Superior oblique myokymia: efficacy of medical treatment

Superior oblique myokymia (SOM) is an uncommon disorder characterized by episodic monocular oscillopsia. Several medications have been reported to be of benefit for some patients with this condition, but the efficacy of medical treatment has not been well established and little long-term follow-up data are available. The purpose of this study was to better clarify the role of medical therapy in the management of SOM.

A retrospective review of patients with this disorder seen in an outpatient neuro-ophthalmology clinic. The diagnosis of SOM was based on a history of episodic unilateral oscillopsia with or without torsional diplopia. Twenty-seven patients with SOM were identified. Twenty of these were treated medically and these formed the basis of the study. Follow-up interval ranged from 1 to 12.5 years (mean, 6.5 years). The main outcome measure was relief of oscillopsia.

Fifteen of the 18 patients treated with carbamazepine (83%) reported some benefit, 6 of whom continue to do well on medication 9 months to 5 years later. In four patients improvement was only transient and in five others treatment was subsequently discontinued for various reasons. In addition, one patient had sustained benefit from phenytoin, one from propranolol, and one from propranolol plus valproic acid. We found no treatment success with baclofen. Overall, nine patients (45%) enjoy sustained benefit unassociated with adverse side effects.

In contrast to previous reports emphasizing the efficacy of surgery for SOM, our data demonstrate the potential benefits of medical treatment for patients with this disorder.