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

Purpose: To compare the outcome of inferior oblique disinsertion and myectomy in patients with unilateral congenital superior oblique palsy.

Methods: 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 ≤5^Δ in primary position and no hypotropia. In cases with preoperative hypertropia of ≤5^Δ, success was defined as improved hypertropia and resolution of abnormal head position (AHP).

Results: A total of 62 patients were included: 34 underwent myectomy; 28, disinsertion. Preoperative primary position hypertropia was 15.8^Δ ± 7.4^Δ in the myectomy group and 14.5^Δ ± 7.3^Δ 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 ± 6.7 months and 6.9 ± 3.0 months in the disinsertion group (P = 0.637). Correction of hypertropia in primary position was more pronounced in the myectomy group (14.3^Δ ± 7.4^Δ vs 10.0^Δ ± 5.4^Δ; 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 ≤15^Δ revealed nonsignificant differences between groups in rate of success (100% vs 81.3% [P = 0.226]) and correction of primary position hypertropia (8.8^Δ ± 3.2^Δ vs 7.6^Δ ± 4.0^Δ [P = 0.336]).

Conclusions: 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 ≤15^Δ. Both procedures effectively corrected AHP and demonstrated self-adjustment.