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 IO 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 IO muscle reduces the symptoms of SO paresis while patients are waiting for recovery.