❖ CASE 52 A 43-year-old right-handed woman presents to the office with hearing loss, facial paralysis, and headache. Her history began 1 month ago with a sudden decrease in hearing in her right ear. One week prior to this visit she began to notice weakness of the right face, which has now progressed to complete paralysis. Over the last 3 months she has had intermittent right occipital headache, and clumsiness and imbalance if she turns quickly. She denies any change in her voice or difficulty with swallowing or swallowing difficulty. Her past medical history is unremarkable. She is not on any medications except birth control pills. Her physical examination shows a 43-year-old woman that has an obvious right facial paralysis. Her pulse is 62 beats/min; blood pressure, 118/62 mmHg; and temperature, 36.7°C (98.6°F). The head and face have no lesions. Her voice is normal, but her speech is slightly distorted because of the facial paralysis. Her extra-ocular movements are normal. Her eye grounds do not show any papilledema. Her ears have normal tympanic membranes. The Weber tuning fork lateralizes to the left ear. Air conduction is louder than bone conduction in both ears. There is no neck lymphadenopathy or other masses. There are no cerebellar signs. The remaining physical examination, including the neurologic examination, is normal. An audiogram shows a mild sen- sorineural hearing loss in the right ear; the left ear has normal hearing. An auditory brainstem response (ABR) is abnormal for the right ear; it is normal for the left ear. ◆ What is the most likely neuroanatomic etiology and diagnosis? ◆ What is the next diagnostic step? 434 CASE FILES: NEUROLOGY ANSWERS TO CASE 52: Meningioma of the Acoustic Nerve Summary: A 43-year-old woman has a history of headache, hearing loss, and facial paralysis. ◆ Neuroanatomic Etiology and Diagnosis: Cerebellopontine angle tumor, with the most common tumors being acoustic neuroma and meningioma ◆ Next diagnostic step: MRI with gadolinium Analysis Objectives 1. Learn the most common tumors that occur in the cerebellopontine angle. 2. Learn the most common imaging features of these tumors. 3. Learn the available treatment options for these tumors. Considerations This 43-year-old woman has symptoms of hearing loss, facial paralysis, and headache. She also has symptoms of imbalance and disequilibrium. The most common cause of facial nerve paralysis is Bell palsy; however, this patient also has hearing loss, balance issues, and headache, which point to a central rather than peripheral disorder. Patients that present with the combination of hearing loss and facial paralysis demand eval- uation by diagnostic imaging. This patient’s symptoms strongly suggest an abnormality in the cerebellopontine angle. Modern imaging techniques have revolutionized the evaluation of this area. MRI with contrast can readily differentiate the various pathologic processes that occur in this area (Table 52-1). CLINICAL CASES 435 APPROACH TO CEREBELLOPONTINE ANGLE TUMORS Definitions Acoustic neuroma: A benign tumor that rises from Schwann cells on the vestibular nerve also called vestibular schwannoma. This is the most common tumor found in the cerebellopontine angle. Table 52–1 MRI CHARACTERISTICS OF COMMON PATHOLOGY IN THE CEREBELLOPONTINE ANGLE Gadolinium Special Tumor Type T1 Appearance* T2 Appearance* Enhancement Features Schwannoma Isointense Intermediate ++++ Can be cystic, inside or centered on the IAC Meningioma Isointense or Hyperintense +++ Dural tail, slightly to hypointense eccentric to the hypointense IAC, can have calcification Epidermoid Hypointense Isointense None Internal stranding Glomus tumor Hypointense Isointense +++ “salt and (Paraganglioma) pepper appearance” Arachnoid cyst Hypointense Hyperintense None Homogenous contents Lipoma Hyperintense Hypointense None Intensity disappears with fat suppression Cholesterol Hyperintense Hyperintense None Located within cysts the petrous apex IAC, internal auditory canal. *Intensity relative to brain. + Minimal enhancement. +++ moderate enhancement. ++++ Maximal enhancement. Auditory brainstem response (ABR): An electrical evoked hearing test. In this test, electrodes are placed on each ear lobe and on the forehead. A stimulus sound (either a click or tone burst) is delivered into the test ear at a specified loudness; an attached computer captures the electrical brain activity that results from this stimulus and filters out background noise. Bell palsy: Idiopathic facial weakness. Cerebellopontine angle: The anatomic space between the cerebellum, pons, and temporal bone. This space contains cranial nerves V through XI. Conductive hearing loss: A form of hearing loss that results from a defect in the sound collecting mechanism of the ear. These structures include the ear canal, tympanic membrane, middle ear, and the ossicles. Epidermoid tumor: A benign tumor composed of squamous epithelial ele- ments thought to arise from congenital rests. Glomus tumor: The common name for paraganglioma. This highly vascular tumor arises from neuroepithelial cells. These tumors are further named by the structures that they arise from: glomus tympanicum (middle ear), glomus jugulare (jugular vein), glomus vagale (vagus nerve), and carotid body tumor (carotid artery). A rule of 10% is associated with this tumor: approximately 10% of these tumors produce a catecholamine-like sub- stance, approximately10% of these tumors are bilateral, approxi- mately10% are familial, and approximately 10% are malignant (i.e., potential to metastasize). Meningioma: Common benign extra-axial tumors of the coverings of the brain. The cell of origin is probably from arachnoid villi. Several histo- logic subtypes are described: syncytial, transitional, fibroblastic, angioblastic, and malignant. Sensorineural hearing loss: A form of hearing loss that results from an abnormality in the cochlea or auditory nerve. Clinical Approach Meningiomas Meningiomas are usually benign tumors, of mesodermic origin, attached to the dura. They commonly are located along the sagittal sinus, over the cerebral con- vexities, and in the cerebellar-pontine angle. Grossly, they are gray, sharply demarcated, and firm. Microscopically, the cells are uniform with round or elon- gated nuclei, and a characteristic tendency to whorl around each other. Meningiomas tend to affect women more than men in the middle age. The typ- ical clinical presentation is the slow onset of a neurologic deficit or a focal seizure; an unexpected finding on a brain imaging is also a common presenta- tion. MRI usually reveals a dural-based mass with dense homogeneous contrast enhancement. Surgical therapy is optimal, and complete resection is curative. For lesions not amenable to surgery, local or stereotactic radiotherapy can ame- liorate symptoms. Small asymptomatic lesions in older patients can be observed. 436 CASE FILES: NEUROLOGY Rarely, meningiomas can be more aggressive and have malignant potential; these tumors tend to have higher mitosis and cellular and nuclear atypia. Surgical therapy followed by radiotherapy should be used in these instances. Approach to Facial Paralysis Facial paralysis is a relatively common disorder. In its most common presen- tation, facial paralysis occurs as a sudden sporadic cranial mononeuropathy. It is not associated with hearing loss; rather, it might be associated with hypera- cusis. This form of facial paralysis, also called Bell palsy, is not associated with middle ear disease, parotid tumor, Lyme disease or any other known cause of facial paralysis. Essentially, Bell palsy is a diagnosis of exclusion. Generally, a pointed history and detailed physical examination will eliminate most of the differential diagnosis. Likewise, the various causes of hearing loss can be eliminated by a careful physical examination. Disease processes, such as otitis media, cholesteatoma, and otosclerosis, can be eliminated by careful history and physical examination with tuning fork tests. However, to know the type and degree of hearing loss, an audiogram is necessary. Although it requires patient cooperation, the audiogram will give the clini- cian a very accurate measure of the patient’s hearing level. The audiogram can distinguish between sensorineural and conductive hearing loss. Occasionally, patients have mixed hearing loss, or a combination of conductive and sen- sorineural losses in a single ear. Furthermore, the audiogram can give a clue regarding the presence of retrocochlear hearing loss or hearing loss caused by diseases proximal to the cochlea. Tests that might indicate retrocochlear pathology include speech discrimination, acoustic reflexes, and reflex decay. Diagnosis Sensorineural hearing loss can be further evaluated by auditory brainstem response (ABR). This test measures the electrical activity within the auditory pathway; and as such, this test helps to evaluate retrocochlear causes of hear- ing loss. The ABR has five waves that are numbered I through V, and these are correlated to major neural connections in the auditory pathway. These waves have expected morphologies and occur at predictable latencies. Waves that are absent or delayed are indicative of pathology at that point in the auditory path- way. The interwave latencies (such as I to III, III to V, or I to V) can be com- pared to the opposite side or to standard norms. Abnormalities on ABR need to be further evaluated by imaging studies. MRI provides excellent definition of the structures within the posterior fossa. Gadolinium contrast allows additional differentiation of various pathologies. Additionally, newer technology, such as fat suppression and dif- fusion weighted imaging can help to identify pathology (Fig. 52–1). The MRI appearances of the most common tumors in the posterior fossa are indicated in the Table 52–1. CLINICAL CASES 437 Although MRI with gadolinium contrast gives excellent resolution for brain, nerve and soft tissues, CT scanning is necessary for bony imaging. Often, both imaging modalities are combined to understand the full extent of the disease process within the skull base. Treatment A treatment plan must be created once a tumor in the cerebellopontine angle is diagnosed. Many factors must be considered when approaching these tumors. The patient’s age, overall health status, tumor size and location, degree of hearing loss, and other neurologic signs are all factors to be taken into account. The various available treatment options must be discussed with the patient; the final decision of treatment course must be decided between the patient and the physician. At least three options should be considered in managing tumors in the pos- terior fossa: observation and serial imaging, stereotactic radiosurgery, or conventional surgery. Some of these options might be unavailable or unwise for certain tumor types or tumor size. Clearly, the patient that has a large tumor that is producing brainstem compression or obstructive hydrocephalus should not be observed over time and serially imaged. These findings demand imme- diate attention. Surgery can provide several benefits to the patient. Removal of tumor allows for final pathologic diagnosis, might correct neurologic deficits, and might prevent further complications caused by continued tumor growth. These benefits can come at a price of new neurologic deficits, meningitis, infection, 438 CASE FILES: NEUROLOGY Figure 52–1. Post-gadolinium T1 MRI with fat suppression. Cerebellopontine angle meningioma. (With permission from Fischbein NJ, Ong KC, Radiology. In: Lalwani A. Current Diagnosis and Treatment in Otolaryngology Head & Neck Surgery, New York: McGraw-Hill; 2004, p 158.) CLINICAL CASES 439 stroke, or even death. The patient’s underlying health status must be consid- ered because these surgical procedures are often lengthy. Patients with low overall health status might not tolerate such a procedure. A relatively new (although more than 20 years experience) type of therapy involves the use of directed, focus radiation beam to the tumor. Several dif- ferent proprietary devices have been developed to destroy or at least prevent growth of these types of tumors. The experience with stereotactic radiotherapy is probably greatest with acoustic neuroma, because that tumor is the most common mass found in the cerebellopontine angle. Stereotactic radiother- apy has been found to be very effective at managing small to medium sized tumors (up to 3 cm). In these tumors, the complication rate for stereotactic radiotherapy is at least as low as that from conventional surgery; and with this type of therapy, a long hospital stay or recovery period is not required. The dis- advantage with stereotactic radiotherapy is the potential for continued growth, and this growth does occur in a significant number of patients. Unfortunately, surgery following stereotactic radiotherapy is technically more difficult, and surgical results are not as good as from surgery alone. Stereotactic radiotherapy does have limitations. It is not useful for certain tumor types (meningiomas and epidermoids). Of course, stereotactic radio- therapy cannot provide pathologic specimens for study, and it should never be used when the pathologic diagnosis is in doubt. Comprehension Questions [52.1] A 45-year-old painter is found to have ataxia. An MRI scan shows a tumor of the cerebellopontine angle. What is the most likely tumor in the location? A. Epidermoid tumor B. Paraganglioma C. Meningioma D. Acoustic neuroma E. Lipoma [52.2] What is the best test to evaluate unilateral sensorineural hearing loss? A. Otoacoustic emissions B. Auditory brainstem response C. MRI of the internal auditory canals with gadolinium D. Electronystagmography E. Detailed physical examination [52.3] What is the most common cause of unilateral facial paralysis? A. Idiopathic B. Otitis media C. Parotid malignancy D. Acoustic neuroma E. Lyme disease 440 CASE FILES: NEUROLOGY Answers [52.1] D. By far, the most common tumor in the cerebellopontine angle is the acoustic neuroma. [52. 2] C. Although ABR is used to evaluate unilateral sensorineural hearing loss, its limitation is a lack of specificity for diagnosis. Otoacoustic emissions can measure the degree of hearing loss, but it cannot shed light on a pathologic cause. Electronystagmography is a test that meas- ures the vestibular ocular reflex. Detailed physical examination is an important prerequisite before any diagnostic tests are ordered. Only MRI with contrast enhancement can elucidate the cause of unilateral sensorineural hearing loss. [52.3] A. The most common form of facial paralysis is idiopathic. It is also called Bell palsy. Recent evidence suggests that the cause of Bell palsy is probably recrudescence of herpes simplex virus. Every patient should have a careful examination to rule out other causes of facial paralysis, such as those diagnoses listed. Where indicated, this exami- nation might require an audiogram or MRI imaging. CLINICAL PEARLS ❖ Idiopathic facial paralysis (also called Bell palsy) is the most com- mon cause of unilateral facial weakness. ❖ Bell palsy is a diagnosis of exclusion, and patients with facial paral- ysis require a careful otologic and cranial nerve examination. ❖ Patients that present with a complaint related to one cranial nerve require evaluation of all cranial nerves. ❖ Acoustic neuromas are the most common tumor of the cerebello- pontine angle. ❖ Unilateral sensorineural hearing loss should be further evaluated by MRI with gadolinium contrast. REFERENCES Fan G, Curtin H. Imaging of the lateral skull base. In: Jackler R, Brackmann D, eds. Neurotology, 2nd ed. Philadelphia, PA: Elsevier; 2004, pp 383–418. Lo W, Hovsepian M. Imaging of the cerebellopontine angle. In: Jackler R, Brackmann D, eds. Neurotology, 2nd ed. Philadelphia, PA: Elsevier; 2005. pp 349–382. ❖ CASE 53 A 59-year-old retired bartender presents with the complaint of headaches and difficulty concentrating over the past 6 weeks. He has been healthy all of his life and presents yearly for an annual checkup. He describes the headaches as occurring primarily over the right frontal temporal region and describes it as “dull” in nature. He has experienced occasional nausea but no vomiting with the headaches. Additionally, he has had difficulty focusing and concentrating on tasks at hand, such as reading the newspaper or playing cards. His wife states that he has been more irritable, moody, and “not himself” for 1 month. There is no history of alcohol abuse or exposure to toxins. He admits to a 30-pack-a-year smoking history. The review of systems is significant for weight loss and productive cough. His examination reveals that he is afebrile with a blood pressure of 124/72 mmHg and a heart rate of 78 beats/min. His general examination is normal. He is oriented to person, time, location, and situation, although he becomes upset during the examination. Cranial nerve and sensory examination findings are unremarkable. Motor strength testing is normal except for questionable weak- ness in the left finger extensors. The deep tendon reflexes are normal except for a Babinski sign present on the left. With ambulation, he has less arm swing on the left than the right. ◆ What is the most likely diagnosis? ◆ What is the next diagnostic step? ◆ What is the next step in therapy? ANSWERS TO 53: Metastatic Brain Tumor Summary: A 59-year-old healthy man presents with a 6-week history of right frontal temporal headaches associated with difficulty concentrating, weight loss, and coughing. His headaches are often associated with nausea and are dull in nature. His wife reports personality changes and the patient himself recognizes mood disturbances. His examination is notable for decreased arm swing on the left, questionable weakness of the left finger extensors, and a left Babinski sign. ◆ Most likely diagnosis: Metastatic brain tumor affecting the right cerebral hemisphere. ◆ Next diagnostic step: MRI of the brain with and without gadolinium and chest x-ray. ◆ Next step in therapy: Corticosteroids and anticonvulsants are started immediately while waiting for surgical evaluation. Analysis Objectives 1. Know the clinical presentation and diagnostic approach to metastatic brain tumor. 2. Be familiar with the differential diagnosis of metastatic brain tumor. 3. Describe the treatment for metastatic brain tumor. Considerations This 59-year-old otherwise healthy man presents with unilateral dull headaches associated with nausea and personality changes. Additionally there is a history of difficulty concentrating, weight loss, and cough. His physical examination sug- gests mild left-sided weakness most likely from a right hemispheric lesion given the left Babinski sign. Based on the history and examination the most likely diag- nosis is a right hemispheric mass lesion. Taking it one step further the history of weight loss and cough are concerning for a lung cancer. With this in mind, metastatic lung cancer should be considered. A chest x-ray will reveal that he has a large right upper-lobe mass lesion highly suggestive of lung cancer. An MRI of the brain will show a right frontal temporal well-circumscribed lesion at the gray- white junction with hemorrhage and surrounding edema. Evidence of midline shift or impending herniation should be evaluated. Corticosteroids such as dex- amethasone should be started as this reduces edema and capillary permeability. Prophylaxis with anticonvulsants in individuals with metastatic tumors that have not experienced a seizure is controversial. Approximately 40% of patients with metastatic brain tumors will experience a seizure. Only 20% of patients with metastatic brain tumors present with seizures. In this particular case the patient has a hemorrhage, which is known to be epileptogenic. Most 442 CASE FILES: NEUROLOGY [...]... macrocytic, 191, 192, 195 megaloblastic, 192 pernicious, 176, 191, 194, 195 aneurysms angiogram, 107 f risk factors, 105 106 ruptured saccular/berry, 105 angiography for aneurysms, 108 for chronic daily headaches, 164 for ischemic stroke, 98 for ptosis, 303 for subarachnoid hemorrhage, 104 , 106 , 107 f, 108 ankle-foot orthosis, for foot drop, 372 anterior cord syndrome, 65 anterior optic neuritis (papillitis),... Polyneuropathy Guillain-Barré Syndrome Dermatomyositis Amyotrophic Lateral Sclerosis Median Nerve Mononeuropathy Foot Drop 18 24 33 40 48 58 64 72 80 88 96 104 112 118 126 136 144 150 162 170 182 190 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 198 206 216 222 230 236 242 252 260 268 276 284 292 300 310 322 330 338 350 360 368 452 CASE FILES: NEUROLOGY CASE NO DISEASE CASE PAGE 44 45 46... This page intentionally left blank S E C T I O N I I I Listing of Cases Listing by Case Number Listing by Disorder (Alphabetical) Copyright © 2008 by the McGraw-Hill Companies, Inc Click here for terms of use This page intentionally left blank 451 LISTING OF CASES LISTING BY CASE NUMBER CASE NO DISEASE CASE PAGE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Essential Tremor Huntington... with supratentorial metastasis 446 CASE FILES: NEUROLOGY Comprehension Questions [53.1] A 56-year-old man who is complaining of confusion and motor deficits is noted to have multiple lesions to the brain A metastatic tumor is suspected Which of the following is the most common tumor causing brain metastasis? A B C D E Breast Melanoma Renal Lung Thyroid [53.2] A 50-year-old man is noted to have some symptoms... Seizures Foot Drop Guillain-Barré Syndrome HIV-Associated Dementia Huntington Disease Infantile Botulism Intracranial Lesion (Toxoplasmosis) Lissencephaly Median Nerve Mononeuropathy 126 96 216 170 350 48 424 410 136 88 162 322 9 21 40 47 3 8 1 35 45 43 39 28 2 27 31 50 42 80 182 338 394 33 72 18 292 380 368 330 236 24 230 260 418 360 453 LISTING OF CASES CASE NO DISEASE CASE PAGE 52 53 18 24 14 44... metastasize to the brain are listed in the Table 53–1, with lung cancer being most common Table 53–1 METASTATIC TUMOR AND FREQUENCY Tumor Type Cases (%) Lung cancer 50% Breast cancer 20% Melanoma 10% Unknown primary 10% Others: thyroid and sarcoma Unknown 444 CASE FILES: NEUROLOGY Tumors metastasize to the brain most commonly by entering the systemic circulation known as hematogenous spread The distribution... Muscular Dystrophy Tourette Syndrome Benign Rolandic Epilepsy Lissencephaly Autism Meningioma Metastatic Brain Tumor 374 380 386 394 403 410 418 424 432 440 LISTING BY DISORDER (ALPHABETICAL) CASE NO DISEASE CASE PAGE 15 11 25 20 41 5 51 49 16 10 19 38 Absence Versus Complex Partial Seizure Acute Cerebral Infarct Acute Disseminated Encephalomyelitis Alzheimer Dementia Amyotrophic Lateral Sclerosis Ataxia,... personality changes, mood and memory problems 33% New onset seizure; more frequently associated with frontal, temporal or multiple metastases 10 20% Stroke-like syndrome 5 10% Papilledema 10% (at time of presentation) Other nonspecific neurologic findings 20–40% CLINICAL CASES 445 unrevealing, than an abdominal or pelvic CT scan should be performed Careful attention should be placed to the prostate, testicles,... (petit mal) vs complex partial seizures, 129t considerations, 127, 380 definition, 127 valproic acid for, 131 acetaminophen, for pediatric headaches, 391 acoustic neuromas, 432, 433, 437, 438 acquired Creutzfeldt-Jakob disease, 243 acquired epileptic aphasia (Landau-Kleffner syndrome), 120 activated partial thromboplastin time (aPTT) assessment, 74 acute communicating hydrocephalus, 108 acute disseminated... brain, accounting for approximately 50% of all cases [53.2] B Headache is the most commonly found symptom associated with brain tumors and is found in approximately half of cases CLINICAL CASES 447 [53.3] B Patients with brain metastasis that present with seizures should be started on anticonvulsant therapy in addition to dexamethasone In this particular case there is associated midline shift that warrants . rule of 10% is associated with this tumor: approximately 10% of these tumors produce a catecholamine-like sub- stance, approximately10% of these tumors are bilateral, approxi- mately10% are familial,. diagnosis? ◆ What is the next diagnostic step? 434 CASE FILES: NEUROLOGY ANSWERS TO CASE 52: Meningioma of the Acoustic Nerve Summary: A 43-year-old woman has a history of headache, hearing loss,. tumors present with seizures. In this particular case the patient has a hemorrhage, which is known to be epileptogenic. Most 442 CASE FILES: NEUROLOGY CLINICAL CASES 443 physicians would begin anticonvulsants.