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Show Journal of Clinical Neuro-ophthalmology 13(3); ]94-]99, ]993. Cysticercosis: Unusual Neuro-ophthalmologic Signs James R. Keane, M.D. Papilledema and pretectal signs are the usual neuroophthalmological manifestations of cysticercosis. The following patients with severe posterior fossa involvement exhibited uncommon signs of bilateral fourth nerve palsy, facial myokymia, upbeat nystagmus, periodic alternating nystagmus, and rhythmic oculopalatal myoclonus. Key Words: Cysticercosis-Facial myokymia-Oculopalatal myoclonus-Periodic alternating nystagmusUpbeat nystagmus-Trochlear nerve palsy. From the Department of Neurology, Los Angeles County University of Southern California Medical Center, Los Angeles, California, U.S.A. Address correspondence and reprint requests to Dr. J. R. Keane, 1200 North State Street, Los Angeles, CA 90033, U.S.A. 194 © 1993 Raven Press, Ltd., New York Cysticercosis is among the commonest neurological diseases affecting the large Mexican and Central American immigrant populations of the Southwestern United States (1-3). (The term "neurocysticercosis" is redundant, as all but the most severe infestations are limited to neurological manifestations,) Seizures are the commonest presentation, while the greatest threat to the patient lies in acute obstructive hydrocephalus (3), Meningitis is common but usually asymptomatic. In an occasional patient, a large cyst will mimic the progressive focal course of a tumor. Rarely, massive infestation results in a dementing profusion of cerebral cysts. In general, cysticercal cysts accommodate to the brain: There are few symptoms until the cysts die and, even then, enlarging cysts conform to neighboring structures to minimize compressive effects. The accompanying meningitic reaction rarely produces clinically significant vasculitis and secondary infarction is uncommon (4). Cranial neuropathies are rare and brainstem dysfunction is generally limited to pretectal signs accompanying hydrocephalus (5). In the following patients, severe involvement of the posterior fossa produced unusual eye signs. PATIENTS Patients seen in neuro-ophthalmological consultation on the neurology and neurosurgery wards of the Los Angeles County/University of Southern California Medical Center during the past 23 years form the basis of this study. Cysticercosis was diagnosed by radiographic imaging studies, aided occasionally by positive cysticercal antibody titers, demonstration of eosinophilic meningitis, and examination of pathologic specimens. The description of neuro-ophthalmologic manifestations was based on clinical observation, supplemented by CYSTICERCOSIS 195 FIG. 1. (Case 1). Bilateral fourth nerve pareses. video and still photographic recordings. From 224 patients diagnosed as having cysticercosis, ten with bilateral fourth nerve palsies, three with unusual nystagmus, and one with facial myokymia were selected for presentation. By comparison, 134 patients showed pretectal signs and 78 had papilledema. CASE REPORTS Bilateral Trochlear Nerve Palsies Ten patients had bilateral trochlear nerve palsies due to cysticercal cysts lodged in the distal cerebral aqueduct. The following patient's presentation is typical. Case 1 Evaluation of an 18-year-old woman following 4 years of headaches revealed four-ventricle hydrocephalus. A ventriculoperitoneal shunt was placed with relief of symptoms, but 6 months later, headache, vomiting, and diplopia appeared. Examination now showed mild left head tilt, alternating adduction hypertropia, limitation of each eye when turned down and in (Fig. 1), V pattern esotropia, and bilateral excyclotropia on funduscopic examination. Magnetic resonance imaging (MRI) revealed normal (shunted) ventricles and several large cysts, including one lodged in the distal cerebral aqueduct (Fig. 2). Facial Myokymia Case 2 A 29-year-old man was admitted with severe pretectal signs. His neurological problems began FIG. 2. (Case 1). Transverse and saggital MRI views show cyst (with bright central scolex) lodged in the aqueduct. I Clin Neuro-ophthalmol, Vol. 13, No.3. 1993 196 ]. R. KEANE FIG. 3. (Case 2). Mild right facial contracture accompanies facial myokymia. Reproduced with permission of patient. with intermittent headaches 7 years before, followed by two left focal seizures 4 years later. Evaluation at that time showed papilledema, pupillary light-near dissociation, and upward gaze paresis. Computed tomographic (CT) scan revealed several cerebral cysticercal cysts in addition to obstructive hydrocephalus. Symptoms resolved following placement of a ventriculoperitoneal shunt. On admission, 3 years after diagnosis, he showed mild papilledema, 3-mm pupils fixed to light and near, upgaze paresis, and alternating adduction hypertropia. Ataxia of limbs and trunk was worse on the left side. Mild right facial contracture (Fig. 3) was accompanied by obvious continuous rippling of that side of his face. Electromyography demonstrated rhythmic motor unit firing typical of facial myokymia. CT and magnetic resonance (MR) scans showed moderate hydrocephalus. The brainstern was severely compressed by large cysts anteriorly and in the fourth ventricle and the cerebral aqueduct (Fig. 4). His shunt was revised, and when seen 1 month later, facial myokymia had resolved and the pretectal signs had improved. Periodic Alternating Nystagmus and Upbeat Nystagmus Case 3 A 28-year-old man developed headaches at age 22. Three years later, evaluation revealed multiple intracranial cysticercal cysts, and he was treated with two courses of Praziquantal without effect. The following year, he was admitted because of mild hydrocephalus due to a fourth ventricular cyst and showed mild papilledema and slight left gaze nystagmus on examination. His symptoms progressed and he developed upbeat nystagmus, reversing to downward nystagmus during convergence. The next month, periodic alternating nystagmus (PAN) appeared with nystagmus beating alternatively to each side for 75-90 seconds, interrupted by 20-second quiet pe- FIG. 4. (Case 2). Enhanced t~ansverse (left) an.d unenhanced saggital (right) MRI views show diffuse meningeal enhancement as well as brainstem compression from large cysts anteriorly (preclival) and posteriorly (within fourth ventricle and aqueduct and in the collicular cistern). 10m NellrtH,/'htha/mol. Vol. 13, No.3, 1993 CYSTICERCOSIS 197 riods. Imaging studies at the time showed large cysticercal cysts within the fourth ventricle and distal aqueduct, in addition to racemose cysts surrounding the brainstem (Fig. 5). Oscillopsia corresponding to his PAN lasted for 2 months and then stopped. Careful examination then showed only mild left gaze nystagmus. Six weeks later, shortly after surgical removal of his enlarging fourth ventricular cyst, oscillopsia recurred. Examination confirmed the return of PAN. When seen 2 years later he denied oscillopsia, but PAN (95- to 105-second active and 10-second null periods) was accompanied by continuous head rotations that matched fixation to the null position. Oculopalatal Myoclonus and Short-Cycle Periodic Alternating Nystagmus Case 4 A 29-year-old man underwent posterior fossa exploration in Mexico at age 17 for removal of a "tumor." Nine years later he was admitted with headache, diplopia, and pulsating tinnitus. Examination showed moderate papilledema and left gaze nystagmus. CT and MR scans revealed fourventricle hydrocephalus, enhancing nodules in the walls of a dilated fourth ventricle, and several large prepontine cysticercal cysts. Ventriculoperitoneal shunting provided only slight improvement and he underwent removal of a choroid plexus papilloma from the fourth ventricle. Six months later he developed severe oscillopsia and decreased vision in the right eye. When examined 1 year following his surgery, he showed PAN with short cycles, beating 10 to 20 seconds in each direction with 2- to 3-second pauses between directional shifts. The amplitude of right-beating nystagmus reached a maximum of about 9 degrees, roughly twice that of the left-beats. Other signs included a mild (25%) right sixth nerve paresis. Despite normal fundi, intact color vision, and an absence of an afferent pupillary defect, vision in the right eye could not be corrected to better than 20/200. The patient ascribed his poor vision to continuous vertical movements of that eye. Fundus examination confirmed vertical pendular oscillations of right eye of 1- to 2-degree amplitude and 3-Hz frequency; the left eye showed synchronous but barely perceptible «1 degree) movements. Observation of his palate revealed subtle left-sided oscillations at the same frequency. CT and MR scans showed compression of the brainstem caused by multiple large cysts lying in the subarachnoid space between clivus and brainstem. Exploration of his posterior fossa with removal of cysts relieved some of the compression but left the bulk of the cysts intact (Fig. 6). Following surgery, the alternating nystagmus disappeared, but oculopalatal nystagmus persisted unchanged. Six months later a return of horizontal oscillopsia was due to continuous, small amplitude (1-2 degrees) movements on forward gaze. Irregular lO-second alternations of horizontal nystagmus were interrupted by square waves of similar FIG. 5. (Case 3). Enhanced transverse (left) and unenh.anced saggital (rig~t) MRI views sho~ mUltipl~ cerebral parenchymal cysts, a large cyst within the fourth ventricle, and cysts and Inflammatory reaction anterior to the brainstem. I Gi" Neuro-ophthalmol. Vol. 13. No.3, 1993 198 J. R. KEANE FIG. 6. (Case 4). Unenhanced MRI views, 1 week following removal of preclival cysts, shows limited surgical effect with large cysts continuing to compress the brainstem. Other cysts indent the medial temporal lobes. size. Palatal and vertical ocular oscillations had not changed. MRI showed enlarging cysts. DISCUSSION Bilateral Trochlear Nerve Palsies Vertical diplopia accompanied by hypertropia of either adducting eye occurs with some regularity in cysticercosis (5). The patients in our hospital can be divided into two groups: A larger "third ventricle" group in which pretectal signs are prominent and imaging studies show hydrocephalus with dilation of the third ventricle. A small "fourth ventricle" group with absent or minor pretectal signs, in whom imaging demonstrates a cyst lodged in the superior fourth ventricle and distal aqueduct. While vertical dissociation of the eyes may appear identical, "third ventricle" patients probably have alternating skew deviation as the cause of alternating hyperdeviation, whereas the distal aqueductal cysts of "fourth ventricle" patients (like Case 1) directly stretch the trochlear fascicles to produce bilateral fourth nerve pareses. Facial Myokymia Facial myokymia refers to a spontaneous, continuous rippling of the face associated with rhythmic firing of motor units. It was first reported by Oppenheim in 1911 and reemphasized by Andermann and associates in 1961 (6). Multiple sclerosis plaques near the facial nerve nucleus remain I C/'d N'·llro-ophthalmol. Vol. 13, No.3, 1993 the most common cause, but other intramedullary pontine lesions such as glioma, metastasis, medulloblastoma, tuberculoma, cardiac arrest, and Joseph's disease have been reported (7). Less commonly, facial myokymia results from extramedullary causes (principally Guillain-Barre polyneuropathy) (7). Our patient had no intrapontine cysts; involvement of his seventh nerve could have occurred either at the facial colliculus in the floor of the fourth ventricle or in the subarachnoid course of the nerve. Upbeat Nystagmus Clinical observation of upbeat nystagmus is surprisingly limited. Not until 1968, when Cogan emphasized nystagmus beating downward on forward gaze (8), did clinicians conscientiously begin to observe and subdivide vertical nystagmus. Upward nystagmus on forward gaze appears to result from interruption of central vestibular pathways mediating upward gaze (9). In the few reported cases with localizing value, the lesions (most often infarcts or plaques) tend to involve the dorsal paramedian areas of the rostral medulla (10,11). Periodic Alternating Nystagmus PAN is a rare form of nystagmus in which the eyes exhibit continuous, alternating crescendodecrescendo runs of horizontal nystagmus to each side, separated by brief pauses (12,13). Prolonged CYSTICERCOSIS 199 observation of the eyes is required to detect the direction shift and, undoubtedly, many cases are overlooked. The usual cycle runs from 1 to 6 minutes in each direction, separated by a 15- to 20second quiet interval. At our hospital, short alternating cycles (14), as seen in Case 4, are more common seen with congenital PAN. Both mechanism and localization of PAN remain obscure. In most patients with localizing evidence, the caudal brainstem and cerebellum are implicated (11). A patient previously reported from our service had demyelinating plaques along the floor of the fourth ventricle and in both restiform bodies (12). Experimentally, damage to the cerebellar nodulus can produce similar alternations of nystagmus (11). Case 3 had large cysts in the fourth ventricle and distal aqueduct as well as having racemose cysts surrounding the brainstem. Case 4 was complicated, having a previously resected choroid plexus papilloma of the fourth ventricle as well as cysticercosis. Worsening of oscillopsia paralleled cyst enlargement and cyst decompression eliminated PAN in this patient, suggesting that cysticercosis was causative. The profusion of posterior fossa cysts and the accompanying arachnoiditis in both patients prevent anatomical localization of the lesion inciting PAN. Oculopalatal Myoclonus Rhythmic palatal oscillation, a form of segmental myoclonus, results from damage to connections from ipsilateral cerebellar dentate nucleus to the opposite inferior olivary nucleus by way of the pontine central tegmental tract (11,15). Accompanying eye movements are usually pendular, vertical- torsional oscillations with a frequency near 2.5 Hz. Ocular myoclonus is often overlooked, and when appreciated is frequently misdiagnosed as "ocular bobbing" or "downbeat nystagmus" by inexperienced observers (16). Although relatively "gentle" as neurological afflictions go, cysticercosis is a common, worldwide neurological disease that affects all regions of the central nervous system. As illustrated by our cases, both medical and surgical therapy, aside from lifesaving ventricular shunting, have limited value. The occasional occurrence of unusual neurological signs is to be expected with severe infestations. Unfortunately, the widespread nature of neurological infestation in our patients limits clinical- anatomicallocalization. For neurologists in the Southwestern United States, cysticercosis rivals syphilis and AIDS as a "great imitator." Acknowledgments: Chi-Shing Zee, M.D., assisted with radiological interpretation; Said Beydoun, M.D., performed electromyography. REFERENCES 1. McCormick GF, Zee C, Heiden JT. Cysticercosis cerebri: review of 127 cases. Arch Neurol 1982;39:534-9. 2. Keane JR. Neuro-ophthalmologic signs and symptoms of cysticercosis. Arch OphthalmoI1982;100:1445--8. 3. Keane JR. Death from cysticercosis: seven patients with unrecognized obstructive hydrocephalus. West JMed 1984;140: 787-9. 4. McCormick GF, Giannotta S, Zee C-S, Fisher M. Carotid occlusion in cysticercosis. Neurology 1983;33:1078--80. 5. Keane JR. The pretectal syndrome: 206 patients. Neurology 1990;40:684-90. 6. Andermann F, Cosgrove JBR, Lloyd-Smith DL, Gloor P, McNaughton FL. 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