Outcome of inferior oblique disinsertion versus myectomy in the surgical treatment of unilateral congenital superior oblique palsy

Abstract

To compare the outcome of inferior oblique disinsertion and myectomy in patients with unilateral congenital superior oblique palsy. In this prospective study, consecutive patients with superior oblique palsy underwent either myectomy or disinsertion of the inferior oblique muscle. Success was defined as postoperative hypertropia of ≤5Δ in primary position and no hypotropia. In cases with preoperative hypertropia of ≤5Δ, success was defined as improved hypertropia and resolution of abnormal head position (AHP). A total of 62 patients were included: 34 underwent myectomy; 28, disinsertion. Preoperative primary position hypertropia was 15.8Δ ± 7.4Δ in the myectomy group and 14.5Δ ± 7.3Δ in the disinsertion (P=0.756). AHP was present in 85.3% and 85.7% of patients, respectively (P=1). Mean follow-up was in the myectomy group 7.5±6.7months and 6.9±3.0months in the disinsertion group (P=0.637). Correction of hypertropia in primary position was more pronounced in the myectomy group (14.3Δ±7.4Δ vs 10.0Δ±5.4Δ; P=0.013). Success was achieved in 91.2% of myectomy and 60.7% of disinsertion patients (P=0.006). Persistence of AHP did not differ between groups (8.8% in the myectomy group vs 7.1% in the disinsertion group [P=1]). Comparison of patients with preoperative hypertropia of ≤15Δ revealed nonsignificant differences between groups in rate of success (100% vs 81.3% [P=0.226]) and correction of primary position hypertropia (8.8Δ±3.2Δ vs 7.6Δ±4.0Δ [P=0.336]). In our study cohort, inferior oblique myectomy had a greater effect in reduction of primary position hypertropia; however, disinsertion proved as effective as myectomy if preoperative vertical deviation was ≤15Δ. Both procedures effectively corrected AHP and demonstrated self-adjustment.