Microvascular decompression for superior oblique myokymia: first experience - Case report

Superior oblique myokymia (SOM) is a rare eye movement disorder presenting as uniocular rotatory microtremor due to intermittent contractions of the s uperior oblique muscle. Medical treatment usually fails to provide long-ter m benefit for the patient and has considerable side effects. Surgical alter natives including tenotomy or partial tenectomy of the superior oblique ten don often result in incomplete resolution of the visual symptoms. The autho rs report a patient who experienced immediate cessation of disabling SOM fo llowing microvascular decompression of the fourth nerve at the root exit zo ne. Temporary double vision at downgaze resolved 5 months after surgery. Th en was no recurrence of oscillopsia during a follow-up of 22 months to date . From this single observation it appears likely that vascular compression of the trochlear nerve could be a significant pathophysiological factor contr ibuting to SOM. In the hands of an experienced surgeon, microvascular decom pression at the brainstem exit zone of this nerve may evolve as the method of choice for selected cases of disabling SOM.