Botulinum toxin in the management of internuclear ophthalmoplegia

Abstract

Internuclear ophthalmoplegia (INO) presents as a complex ocular motility problem due to medial longitudinal fasciculus damage. The symptoms are disabling and challenging to manage. We evaluate the efficacy of botulinum toxin in the management of INO. A retrospective review of 16 patients with INO managed by botulinum toxin A injection into one or more extraocular muscles over the past 20 years was performed. The age, sex, etiology, symptoms, angle of deviation, and binocular function pre- and postinjection were analyzed. The mean age at presentation was 45.1 years with a male/female ratio of 9:7. The most common etiologies included brainstem hemorrhage in five and multiple sclerosis in four. After injection diplopia reduced in 14 (87.5%), appearance improved in 9 (56.3%), and the head posture improved in 4 (25%). Convergence recovered in two patients (12.5%) and stereopsis improved in three patients (18.8%). Complications included transient ptosis in one patient, and one patient had an overcorrection. Two patients complained of transient vertical diplopia that resolved within 3 weeks. At final follow-up, five (31.5%) patients continued on maintenance injections, three (18.8%) were stable and discharged, while the rest were managed by occlusion (five), prisms (one), or surgery (two). We report on the management of INO by botulinum toxin. Benefit was noted in terms of reduced diplopia and occasionally improved binocular function. Though the benefits are limited by the need for repeated injections, for patients with this debilitating condition, botulinum toxin provides some symptomatic relief.