Neurology neurology
Medical Knowledge Self-Assessment Program
Neurology All New Content, Including 96 Multiple-Choice Questions
150591010
14 AMA PRA Category 1 Credits™ available until July 31, 2015.
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Table of Contents
Headache and Facial Pain Approach to the Patient with Headache . . . . . . . . . . . . 1 Secondary Headaches . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Common Features and Evaluation . . . . . . . . . . . . . 1 Thunderclap Headache . . . . . . . . . . . . . . . . . . . . . 3 Idiopathic Intracranial Hypertension (Pseudotumor Cerebri) . . . . . . . . . . . . . . . . . . . . . 4 Trigeminal Neuralgia (Tic Douloureux). . . . . . . . . 4 Primary Headaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Migraine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Tension-Type Headache . . . . . . . . . . . . . . . . . . . . 9 Cluster Headache . . . . . . . . . . . . . . . . . . . . . . . . 10 Related Primary Headache Syndromes. . . . . . . . . 10
Head Injury Traumatic Brain Injury . . . . . . . . . . . . . . . . . . . . . . . . 10 Concussive Head Injury . . . . . . . . . . . . . . . . . . . . . . . 11 Postconcussion Syndrome. . . . . . . . . . . . . . . . . . . . . . 11 Epidural and Subdural Hematoma . . . . . . . . . . . . . . . 12 Head Injury in a Military Population . . . . . . . . . . . . . 12
Epilepsy Features and Epidemiology of Epilepsy . . . . . . . . . . . . 12 Initial Approach to the Patient with a First Seizure . . . 13 Clinical Presentations of Seizures . . . . . . . . . . . . . . . . 14 Partial Seizures . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Generalized Seizures . . . . . . . . . . . . . . . . . . . . . . 14 Epilepsy Syndromes . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Partial (Focal) Epilepsy . . . . . . . . . . . . . . . . . . . . 15 Idiopathic Generalized Epilepsy . . . . . . . . . . . . . . 15 Comorbidities and Complications of Epilepsy . . . . . . . 16 Mood Disorders . . . . . . . . . . . . . . . . . . . . . . . . . 16 Cognitive Problems . . . . . . . . . . . . . . . . . . . . . . . 16 Osteoporosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Sudden Unexplained Death in Epilepsy . . . . . . . . 16 Diagnostic Evaluation of Seizures and Epilepsy . . . . . . 16 Imaging Studies. . . . . . . . . . . . . . . . . . . . . . . . . . 16 Electroencephalography. . . . . . . . . . . . . . . . . . . . 17 Clinical Evaluation and Video Electroencephalographic Monitoring . . . . . . . . . . 17 Treatment of Epilepsy. . . . . . . . . . . . . . . . . . . . . . . . . 18 Antiepileptic Drug Therapy . . . . . . . . . . . . . . . . . 18 Nonpharmacologic Therapy . . . . . . . . . . . . . . . . 21
Status Epilepticus . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Generalized Convulsive Status Epilepticus . . . . . . 22 Nonconvulsive Status Epilepticus . . . . . . . . . . . . . 22
Stroke Epidemiology and Definition of Stroke. . . . . . . . . . . . 24 Diagnosis of Stroke. . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Stroke Subtypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Transient Ischemic Attack . . . . . . . . . . . . . . . . . . 24 Ischemic Stroke . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Hemorrhagic Stroke . . . . . . . . . . . . . . . . . . . . . . 27 Acute Ischemic Stroke . . . . . . . . . . . . . . . . . . . . . . . . 28 Clinical Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . 28 Imaging Techniques . . . . . . . . . . . . . . . . . . . . . . 29 Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Acute Hemorrhagic Stroke . . . . . . . . . . . . . . . . . . . . . 32 Intracerebral Hemorrhage . . . . . . . . . . . . . . . . . . 32 Subarachnoid Hemorrhage . . . . . . . . . . . . . . . . . 33 Other Types of Stroke . . . . . . . . . . . . . . . . . . . . . . . . 33 Dural Sinus Venous Thrombosis . . . . . . . . . . . . . 33 Carotid and Vertebral Artery Dissection. . . . . . . . 36 Asymptomatic Aneurysm . . . . . . . . . . . . . . . . . . . 36 Admission to Stroke Units and Stroke Centers . . . . . . 36 Secondary Stroke Prevention . . . . . . . . . . . . . . . . . . . 36 Hypertension. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Dyslipidemia . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Antithrombotic Treatment. . . . . . . . . . . . . . . . . . 37 Surgery for Secondary Stroke. . . . . . . . . . . . . . . . 38 Prevention of Stroke Complications . . . . . . . . . . . . . . 38 Neurologic Worsening . . . . . . . . . . . . . . . . . . . . . 38 Medical Complications . . . . . . . . . . . . . . . . . . . . 39 Perioperative Stroke. . . . . . . . . . . . . . . . . . . . . . . 39 Primary Prevention of Stroke . . . . . . . . . . . . . . . . . . . 40 Asymptomatic Carotid Stenosis . . . . . . . . . . . . . . 40 Stroke Recovery and Long-Term Prognosis . . . . . . . . 40
Dementia General Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Definition and Description . . . . . . . . . . . . . . . . . 40 Evaluation of the Patient with Suspected Dementia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Differential Diagnosis of Dementia . . . . . . . . . . . 42 Diagnosis of Alzheimer Diseaseand Other Dementias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 ix
Alzheimer Disease. . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Prevalence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Pathogenesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Clinical Features . . . . . . . . . . . . . . . . . . . . . . . . . 43 Pathologic Features . . . . . . . . . . . . . . . . . . . . . . . 44 Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Non-Alzheimer Dementias . . . . . . . . . . . . . . . . . . . . . 45 Dementia with Lewy Bodies . . . . . . . . . . . . . . . . 45 Frontotemporal Dementia . . . . . . . . . . . . . . . . . . 46 Vascular Dementia . . . . . . . . . . . . . . . . . . . . . . . . 46 Normal Pressure Hydrocephalus . . . . . . . . . . . . . 46 Dementia and Driving . . . . . . . . . . . . . . . . . . . . . 47
Movement Disorders Overview of Movement Disorders . . . . . . . . . . . . . . . 47 Parkinson Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Clinical Features of Parkinson Disease . . . . . . . . . 48 Diagnosis of Parkinson Disease . . . . . . . . . . . . . . 49 Treatment of Parkinson Disease . . . . . . . . . . . . . . 49 Parkinson-Plus Syndromes . . . . . . . . . . . . . . . . . . . . . 51 Gait Disturbance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Ataxia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Essential Tremor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Dystonia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Chorea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Tardive Dyskinesia . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Myoclonus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Tic Disorders and Tourette Syndrome . . . . . . . . . . . . 55 Wilson Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Neuroleptic Malignant Syndrome . . . . . . . . . . . . . . . . 56 Restless Legs Syndrome . . . . . . . . . . . . . . . . . . . . . . . 56
Multiple Sclerosis and Other Demyelinating Diseases Spectrum, Pathophysiology, and Epidemiology. . . . . . 57 Presenting Signs and Symptoms of Multiple Sclerosis . . 57 Diagnosis of Multiple Sclerosis . . . . . . . . . . . . . . . . . . 58 Diagnostic Criteria and Testing . . . . . . . . . . . . . . 58 Differential Diagnosis of Multiple Sclerosis . . . . . 59 Clinical Course of Multiple Sclerosis . . . . . . . . . . . . . . 59 Treatment of Multiple Sclerosis. . . . . . . . . . . . . . . . . . 61 Lifestyle Modifications and General Health Care . . 61 Treatment of Acute Exacerbations . . . . . . . . . . . . 61 Disease-Modifying Therapies . . . . . . . . . . . . . . . . 62 Symptomatic Management . . . . . . . . . . . . . . . . . 63
x
Disorders of the Spinal Cord Presenting Symptoms and Signs of Myelopathies . . . . 64 Compressive Myelopathies . . . . . . . . . . . . . . . . . . . . . 65 Clinical Presentation . . . . . . . . . . . . . . . . . . . . . . 65 Diagnosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Noncompressive Myelopathies . . . . . . . . . . . . . . . . . . 66 Clinical Presentation, Diagnosis, and Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Neuromuscular Disorders Peripheral Neuropathies . . . . . . . . . . . . . . . . . . . . . . . 68 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Classification, Findings, and Diagnosis . . . . . . . . . 68 Mononeuropathies . . . . . . . . . . . . . . . . . . . . . . . 70 Polyneuropathies . . . . . . . . . . . . . . . . . . . . . . . . . 70 Treatment of Neuropathic Pain. . . . . . . . . . . . . . . . . . 73 Amyotrophic Lateral Sclerosis . . . . . . . . . . . . . . . . . . . 73 Neuromuscular Junction Disorders . . . . . . . . . . . . . . . 74 Myasthenia Gravis . . . . . . . . . . . . . . . . . . . . . . . . 74 Lambert-Eaton Myasthenic Syndrome. . . . . . . . . 74 Myopathies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Inflammatory Myopathy . . . . . . . . . . . . . . . . . . . 76 Endocrine-Related Myopathies . . . . . . . . . . . . . . 76
Neuro-oncology Intracranial Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Primary Central Nervous System Tumors . . . . . . . . . . 78 Management of Intracranial Tumors . . . . . . . . . . . . . . 79 Paraneoplastic Syndromes . . . . . . . . . . . . . . . . . . . . . . 79
Brain Death Description and Findings . . . . . . . . . . . . . . . . . . . . . . 80 Apnea Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Self-Assessment Test . . . . . . . . . . . . . . . . . . . . . . 85 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Neurology
Headache and Facial Pain
physician’s office will have migraine. An algorithmic approach to a patient with headache is presented in Figure 1.
Approach to the Patient with Headache
Secondary Headaches
Headache is a nearly universal phenomenon, with a lifetime prevalence greater than 90% in the general population. A headache is most often symptomatic of a benign recurrent disorder but, at times, may reflect an isolated catastrophic condition. The second edition of the International Classification of Headache Disorders (ICHD-2) divides headache into primary (defined by symptoms) and secondary (defined by cause) disorders (Table 1). Less than 5% of headache presentations to emergency departments result from secondary headache. Once serious underlying causes of headache are excluded, the possibility of migraine must be considered because greater than 90% of patients who have recurrent headache on presentation to an emergency department or TA B L E 1 .
Common Features and Evaluation Because primary headaches are defined by symptom complex and secondary headaches by cause, extensive symptom overlap is possible. The presence of a secondary headache syndrome may be signaled by the presence of one of the following red flags in the history or examination: • First or worst headache • Abrupt-onset or thunderclap attack • Progression or fundamental change in headache pattern • Abnormal physical examination findings • Neurologic symptoms lasting longer than 1 hour
International Classification of Headache Disorders
Primary Headaches Migraine Tension-type headache Cluster headache and other trigeminal autonomic cephalalgias Other primary headaches Primary stabbing, cough, exertional, and sexual headaches Primary thunderclap headache Hemicrania continua Hypnic headache New daily persistent headache Secondary Headaches Headache attributed to head and neck trauma (postconcussion syndrome, subdural hematoma) Headache attributed to a cranial or cervical vascular disorder (stroke, hemorrhage, dissection) Headache attributed to a nonvascular intracranial disorder (brain neoplasm, arachnoid cyst) Headache attributed to a substance or its withdrawal (nitrates, alcohol, caffeine) Headache attributed to infection (meningitis, cerebral abscess) Headache attributed to a disorder of homeostasis (hypercapnia, dialysis, hypertension) Headache or facial pain attributed to a disorder of extracranial head and neck structures (eye, sinus) Headache attributed to a psychiatric disorder (depression, anxiety disorders) Cranial neuralgias, central and primary facial pain, and other headaches (trigeminal neuralgia) Headache, neuralgia, and facial pain disorders not already mentioned Source: Headache Classification Subcommittee of the International Headache Society. The International Classification of Headache Disorders: 2nd edition. Cephalalgia. 2004;24(suppl 1):1622. [PMID: 14979299].
1
Headache and Facial Pain
F I G U R E 1 . Algorithmic approach to a patient with headache. CRP = C-reactive protein level; CTA = CT angiography; ESR = erythrocyte sedimentation rate; GCA = temporal (giant cell) arteritis; IIH = idiopathic intracranial hypertension; LP = lumbar puncture; MRA = magnetic resonance angiography; SAH = subarachnoid hemorrhage; SUNCT = short-lasting unilateral neuralgiform headache with conjunctival injection and tearing syndrome.
• New headache in persons younger than 5 years or older than 50 years • New headache in patients with cancer, immunosuppression, or pregnancy • Headache associated with alteration in or loss of consciousness • Headache triggered by exertion, sexual activity, or Valsalva maneuvers Although most of these warning signs are found in the history, a focused neurologic examination is essential in the complete evaluation of a patient with headache. In addition to cognitive, sensorimotor, and reflex testing, a thorough cranial nerve assessment is essential, with examination of the optic discs, visual fields, and eye movements. Further information may be gained by evaluating the cranium, cervical spine, carotid and temporal arteries, temporomandibular joint, and the ears and sinuses. Further diagnostic evaluation is required when a red flag of secondary headache is identified. Neuroimaging is the most sensitive diagnostic tool in the assessment of this type of headache. CT of the head is the preferred imaging modality in the settings of skull fracture, acute subarachnoid or intracerebral hemorrhage, and paranasal sinus disease. Although CT may be more widely available and less expensive than MRI, an 2
MRI of the brain is more sensitive in identifying intracranial pathology and, therefore, is the study of choice in most other clinical settings of acute or chronic headache. Contrast administration may be helpful in settings of malignant or inflammatory disease. The addition of CT or MR angiographic or venographic studies may be useful when vascular pathology, such as vascular occlusion, aneurysm, or malformation, is considered. Cerebrospinal fluid (CSF) examination may be warranted in patients with subarachnoid hemorrhage (SAH) with a normal CT or when meningoencephalitis, meningeal carcinomatosis, and disorders of intracranial hypertension or hypotension are suspected. Electroencephalography, evoked potentials, or plain radiographs play no role in the routine evaluation of the patient with headache. On occasion, serologic studies may be of value. Measurement of the erythrocyte sedimentation rate and Creactive protein level are necessary to evaluate potential temporal (giant cell) arteritis, which often presents as a global nondescript headache in an older person reporting a new headache associated with malaise and fatigue. Temporal artery biopsy may be required to confirm the diagnosis. (For a further discussion of giant cell arteritis, see MKSAP 16 Rheumatology.) Serum toxicology, carboxyhemoglobin determination, and thyroid function tests also may help identify specific secondary explanations for a headache presentation.
This self-assessment test contains one-best-answer multiple-choice questions. Please read these directions carefully before answering the questions. Answers, critiques, and bibliographies immediately follow these multiple-choice questions. The American College of Physicians is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians. The American College of Physicians designates MKSAP 16 Neurology for a maximum of 14 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
Earn “Same-Day” CME Credits Online For the first time, print subscribers can enter their answers online to earn CME credits in 24 hours or less. You can submit your answers using online answer sheets that are provided at mksap.acponline.org, where a record of your MKSAP 16 credits will be available. To earn CME credits, you need to answer all of the questions in a test and earn a score of at least 50% correct (number of correct answers divided by the total number of questions). Take any of the following approaches: ➢ Use the printed answer sheet at the back of this book to record your answers. Go to mksap.acponline.org, access the appropriate online answer sheet, transcribe your answers, and submit your test for same-day CME credits. There is no additional fee for this service. ➢ Go to mksap.acponline.org, access the appropriate online answer sheet, directly enter your answers, and submit your test for same-day CME credits. There is no additional fee for this service. ➢ Pay a $10 processing fee per answer sheet and submit the printed answer sheet at the back of this book by mail or fax, as instructed on the answer sheet. Make sure you calculate your score and fax the answer sheet to 215-351-2799 or mail the answer sheet to Member and Customer Service, American College of Physicians, 190 N. Independence Mall West, Philadelphia, PA 19106-1572, using the courtesy envelope provided in your MKSAP 16 slipcase. You will need your 10-digit order number and 8-digit ACP ID number, which are printed on your packing slip. Please allow 4 to 6 weeks for your score report to be emailed back to you. Be sure to include your email address for a response. If you do not have a 10-digit order number and 8-digit ACP ID number or if you need help creating a username and password to access the MKSAP 16 online answer sheets, go to mksap.acponline.org or email custserv@ acponline.org. CME credit is available from the publication date of July 31, 2012, until July 31, 2015. You may submit your answer sheets at any time during this period.
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Self-Assessment Test
Neurology Self-Assessment Test
Each of the numbered items is followed by lettered answers. Select the ONE lettered answer that is BEST in each case.
Item 1
Item 3
A 37-year-old woman is evaluated for a 1-week history of headache. She describes the headache as constant, worse when she first awakens, and characterized by a feeling of increased pressure. She reports no other focal neurologic symptoms. The patient has a 10-pack-year history of tobacco use. Her only medication is a low-dose estrogen oral contraceptive. On physical examination, temperature is normal, blood pressure is 112/78 mm Hg, pulse rate is 62/min and regular, and respiration rate is 16/min; BMI is 37. Bilateral papilledema is noted. The Valsalva maneuver increases the headache pain. All other general and neurologic examination findings are unremarkable. Results of laboratory studies show a normal leukocyte count, a platelet count of 322,000/µL (322 × 109/L), an INR of 1.1, and an activated partial thromboplastin time of 36 s. An MRI of the brain without contrast is normal.
A 50-year-old man is seen for a new-patient evaluation. He reports a recent diagnosis of Parkinson disease made after a 2-year history of stiffness in his right arm, a tendency to posture when walking, an awkward and stiffly inverted step when using the right leg, but no tremor. During this period, his voice became softer and slightly high pitched. The patient lost his sense of smell 10 years ago and has a 2-year history of diplopia when reading, a 9-month history of urinary urgency and impotence, and no history of dementia, depression, or psychosis. He has been taking high-dose levodopa replacement therapy since diagnosis without improvement in symptoms.
Which of the following is the most appropriate next diagnostic test? (A) (B) (C) (D)
Cerebral angiography Lumbar puncture Magnetic resonance venography Measurement of serum lupus anticoagulant level
Item 2 A 71-year-old man is evaluated in the intensive care unit 11 days after undergoing surgery to relieve a bowel obstruction. His postoperative course has been complicated by septic shock and multiorgan failure, for which he has received intravenous fluids, broad-spectrum antibiotics, vasopressors, corticosteroids, and insulin. He has been on mechanical ventilation for 10 days. For the past 72 hours, he has been hemodynamically stable, but attempts at weaning him from the ventilator have been unsuccessful. The patient previously was given muscle relaxants and neuromuscular junction–blocking agents, but these have been withheld for the past 4 days. On physical examination, the patient is alert, follows commands, and cooperates with the examiner. Vital signs are stable. Cranial nerves are intact. Flaccid quadriparesis of the upper and lower extremities is noted that is greater proximally than distally. Areflexia is present. Results of laboratory studies show a serum creatine kinase level of 850 units/L and a plasma glucose level of 200 mg/dL (11.1 mmol/L). Results of electromyography show absent sensory responses in the legs and low amplitudes in the hands. Short duration, low-amplitude motor units consistent with myopathy are noted. Which of the following is the most likely diagnosis? (A) (B) (C) (D)
Corticosteroid myopathy Critical illness myopathy Guillain-Barré syndrome Myasthenia gravis
Which of the following features in the patient’s history is most suggestive of an atypical parkinsonism syndrome? (A) (B) (C) (D) (E)
Absence of a tremor Diplopia Impotence Loss of olfaction Poor response to levodopa
Item 4 A 50-year-old man is evaluated in the emergency department for recent onset of vomiting and a 2-week history of headache that has become progressively worse. His wife reports that for the past 2 months, he has been much clumsier than usual and has otherwise “not seemed himself.” The patient has no personal or family medical history of note and takes no medication. On physical examination, temperature is 37.2 °C (99.0 °F), blood pressure is 150/90 mm Hg, pulse rate is 110/min, and respiration rate is 13/min. Signs of left neglect are noted. Fingers in the left visual field are also not recognized. Subtle left facial weakness, a left pronator drift, and decreased sensation on the left are present. Reflexes are 1+ on the right and 3+ on the left. The left toe is upgoing. An MRI shows a 4- × 3- × 3-cm intraparenchymal ringenhancing lesion in the right parietal lobe with surrounding edema and areas of central necrosis and hemorrhage. A chest radiograph shows no lesion. Which of the following is the most likely diagnosis? (A) (B) (C) (D)
Glioblastoma multiforme Meningioma Oligodendroglioma Schwannoma
Item 5 A 56-year-old man is evaluated in the emergency department 6 hours after onset of left hemiplegia, right gaze deviation, 87
Self-Assessment Test
Directions
Answers and Critiques Answer:
C
Educational Objective: Evaluate suspected dural sinus venous thrombosis with magnetic resonance venography. This patient should next undergo magnetic resonance venography. Her headache, which is worse in the morning and with performing the Valsalva maneuver, is consistent with one caused by elevated intracranial pressure. Given the headache characteristics, her history of tobacco and oral contraceptive use, and the presence of papilledema, she most likely has dural sinus venous thrombosis. Dural sinus venous thrombosis may present with signs and symptoms of intracranial hypertension, such as headache, papilledema, and visual problems; focal neurologic findings or seizures; and mental status changes, including stupor and coma. Major risk factors for cerebral sinus venous thrombosis in adults include conditions that predispose to spontaneous thromboses, such as inherited or acquired thrombophilia, pregnancy, oral contraceptive use, malignancy, sepsis, and head trauma. Other diagnostic possibilities include pseudotumor cerebri and viral or bacterial meningitis. Of all the possible imaging modalities, magnetic resonance venography is the most sensitive test for detecting the thrombus and the occluded dural sinus or vein and thus is the test of choice for diagnosing dural sinus venous thrombosis. After the diagnosis is established, the recommended treatment is smoking cessation, discontinuation of oral contraceptives, and systemic anticoagulation to prevent sequelae related to elevated intracranial pressure for 6 months if no hypercoagulable disorder is found. Cerebral angiography may demonstrate absence of the dural sinuses but is an expensive and invasive test and is not routinely indicated for diagnosing dural sinus venous thrombosis. Lumbar puncture may ultimately be required in this patient to confirm elevated intracranial pressure, which is already suggested by the presence of papilledema, or to diagnose pseudotumor cerebri. This diagnosis, however, requires exclusion of a dural sinus venous thrombosis. The lack of fever or elevated leukocyte count makes meningitis unlikely as a diagnosis and a lumbar puncture unnecessary. Measurement of the serum lupus anticoagulant level in this patient is inappropriate. Hypercoagulable testing would be indicated to determine the duration of anticoagulation needed in this patient only after a dural sinus venous thrombosis was diagnosed. The lupus anticoagulant is unlikely to be present if the coagulation profile is normal.
KEY POINT
• The diagnostic test of choice for diagnosing dural sinus venous thrombosis is magnetic resonance venography. Bibliography Stam J. Thrombosis of the cerebral veins and sinuses. N Eng J Med. 2005;352(17):1791-1798. [PMID: 15858188]
Item 2
Answer:
B
Educational Objective: Diagnose critical illness myopathy. This patient has critical illness myopathy, which is seen in severely ill patients after a prolonged (>7 days) stay in the intensive care unit (ICU). Inability to extubate and predominantly proximal flaccid limb weakness are classic findings. Critical illness myopathy is characterized by an elevated serum creatine kinase (CK) level. Predisposing factors include the patient’s prolonged ICU stay, use of corticosteroids and neuromuscular junction–blocking agents, and hyperglycemia. Corticosteroid myopathy presents with predominantly proximal weakness, preserved reflexes, a normal serum CK level, and normal or only mildly myopathic findings on electromyography (EMG). Guillain-Barré syndrome can share the clinical presentation of critical illness myopathy. The serum CK level, however, would be normal. Patients with generalized myasthenia gravis typically have limb weakness, diplopia, slurred speech, dysphagia, and dyspnea. Findings on neurologic examination include ptosis, impaired ocular motility, and limb weakness that increases with repeated testing (fatigable weakness). Deep tendon reflexes and sensory examination findings are normal. Results of EMG in myasthenia gravis would show characteristic decremental motor responses on repetitive stimulation. The patient’s findings are not consistent with myasthenia gravis. KEY POINT
• Critical illness myopathy can occur in severely ill patients after a prolonged stay in the intensive care unit and is characterized by an inability to extubate, flaccid limb weakness, and an elevated serum creatine kinase level. Bibliography Griffiths RD, Hall JB. Intensive care unit-acquired weakness. Crit Care Med. 2010;38(3):779-787. [PMID: 20048676]
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Answers and Critiques
Item 1