A 13-year-old girl who had Duane retraction syndrome associated with Chiari I malformation is reported. Neuro-ophthalmologic examination revealed severe limitation of abduction of the left eye, as well as narrowing of the palpebral fissure and retraction of the globe on adduction. Electro-oculography of the affected eye revealed decreased saccadic velocity on attempted abduction and adduction. Midsagittal magnetic resonance imaging demonstrated cerebellar tonsillar herniation to 6 mm below a line from the basion to opisthion. Taking into consideration the relative rarity of the two disorders, the association may not be coincidental. Magnetic resonance imaging of the posterior fossa is recommended in Duane retraction syndrome.

Adolescent↗

PubMedDate not supplied

Direct parasympathetic pathway from midbrain to ciliary muscles in cats and monkeys.

In cats and monkeys, we examined the parasympathetic component of the oculomotor complex, which directly innervates the ciliary muscle, using horseradish peroxidase (HRP). Labeled neurons of varying form and size were found in the Edinger-Westphal(EW) and the Perlia nuclei of the cat and in the anteromedian, EW, and Perlia nuclei of the monkey. Our study confirmed that a direct parasympathetic pathway exists from the midbrain to the ciliary muscles, and that accommodation is controlled in part by this direct link from the midsagittal region via a parasympathetic neuron of the oculomotor nuclear complex.

Animals↗

PubMedDate not supplied

Presynaptic effects of botulinum toxin type A on the neuronally evoked response of albino and pigmented rabbit iris sphincter and dilator muscles.

PURPOSE: To investigate the effects of botulinum toxin type A (botulinum A toxin) on the autonomic and other nonadrenergic, noncholinergic nerve terminals. METHODS: The effects of botulinum A toxin on twitch contractions evoked by electrical field stimulation (EFS) were studied in isolated albino and pigmented rabbit iris sphincter and dilator muscles using the isometric tension recording method. RESULTS: Botulinum A toxin inhibited the fast cholinergic and slow substance P-ergic component of the contraction evoked by EFS in the rabbit iris sphincter muscle without affecting the response to carbachol and substance P. These inhibitory effects were more marked in the albino rabbit than in the pigmented rabbit. Botulinum A toxin (150 nmol/L) did not affect the twitch contraction evoked by EFS in the rabbit iris dilator muscle. CONCLUSIONS: These data indicated that botulinum A toxin may inhibit not only the acetylcholine release in the cholinergic nerve terminals, but also substance P release from the trigeminal nerve terminals of the rabbit iris sphincter muscle. However, the neurotoxin has little effect on the adrenergic nerve terminals of the rabbit iris dilator muscle. Furthermore, the botulinum A toxin binding to the pigment melanin appears to influence the response quantitatively in the two types of irides.

Albinism↗

PubMedDate not supplied

[Chronic progressive external ophthalmoplegia (CPEO)--clinical features and histopathology of the extraocular muscles (author's transl)].

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Adolescent↗

PubMedDate not supplied

Representation of the visual field in the striate cortex: comparison of MR findings with visual field deficits in organic mercury poisoning (Minamata disease).

PURPOSE: To compare MR imaging findings of the striate cortex with visual field deficits in patients with Minamata disease and to reestimate the classical Holmes retinotopic map by using the data obtained from comparing visual field abnormalities with degree of visual cortex atrophy. METHODS: MR imaging was performed in eight patients with Minamata disease who had been given a full neuroophthalmic examination, including Goldmann dynamic perimetry. The atrophic portions of the calcarine area were measured in the sagittal plane next to the midsagittal image and represented as a percentage of atrophy of the total length of the calcarine fissure. MR findings were compared with results of a visual field test. RESULTS: The visual field test revealed moderate to severe concentric constriction of the visual fields, with central vision ranging from 7 degrees to 42 degrees (mean, 19 degrees). The ventral portion of the calcarine sulcus was significantly dilated on MR images in all patients. A logarithmic correlation was found between the visual field defect and the extent of dilatation of the calcarine fissure. The central 10 degrees and 30 degrees of vision seemed to fill about 20% and 50% of the total surface area of the calcarine cortex, respectively. CONCLUSION: Visual field deficits in patients with Minamata disease correlated well with MR findings of the striate cortex. Our data were consistent with the classical Holmes retinotopic map.

Atrophy↗