Results of a prospective randomized trial of botulinum toxin therapy in acute unilateral sixth nerve palsy.

Forty-seven patients entered a prospective randomized trial to assess the effect of early botulinum neurotoxin A treatment to the ipsilateral antagonist medial rectus on the ultimate recovery rate of acute unilateral sixth nerve palsy. Twenty-two patients received injections and 25 acted as controls. The overall etiologies were microvascular (72.3%), unknown (17%), multiple sclerosis (6%), and one case each of central nervous system (CNS) sarcoidosis and basilar artery ectasia. Eighty-three percent of the patients entered the trial within 2 weeks of the onset of symptoms and 95.7% within 3 weeks. The controls had a final recovery rate of 20/25 (80%), and the injected group had a final recovery rate of 19/22 (86%). No serious side effects were encountered. We conclude that there is no evidence for a prophylactic effect of botulinum toxin in the group that we have studied.