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

Purpose To evaluate long-term outcomes of surgical treatment for 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 several times postoperatively. Successful collapse of AHP was defined as being ≤10°. Results Thirty-one patients had surgery for AHP in the pitch (chin up/down) position, whereas 119 had surgery for a horizontal AHP. In addition, 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 whereas 0% were undercorrected. Over- and undercorrection rates peaked at 2 years postoperatively. Ten years out, there were no overcorrections and 7% undercorrections. Four percent 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 postoperatively. Overcorrection presents early and resolves either over time or with additional surgery. Undercorrection develops later and can persist despite reoperation.