Superior oblique myokymia

Superior oblique myokymia is a neurological disorder affecting vision and was termed by Hoyt and Keane in 1970. ^[1]

In 1983, Bringewald postulated that superior oblique myokymia resulted from vascular compression of the trochlear nerve (fourth cranial nerve), which controls the action of the superior oblique muscle in the eye. ^[2] By 1998, there had been only one reported case of compression of the trochlear nerve by vessels. ^{[3] [4]} More recently, magnetic resonance imaging experiments have shown that neurovascular compression at the root exit zone of the trochlear nerve can result in superior oblique myokymia. ^[5]

The onset is usually in adulthood.

The course of the disease is benign and is not commonly associated with other disorders.

It is a condition that presents as repeated, brief episodes of movement, shimmering or shaking of the vision of one eye, a feeling of the eye trembling, or vertical/tilted vision. It can present as one or more of these symptoms.

Treatment can include pharmaceutical or surgical means. The drug Oral carbamazepine (Tegretol) has been used successfully. Successful surgery options include superior oblique tenectomy accompanied by inferior oblique myectomy. ^[6]

Samii et al^[7] and Scharwey and Samii^[8] described a patient who had superior oblique myokymia for 17 years. The interposition of a Teflon pad between the trochlear nerve and a compressing artery and vein at the nerve’s exit from the midbrain led to a remission lasting for a follow-up of 22 months.

• SOM People internet support group