Surgery for nystagmus related head turn: Kestenbaum procedure and artificial divergence

Abstract.

Purpose: An abnormal head posture adopted to reduce a nystagmus can be treated by Kestenbaum surgery or by creating an exodeviation which is compensated by convergence (artificial divergence). We evaluated the effects of Kestenbaum surgery and artificial divergence surgery in a retrospective study. Methods: Seventy-eight patients who received surgery for horizontal head turn (HT) due to nystagmus were included in the study. Exclusion criteria were previous extraocular muscle surgery, strabismus, lack of binocular vision, and cerebral disease. The millimetres of surgery and the findings before and 3 months after operation [HT, binocular visual acuity (VA), binocular vision (BV)] were evaluated. The patients were divided into three groups: the Kestenbaum group, the artificial divergence group, and the artificial divergence plus Kestenbaum group. Results: Of the 78 patients, aged 3–68 years, 52 had HT to the left side and 47 were male. In the Kestenbaum group (n=31), the median (10% and 90% quantile) HT was 30° (range 20–40°). A total of 28 mm (range 20–40 mm) surgery reduced the HT to 10° (0–30°). The efficacy of surgery was 1.4° HT reduction per millimetre surgery on one eye (range 0.4–2.5°). Four patients received further surgery. In the artificial divergence group (n=27), 10 mm (range 7–12 mm) surgery reduced the HT of 30° (range 25–40°) to 5° (range 0–20°). Seven patients received further surgery. In the artificial divergence plus Kestenbaum group (n=20), the HT was 30° (range 25–40°). A total of 29 mm (range 21–37 mm) surgery reduced the HT to 7° (range –5° to 15°). No further surgery was performed. Postoperatively, the maximum VA and BV was available without large HT, but an increase in the absolute VA and BV could not be proved. Conclusion: Artificial divergence is preferable or should be combined with Kestenbaum surgery, if possible. Kestenbaum surgery alone has an effect/dose ratio similar to recess-resect surgery for strabismus. Thus, to correct x° HT, 2/3x mm surgery on each eye is adequate.