Botulinum toxin in the management of acquired abducens nerve palsy: Prospective Interventional controlled trial

Aim: The aim of this study is to assess the effectiveness of botulinum toxin in patients presenting with isolated lateral rectus palsy. Materials and Methods: This prospective interventional controlled trial from March 2012 to March 2015. Inclusion criteria were acquired lateral rectus palsy, no other neurological defects, normal magnetic resonance imaging scan, and age> 30 years. The cases were treated with 15–25 units of botulinum toxin depending on the angle of squint. The surgical field is prepared, the medial rectus insertion grasped firmly with forceps, and the eye rotated to the primary position. Botulinum toxin is injected 5 mm from the medial rectus insertion, inside the bulk of muscle through a 27-gauge needle (without electromyographic guide) under topical anesthesia. No peritomy is done. Controls were treated with intravenous steroids for 3 days changed to oral steroids on tapering doses. Cases and controls were followed up 10, 30, 60, 120, and 180 days after initiating treatment. Wilcoxon signed-rank test is used for paired samples; Mann–Whitney U-test is for independent samples; P< 0.05 was considered statistically significant. Results: Ten cases (six female) were enrolled into the study. Ten age-matched controls (six female) were also enrolled. The baseline characteristics of cases and controls were comparable in terms of duration of symptoms, head posture, primary deviation in the primary position, and limitation of abduction. After 10 days of injection, 100% of cases attained primary deviation <10 prism diopters and subsidence of diplopia in the primary position. Nearly 80% of cases showed partial recovery of abduction after 30 days. Controls attained primary deviation