Superior Oblique Posterior Tenectomy in Patients With Brown Syndrome with Small Deviations in the Primary Position

Abstract

Procedures used to weaken the superior oblique muscle (SO) tendon in the treatment of patients with Brown syndrome, may result in severe complications, including complete SO palsy, overcorrections, foreign body extrusion, and scarring with limitation to ocular rotations. SO posterior tenectomy moderately weakens abduction and depression while preserving most of the torsional action of the SO muscle. We sought to evaluate motor and sensorial results after SO posterior tenectomy in patients with Brown syndrome who had a small vertical deviation (less than 7 prism diopters [PD]) in primary position but severe limitation to elevation in adduction. We retrospectively analyzed 12 consecutive patients with unilateral Brown syndrome who underwent a 15 mm tenectomy of the posterior four-fifths fibers of the ipsilateral SO tendon. Intraoperative forced duction showed restriction to elevation in adduction in all subjects. No patient had concomitant surgery on any other extraocular muscle. The mean patient age at diagnosis was 6.9 +/- 1.7 years. Preoperative vertical deviation measured 4 +/- 1 PD in the primary position and 12 +/- 2 PD in elevation in adduction. Postoperative follow-up was 24.7 +/- 9.2 months. Postoperatively, all patients had less than 2 PD of orthotropia in the primary position, and the deviation in elevation in adduction was significantly improved at 3 +/- 2 PD (P < 0.05). Elevation in adduction improved from -4.0 preoperatively to -1.9 +/- 1 postoperatively (P = 0.0000003) and no patient experienced underaction of the SO. Postoperatively, all patients had stereopsis in primary position. The use of SO posterior tenectomy improves alignment and ocular rotations in patients with Brown syndrome, resulting in fusion, small vertical deviation in primary position, and minimal-to-no anomalous head posture, in whom the most important finding is a disfiguring downshoot on attempted adduction. Other advantages include minimal-to-no postoperative SO muscle underaction and no risk of foreign body extrusion, fibrosis, and scarring.