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

BACKGROUND Unilateral and bilateral anterior transpositions of the inferior oblique muscle (ATIOs) for primary inferior oblique (IO) muscle overaction may produce apparent new or recurrent overaction of the contralateral IO muscle. This effect has been termed "antielevating" and can produce overaction of the contralateral elevators in adduction that mimics recurrent or new overaction of the IO muscle of the other eye. This phenomenon may be termed the antielevation syndrome (AES). Kushner has hypothesized that this complication of the ATIO is produced primarily by the posterior fibers 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 displacement (spreading) of the IO muscle reattachment site. METHODS There was a combination of 123 patients who received ATIO from Mims and 77 patients who received ATIO from Kushner. ATIO was performed according to a previously published technique. RESULTS All 16 patients (14 from Mims and 2 from 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 muscle, the incidence of AES was significantly larger with more spreading out of the new IO muscle insertion. CONCLUSIONS AES may be prevented by attaching 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 muscle myectomy in many cases.