Torsion as a contributing cause of the anti-elevation syndrome

Background: The anti-elevation syndrome is an adverse outcome of anterior t ransposition of the inferior oblique muscle. The presumed cause is an exces sive anti-elevating force vector that occurs with attempted elevation in ab duction. This causes apparent overaction of the contralateral inferior obli que muscle due to fixation duress. It has been suggested that excessive res idual extorsion may help explain this phenomenon. Methods: Fundus photograp hs to assess torsion were evaluated by masked observers in 18 patients who had undergone anterior transposition of the inferior oblique muscle. Eight of the patients were found to have the anti-elevation syndrome and 10 were not. Results: Patients with the anti-elevation syndrome had more extorsion (mean, 16.6 degrees +/- 3.4 degrees) than the patients who did not have the anti-elevation syndrome (mean, 8.8 degrees +/- 2.3 degrees). This differen ce was significant (P<.0001). In addition, 2 patients who initially did not show the anti-elevation syndrome were found to have an increase in their f undus extorsion after they subsequently developed the anti-elevation syndro me. Two patients who had the anti-elevation syndrome showed a marked decrea se in fundus extorsion after the anti-elevation syndrome was surgically eli minated by converting the anterior transposition to a simple recession. Con clusion: The presence of substantial extorsion may contribute to the cause of the anti-elevation syndrome after inferior oblique muscle anterior trans position. Lateral pla cement of the posterior (lateral) corner of the infer ior oblique muscle at the time of surgery may cause substantial extorsion a fter surgery.