Journal of Neuro-Ophthalmology, September 1991, Volume 11, Issue 3

The effect of chronic one-eye patching on ocular myoclonus.

Ocular myoclonus developed in our 34-year-old patient 4 months after massive brain stem hemorrhage due to eclampsia. On chronic patching of the left eye, the vertical pendular nystagmus in the fixating right eye disappeared, whereas the covered eye was esotropic. While fixating, the left eye showed horizontal pendular nystagmus. With both eyes fixating, the right eye presented markedly vertical pendular nystagmus and the left eye a horizontal pendular nystagmus. It seems that chronic patching of one eye has a beneficial modulating effect on the vertical pendular nystagmus in the fixating eye.

! ournal of Clinical Neuro- ophthalmology 11( 3): 166- 168, 1991. The Effect of Chronic One- Eye Patching on Ocular Myoclonus Yuval O. Herishanu, M. D. and Raoul Zigoulinski, M. D. © 1991 Raven Press, Ltd., New York Ocular myoclonus developed in our 34- year- old patient 4 months after massive brain stem hemorrhage due to eclampsia, On chronic patching of the left eye, the ver­tical pendular nystagmus in the fixating right eye disap­peared, whereas the covered eye was esotropic. While fixating, the left eye showed horizontal pendular nystag­mus. With both eyes fixating, the right eye presented markedly vertical pendular nystagmus and the left eye a horizontal pendular nystagmus. It seems that chronic patching of one eye has a beneficial modulating effect on the vertical pendular nystagmus in the fixating eye. Key Words: Ocular myoclonus- Eye patching­Nystagmus. . From the Department of Neurology, Soroka University Med­ical Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer- Sheva, Israel. Address correspondence and reprint requests to Dr. Y. O. Henshanu at Department of Neurology, Soroka Medical Cen­ter, P. O. Box 151, Beer- Sheva, Israel. 166 Ocular myoclonus may develop after a brain stem lesion, and the movements of the eyes as well as the associated myoclonus of the palate, vocal cords, diaphragm and limbs are attributed to dis­ruption of the connection between the dentate nu­cleus, contralateral red nucleus, and inferior oli­vary nucleus ( 1). Few cases have recovered spontaneously. Ther­apeutic trials have met with variable success. 5­Hydroxytryptophan in combination with carbi­dopa ( 2), carbamazepine ( 3), clonazepam ( 4), and trihexyphenidyl ( 5) improved palatal myoclonus. Amobarbital ( 6), diazepam ( 7), scopolamine ( 8), and trihexyphenidyl ( 9) improved vertical pendu­lar nystagmus. This paper reports the changes in the amplitude and the direction of the ocular myoclonus that oc­curs with chronic patching of one eye. CASE REPORT A 34- year- old patient [ whose history was previ­ously reported by Herishanu and Louzoun ( 9)] presented in the 32nd week of pregnancy with se­vere toxemia of pregnancy which led to general­ized tonic convulsions controlled with diazepam and magnesium sulfate. This was followed by a stuporous state accompanied by left hemiparesis. Cesarean section was performed. Several hours later she was alert but presented dysarthria, bilat­eral horizontal gaze palsy on volition and reflex stimulation, slight limitation of upward gaze, and skew deviation. Downward gaze was possible but down- beating nystagmus was present. The fundi were normal. Right peripheral facial palsy, de­creased right pharyngeal reflex, left flaccid hemi­paresis with overactive tendon reflexes, left exten­sor plantar response, and decreased perception of all modalities were also found. ONE- EYE PATCHING AND OCULAR MYOCLONUS 167 Computed tomography showed massive bleed­ing into the brain stem from the pons to the mid­brain. She gradually improved. Two months later there still was marked limitation of gaze to the right and to the left, whereas upward and down­ward gaze and convergence were normal. Four months after the onset, she noted vertical oscillop­sia and presented marked vertical pendular nystagmus. On upward gaze the nystagmus de­creased in amplitude and on downward gaze the nystagmus became horizontal with a rotatory com­ponent. No palatal myoclonus was found at that time. Artane markedly reduced the amplitude of the nystagmus, but the patient stopped this treatment after 1 year because of psychomotor irritability. The patient was advised by a general practition­er to cover one eye with a patch. She covered the left eye, and 3 months later a marked decrease in the amplitude of the vertical pendular nystagmus in the right uncovered eye was seen. On different occasions, the eye movements were recorded using a Nihon Kohden Electronystagmo­graph, an infrared reflection device ( Eyetrac 200), and video. Three years after first patching her left eye, the right eye, kept uncovered, is free of nystagmus. There is limitation of right eye adduction and absent right eye abduction. When the left eye was unpatched, this eye was found to be markedly es­otropic (+ 25 ~ distance and near). Corrected vi­sual acuity was 20/ 20 in both eyes. When the right eye was patched, horizontal pendular nystagmus of the left eye was seen. On attempted right gaze, a very slight move­ment was elicited- more with the left eye. On at­tempted left gaze, only slight adduction of the right eye was seen. With both eyes uncovered, the right eye showed vertical pendular nystagmus, and the left eye executed an horizontal pendular nystagmus. On upward gaze, oblique pendular nystagmus was noted. On downward gaze vertical pendular nystagmus of both eyes was seen. Palatal myoclonus was still present. Head titubation and left arm postural tremor with a same rhythm as the nystagmus were also seen. DISCUSSION In a few cases, ocular myoclonus was reported to disappear spontaneously ( 10- 12). In all other cases, ocular myoclonus does not change unless pharmacologically treated. . In this case, the ocular myoclonus changed Its characteristics on long term follow- up as a result of one- eye patching, i. e., it disappeared in the uncov­ered eye while the covered eye became esotropic. This finding shows some similarity to the nystag­mus blockage syndrome that has been well docu­mented in a few cases of congenital nystagmus ( 13). On follow- up our patient presented bilateral horizontal gaze paresis with a slightly more limited abduction on both sides. The latter finding can be explained by damage to the abducens nerve fasci­cles, which in turn probably explains the esotropia of the occluded left eye. We presume that the es­otropia " blocked" the nystagmus in the fixating eye. During binocular viewing of a distant target for awhile, the esotropia almost disappeared and the nystagmus recurred in both eyes. The possibil­ity of tactile feedback from the inner eyelid reduc­ing the nystagmus in the fellow eye ( 14) can be ruled out, since the effect of attaching the patch to the eyeglass was the same as that of attaching the patch to the eyelid. When the right eye was cov­ered and the left eye was fixing, the left eye pre­sented horizontal pendular nystagmus. Changes in the vectors of the horizontal saccades in the patched eye were reported in studies on monkeys ( 15). In the light of our findings, it seems that patch­ing of one eye might be beneficial in alleviating this disturbing symptom in similar patients suffering from ocular myoclonus. REFERENCES 1. Guillain G, MoUaret P. Deux cas de myoclonies synchrones et rythmees velo- pharyngo- laryngo- oculodiaphragma­tiques: Ie probleme anatomique et physiopathologique de ce syndrome. Rev Nellrol ( Paris) 1931; 12: 545-- 66. 2. Magnussen I, Dupont E, Prange- Hansen AC de Fine Oli­varius B. Palatal myoclonus treated with 5- hydroxy­tryptophan and a decarboxylase inhibitor. Acta Nellrol Scand 1977; 55: 251- 3. 3. Sakai T, Shiraishi 5, Murakami S. Palatal myoclonus re­sponded to carbamazepine. Ann Nellrol 1981; 9: 199- 200. 4. Gauthier S, Young SN, Baxter OW. Palatal myoclonus as­sociated with a decrease in 5- hydroxy- indolacetic acid in cerebrospinal fluid and responding to c1onazepam. Can I Nwrol Sci 1981; 8: 51- 4. 5. Jabbari B, Gunderson CH. Palatal myoclonus responding to trihexyphenydyl. AIIII NellroI1983; 14: 95. 6. Lawrence WH, Lightfoote WE. Continuous vertical pendu­lar eye movements after brain stem hemorrhage. Neurology ( Min neap) 1975; 25: 896- 8. 7. Takahashi Y, Tazawa. Vertical pendular oscillation. Proc 6th Meeting Intern Neuro- ophthalmol Soc. Neuro- Oph­thalmollapan 1986; 3: 347- K 8. Gresty MA, Ell Jj, Findley LJ. Acquired pendular nystag­mus: its characteristics, localizing value and patho- phys­iology. I Neurol Nellrosllrg Psychiatry 1982; 45: 431- 9. 9. Herishanu Y, Louzoun Z. Trihexyphenidyl treatment of vertical pendular nystagmus. Neurology ( NY) 1986; 36: 82- 4. 10. Carmon A, Behar M, Bornstein B. Transient branchiorespi- I CIill Neuro- ophthalmol, Vol. 11, No. 3, 1991 168 Y. O. HERISHANU AND R. ZIGOULINSKI ratory and ocular myoclonus in encephalitis. Confinia Neu­roI1963; 23: 63- 72. 11. Walsh FB, Hoyt WF. Clinical neuro- ophthalmology. Vol. 1. 3rd ed. Baltimore: Williams & Wilkins, 1969: 28B- 9. 12. Cordonnier M, Goldman 5, Zegers de Beyl D, Baleriaux D, et al. Reversible acquired pendular nystagmus after brain­stem hemorrhage. Neuro- ophthalmol 1985; 5: 47- 50. 13. DeIl'Osso LF, Ellenberger C Jr., Abel LA, and Flynn JT. The nystagmus blockage syndrome. Congenital nystagmus, J (;;! in NeurCHfflhthalmol, Vol. 11. No. 3, 1991 manifest latent nystagmus, or both? Invest Ophthalmol Vi­sual Sci 1983; 24: 158(}"' 7. 14. Dell'Osso LF, Traccis 5, Abel LA, Erzurum 51. Contact lenses and congenital nystagmus. Presented at the 7th Meeting of the Int Neuro- ophthalmol Soc, Vancouver, Can­ada, 1988. 15. Virre E, Cadera W, Vilis T. The pattern of changes pro­duced in the saccadic system and vestibulo- ocular reflex by visually patching one eye. JNeurophysiol 1987; 57: 9B- I03.