Antielevation syndrome after bilateral anterior transposition of the inferior oblique muscles: Incidence and prevention

Background: Unilateral(1) and bilateral(2) anterior transpositions of the i nferior oblique muscle (ATIOs) for primary inferior oblique (IO) muscle ove raction may produce apparent new or recurrent overaction of the contralater al IO muscle. This effect has been termed "antielevating" and can produce o veraction of the contralateral elevators in adduction that mimics recurrent or new overaction of the IO muscle of the other eye. This phenomenon may b e termed the antielevation syndrome (AES), Kushner(2) has hypothesized that this complication of the ATIO is produced primarily by the posterior fiber s of the IO muscle. The purpose of this study is to correlate the frequency of this syndrome in a large series of patients with the mm of lateral disp lacement (spreading) of the 10 muscle reattachment site. Methods: There was a combination of 123 patients who received ATIO from Mims and 77 patients who received ATIO from Kushner.(2) ATIO was performed according to a previo usly published technique.(3) Results: All 16 patients (14 from Mims and 2 f rom Kushner) with AES had received bilateral anterior transposition of the posterior fibers of the IO muscle to at least 2 mm anterior to the lateral end of the inferior rectus (IR) muscle with spreading laterally 3 to 5 mm, Among children who had the posterior fibers of their IO muscles placed 2 to 4 mm anterior to a line drawn laterally from the insertion of the IR muscl e, the incidence of AES was significantly larger with more spreading out of the new IO muscle insertion. Conclusions: AES may be prevented by attachin g the posterior fibers of the IO muscle no more than 2 mm lateral to the IR muscle insertion site. This complication responds to bilateral nasal IO mu scle myectomy in many cases.