Masashi Shimo-Oku

A CASE OF MESENCHYMAL CHONDROSARCOMA OF THE ORBIT

A case of mesenchymal chondrosarcoma occurring in the right orbit of a 84‐year‐old Japanese female was reported. The ultrastructural findings of tumour are composed of three cell types: well‐differentiated cartilaginous cells, undifferentiated cells and transitional cells. The well‐differentiated cells showed scalloped cytoplasmic membranes, numerous mitochondria showing dense electron matrix, various size of lipid granules, and abundant amount of extracellular matrix. The extracellular matrix were collagen fibres and ground substances and matrix vesicle. The undifferentiated cells showed smooth cytoplasmic membranes, large nuclei resembling primitive mesenchymal cells.

Neuro-Ophthalmological Evaluation Of Superior Oblique Myokymia

Three cases of superior oblique myokymia (SOM) were analyzed neuro-ophthal-mologically using single neuromuscular unit (NMU)-electromyography (EMG), single fiber EMG, and a two-dimensional eye movement analyzing system.The action potentials of the superior oblique muscle had high amplitude, long duration and many turns, and single NMU-EMG of the inferior oblique muscle showed no decrease of discharge synchronized with the burst discharges of the superior oblique muscle. Moreover, the jitter value calculated from single fiber EMG of the superior oblique muscle was relatively small and essentially the same as in normal controls and muscles completely recovered from oculomotor nerve palsy.Two-dimensional eye movement analysis showed unilateral rotary eye movements with a lower frequency than had been previously reported.These studies suggested that the lesion responsible for SOM was in either the ipsilateral trochlear nucleus or its infranuclear tract and that SOM might be associated with the recovery stage ...

Optic nerve involvement in posterior paranasal sinus diseases

During a 13-year period, we encountered 18 cases of involvement by posterior paranasal sinus diseases in patients with optic neuritis. These could be divided into two groups, a mucocele and pyocele group (nine cases) and a sinusitis group (nine cases), both with the following clinical profile: The chief complaint was decreased vision, prodromal symptoms were noticed in a few cases, the visual field showing central or paracentral scotoma in almost all cases. Recurrence of visual disturbance was obscured in all patients in the mucocele and pyocele group; several cases resembled multiple sclerosis, but could be distinguished from this disease after thorough neuro-ophthalmological examination and by long-term absence of neurological signs and symptoms after nasal surgery. CSF examination showed that inflammatory changes occurred in some patients in the sinusitis group. Although there is general agreement at present that a major cause of optic neuritis is demyelination, posterior paranasal diseases should also...

A CASE WITH LEIOMYOMA OF IRIS EXTIRPATED WITH CRYOSURGERY AND ITS PATHOLOGICAL FINDINGS

This report describes surgical observation and histopathological findings in a case of a 44‐year‐old male with leiomyoma of the iris in his left eye which had initiated from uveitis. In view of clinical efficiency and electron microscopic detection of leiomyoma, it is recommended that the tumour be excised after freezing coagulation. For confirmative diagnosis of leiomyoma of the iris, an electron microscopic detection is necessary to demonstrate the characteristic findings including cells with cigar‐shaped nuclei, cytoplasmic and plasma‐lemmal density, fine filaments, surface‐connected vesicles and basement membrane.

Influence of visual deprivation on the visual and oculomotor system: Acetylcholinesterase activity in oculomotor neurons

The effects of visual deprivation (dark-rearing) on neurons in both the visual and oculomotor systems of black mice were studied using morphologic and histochemical techniques. In the neurons of the dorsal nucleus of the lateral geniculate body, the cytoplasm of dark-reared mice was less developed and the cytoplasm/nucleus ratio was significantly smaller in the dark-reared mice than in the controls. In contrast, large motoneurons in the oculomotor nucleus did not show any ultrastructural changes and the cytoplasm/nucleus ratio was normal. However, in large motoneurons of dark-reared mice, acetylcholinesterase (AChE)-positive areas were scattered in the cytoplasm, and the ratio of the AChE-positive areas to the cytoplasm area was significantly smaller than that in the controls.

Single-fiber electromyography of extraocular muscles in myasthenia gravis

The jitter phenomenon of extraocular muscles (EOMs) was investigated in 11 healthy controls and 42 patients with diplopia and/or blepharoptosis using single fiber electromyography (SFEMG). The authors compared the usefulness of SFEMG of EOMs with two other diagnostic techniques (Tensilon test and the titers of anti-acetylcholine receptor antibodies: Anti-AChR ABs) in the differential diagnosis of myasthenia gravis (MG). The Tensilon test was positive in 72.7% of MG patients. Anti-AChR ABs were detected in 100% of generalized MG patients and in 63.6% of ocular MG patients. SFEMG demonstrated an abnormal jitter phenomenon in all MG patients. The authors conclude that SFEMG of EOMs is the most decisive examination in the differential diagnosis of ocular MG, and recommend its use when the etiology of fluctuating diplopia and blepharoptosis cannot otherwise be established.

Optic neuritis due to Aspergillus infection

A 67-year-old woman who complained of unilateral progressive visual disturbance and headache was initially diagnosed as having anterior ischemic optic neuropathy because of pale optic disc swelling and a small hemorrhage. Corticosteroid administration restored her visual acuity; however, this was only temporary and she eventually lost her vision and the headaches became severe. She died from a subarachnoid hemorrhage five months after the onset. In spite of having no remarkable problems in general condition or past history, during autopsy Aspergillus infection was unexpectedly found in the intracranial optic nerve and its surrounding tissues. Although optic nerve disturbance due to mycotic infection is rare, the latter should be considered in the etiology of optic nerve disturbances.

Analysis of Wallace mutation in patients with Leber's hereditary optic neuropathy: familial study and tissue distribution

Lebers hereditary optic neuropathy (LHON) is a disorder considered to be due to a mutation in the mitochondrial DNA (mtDNA). The authors analyzed the mtDNA genotype of peripheral blood leukocytes from two family members with LHON, and further analyzed mtDNA in various tissues originating from the separate germ layers (skin, hair, leukocyte, muscle, arachnoid, CSF cells, and buccal mucosa) in two LHON patients. A G-to-A transition of mtDNA np 11778 (Wallace mutation) was detected by the elimination of a SfaN I site and the acquisition of a Maelll site in all individuals and tissues examined.

Common interneurones mediating cortical and tectal excitation of abducens motoneurones in the cat

SummaryTectal and cortical effects on abducens motoneurones were examined with intracellular recording techniques in cats under chloralose anaesthesia. Abducens motoneurones exhibited disynaptic EPSPs after stimulation of the contralateral superior colliculus and cerebral peduncle. The tectal disynaptic EPSPs were observed invariably in all motoneurones tested, while the peduncular EPSPs were observed only in 40% of motoneurones after stimulation of the contralateral cerebral peduncle. However, the tectal disynaptic EPSPs were consistently facilitated by conditioning pedunclar stimulation in all motoneurones tested. These results indicated that the disynaptic excitatory tecto-abducens and cortico-abducens pathways shared common premotor interneurones. The common interneurones which mediated the tectal and cortical disynaptic excitation of abducens motoneurones were explored in the pons. These interneurones were identified by the criteria that they were fired monosynaptically from both the tectum and the cerebral peduncle and were activated antidromically from the abducens nucleus. Systematic threshold mapping for the antidromic activation in and around the abducens nucleus indicated that they gave off many collateral branches in the nucleus. Such neurones were found in the nucleus reticularis pontis caudalis, being distributed in the area extending 0.8–3 mm rostral to the rostral pole of the abducens nucleus, 1.3–2.7 mm deep from the dorsal surface of the brain stem, and 0.8–1.8 mm lateral from the midline. The present experiments strongly suggest that a group of neurones in the paramedian pontine reticular formation make direct excitatory connexions with abducens motoneurones and play a role of common interneurones that transmit both tectal and cortical commands.

Ocular myasthenic syndrome after interferon therapy for chronic hepatitis

Abstract A 68-year-old woman suffering from chronic hepatitis complained of vertical diplopia after long-term administration of alpha-II-inter-feron (IFN). Ocular symptoms worsened and left ptosis appeared during IFN treatment, but disappeared after IFN therapy was discontinued. Thorough serological and neuro-ophthalmological diagnostic examinations failed to disclose any reasons for these ocular symptoms. Fatigable lid ptosis, negative results of diagnostic examinations for ocular myasthenia, and the clinical course suggest that this patient developed an ocular myasthenic syndrome secondary to IFN.