Results of extraocular muscle surgery for superior oblique myokymia

To report results of extraocular muscle surgery for superior oblique myokymia when medical treatment fails.

A retrospective review of 14 consecutive patients undergoing superior oblique tenectomy and inferior oblique myectomy between 1976 and 2008.

The mean age of onset of symptoms was 35.4 +/- 12.6 years (range, 16-59.5), with a mean duration of oscillopsia of 5 +/- 4 years (range, 1.5-17) prior to surgery. Medical treatment was unsuccessful in all 14. Preoperatively, 2 had a small hypertropia that was consistent with an ipsilateral fourth (trochlear) nerve palsy; 12 had no manifest tropia. Postoperatively, all had complete elimination of oscillopsia, and 12 of 14 were free of diplopia in the primary position at 6 meters and 1/3 meter. The only 2 with diplopia in the primary position after surgery were the 2 with a manifest hypertropia preoperatively. Of the remaining 12 patients, 5 had a hypertropia of the affected eye limited to downgaze after surgery (mean of 6.2(Delta) +/- 1.6(Delta)). Of the 5, 3 needed contralateral inferior rectus surgery, and 1 required prism for downgaze. The mean follow-up was 4.1 +/- 2.4 years (range, 0.5-10). At the final visit, none had oscillopsia or uncontrolled diplopia, but 3 (21%) needed prisms.

Superior oblique tenectomy and inferior oblique myectomy effectively eliminate oscillopsia associated with superior oblique myokymia but result in diplopia in downgaze in approximately 36% of patients, which may cause symptoms in patients who require a bifocal for near work.