Inferior oblique overaction in trochlear nerve palsy: anterior transposition versus myectomy.

Purpose: To compare the effectiveness of inferior oblique myectomy and anterior transposition for correction of hypertropia in trochlear nerve palsy.

Methods: This retrospective study compares the surgical outcome of 40 patients with hypertropia secondary to trochlear nerve palsy who underwent either a unilateral myectomy or anterior transposition of the inferior oblique muscle. The primary outcome measure was the change in vertical deviation in primary gaze.

Results: A total of 40 patients with a mean age of 41 years were included. There was no statistically significant difference between groups (near preoperative hypertropia, P = 0.134 [Mann-Whitney test]). Of these, 19 underwent anterior transpositions and 21 myectomies. Both surgical techniques were successful at reducing levels of vertical deviation (anterior transposition, 89%; myectomy, 76%). However, the relative percentage reduction showed a statistically significant difference in postoperative outcomes, with anteriorization being more effective (anteriorization, 82%; myectomy 48%; P = 0.003).

Conclusions: In this study cohort, anterior transposition was more effective than myectomy at correcting vertical deviation in patients with inferior oblique overaction secondary to trochlear nerve palsy.