Typically, bilateral superior oblique palsies manifest with small vertical deviation in primary position, reversing in lateral gaze, with a positive headtilt test on both sides, a V pattern, and a chin-down head position. In primary position, excyclotropia often exceeds 10 degrees and markedly increases in inferior gaze.
Retrospective study of 21 patients with bilateral SO palsy who underwent operations including various surgical techniques such as SO tucking, inferior oblique recessions and inferior rectus weakering procedures (recession, posterior fixation). Preoperative symptoms of this group of patients was compared to those of 60 patients with unilateral SO palsy.
No significant difference was found between cases operated with complete SO tucking and cases operated with specific surgery on the anterior part of the tendon when pre- and postoperative excyclotropia was compared. Severe excyclotropia in primary gaze, markedly increasing in downgaze, was found to be statistically significantly associated with bilateral lesions (p = 0.001).
Bilateral SO palsy, even when highly asymetrical, can be surely diagnosed by carefully measuring excyclotorsion in both primary and downgaze by using dissociating devices. To avoid iatrogenic postoperative Brown syndrome it is recommended to adjust the amount of bilateral superior oblique tucking peroperatively, according to the degree of tendon extensibility. In cases of very severe excyclotorsion such a procedure can be completed by mild bilateral simultaneous inferior oblique recessions.