Botulinum toxin injection of the inferior oblique muscle for the treatment of superior oblique muscle palsy
PURPOSE To evaluate botulinum toxin injection of the inferior oblique muscle for management of superior oblique (SO) paresis. METHODS We undertook a prospective case series of injections of the ipsilateral inferior oblique (IO) muscle with 10-20 units of botulinum toxin type A in patients with a SO muscle palsy/paresis of less than 2 years' duration. RESULTS We enrolled 16 patients (18 eyes) with a mean age of 33.7 years. The median time from onset of symptoms until injection was 6 months. The cause of paresis was trauma for 81% of the patients. The mean hypertropia decreased from 6.4(Delta) to 1.9(Delta) at 6 months after treatment. Other clinical measures improved: mean 10 overaction from + 1.7 to + 0.6, mean SO underaction from -1.5 to -0.4, mean subjective torsion from 9.3 degrees to 0.4 degrees, and mean head tilt from 8.4 degrees to 1.1 degrees. CONCLUSIONS Botulinum toxin injection to 10 muscle reduces the symptoms of SO paresis while patients are waiting for recovery.