Ocular neuromyotonia treated by microvascular decompression: usefulness of preoperative 3D imaging

Abstract

Ocular neuromyotonia is a rare ocular motility disorder characterized by involuntary contraction of extraocular muscles resulting in paroxysmal diplopia. Although ocular neuromyotonia is reported as a rare complication after radiation therapy, there are a few cases of ocular neuromyotonia in the absence of irradiation. In the reported cases the possibility of vascular compression has been suggested on radiological imaging. The authors report a case of ocular neuromyotonia treated by microvascular decompression of the third cranial nerve, supporting the hypothesis that neurovascular compression may play a role in its pathogenesis. The usefulness of preoperative 3D imaging for microvascular decompression is also discussed.

Abducent nerve palsy treated by microvascular decompression: a case report and review of the literature

“…Of those, 3 cases caused by neurovascular compression of the posterior cerebral artery and/or superior cerebellar artery at the cisternal portion of the oculomotor nerve were successfully treated with MVD [1,10,17]. On the other hand, we identified only 1 case, reported by Inoue et al, in which the presenting symptom was ocular neuromyotonia (hyperactive dysfunction) caused by pinching between the posterior cerebral and superior cerebellar arteries, that was successfully treated with MVD [4]. In their case also, the cisternal portion of the oculomotor nerve was found to be the site of the vascular compression.…”

“…It is likewise a clinical manifestation supposedly similar to oculomotor nerve palsy caused by posterior communicating artery aneurysms. Several cases with ocular motor dysfunction (oculomotor nerve [1,4,10,17], trochlear nerve [3,7,15], and abducent nerve [2, 8, 11-14, 16, 18, 19, 21]) attributed to non-aneurysmal vascular compression have so far been reported. Two cases have been reported in which the patient presented with superior oblique myokymia caused by vascular compression of the trochlear nerve at its REZ as a hyperactivity dysfunction; both cases were successfully treated with MVD [3,15].…”

“…Although it is generally thought that vascular compression for the REZ of the nerves causes hyperactive dysfunction while that for the cisternal portion leads to hypoactive dysfunction, the pathogenetic differences between the hyperactive and hypoactive dysfunctions in the ocular motor nerves remain unclear. They are supposedly associated with severity and/or sites of compression as well as varying vulnerability of the nerves related to the severity of nerve demyelination, length of the central myelin-peripheral myelin transitional zone of the nerves, and so forth [4,18]. Table 1 summarizes the published cases of isolated abducent nerve palsy due to neurovascular compression of the vertebrobasilar arteries or the anterior inferior cerebellar artery.…”

Trigeminal Neuralgia due to an Isolated Cerebral Varix: Case Report

“…The surgeon's view enables us to clearly understand the anatomical relation of the nerve and adjacent vessels so we can make an exact plan for decompression before surgery. 6,13 In the present case, the varix, its related veins, and the site of neurovascular compression were clearly depicted to facilitate understanding of this rare pathologic condition.…”

Ocular Neuromyotonia Associated with Chronic Inflammatory Demyelinating Polyneuropathy

“…However, our survey of the literature identified seven patients reported by Shults et al, 1 Ezra et al, 3 Lessel et al, 7 and Inoue et al, 8 who did not have this characteristic feature. Furthermore, six of these seven patients had completely normal interictal examinations with no history of focal ocular motor nerve paresis prior to the onset of the ONM.…”