Botulinum toxin injection with and without electromyographic assistance for treatment of abducens nerve palsy: A pilot study

To compare the effects and complications of botulinum toxin injection into the medial rectus muscle with and without electromyographic (EMG) assistance for treatment of abducens nerve palsy.In a prospective, comparative, interventional case series, botulinum toxin was injected into the medial rectus muscle of 23 patients with esotropia secondary to abducens nerve palsy within 3 months of onset. Patients were randomly assigned to two groups. The injection was given with EMG assistance in the first (EMG group) and without EMG in the second group (no-EMG group). Success was defined as a distance esotropia of no more than 10(Delta) in the primary position. Angle of deviation was recorded preoperatively and at 1 week, 3 months, and 6 months; any postoperative complications and side effects were noted.There were 11 patients in the EMG and 12 patients in the no-EMG group. The ocular deviations were significantly improved in both groups with an overall 6 month success rate of 52.2% (p = 0.008 in the EMG group, p = 0.006 in the no-EMG group). Success rates and mean changes of the angle of deviation were not statistically different between the two groups. Postinjection blepharoptosis was found to be significantly more in the EMG group (p = 0.009).The effectiveness of botulinum toxin injection is the same with or without EMG assistance into the medial rectus muscle for treatment of abducens nerve palsy. EMG assistance is associated with more blepharoptosis.