Case Files Neurology - part 7 pot

❖ CASE 34 A 65-year-old man with a history of hypertension, coronary artery disease, and early Alzheimer disease presents with a complaint of double vision since yesterday. He has not experienced chest pain, chest palpitations, nausea, light- headedness, vertigo, headache, facial weakness, hemisensory loss, hemiparesis, loss of balance, hearing loss, tinnitus, visual loss, ptosis, or proptosis. He has noticed that covering up either eye corrects his double vision. He has resorted to wearing an eye patch since yesterday so that he can see and walk without falling. In fact he was able to drive on his own on the freeway to your office much to his family’s dismay. On further questioning you elicit the history that his double vision occurs only on horizontal gaze and not vertical gaze. He has been com- pliant with his medications for hypertension and coronary artery disease. On examination, his blood pressure (BP) is 124/72 mmHg with a heart rate (HR) of 88 beats/min. He is afebrile and has a regular rate and rhythm without murmurs on cardiac examination. There are no carotid bruits, and his peripheral pulses are normal. His neurologic examination is notable for intact orientation and intact motor strength. His cranial nerve examination is remarkable only for a right lat- eral rectus palsy. Sensory examination is normal, and his deep tendon reflexes are 2+ throughout. Plantar responses are flexor. His gait is normal. Review of his daily blood pressure log shows stable pressures of 130/70 mmHg. ◆ What is the most likely diagnosis? ◆ What is the neurologic deficit? ANSWERS TO CASE 34: Sixth Nerve Palsy (Ischemic Mononeuropathy) Summary: A 65-year-old man with hypertension, coronary artery disease, and early Alzheimer disease presents with a 24-hour history of binocular horizontal diplopia (double vision). He has not experienced associated symptoms such as chest pain or headache. His examination is significant for a normal blood pressure and heart rate and the findings of the isolated right sixth nerve palsy. ◆ Most likely diagnosis: Sixth nerve palsy secondary to ischemic mononeuropathy ◆ Likely neurological deficit: Sixth nerve palsy Analysis Objectives 1. Understand the diagnostic approach in evaluating diplopia. 2. Describe the difference between monocular and binocular diplopia. 3. Know the differential diagnosis of a sixth nerve palsy. Considerations This 65-year-old man with known risk factors for cerebral vascular disease (hypertension and coronary artery disease) presents with an acute episode of binocular diplopia. The history suggests binocular diplopia as he tells you that covering up an eye resolves the diplopia. You are given the history that he has diplopia only on horizontal gaze. In this particular case you are told that the patient’s blood work and MRI brain is normal. Given the history of hyperten- sion and coronary artery disease he is at risk for cerebrovascular disease and ischemia. In this setting, the most likely cause of this man’s diplopia is an ischemic mononeuropathy to the abducens nerve. In this particular case the patient has a completely normal examination except for a sixth nerve palsy. This makes it easy to pinpoint the location of the abnormality as the only loca- tion for an isolated abducens nerve palsy is in the nucleus. Table 34–1 shows locations where the sixth nerve can be affected and its associated clinical findings. 284 CASE FILES: NEUROLOGY APPROACH TO BINOCULAR DIPLOPIA Definitions Ptosis: Drooping of the eye lids Proptosis: Abnormal protrusion of the eyeball Diplopia: Double vision Ischemic mononeuropathy: Isolated nerve injury from inadequate blood flow to the nerve CLINICAL CASES 285 Table 34–1 CLINICAL FINDINGS ASSOCIATED CLINICAL LOCATION FINDINGS ETIOLOGIES Nuclear Horizontal gaze palsy, sixth Ischemia, demyelinating, nerve dysfunction or other inflammatory, trauma, brainstem signs vascular (aneurysm or other vascular malformations), neoplastic, congenital, metabolic Fascicle Contralateral hemisensory Ischemia, inflammatory, loss, contralateral hemiparesis, vascular, neoplastic, trauma, central Horner syndrome demyelinating Subarachnoid Signs of increased intracranial Inflammatory, infectious, space pressure (e.g., headache, toxic, vascular, neoplastic, papilledema) or other cranial cervical traction, neuropathies myelogram, infiltrative Petrous apex Facial pain or fifth, seventh, Traumatic, infectious, or eighth cranial nerves inflammatory (sarcoid), dysfunction neoplastic (meningioma) Cavernous sinus Sixth nerve palsy with any Ischemic, neoplastic, inflam- combination of third, fourth matory, infectious, vascular, or ophthalmic division of the fistula, or thrombosis fifth cranial nerve dysfunction; Horner syndrome Orbit/superior Can have proptosis or optic Traumatic, infectious, orbital fissure nerve atrophy/edema inflammatory, neoplastic Clinical Approach Sixth nerve palsy has a variety of causes, and clinical examination usually leads to an accurate diagnosis. The abducens nucleus is located in the lower dorsal pons. The motor neurons of this nucleus send axons that course anteriorly in the pons and travel near the corticospinal tract and emerge in the sulcus between the pons and medulla. The abducens nerve exits the pons ventrally and ascends in the prepontine cistern via the subarachnoid space. It then rises over the petrous apex of the temporal bone and enters the cavernous sinus laying between the carotid artery and the ophthalmic branch of the trigeminal nerve laterally. It finally passes into the orbit through the superior orbital fissure. Etiology of Sixth Nerve Palsy After the localization of the sixth nerve lesion, the next step is to determine the etiology of the abnormality. Table 34–1 shows there are various causes for a nuclear abducens abnormality. The evaluation includes serologic studies including an erythrocyte sedimentation rate, antinuclear antibody (ANA), complete blood count (CBC), glycosylated hemoglobin, and if appropriate a 2-hour glucose tolerance test. An MRI of the brain without contrast should be ordered concomitantly. An erythrocyte sedimentation rate (ESR) and ANA can help exclude inflammatory causes such as vasculitis; glycosylated hemoglobin can exclude diabetes mellitus, and a CBC can exclude infectious processes. An MRI brain and orbits can exclude vascular abnormalities such as an aneurysm and can exclude mass lesions that are inflammatory (sarcoid), demyelinating, neoplastic, or traumatic. An ischemic process may not be readily visualized on imaging studies and is often a diagnosis of exclusion. Evaluation of Diplopia Diplopia results from lack of visual fusion. The first step in evaluating a patient with diplopia is to determine whether it is binocular or monocular. Binocular diplopia is usually caused by an underlying primary neurologic problem. Monocular diplopia, conversely, is primarily caused by an oph- thalmologic disorder such as abnormalities of the lens, cornea, vitreous humor, or iris. Rarely, monocular diplopia can be caused by occipital lobe dis- ease or seizures. Binocular diplopia denotes double vision arising from mis- alignment of both eyes. Covering up one eye resolves the double vision. Monocular diplopia, however, arises from a primary problem within one eye. This type of diplopia does not resolve when an eye is covered. The next step in evaluating someone with binocular diplopia is to determine if it is horizontal or vertical. Different eye muscles are involved in moving the eyes horizontally or vertically. There are only two muscles in each eye respon- sible for horizontal gaze and those are the medial rectus, which is innervated by the third nerve, and the lateral rectus, which is innervated by the sixth 286 CASE FILES: NEUROLOGY nerve. Worsening diplopia on near vision suggests a problem with the medial rectus, whereas diplopia that worsens when viewing distant and lateral objects suggest a problem with the lateral rectus. The other four eye muscles (superior rectus, inferior rectus, inferior oblique, and superior oblique) move the eyes vertically. Individuals that pres- ent with vertical binocular diplopia are experiencing weakness in one or sev- eral of these muscles. Vertical diplopia that worsens on near vision suggests a problem with either the inferior oblique or superior oblique. At this point in the evaluation, it must be differentiated whether or not the patient’s binocular diplopia is secondary to a medial rectus or a lateral rectus problem. Examining extra-ocular muscles in the nine cardinal fields of gaze can read- ily point out which of the two muscles is affected. For example, if the right eye cannot cross the midline and look out laterally, the lateral rectus is affected. Conversely, if the right eye cannot cross the midline and turn inward, the medial rectus is affected. One of these tests is called the alternate cover test and is performed by ask- ing the patient to fixate on an object in each position of gaze. As the patient moves the eyes in each position, deviations in the eye as each one is alternately covered may be seen. The second test often used for evaluating binocular diplopia is the red lens test. In this test, a red lens is placed over an eye, most commonly the right eye, and the patient is asked to look at the nine positions of a cardinal gaze. The key to performing this test is to understand the follow- ing: (1) image separation will be greatest in the direction of the weak muscle and (2) the image that is the furthest away from the midline is a false image and corresponds to the eye with impaired motility. Evaluating other aspects of the cranial nerve examination will help deter- mine where the diplopia is arising from. Special attention should be given to the eyelid, pupillary responses, symmetry of the pupillary size, abnormalities of cranial nerves V, VII, and VIII. For example, ptosis or droopiness of the eye- lid can suggest a third nerve problem. Likewise, pupillary asymmetry suggests a third nerves problem. Fatigue of the eyelid can suggest myasthenia gravis. Patients who have a head tilt can also provide you with clues as to where the problem may lie. For example, someone with a right superior oblique palsy may have a leftward tilt of the head. Treatment Treatment of the underlying disorder of sixth nerve palsy is indicated when significant and persistent. An isolated and presumed ischemic-related sixth nerve palsy can be observed for improvement for 1 to 3 months. Patching of the involved eye can help alleviate diplopia symptoms temporarily. Prism ther- apy can also be used. Some suggest using botulinum toxin as a temporizing measure. However if these measures fail, surgery may be the only way to cor- rect this problem. CLINICAL CASES 287 288 CASE FILES: NEUROLOGY Comprehension Questions [34.1] Which of the following is most accurate regarding diplopia? A. Binocular diplopia refers to double vision occurring from intrinsic problems in both eyes B. Monocular diplopia most commonly occurs because of extrinsic eye problems C. The green lens test is a way of evaluating binocular diplopia D. The key in evaluating diplopia is to start by determining if it is monocular or binocular [34.2] A 33-year-old woman has a 3-minute seizure episode caused by her epilepsy. There are no underlying medical disorders or brain structural lesions. Which of the following indicates a more complicated underly- ing neurologic problem? A. Urinary incontinence with seizure B. Confusion and lethargy after seizure C. Headache after the seizure D. Sixth nerve palsy after seizure [34.3] A 58-year-old woman suffers from an ischemic-related sixth nerve palsy which occurred 6 months ago. Various methods have been tried with limited success, and the patient still has diplopia. Which of the following is most likely to be helpful at this stage? A. Surgery B. Eye patch C. Prisms D. Prednisone at a dose of 10 mg per day E. Botulinum toxin Answers [34.1] D. The key to evaluating diplopia is to assess unilateral versus bilateral. Binocular diplopia arises from misalignment of the eye muscles on a target. [34.2] D. Seizures have not been reported to cause sixth nerve dysfunction and thus, its presence indicates a more complex situation. [34.3] A. Surgery is the best option for persistent symptoms that have not resolved. Prednisone has not been used for sixth nerve palsies from ischemia. It can be used for inflammatory causes of sixth nerve abnormalities. REFERENCES Dorland’s Illustrated Medical Dictionary, 27th ed. Philadelphia, PA: WB Saunders; 1988. Patel SV, Mutyala S, Leske DA, et al. Incidence, associations, and evaluation of sixth nerve palsy using a population-based method. Ophthalmology 2004; 111:369–375. Quah BL, Ling YL, Cheong PY, et al. A review of 5-years experience in the use of botulinum toxin A in the treatment of sixth cranial nerve palsy at the Singapore National Eye Centre. Singapore Med J 1999;40:405–409. Savino PJ. Diplopia and sixth nerve palsies. Semin Neurol 1986;6:142–146. CLINICAL CASES 289 CLINICAL PEARLS ❖ Binocular diplopia occurs from misalignment of the eye muscles on a target and commonly denotes an underlying primary neurologic problem within the brain parenchyma. ❖ Younger patients with sixth nerve palsies more often have malig- nant etiologies, whereas older patients usually have more benign etiologies. ❖ Monocular diplopia results from intrinsic eye problems, including ocular muscles and neuromuscular junction. ❖ MRI of the brain is critical in evaluating patients with binocular diplopia as it allows for the detection of vascular or demyelinating processes. This page intentionally left blank ❖ CASE 35 A 68-year-old woman presents with right facial paralysis. She states she was well until approximately 3 days ago when she began to have right ear pain. She has not taken any pain medication and has not had any fever. Today, she awoke with right facial paralysis. She feels slightly dizzy and notices that she has right-sided hearing loss. She denies any past history of ear infections. Her med- ical history is unremarkable. She does have a past history of chicken pox as a child. Her physical examination shows a 68-year-old woman with obvious right facial paralysis involving her forehead and mouth. She is afebrile but is anxious because of the loss of facial function. There is no motion in any of the branches of the right facial nerve. Her head and neck examination finds small blisters on an erythematous base in the right conchal bowl of the external ear. The exam- ination of the ear canal is painful to her, but the tympanic membrane is intact. No pus is seen in the ear canal. The left ear canal is normal. The Weber tuning fork test lateralizes to the left ear. The Rinne test is normal in both ears. The examination of the nose, oral cavity, throat, and neck are normal. The cranial nerve (CN) examination is normal except for the right VII and VIII nerve prob- lems listed above. The remaining physical examination is normal. ◆ What is the most likely diagnosis? ◆ What is the next diagnostic step? ◆ What is the next step in therapy? ANSWERS TO CASE 35: Facial Paralysis Summary: A 68-year-old woman presents with right facial paralysis, a 3-day history of right ear pain, and right-sided hearing loss. There is no motion in any of the branches of the right facial nerve. There are small blisters on an ery- thematous base in the right conchal bowl of the external ear. The examination of the ear canal is painful to her, but the tympanic membrane is intact. The Weber tuning fork test lateralizes to the left ear. The Rinne test is normal in both ears. The cranial nerve examination is normal except for the right VII and VIII nerve problems listed above. ◆ Most likely diagnosis: Herpes zoster oticus (Ramsay Hunt syndrome) ◆ Next diagnostic test step: Tzanck smear, audiogram, consider facial nerve electrodiagnostic studies and diagnostic imaging, if indicated ◆ Next therapeutic step: anti-herpes virus medication Analysis Objectives 1. Describe the clinical presentation and diagnostic approach to facial weakness. 2. Be familiar with the differential diagnosis of facial weakness. 3. Know the treatment for Ramsey Hunt syndrome. Considerations This elderly woman has a history of chicken pox, blisters on her ear, hearing abnormalities, and unilateral facial paralysis. Her entire right facial muscles are affected, suggestive of a peripheral facial nerve palsy; a central defect usu- ally spares the forehead. The Weber and Rinne tests are consistent with a sen- sorineural hearing loss rather than a conductive disorder. This constellation of findings is most consistent with Ramsey Hunt syndrome, which is reaction of the herpes zoster affecting both CNs VII and VIII. A diligent history and phys- ical examination should be performed to exclude other possibilities such as central nervous system disorders, cholesteatomas, facial neuromas, and tumors of the parotid. Corticosteroid and antiviral therapy are recommended, with the probability of good recovery. APPROACH TO FACIAL NERVE PARALYSIS Definitions Audiogram: A test that measures the level of hearing in each ear. Bell palsy: An idiopathic form of facial paralysis, thought to be caused by herpes simplex virus reactivation. 292 CASE FILES: NEUROLOGY [...]... should be referred to a specialist for further evaluation and treatment 318 CASE FILES: NEUROLOGY Comprehension Questions [ 37. 1] Which of the following tests is used to diagnose benign paroxysmal positional vertigo? A B C D E Weber test Rinne test Dix-Hallpike maneuver Brandt-Daroff maneuver Epley maneuver [ 37. 2] A 40-year-old woman has recurring episodes of disabling vertigo, lasting 30 minutes, and... next step in therapy? 310 CASE FILES: NEUROLOGY ANSWERS TO CASE 37: Vertigo, Benign Paroxysmal Positional Summary: A 63-year-old man with brief episodes of dizziness that are brought on by different positions, not associated with hearing loss, tinnitus, aural pressure, or headache ◆ ◆ ◆ Most likely diagnosis: Benign paroxysmal positional vertigo Next diagnostic step: Perform a Dix-Hallpike maneuver Next... What is the most likely diagnosis? ◆ What is the best test to confirm the diagnosis? ◆ What is the next step in therapy? 300 CASE FILES: NEUROLOGY ANSWERS TO CASE 36: Ptosis (Myasthenia Gravis) Summary: A 30-year-old healthy female presents with a 2-month history of fatigue and a 1-month history of intermittent ptosis She has not experienced proximal muscle weakness, dysarthria, shortness of breath, or... features Repetitive nerve stimulation, a part of EMG/NCS, consists of repeatedly stimulating a nerve and recording the compound muscle action potential obtained This test is usually 306 CASE FILES: NEUROLOGY performed at 2 or 3 Hz The ulnar, spinal accessory and facial nerves most commonly evaluated Greater than 10% decrement in the amplitude of the compound muscle action potential is considered an abnormal... Dorland’s Illustrated Medical Dictionary, 27th ed Philadelphia, PA: WB Saunders; 1988 Keesey JC Clinical evaluation and management of myasthenia gravis Muscle Nerve 2004 Apr;29(4):484–505 Saperstein DS, Barohn RJ Management of myasthenia gravis Semin Neurol 2004 Mar;24(1):41–48 This page intentionally left blank ❖ CASE 37 A 63-year-old man presents with a 3-month history of dizziness His dizziness... Zinis LO, Gamba P, Balzanelli C Acute otitis media and facial nerve paralysis in adults Otol Neurotol 2003;24(1):113–1 17 Sweeney CJ, Gilden DH Ramsay Hunt syndrome J Neurol Neurosurg Psychiatry 2001 ;71 (2):149–154 ❖ CASE 36 A 30-year-old female plastic surgery resident presents with a 1-month history of intermittent ptosis (droopiness of the eyelids) and fatigue She has been on call every third night... fibrillation potentials Evoked potentials, such as the blink reflex, can also be performed with EMG An absence of motor unit potentials signifies severe damage or loss or nerve continuity Fibrillation potentials are signs of a lack of facial nerve input, and are a particularly bad prognostic sign Facial nerve electroneurogram (ENoG): An electrical test that evokes a compound muscle action potential (cMAP)... weakness In this particular case the patient does not complain of shortness of breath; however, the history of fatigue and having difficulty keeping up with her children while bike riding should raise the concern Forced vital capacity is a simple bedside test that can provide further information on the respiratory status of an individual 301 CLINICAL CASES APPROACH TO PTOSIS Definitions Anti-MuSK antibodies:... pressure and headache His past medical history is otherwise unremarkable He is not on any medications On physical examination, he is a healthy appearing 63-year-old man His temperature is 37. 1°C (98.8°F); pulse, 64 beats/min; and blood pressure, 124 /74 mmHg There are no lesions or masses on his face or head His voice is normal, and his speech is fluent His facial nerve function is normal His ear canals... blow drying hair, difficulty reaching over the head) 302 CASE FILES: NEUROLOGY Table 36–1 ETIOLOGIES OF PTOSIS LOCATION OF LESION ETIOLOGIES Local mechanical lid abnormalities Thyroid disease, ocular surgery, infiltrative processes (sarcoid, amyloid), orbital cellulitis, primary or metastatic tumors Myopathy Mitochondrial cytopathies (Kearns-Sayre), congenital myopathies (centronuclear myopathy), oculopharyngeal . temporizing measure. However if these measures fail, surgery may be the only way to cor- rect this problem. CLINICAL CASES 2 87 288 CASE FILES: NEUROLOGY Comprehension Questions [34.1] Which of the following is most. respiratory status of an individual. 300 CASE FILES: NEUROLOGY APPROACH TO PTOSIS Definitions Anti-MuSK antibodies: Muscle-specific receptor tyrosine kinase anti- bodies. MuSK is a surface membrane. adults. Otol Neurotol 2003;24(1):113–1 17. Sweeney CJ, Gilden DH. Ramsay Hunt syndrome. J Neurol Neurosurg Psychiatry 2001 ;71 (2):149–154. 298 CASE FILES: NEUROLOGY CLINICAL PEARLS ❖ Bell palsy