Long-term outcomes following surgery for infantile nystagmus syndrome with abnormal head positioning.

Abstract Purpose To describe long-term results from surgical treatment of abnormal head positioning (AHP) associated with infantile nystagmus syndrome (INS). Design Retrospective observational case series. Methods Review of 150 patients who underwent surgery for AHP associated with nystagmus. Outcomes included head positioning, duction limitations, and strabismus, and were evaluated at multiple times postoperatively. Successful collapse of AHP was defined as being ≤10°. Results 31 patients had surgery for AHP in the pitch (chin up/down) position, whereas 119 had surgery for a horizontal AHP. 54 underwent 50-60% augmentation, 19 underwent 40% augmentation, 5 underwent less than 40% augmentation. Thirty-eight had surgical dose modified to correct strabismus, and 3 underwent surgery different from standard Kestenbaum procedures. Collapse of AHP At the 1-3 week follow up (n=131), 125 patients (95%) had collapse of AHP. The percentage trended down at the 2-5 month (91%, n=106) and 2-year follow-ups (83%, n=57). However, at 5 and 10 years it was 93% (n=42) and 93% (n=14) respectively due to reoperation in a small minority. Over and Undercorrection At 1-3 weeks, 5% of patients were overcorrected while 0% were undercorrected. Over and undercorrection rates peaked at 2 years postoperatively. Ten years out, there were no overcorrections and 7% undercorrections. 4% of patients required reoperation for overcorrection (mean 2.7 years) and 5% did for undercorrection (mean 3.9 years). Conclusion Surgery for the head positioning associated with INS produces excellent outcomes throughout 10 years post-operatively. Overcorrection presents early and resolves either over time or with additional surgery. Undercorrection develops later, and can persist despite reoperation.