Password recovery. Recover your password. Thursday, November 25, Get help. You may send an email to freeusmlebooks gmail. Victor, pp — The facial nerve innervates the stapedius muscle of the middle ear. Hyperacusis is an indication that the damage to the facial nerve is close to its origin from the brainstem, because the nerve to the stapedius muscle is one of the first branches of the facial nerve.
The tensor tympani is controlled by the motor fibers in the fifth cra- nial nerve. With damage to this nerve, the tympanic membrane has some inappropriate slack, but the patient does not usually comment on increased sensitivity to sound in the affected ear. Walking along a straight line with the heel of one foot touching the toe of the other foot is called heel-to- toe walking, or tandem gait.
It is a routine test for ethanol intoxication because alcohol exposure impairs the coordination of gait as governed by the cerebellum. Tandem gait will be abnormal with many other problems, including weakness, poor position sense, vertigo, and leg tremors, but such abnormality in the absence of these other problems suggests a cerebellar basis for the problem.
The hypoglossal nerve inner- vates the tongue. The fine movements noted under the surface of the tongue with injury to the hypoglossal nerve are called fasciculations and are an indication of denervation.
They are presumed to occur through hypersensi- tivity to acetylcholine acting at the denervated neuromuscular junction. Atrophy and fasciculations are likely to occur together and are highly sug- gestive of denervation of the tongue. This is most often seen with brainstem disease, such as stroke or bulbar amyotrophic lateral sclerosis ALS , or with transection of the hypoglossal nerve.
This patient has a history most consistent with a herniated lumbar disk. The most common locations for lumbar disk herniation are between the fifth lumbar and first sacral verte- brae producing S1 nerve root compression and between the fourth and fifth lumbar vertebrae producing L5 root compression. S1 nerve root compression, or radiculopathy, is associated with pain in the lower back or buttock region, often radiating down the posterior thigh and calf to the lat- eral and plantar surfaces of the foot and affecting the fourth and fifth digits of the foot.
Motor function of the foot and toe flexors, toe abductors, and hamstring muscles may be impaired but more often is not. The loss of the ankle jerk, or Achilles tendon reflex, is often the only objective sign of S1 radiculopathy. Deep tendon reflexes such as the ankle jerk are diminished or lost when there is damage to the sensory fibers from the tendon stretch organs.
A Babinski sign is an indication of upper motor neuron damage, which is not expected in this case with preserved autonomic and motor function. Loss of pinprick sensation over the web space between first and second toes is found in association with injury to the fifth lumbar nerve root or to the peroneal nerve. Hyperreflexia of the knee jerk is another sign of an upper motor neuron lesion and would not be expected in this case.
This test may be positive on the contralateral side crossed straight-leg raising sign , but it is usually more prominent on the affected side. Victor, pp —, — The presentation with subacute onset of morning headaches culminating in confusion, right hemiparesis, and seizure in a young person suggests an expanding mass lesion, most likely a tumor. The weakness of eye abduction bilaterally is what may be referred to as a false localizing sign. Although this suggests injury to the sixth cranial nerves bilaterally, the injury is not restricted to the sixth cranial nerve.
The increase in intracranial pressure ICP from the mass causes stretching of the sixth-nerve fibers, which consequently leads to their dysfunction.
Diplopia may be appreciated only on lateral gaze, which requires full function of the sixth nerve. Funduscopic exam in such a case would most likely reflect changes of increased ICP. The first sign of this is usually blurring of the margins of the optic disc and elevation of the disc due to swelling. Changes in the optic disc—the area in which all the nerve fibers from the retina come together and exit as the optic nerve— occur with problems other than increased ICP such as optic neuritis , but blurring of the margins should be routinely considered a sign of increased ICP.
This is especially true if the appearance of the disc has changed in asso- ciation with the development of headache, obtundation, and vomiting.
Pigmentary degeneration of the retina may occur with some infections, such as congenital toxoplasmosis or cytomegalovirus, or as part of a hered- itary metabolic disorder, as in retinitis pigmentosa.
Caloric stimulation of the ear drives the endolymphatic fluid in the inner ear up or down, depending on whether warm or cold water is used. The vestibular organ exposed to warm water sends impulses to the brainstem that indicate that the head is moving to the side that is being warmed.
The eyes deviate to the opposite side to maintain fixation on their targets, but the eye movement actually breaks fixation. A reflex nystagmus toward the ear that is being stimulated develops as the brain tries to establish refixation while the vestibular signals repeatedly prompt deviation of the eyes contralateral to the warm stimulus. Kandel, p The presence of ptosis and miosis indicate oculosympathetic palsy, or Horner syndrome. This indicates injury to the sympathetic supply to the eye.
This pathway begins in the hypothalamus, travels down through the lateral aspect of the brain- stem, synapses in the intermediolateral cell column of the spinal cord, exits the spinal cord at the level of T1, and synapses again in the superior cervi- cal ganglion. From there, postganglionic fibers travel along the surface of the common carotid and internal carotid artery until branches leave along the ophthalmic artery to the eye. Fibers of the sympathetic nervous system, which are destined to serve the sudomotor function of the forehead, travel with the external carotid artery.
Thus, diseases affecting the internal carotid artery and the overlying sympathetic plexus do not produce anhidrosis, the third element of Horner syndrome. In this case, the occurrence of painful Horner syndrome acutely after vigorous activity is virtually diagnostic of carotid artery dissection. Dissections may occur more frequently in mi- graineurs. The preservation of visual fields and acuity excludes significant disease of the optic tract and chiasm, which also would not be expected to cause ptosis.
The sympathetic pathway does exit the spinal cord at T1, but injury at this location would not cause orbital pain, which is typical of carotid arterial dissection. The answer is c. Dissections are caused by a tear in the intimal lining of the vessel with penetration of blood beneath the intimal surface, forming an intramural hematoma blood clot within the wall of the vessel.
This may be seen as an area of increased signal within the lining of the vessel on T1-weighted images, on which a blood clot appears bright. Typically, this takes a crescentic pattern, and the lumen of the vessel is displaced eccentrically.
An increased T2 signal in a periventricular distri- bution is typical of the plaques of demyelinating disease seen in multiple sclerosis. Contrast enhancement along the tentorial margin might be seen in inflammatory diseases of the dura mater or meninges.
An enlarged optic nerve might be seen in the setting of optic neuritis or infiltration of the nerve by a tumor or other process, and this would be expected to cause visual impairment. A cavernous sinus aneurysm that is sufficient to produce ocu- losympathetic palsy would be expected to cause other deficits in ocular motility because the cranial nerves subserving oculomotor function course through the cavernous sinus.
After injury to the facial nerve, regen- erating fibers may be misdirected. Aberrant regeneration is possible only if the nerve cell bodies survive the injury and produce axons that find their way to neuromuscular junctions. Fibers intended for the periorbital muscles end up at the perioral muscles, and signals for eye closure induce mouth retraction. With a habit spasm or idiopathic tic, similar movements may occur, but the movement disorder would not be linked to facial weakness.
This patient gives a good his- tory for subarachnoid hemorrhage. A cerebral angiogram could diag- nose the etiology of a subarachnoid hemorrhage, such as an aneurysm.
How- ever, it is an invasive test and should not be done without first attempting to confirm the diagnosis with less risky tests. If you suspected seizures an elec- troencephalogram might be useful. As this patient did not have any loss of consciousness, personality changes, hallucinations, or rhythmic movements suggestive of seizures, there is no indication for a psychiatry consult.
However, if no blood is seen, the physician should proceed to a lum- bar puncture. A cerebral an- giogram could diagnose the etiology of a subarachnoid hemorrhage, such as an aneurysm; however, it is an invasive test and should not be done without first attempting to confirm the diagnosis with less risky tests. An MRI is un- likely to give new useful information in this case. Zolmitriptan is a treatment for migraines.
This patient probably has a subarach- noid hemorrhage and must be evaluated for an aneurysm. This does not appear to be bacterial meningitis. It is not emergent that ceftriaxone be given in this case. Repeating the lumbar puncture will not help with the diagnosis or treatment. Intravenous acyclovir would be used to treat herpes encephalitis. Although there are often red blood cells in the spinal fluid of such patients, the overall history makes herpes encephalitis unlikely.
Computed tomographic scan- ning is especially sensitive to intracerebral hemorrhage, but not to aneurysms unless they are more than 5 mm across. Even such relatively large aneurysms may not be revealed by CT scanning unless there is bleeding from the aneurysm or distortion of adjacent structures by the aneurysm.
Microscopic aneurysms may be localizable on CT only because of the high signal left near the aneurysm by telltale blood. In most cases of aneurysmal bleeding, angiography is needed to characterize and localize the lesion.
The open black arrow denotes the aqueduct of Sylvius, which connects the third ventricle with the fourth ventricle. This sagittal view of the lower part of the brain provides a high- resolution view of the posterior fossa. What appears to be a connection between the most inferior aspect of the fourth ventricle and the cisterna magna at the straight black arrow is an artifact.
This is the obex of the fourth ventricle, and there is a complete roof over this ventricle, which communicates with the subarachnoid space through the foramens of Luschka and Magendie. Bone has low signal on this T1- weighted image of the head, and so it may not be obvious that this cerebel- lar tonsil is sitting above the opening of the foramen magnum.
The white streak just above the curved white arrow is the bone marrow in the occipi- tal bone. With Arnold-Chiari malformations, the tonsil would be expected to sit below the foramen magnum. With Dandy-Walker syndrome or giant cisterna magna, the tonsil would be inapparent or at least sitting much more cephalad. All five of the tumors listed are common in the posterior fossa. The tentorium cerebelli is a fold of meninges. Consequently, it is a relatively common site for the development of meningiomas.
A tumor arising on the tentorium may extend either supe- riorly or inferiorly. Inferior extension of the tumor may damage cranial nerves and make complete extirpation of this benign neoplasm impossible. Calcified masses appear hyper- dense without contrast enhancement, whereas highly vascular lesions may appear dense on CT scanning after the patient has received intravenous con- trast material.
Tumors, granulomas, and other intracranial lesions enhance because of a breakdown in the blood-brain barrier. More cystic lesions may exhibit enhancement limited to the periphery of the cyst. Bradley, pp , With signs and symptoms that evolve slowly, a neo- plasm is more likely. Because there was no involvement of the eighth cra- nial nerve and because the lesion on CT scan is calcified, the most probable neoplasm is a meningioma.
This tumor also appears to arise from the petrous bone, another indication that it is most likely a meningioma. Complete resection of this large meningioma is probably impractical because of the damage to cranial nerves that would be sustained with any attempt at complete extirpation.
If tumor must be left behind, repeated surgery may be necessary. Chemotherapy is not helpful because these tumors are notoriously insensitive. Radiation ther- apy is controversial because some tumors may become more anaplastic after radiation, but the current evidence supports irradiating residual tumor.
Meningiomas occur with increased frequency in type 2 neurofibromatosis, a dominantly inherited disorder aris- ing with a deletion on the long arm of chromosome Women with breast cancer and other gynecologic cancers are also at increased risk of develop- ing meningiomas, perhaps because of sex steroid receptors on these tumors that enhance their growth when gynecologic disturbances occur. Estrogen or progesterone antagonists may be useful in the management of these tumors, but tamoxifen, an estrogen inhibitor, paradoxically stimulates the growth of meningioma cells.
Victor, pp 93— Dysdiadochokinesia is usually apparent with cerebellar damage. It is most evident when strength and sen- sation are intact.
Alternately tapping one side of the hand and then the other, or tapping the heel and then alternating with the toe of the foot, is the test usually employed to check this aspect of coordination. Multiple sclerosis in adults and cerebellar tumors in children are two of many causes of problems with this part of the neurologic examination.
Focal lesions in the nervous sys- tem may produce highly asymmetric dysdiadochokinesia. A variety of move- ment disorders, such as parkinsonism and choreoathetosis, may interfere with rapid alternating movements and give the false impression that the patient has a lesion in systems solely responsible for coordination.
Victor, pp 27— This brain wave activity should be equally well developed over both sides of the head. The answer is i. Shuaib, p This man has suffered an acute cere- brovascular event. The most important test in the immediate period is a CT scan of the head to establish whether the lesion is hemorrhagic or ischemic.
If there is no evidence of hemorrhage on head CT, then the patient is within the 3-h time window permitting therapy with intravenous recombinant tis- sue plasminogen activator r-TPA , which has been shown to improve functional outcome after stroke.
Bradley, p A nerve conduction study should confirm that this woman has a peripheral neuropathy—that is, a distur- bance of sensory and motor nerve function in the limbs. Given her social condition, she is at high risk for a nutritional neuropathy. A glove-and- stocking pattern of sensory disturbance is usually seen with lesions that involve peripheral nerves, specifically the nerves extending out into the limbs. The meaning of glove-and-stocking is self-evident: sensation is dis- turbed over the hands and the feet with extension up the arms and the legs being quite variable.
With severe neuropathy of the hands or the feet, ulcer- ations and pressure sores will develop over the skin that is innervated by the damaged nerves. The most severe sensory deficit affects the most terminal elements of the limbs. Metabolic or nutritional problems are the usual causes of a glove-and-stocking pattern of sensory disturbance.
Diabetes mellitus, thiamine deficiency, and neurotoxin damage e. Affected persons usually report the sensation of pins and needles in the hands and feet, but with some neuropathies severe pain may develop along with the loss of sensory acuity.
This boy is probably having general- ized absence seizures. The EEG will show the typical 3-Hz spike-and-wave pattern characteristic of this type of seizure disorder. Even if this patient does not have the typical pattern, the character of his episodes suggests epilepsy i.
Swaiman, pp — Seizures associated with fever at this age are worrisome and must be aggressively investigated. The neck stiffness, fever, and recurrent seizures necessitate a spinal tap to allow examination of the cerebrospinal fluid. The fluid should be checked for the opening pressure, Gram staining, protein and glucose content, cell count, bacterial and fungal cultures, acid-fast bacillus AFB staining, and flagel- lated treponemal antigen FTA-ABS.
Antibiotic treatment should be started immediately if there is any indication of an infection. Haemophilus influenzae was commonly responsible for meningitis at this early age prior to the avail- ability of vaccination against it, but infections with a variety of bacteria, including gram-negative bacteria, are also possible causes of the clinical scenario described.
The answer is f. This patient probably has a myopathy. The elevated ESR and periungual telangiectasias suggest an inflammatory myopathy, and specifically dermatomyositis. Creatine phos- phokinase would help to confirm that this is a primary muscle disease. Addi- tional tests that will be of use are electromyography EMG and muscle biopsy. Electromyography may show brief, low-voltage action potentials, fib- rillation potentials, positive sharp waves, polyphasic units, and some evi- dence of denervation.
Muscle biopsy may show changes characteristic of the particular inflammatory myopathies. In polymyositis, extensive necrosis of muscle fiber segments is seen with macrophage and lymphocyte infiltration. In dermatomyositis, the picture is quite different: there is perifascicular mus- cle fiber atrophy, and the inflammatory infiltrate occurs in the perimysial connective tissue rather than throughout the muscle fibers themselves.
In addition, electron microscopy shows characteristic tubular aggregates. In the rarer inclusion body myositis, the appearance is similar to that of polymyosi- tis except that rimmed vacuoles are also seen. This CSF profile is essentially nor- mal. With idiopathic seizures, the CSF should be normal. Seizure activity does not ordinarily drive up the CSF protein content or significantly change the cellular content of the fluid.
The acidosis that is observed in this patient is inconsequential and is routinely found during the early postictal period after a generalized tonic-clonic seizure. This man with fever, generalized seizure, lethargy, cough, headache, blurred vision, and progressive stupor probably has an acute bacterial meningitis.
Given his age of 72 and his- tory of probable upper respiratory infection, a pneumococcal meningitis is highly probable. In bacterial meningitis, the CSF typically exhibits an elevated protein content, no or few RBCs, an elevated opening pressure, milky or xanthochromic fluid, and a normal or slightly elevated gamma globulin content. If there are relatively few white cells and the CSF pro- tein is not greatly elevated, the fluid may appear clear and colorless. A very low CSF glucose content supports the diagnosis of bacterial meningitis.
Tuberculous menin- gitis, however, produces an atypical pattern of CSF changes distinct from that caused by other bacterial pathogens and reminiscent of that caused by fungi. His CSF is largely normal except for its markedly high protein. The CSF is xanthochromic i. Despite the pattern of weakness, which suggests an ascending myelitis, his CSF reveals a normal cell count.
That a bacterial meningitis is not responsible for his weakness is supported by a normal CSF glucose con- tent. The answer is g. This man involved in an auto- mobile accident, probably has subarachnoid blood associated with his head trauma. This is suggested by his neck stiffness, photophobia, and vomiting. That he had transient loss of consciousness and that there was obvious trauma to his head supports the notion that he suffered enough of a blow to his head to produce intracranial bleeding of some sort.
A high CSF protein content and xanthochro- mia suggest that much of the blood in the CSF has already broken down by the time of the tap. Many RBCs will persist for days with a substantial sub- arachnoid hemorrhage. The WBC count will be elevated because the sub- arachnoid blood is irritating and produces a chemical meningitis.
The opening pressure may be slightly elevated if there has been much bleeding into the subarachnoid space. This young woman with progressive behavioral disturbances, hallucinations, seizures, and obtunda- tion probably has a herpes simplex type 1 encephalitis. The CSF protein is elevated, but the glu- cose content is relatively normal with this viral infection. As the CSF pro- tein increases, the percentage that is gamma globulin generally increases.
This is not an indication that the problem is an infection, but this increase in total protein and gamma globulin component does occur with infec- tions. The opening pressure may be markedly elevated, but the fluid may remain clear or be only slightly cloudy if the white blood cell count does not increase substantially.
This young man has signs and symptoms of multiple sclerosis that are largely referable to the spinal cord. Gait ataxia is an especially common presenting complaint. Impotence is troublesome and common. The CSF fluid picture is distinctive in its eleva- tion of the gamma globulin content. Oligoclonal banding studies of the fluid would most likely be positive. This woman with head- aches, papilledema, and slightly blurred vision probably has pseudotumor cerebri.
This idiopathic increase in intracranial pressure usually occurs in obese young women, during pregnancy, or with hypervitaminosis. The ex- traordinarily high CSF opening pressure associated with pseudotumor cere- bri does not produce herniation of the brain, and performing a spinal tap does not place the patient at increased risk for transforaminal herniation.
The CSF glucose content, protein content, cell count, and gamma globulin stud- ies in persons with pseudotumor cerebri should all be unremarkable. A year-old woman with a history of type II diabetes mellitus and atrial fibrillation presents to the emergency room with right body weakness and slurred speech. The onset was sudden while she was brushing her teeth 1 h ago, and she was brought immediately to the emergency room. She has no complaints of word-finding difficulties, no dysesthesia, and no headache.
Which of the following should be done next? Administer tissue plasminogen activator b. Call a vascular surgery consult for possible endarterectomy c. Order a brain CT d. Order a cerebral angiogram e. Start heparin The patient has an MRI that is consistent with an acute stroke.
The most common cause of stroke is a. Atherosclerosis b. Fibromuscular dysplasia c. Mitral valve prolapse d. Arterial dissection e. A pure motor stroke is most likely with damage to the a. Internal capsule b. Putamen d. Caudate e. Amygdala A pure sensory stroke is most likely with damage to the a.
Thalamus c. Hippocampus d. Globus pallidus e. Pons Items 49—51 A year-old man with a history of hypertension has been in excellent health until he presents with vertigo and unsteadiness lasting for 2 days. He then develops nausea, vomiting, dysphagia, hoarseness, ataxia, left facial pain, and right-sided sensory loss.
There is no weakness. On examination, he is alert, with a normal mental status. He vomits with head movement. There is skew deviation of the eyes, left ptosis, clumsiness of the left arm, and titu- bation. He has loss of pin and temperature sensation on the right arm and leg and decreased joint position sensation in the left foot. He is unable to walk.
Magnetic resonance imaging MRI in this patient might be expected to show which of the following? Basilar artery tip aneurysm b. Right lateral medullary infarction c.
Left lateral medullary infarction d. Left medial medullary infarction e. Right medial medullary infarction The dysphagia in this case is secondary to involvement of which of the following structures?
Nucleus solitarius b. Nucleus and descending tract of CN V5 c. Nucleus ambiguus d. Lateral spinothalamic tract e. Occlusion of which of the following arteries typically produces this syndrome?
Basilar artery b. Vertebral artery c. Superior cerebellar artery d. Anterior inferior cerebellar artery AICA e. Anterior spinal artery A year-old man with a history of recent memory impairment is admitted with headache, confusion, and a left homonymous hemianopsia. He has recently had two episodes of brief unresponsiveness. There is no his- tory of hypertension. Computed tomography CT scan shows a right occip- ital lobe hemorrhage with some subarachnoid extension of the blood.
An MRI scan with gradient echo sequences reveals foci of hemosiderin in the right temporal and left frontal cortex. Gliomatosis cerebri b. Multi-infarct dementia c. Mycotic aneurysm d. Amyloid angiopathy e. Undiagnosed hypertension Items 53—56 A year-old male abuser of intravenous heroin complains of severe headache while having sexual intercourse. Within a few minutes of that complaint, he develops right-sided weakness and becomes stuporous.
His neurologic examination reveals neck stiffness as well as right arm and face weakness. An unenhanced emergency CT scan reveals a lesion of 3 to 4 cm in the cortex of the left parietal lobe.
The addition of contrast enhancement reveals two other smaller lesions in the right frontal lobe but does not alter the appearance of the lesion in the left parietal lobe. The infarct has damaged the left sixth and seventh cranial nerves or nuclei in the left pons with resultant diplopia The differential diagnosis of headaches associated with neurological or visual dysfunction is important because it Prepare Early…Score Higher Completely revised and small enough to fit in a lab coat pocket, this review of Medicine features questions with answers and explanations, including new questions in clinical vignette format.
McGraw - Hill ; Roland , L. Merritt's Textbook of Neurology. Post a Comment. Author : David J. Author : Francis J. Author : Joseph R. Author : Eileen M. Author : Richard C. Author : National Library of Medicine U. Author : Richard T. Great for course review and clinical rotations, too! This one-of-a-kind test prep guide helps you: get to know material on the medicine shelf exam and the USMLE Step 2; practice with clinical vignette-style questions and referenced answers; build confidence, skills, and knowledge; learn key facts.
There are plenty of answers out there. Open this PreTest for: a format that simulates the exam; board-type questions; referenced answers and explanations; material reviewed by recent. Moreover Cmecde. If you feel that we have violated your copyrights, then please contact us immediately.
0コメント