Botulinum Toxin Injection of the Inferior Oblique Muscle for the Treatment of Superior Oblique Muscle Palsy

PurposeTo evaluate botulinum toxin injection of the inferior oblique muscle for management of superior oblique (SO) paresis.MethodsWe 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.ResultsWe 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 6.4Δ to 1.9Δ at 6 months after treatment. Other clinical measures improved: mean IO overaction from + 1.7 to + 0.6, mean SO underaction from –1.5 to –0.4, mean subjective torsion from 9.3° to 0.4°, and mean head tilt from 8.4° to 1.1°.ConclusionsBotulinum toxin injection to IO muscle reduces the symptoms of SO paresis while patients are waiting for recovery.