Evolution of the Augmented Sinskey Extirpation Procedure for Nystagmus
Abstract
Purpose: In 2002, Robert Sinskey first reported on anterior subtotal extirpation (ASE) of the horizontal recti for nystagmus. Although highly effective in reducing nystagmus fifty percent experienced exotropia. We report on an augmentation to reduce the risk of secondary surgery for exotropia. Methods: We report on 9 patients with early onset nystagmus. Three underwent the ASE alone: the four horizontal recti are cleaned of all intermuscular attachments until their exit from posterior tenon’s is clearly visualized. A snare excises the muscle at this junction and the anterior muscle is removed. Direct compression for 10 minutes by the clock. A secondary function of the oblique muscles is abduction contributed by the posterior fibers insertion posterior to the equator. Anterior placement of their insertion should negate any abduction tone. Six patients underwent the Augmented ASE (AASE): ASE and tenotomy and transposition of the inferior oblique to the temporal border of the inferior rectus, and, tenotomy and anterior transposition of the superior oblique to the nasal border of the superior rectus. Results: Two of three patients undergoing the ASE alone experienced exotropia in the immediate postoperative period requiring secondary surgery. In follow up of 1-20 months, none of the six patients operated with the AASE have required secondary surgery for exotropia. All experienced a reduction in nystagmus and an increase in binocular best corrected visual acuity from 1-8 lines. Underaction of the horizontal recti is noted from -1 to -4. Conclusion: In my opinion, augmentation of the ASE with anterior transposition of the oblique muscles effectively quiets the nystagmus and reduces the risk of secondary surgery for exotropia. There may be a critical amount of extirpation that optimally reduces nystagmus and preserves side gaze as lateroversion is preserved in some patients. Prospective studies to evaluate this relationship are in application.