OCR Text |
Show Journal of Cli"' cal Neuro- ophthalmology 9( 3): 211- 213, 1989. The 1988 Japanese Neuro- ophthalmology Society Meeting Masato Wakakura, M. D., D. Se. © 1989 Raven Press, Ltd., New York The 26th meeting of the Japanese Neuroophthalmology Society was held in Morioka ( organizer: Professor Yutaka Tazawa), October 19- 21, 1988. Ninety papers, including 10 on basic research in neuro- ophthalmology, were presented. Two guest speakers from the U. S. A., Professor Barry E. Stein of Virginia and Professor William F. Hoyt of San Francisco, also gave lectures. This article introduces several of these papers of particular interest. OPTIC PATHWAY Eleven cases considered to be melanocytoma of the optic disc were presented by Dr. Usui ( Niigata). The visual field defects included enlargement of the blind spot and nerve fiber bundle defects, which were clearly evident in some cases. Also presented was an unusual case complicated with anterior ischemic optic neuropathy. It was concluded that melanocytoma of the optic disc was not always benign in prognosis, Bilateral reversible visual loss, possibly due to phenobarbiturate treatment to prevent posttraumatic seizure, was discussed by Dr. Honma ( Kitasato). The patient ( a 12- year- old boy) had recently experienced two episodes of bilateral visual loss, then recovered within 2 days. The third episode was prolonged, prompting the individual to seek clinical advice. Visual acuity was 0.4 00 and 0.05 OS. Left relative afferent pupillary defect was apparent. Visual acuity gradually recovered, even before termination of phenobarbiturate treatment. A follow- up for > 1 year indicated no recurrence of visual loss. It was concluded that transient and reversible visual loss were possibly characteristic of phenobarbital intoxication. From the Department of Ophthalmology, School of Medicine, Kitasato University, 1- 15- 1 Kitasato sagamihara Kanagawa 228, Japan. 211 Four migrainous patients with either visual field defects or visual negative phenomena, such as transient visual loss, were the subject presented by Dr. Wakakura ( Kitasato). All patients were teenage females. Three of the patients had a history of migraine with transient visual loss, and two of the patients had manifested permanent visual field defects. In one case, the permanent visual field defect had not been accompanied by visual negative phenomenon. In the two cases with visual field defects, fluorescein angiography showed the presence of a prolonged watershed zone about the discs, indicating a possible ischemic cause. Scintillation scotoma was not a prodrome in any of these cases. The visual negative phenomenon observed in the migrainous patients may perhaps be a warning of migrainous ischemic optic neuropathy. A diagnostically difficult case of a 44- year- old man with abrupt visual loss and ophthalmoplegia in both eyes was discussed by Dr. Azuma ( Hyogo). An enhanced mass with calcification appeared at the suprasellar area on the CT scan. Craniopharyngioma was foremost suspected. Surgical findings indicated sphenoidal mucocele extending into the intracranial space. Infarct about the lateral geniculate or the initial part of the optic radiation causes homonymous hemianopia or quadrantanopia, a condition referred to as " anterior choroidal artery" syndrome. Dr. Terao ( Nagoya) reported five such cases, with particular reference to their CT findings. Low density areas on the CT were variable, but were quite consistent with the clinical features. An unusual complication of morning glory syndrome was reported by Dr. Hagiwara ( Kumamoto). An 8- year- old girl experienced morning glory syndrome in the right eye and persistent hyaloid artery in the left. Radiological examination disclosed basal encephalocele. Basal encephalocele can be suspected with optic nerve anomalies ( Goldhammer et aI., 1975). 212 M. WAKAKURA OCULAR MOTOR SYSTEM Neuromuscular unit ( NMU) electromyography was carried out on the superior oblique muscle in three cases with superior oblique myokymia ( Dr. Komai, Hyogo). The waves were polyphasic and of long duration. The jitter values were relatively low in all cases. A reinnervation pattern was apparent, indicating the possibility of superior oblique myokymia as an aftereffect of superior oblique paresis. Dr. Fukushima ( Akita) presented an interesting case with presumed bacterial cerebral aneurysm. A 31- year- old man complained of severe pulsating headaches lasting for as long as 1 week. The cerebrospinal fluid indicated bacterial meningitis. Despite antibiotic treatment, ptosis and total ophthalmoplegia developed in the left eye, suggesting left cavernous sinus syndrome. A large aneurysm ( 14 x 10 mm) at the cavernous sinus part of the left internal carotid artery was found by angiography. Antibiotics administered along with corticosteroids gave gradual improvement of the clinical features. The aneurysm may have been due to bacterial meningitis. Although pineal cyst is usually clinically quiet, Dr. Koyama ( Tokyo) reported a 54- year- old woman with mild skew deviation; she eventually showed a pineal cyst on MRl ( 10 x 10 x 10 mm) compressing the superior colliculus. . Dr. Okano ( Kitasato) analyzed 120 cases with myasthenia gravis and found steroid treatr:' ent for the ocular form of the disease to be considerably effective. In most cases of the ocular form, indicating either a decremental response in electromyography of an affected ocular muscle or high titer of the antiacetylcholine receptor antibody, the general form was eventually assumed. Dr. Kamei ( Chigasaki) centered his discussion on the supratentorial pathway for lateral gaze in two cases with pure motor hemiplegia. Both patients showed lateral gaze palsy, making eye movement to the affected side impossible. The lesions were found situated on the anterior limb of the internal capsule. It would therefore appear that the human fronto- mesencephalic pathway from the frontal eye field passes through the anterior limb of the internal capsule. Dr. Takahashi ( Iwate) discussed the effects of proprioceptive sensation on the optokinetic nystagmus and vestibula- ocular reflex. In hiS very innovative approach, he used seven patients with herpes 7()~ ter ophthalmiclls to confirm whether ,-.•. " ,,-,. ".'.. .•... ", 1,'.('" through tht' oph- ''', 111' , depended • J elm Nrum- Ilplllhlllflw{, VIII '- J. ,' 1/( 1 on each particular stage of the disease. In two eyes at the acute stage, initiation from the quick to slow phase of the optokinetic nystagmus was delay~ d, and there was no indication of visual suppressIOn in the vestibulo- ocular reflex. The results appear to support the above possibility. PUPILLARY SYSTEM In a study using cats, Dr. Shomura ( Hirosaki) obtained direct evidence that psychosensory pupillary dilation is produced by cathecholamines secreted from the adrenal medulla. Parasympathetic nerves were inhibited by either oculomotor nerve transection or atropine instillation. The superior cervical ganglia were also removed. As a resu~ t ~ f subsequent electrical stimulation of the sCIatic nerve, the pupil dilated with a long latency (- 6 s). This response was completely inhibited by Ct blockers, but not by 13 blockers. No such mydriatic response occurred during the shutdown of bilateral adrenal circulation. Dr. Atsumi ( Aichi) examined pupillary response to various eye drops in 12 eyes with pseudoexfoliation syndrome. With parasympathomimetic drugs, the response in most cases was normaL whereas after 0.4% tropicamide treatment, 8 out of 12 eyes showed a reduced mydriatic rate.. These findings indicate a possible sympathetic disorder, arising perhaps from pseudoexfoliation substances. Dr. Hiraoka ( Tokyo) conducted an electrophysiological study on the near- response system i~ cats. Electromyography was carried out on the bilateral sphincter muscles of the iris, ciliary muscles, and medial rectus muscles while subjecting them to electrical stimulation of certain areas. In all cases, the response was positive during stimulation of the Clare- Bishop area or midbrain reticular formation. Thus, the output of near response may originate from the Clare- Bishop area and pass through the midbrain reticular formation. Stimulation of the antero- median nucleus induced two types of sphincter response: monophasic. waves with short latency and polyphasic waves with long latency. The monophasic waves suggest a direct pathway from the nucleus to the sphincter muscle. These electrophysiological results would support current neuroanatomical studies and possibly provide some clarification of the mechanism for lightnear dissociation. MISCELLANEOUS Miss Chino ( Kitasato) presented results on the pattern of visually evoked cortical potential ( VECP) JAPANESE NEURO- OPHTHALMOLOGY SOCIETY 213 obtained for 10 cases with classic migraine and 10 age- matched controls. The migrainous patients showed asymmetric VECPs between the right and left occipital recordings, although the asymmetry was not correlated with either the headache side or the side responsible for the scintillation scotoma. The asymmetry may be a predisposition in patients with classic migraine, suggesting the presence of hemispheric asymmetry in neuronal activity and/ or the blood circulation. Dr. Isashiki ( Kagoshima) reported another case with myotonic dystrophy in which skeletal muscles showed mitochondrial abnormalities. Reduced activity of a mitochondrial enzyme, cytochrome C oxidase, was noted in an extraocular muscle biopsy. This is the first report indicating abnormality of a mitochondrial enzyme in an extraocular muscle. Minamata disease results from intoxication by organic mercury and involves various neurological problems, including disorders of the optic pathway and ocular motor system. Dr. Kairada ( Saga) examined the level of organic mercury in the lens using rats in an experimental model of the disease. The level in the lens remained essentially constant for 180 days after acute intoxication. Following exposure, toxic materials continued to remain in the lens, which may be considered useful for determining previous intoxication. The next meeting is scheduled to be held in Tokyo ( organizer: Professor Hiroshi Matsuzaki), October 20- 22, 1989. JClin Neuro- ophthalmol, Vol. 9. No. 3, 1989 |