocephalus.
A Posterior columns
A positive Romberg test is not a test of cerebellar function. Patients with cerebellar ataxia are not able to balance even with their eyes open. The cerebellum is responsible for unconscious proprioception and receives input from the dorsal nucleus of Clarke, with information traveling through the ipsilateral dorsal spinocerebellar tract. Vestibular disorders can have a positive Romberg sign; however, the sign most commonly is seen in patients with loss of conscious proprioception or dorsal column-medial longitudinal fasciculus system dysfunction.
C Herpes simplex encephalitis; begin intravenous acyclovir
Herpes simplex virus (HSV) encephalitis presents acutely and most commonly with fever and an altered level of consciousness often accompanied by seizures. There is a predilection for the temporal and orbitofrontal lobes with edema in these areas visualized on MRI (bilateral lesions raise the suspicion for HSV encephalitis). Treatment should be initiated quickly if a patient has fever, encephalopathy, supporting cerebrospinal fluid studies, and another supporting study. (A, B) Varicella zoster encephalitis more commonly affects immunocompromised individuals and typically follows cutaneous herpes zoster.
C Mental retardation
Both Apert and Crouzon syndromes are associated with craniosynostosis and a high incidence of hydrocephalus, and are inherited in an autosomal dominant manner. Individuals with Crouzon syndrome usually are of normal intelligence once the hydrocephalus is treated. On the other hand, individuals with Apert syndrome have with mental retardation, complex syndactyly, short thumbs, and cleft palates.
A Mid-fusiform gyrus and inferior occipital gyrus
Damage to or inappropriate development of the mid-fusiform and inferior occipital gyri independently and with either unilateral or bilateral defects are associated with prosopagnosia (difficulty with face recognition). (B) Kluver-Bucy syndrome occurs in bilateral amygdala lesions. It is associated with hyperoral and hypersexual behaviors, visual agnosia, and hypomotility. (C) Mesial temporal lobe lesions result in long-term memory deficits. (D) Damage to the dominant angular gyrus results in dysgraphia (writing apraxia). (E) The superior parietal lobule and supramarginal gyrus are part of the association cortex. Damage to these areas can cause contralateral astereognosis, resulting in failure to recognize objects when felt with the contralateral hand but not when visualized.
C Progressive supranuclear palsy
The progressive supranuclear palsy (Steele-Richardson-Olszewski syndrome) triad is progressive supranuclear ophthalmoplegia (paresis of voluntary eye movements with down-gaze palsy and frequent falls as a result), pseudobulbar palsy (masked facies with dysarthria, dysphagia, and a hyperactive jaw jerk), and axial dystonia. Patient with this condition do not walk bent forward and do not have a tremor despite progressive supranuclear palsy being characterized as pseudoparkinsonism. Progressive supranuclear palsy can be differentiated from Parkinson disease by a poor response to levodopa in the former. (A) Triad of parkinsonism is resting tremor, cogwheel rigidity, and bradykinesia. (B) Olivopontocerebellar degeneration is related to multiple system atrophy and often presents with cerebellar ataxia, dysarthria, and dysphagia without paresis. (D) Multiple system atrophy (Shy-Drager syndrome) is a Parkinson plus syndrome. It is a progressive disorder of the central and autonomic nervous systems with idiopathic orthostatic hypotension.
C Herpes simplex encephalitis
Bilateral periodic lateralizing epileptiform discharges (PLEDs) are seen with acute focal insults and in 85% of cases of herpes simplex encephalitis. (A) Subacute sclerosing panencephalitis has a pathognomonic pattern of periodic high-amplitude complexes with accompanying myoclonic jerks that does not change with painful stimulation. (B) PLEDs are defined as spikes occurring at regular intervals. The electroencephalogram in sporadic Creutzfeldt-Jakob disease often shows bilateral sharp waves that may resemble PLEDs but are reactive to painful stimulation. (D) Hepatic encephalopathy may show nonspecific triphasic waves on electroencephalography.
B Measuring the middle cerebral to internal carotid artery velocity ratio
A Lindegaard ratio (VMCA/VICA) greater than 3 is seen in vasospasm. In a hyperemic state, velocities in both the middle cerebral and internal carotid arteries are elevated equally, so the ratio is near 1. (A) Multiple factors can influence cerebral artery flow velocity, including systemic blood pressure, cerebral blood flow, and cerebral perfusion. Transcranial Doppler measures the cervical carotid and intracranial artery velocities. Elevated flow velocity more than 100 cm/s can be seen in both hyperemic and vasospastic states. (C) Vasospasm can affect the circulation bilaterally, so symmetry is not a key differentiating factor. (D) Vessel diameter is not a determining factor in either state. (E) Antegrade versus retrograde flow is not used to differentiate between hyperemia and vasospasm.
A Hemifacial spasm
Hemifacial spasm and palatal myoclonus are involuntary movement disorders that persist during sleep. (B) Blepharospasm is sustained, abnormal blinking. It involves the orbicularis oculi muscle only (in contrast to hemifacial spasm, which involves various muscles on one side of the face). Blepharospasm typically ceases during sleep. (C) Athetosis is slow, writhing movements of the distal muscles (fingers, hands, toes, feet, and even face). (D) Facial myokymia is continuous facial spasms secondary to multiple sclerosis or a brainstem glioma. One of the treatments is rest.
D Loss of consciousness, posttraumatic amnesia, and symptom duration
The Cantu concussion grading system is a three-grade system based on posttraumatic amnesia (PTA), loss of consciousness (LOC), and symptom duration. The scoring system is as follows: grade 1: no LOC, PTA less than 30 minutes, and postconcussion symptoms lasting no more than 15 to 30 minutes; grade 2: LOC less than 1 minute and PTA and symptoms lasting 30 minutes to 24 hours; grade 3: LOC of 1 minute or longer, PTA lasting more than 24 hours, and symptoms lasting as long as 1 week. (A) The American Academy of Neurology system uses a progressive three-grade system for concussion grading based on transient confusion, symptom duration, and loss of consciousness. (B) The Ruff Concussion system is a progressive three-grade system based on loss of consciousness, posttraumatic amnesia, and neurologic deficits. (C) The Glasgow Coma Scale ranges from a minimum score of 3 to a maximum score of 15. The score is the sum of the individual scores for eye opening, verbal response, and motor response. The scoring system is as follows: eye opening score: spontaneous (4), to speech (3), to pain (2), no response (1); verbal response score: alert and oriented (5), confused (4), inappropriate words (3), incomprehensible sounds (2), no response (1); motor response score: follows commands (6), localizes to pain (5), withdraws to pain (4), flexor (decorticate) posturing (3), extensor (decerebrate) posturing (2), no response (1).
C Posterior interosseous neuropathy
The posterior interosseous nerve is a continuation of the deep branch of the radial nerve. Entrapment occurs in the forearm at the arcade of Frohse, causing extensor weakness of the thumb and fingers without involvement of the wrist extensors or triceps. This is a motor syndrome, and there is no sensory loss as seen in a radiculopathy. (A) A radial nerve palsy can occur at the axilla, causing triceps and distal weakness or at the mid-upper arm (spiral groove or intramuscular septum), sparing the triceps but causing weakness of wrist and finger extensors. (B) Tennis elbow (also known as lateral epicondylitis) is an inflammatory process of the tendons on the lateral aspect of the elbow. This results in pain of the extensor muscles of the forearm, wrist, and fingers. The tendon of the extensor carpi radialis brevis is usually involved. (D) A C8 radiculopathy results in flexion weakness of the index and middle fingers and paresthesias in the fifth digit. (E) Radial tunnel syndrome (also known as supinator syndrome) causes inflammation and pain in the origin of the extensor muscles at the lateral epicondyle on resisted extension of the middle finger. The condition may mimic lateral epicondylitis, and though the compression site is similar to the compression site in posterior interosseous nerve compression, there is usually no muscle weakness with radial tunnel syndrome.
D Incomplete Horner syndrome with neck pain and delayed contralateral weakness and sensory loss
Spontaneous internal carotid artery dissections usually present with ipsilateral headache. Although difficult to detect clinically, these dissections often present with an incomplete Horner syndrome (oculosympathetic palsy) with ptosis and miosis without anhydrosis. The lack of anhydrosis is because the sympathetic nerves to the facial sweat glands travel on the external carotid artery. Ischemic events can be a complication of carotid artery dissection. (A) Wallenberg (also known as lateral medullary) syndrome is characterized by dissociated sensory loss from vertebral or posterior inferior cerebellar artery occlusion. This results in a complete Horner syndrome, dysphagia, ataxia, vertigo, nystagmus, hoarseness, and loss of pain and temperature sensation in the ipsilateral face and contralateral body. (B) Pancoast tumors cause Horner syndrome with shoulder and arm pain. (E) Weber syndrome results from a stroke of the ventral midbrain and is characterized by ipsilateral mydriasis and contralateral hemiparesis.
D Gradenigo syndrome
The classic triad of symptoms in Gradenigo syndrome is an abducens palsy, retro-orbital pain, and a draining ear from acute otitis media with mastoiditis and involvement of the petrous apex. The abducens palsy occurs when the infection involves the Dorello canal and ophthalmic branch of the trigeminal nerve, given the anatomic proximity of these structures to the petrous apex. (A) Cranial nerve VI palsies can be a false localizing sign, so intracranial hypertension (sinus thrombosis) must be in the differential. This is not the patient’s most likely diagnosis, however. (B) Tolosa-Hunt syndrome is inflammation of the superior orbital fissure/cavernous sinus that usually includes painful ophthalmoplegia, multiple cranial nerve palsies with sparing of the pupil, and dramatic improvement with steroids. (C) Raeder paratrigeminal neuralgia consists of Horner syndrome and trigeminal neuralgia-like pain. (E) Ramsay-Hunt syndrome (also known as Herpes zoster oticus) is reactivation of the varicella zoster virus in the geniculate ganglion, causing otalgia, auricular vesicles, and peripheral facial paralysis.
D Spinocerebellum
Common cerebellar syndrome is found in alcoholics and is due to damage to the anterior part of the cerebellar cortex (spinocerebellum). (A) A vestibulocerebellum (flocculonodular lobe and adjacent vermis) lesion impairs the ability to stand upright and maintain gaze direction. Patients have a wide-based stance with small, shuffling movements. (B) Cerebellar tonsil pathology often is seen in patients with Chiari 1 malformations. (C) The cerebrocerebellum (lateral cerebellar hemispheres) is involved in highly skilled, learned movements. (E) Lesions interfering with the triangle of Guillain-Mollaret (olivary nucleus, dentate gyrus, and red nucleus) may result in palatal myoclonus.
D Abduction of fifth digit due to weakness of the third palmar interosseous muscle
The Wartenberg sign is abduction of the fifth digit due to paralysis of the adducting palmar interosseous muscle and unopposed action of the extensor digiti minimi and digitorum communis muscles (innervated by the radial nerve). (A) Wasting of the interossei muscles in the hand is common in ulnar neuropathies. (B) A Froment thumb sign is seen when a patient grasps a sheet of paper resulting in extension of the proximal phalanx and flexion of the distal phalanx. This occurs as the anterior interosseous and flexor pollicis longus substitute for the weakened, ulnar-innervated adductor pollicis. (C) Hyperextension at the metacarpophalangeal joints and flexion at the interphalangeal joints in digits four, five, and partially three describes a “claw hand” deformity (also called “main en griffe”), resulting from an ulnar nerve injury. This condition should not be confused with a median nerve injury resulting in a “hand of benediction” deformity. (E) Ulnar nerve compression at the Guyon canal spares the dorsal cutaneous nerve that branches from the ulnar nerve in the forearm proximal to the wrist. Compression at this site also spares the flexor digitorum profundus medial heads.
B Tumor compression of the stellate ganglion
The stellate ganglion is a sympathetic ganglion implicated in some pain syndromes, and lesions of this ganglion can cause a Horner syndrome. Iatrogenic injuries sometimes occur during injections or blocks for complex regional pain syndrome. A Pancoast tumor also may compress the nerve roots or trunks of the brachial plexus to cause upper extremity weakness.
D Acute disseminated encephalomyelitis
Acute disseminated encephalomyelitis (ADEM) is the most common white matter disease in children. It typically follows an illness or vaccination and is differentiated from multiple sclerosis because multiple sclerosis has a multiphasic presentation. The first-line treatment for ADEM is intravenous steroids followed by a prednisone taper. Cases that do not respond to steroids may require intravenous immunoglobulins.
C Thiamine; irreversible; medial dorsal thalamic nuclei
Korsakoff psychosis/syndrome is present in 80% of individuals who survive the preceding Wernicke encephalopathy, which is triggered by a thiamine deficiency. Korsakoff syndrome is irreversible. The classic triad for Wernicke encephalopathy is encephalopathy, ophthalmoplegia, and ataxia. With either condition, MRI FLAIR sequences typically demonstrate signal in the medial thalamus, floor of the fourth ventricle, and periaqueductal gray matter of the midbrain.
C Intubate the patient.
This question emphasizes the importance of the “ABCs” (airway, breathing, and circulation) in emergency situations. Although quick initiation of treatment for Guillain-Barré syndrome is important, the patient is showing clinical signs of impending respiratory failure, making intubation the correct option.
B Left lateral medulla
Lateral medullary syndrome (also known as Wallenberg syndrome) is due to infarction of the lateral medulla. Structures in this region include the nucleus and descending tract of the fifth cranial nerve, nucleus ambiguus, lateral spinothalamic tracts, inferior cerebellar peduncle, and descending sympathetic fibers of the vagus and glossopharyngeal nerves. Patients with Wallenberg syndrome have a classic constellation of symptoms including (1) ipsilateral Horner syndrome, (2) ipsilateral ataxia, (3) ipsilateral loss of facial pain and temperature perception, (4) ipsilateral loss of the corneal reflex, (5) ipsilateral impairment of corneal reflexes, (6) contralateral loss of pain and temperature sensation, (7) dysphagia, and (8) dysphonia.
D INR of 2.3
An INR over 1.7 is an absolute contraindication to thrombolysis. Other absolute contraindications to thrombolysis include (1) uncertainty about time of stroke onset (e.g., patients awakening from sleep); (2) coma or severe obtundation with fixed eye deviation and complete hemiplegia; (3) hypertension with a systolic blood pressure at least 185 mm Hg or a diastolic blood pressure over 110 mm Hg on repeated measures (if reversed, a patient can be treated); (4) clinical presentation suggestive of subarachnoid hemorrhage, even if the CT scan is unremarkable; (5) presumed septic embolus; (6) patient having received a heparin medication within the last 48 hours, with an elevated activated prothrombin time (APTT) or with a known hereditary or acquired hemorrhagic diathesis; (7) known advanced liver disease, advanced right heart failure, or coagulopathy disorder with an INR over 1.5; (8) platelet count less than 100,000/μL; and (9) serum glucose less than 2.8 mmol/L or greater than 22.0 mmol/L. (A–C) Age over 80 years, major surgery within 2 weeks of presentation, hip replacement within 3 weeks of presentation, and recent myocardial infarction all are relative contraindications to thrombolysis.
A Hartnup disease
Hartnup disease (also known as pellagra-like dermatosis) is an autosomal recessive disease affecting the absorption of nonpolar amino acids, particularly tryptophan, which is a precursor to serotonin, melatonin, and niacin. Niacin is a precursor to nicotinamide, which is a necessary component of NAD. Clinically, the disease is characterized by a childhood presentation, with symptoms ranging from failure to thrive, photosensitivity, intermittent ataxia, nystagmus, and tremor. Supplementation with high doses of nicotinamide usually is sufficient to treat the disease. (B) Phenylketonuria is caused by absent phenylalanine hydroxylase. It usually is treated with a strict phenylalaninerestricted diet. If untreated, patients suffer intellectual disability and seizures and eventually could die. (C) Homocystinuria leads to multisystemic disorders of connective tissue, muscles, and the central nervous and cardiovascular systems. There is no specific cure for homocystinuria; however, many people are treated with high doses of vitamin B6. (D) G6PD deficiency does not affect the central nervous system. Treatment is by preventing exposure to drugs and foods that cause hemolysis. (E) Tetrahydrobiopterin deficiency is a rare metabolic disorder that increases the blood levels of phenylalanine, which leads to low muscle tone and possible difficulty swallowing, seizures, progressive problems with development, and an inability to control body temperature. Treatment consists of tetrahydrobiopterin supplementation and a low phenylalanine diet.
A Multiple sclerosis
Multiple sclerosis is the most common autoimmune disorder affecting the central nervous system, and patients can have a wide range of neurologic symptoms. In this clinical vignette, the patient has symptoms of optic neuritis, which affects up to 50% of multiple sclerosis patients. (B) Guillain-Barré syndrome is characterized by a rapid-onset weakness of the limbs as a result of an acute polyneuropathy affecting the peripheral nervous system. (C) Transient ischemic attacks are characterized by focal neurologic deficits that resolve within 24 hours. (D) Myasthenia gravis is an autoimmune or congenital neuromuscular disease characterized by fluctuating muscle weakens and fatigue. Extraocular muscles often are involved. (E) Amyotrophic lateral sclerosis is characterized by gradually worsening weakness and stiff muscles with fasciculations.
C Angiogram
An angiogram is the most sensitive modality to diagnose sagittal sinus thrombosis. The presence of headache, hemiparesis, and focal epilepsy in a relatively young patient is indicative of sagittal sinus thrombosis. The likelihood of having the pathology is much higher in patients with a history of hypercoagulable disorders such as homocystinuria.
B Proprioception
The tests described are the Romberg and heelshin tests. Both of these test proprioception. The Romberg test combines vision, proprioception, and vestibular function. The heel-shin test assesses vision, proprioception, and cerebellar function.
D Deposition of β-amyloid plaques
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