botulinum toxin injection into inferior oblique muscle for treatment of acquired superior oblique palsy

purpose: to evaluate the effect of botulinum toxin-a (bta) injection into the inferior oblique (io) muscle in releaving the symptoms of superior oblique (so) palsy. methods: the study was conducted on patients who were referred for acquired so palsy with less than 2 years of duration. about 10-20 unit of bta was injected into the belly of the inferior oblique muscle through the inferotemporal quadrant of the involved eye without opening the conjunctiva. results: eighteen eyes from 16 patients were injected. mean age was 33.7 years and mean duration of paresis was 6 months. trauma was the cause of paresis in 81.2%. six months after the injection, mean deviation decreased from 6.4 r to 1.9r; mean io over-activity decreased from +1.7 to +0.6; mean so upper-activity decreased from -1.5 to -0.4; mean subjective torsion decreased from 9.3º to 0.4º; and mean head tilt decreased from 8.4º to 1.1º. conclusion: botulinum toxin-a injection into the io muscle can decrease the symptoms of patients with so palsy and cause faster rehabilitation of these patients before stabilization of signs for final decision.