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Ocular neuromyotonia (ONM) is a rare eye movement disorder, presenting as a paroxysmal involuntary spasm of one or more extra-ocular muscles, that can persist for a few seconds up to several minutes. The phenomenon is caused by the contraction of an extra-ocular muscle, excited by a damaged nerve, which leads to delayed muscle relaxation. We present eight patients with this rare condition together with an overview of the literature on all published ONM cases. One of the presented cases is possibly secondary to hypovitaminosis D. This association has not been reported previously in the literature. A possible underlying mechanism is given.

Ocular neuromyotonia (ONM) is a rare disorder of ocular mal-alignment in which painless, transient spontaneous or gaze-induced abnormal deviation of the eye manifests as episodic diplopia. With only a few cases reported in the literature, ONM mostly follows months to years after cranial irradiation for sellar or suprasellar lesions. Here we present two patients with this rare ocular condition, secondary to brainstem demyelination, the association of which is hitherto unreported in the literature. Both patients were 15-year-old girls who presented to us with episodic forced-eye deviation with diplopia. Examination during these attacks revealed ONM involving the superior rectus and medial rectus in the first and second patient, respectively. There was clinical evidence of intrinsic brainstem involvement with downbeat nystagmus and skew deviation in one patient without any other cerebellar or long tract signs. MRI showed evidence of demyelination involving the brainstem in both, with CSF showing positive immunological markers and with positive aquaporin-4 antibody in one patient. Both patients responded remarkably to immunomodulatory therapy and are asymptomatic at follow-up. That ONM can occur with brainstem demyelination has not been reported in the literature. This association may help in explaining the pathophysiology of ONM as secondary to segmental demyelination., (© The Author(s) 2014.)

Ocular neuromyotonia is an episodic involuntary contraction of one or more of the extraocular muscles resulting from spontaneous neural discharges of the oculomotor nerve. It is characterized by symptomatic diplopia for the duration of the contraction and occurs either spontaneously or after a sustained eccentric gaze. Although the mechanism of ocular neuromyotonia is not fully understood, primary or secondary aberrant regeneration and consequent ephaptic transmission generally are held to be involved. We report the case of a patient with right oculomotor neuromyotonia accompanied by lid ptosis on abduction of the left eye who was successfully treated with oral carbamazepine., (Copyright © 2013 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.)

Purpose: To present a novel case of pupillary involvement in ocular neuromyotonia (ONM), a rare ocular syndrome that causes intermittent diplopia because of an abnormal delay in extraocular muscle relaxation and to conduct a literature review., Methods: A case report is presented to demonstrate clinical characteristics and treatment of ONM. In addition, a literature review is conducted by searching Medline and Embase databases. Data are collected from all known published cases listed in these databases to collate patient demographic data, presumed etiology or associated pathologies, and treatment strategies., Results: The presented case demonstrates successful carbamazepine treatment of thyroid-related orbitopathy-associated ONM involving cranial nerve III. A review of the literature elicits 66 published cases of ONM, three of which were deemed to be associated with thyroid-related orbitopathy. The most common cause of reported ONM is suprasellar pathology, comprising approximately 60% of documented cases. Most published ONM cases (n = 41) were treated with carbamazepine, demonstrating a success rate of 87.8%. Of the published cases, cranial nerve III was involved 56% of the time, cranial nerve VI was affected in 39% of cases, and only 9% of ONM cases involved cranial nerve IV., Conclusions: Ocular neuromyotonia is a rare cause of intermittent diplopia. Unlike most neurologic etiologies of diplopia, this syndrome can often be treated effectively with carbamazepine by stabilizing the neural cell membrane. To the authors' knowledge, this is the first presentation of ONM associated with thyroid-related orbitopathy, demonstrating bilateral but asymmetric miosis during episodes of muscle spasm.

Ocular neuromyotonia is an uncommon disorder resulting from episodic involuntary discharge of ocular motor nerves producing sustained contraction of their respective ocular muscles. Ocular neuromyotonia manifests in brief spells of diplopia occurring spontaneously or after eccentric gaze holding. In most cases, ocular neuromyotonia follows months or years after radiotherapy to the sellar and parasellar region and involves the oculomotor nerve. We report two unusual cases of abducens nerve ocular neuromyotonia that followed radiation therapy of tumors in areas other than the sellar or parasellar region.

Ocular neuromyotonia is a rare motility disorder occurring after tumor irradiation near the skull base or as a consequence of vascular abnormalities. Ocular myasthenia, convergence spasm and a cyclic third nerve palsy must be considered as differential diagnoses. The case of a 32-year-old woman suffering from intermittent diplopia six months after radiation therapy of a recurrent pituary gland adenoma is presented.