Torsion as a contributing cause of the anti-elevation syndrome

The anti-elevation syndrome is an adverse outcome of anterior transposition of the inferior oblique muscle. The presumed cause is an excessive anti-elevating force vector that occurs with attempted elevation in abduction. This causes apparent overaction of the contralateral inferior oblique muscle due to fixation duress. It has been suggested that excessive residual extorsion may help explain this phenomenon.

Fundus photographs 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.

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 difference 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 fundus extorsion after they subsequently developed the anti-elevation syndrome. Two patients who had the anti-elevation syndrome showed a marked decrease in fundus extorsion after the anti-elevation syndrome was surgically eliminated by converting the anterior transposition to a simple recession.

The presence of substantial extorsion may contribute to the cause of the anti-elevation syndrome after inferior oblique muscle anterior transposition. Lateral placement of the posterior (lateral) corner of the inferior oblique muscle at the time of surgery may cause substantial extorsion after surgery.