Medial rectus disinsertion for management of chronic complete sixth nerve palsy

Purpose To report the outcomes of the medial rectus (MR) disinsertion procedure for the management of refractory esotropia (ET) with or without Abnormal head posture (AHP) in chronic complete sixth nerve palsy. Methods This is a retrospective case series of patients with sixth nerve palsy who suffered from residual ET and diplopia following the conventional strabismus surgeries and underwent MR disinsertion procedure between April 2017 and February 2020. This procedure was offered to the patients who declined to use prism and did not wish to perform surgery on the fellow eye. The demographic and clinical data, including sex, age, visual acuity, pre and postoperative angle of strabismus, duction limitations, results of forced duction and force generation tests, details of prior strabismus surgeries, orbital CT scan findings, and follow up duration were collected from the medical records. Results Six patients were enrolled in this study. Mean age was 35.0 ± 14.0 years, and mean follow-up was 15.3 ± 5.9 months. The ET at the Primary position (PP) was 35.0 ± 18.4 prism dioptre (PD) before MR disinsertion, which decreased to 14.2 ± 17.4 PD after MR disinsertion procedure. Four cases needed additional complementary surgeries to improve residual ET in PP. No case developed overcorrection. Abduction deficiency was −5.0 ± 1.3 before MR disinsertion, which improved to − 2.8 ± 0.5 units at last follow-up. The mean of induced adduction deficiency was − 2.9 ± 0.4 at last follow-up. Conclusions MR disinsertion can be considered in patients with chronic complete sixth nerve palsy and refractory diplopia when the conventional methods have failed.

Outcomes of half-width vertical rectus transposition augmented with posterior fixation sutures for sixth cranial nerve palsy

AIM: To describe the experience with half-width vertical muscles transposition (VRT) augmented with posterior fixation sutures. METHODS: The clinical charts of all patients, who underwent half-width VRT augmented with posterior fixation sutures for sixth cranial nerve palsy from January 2003 to December 2018, were retrospectively reviewed. For each patient, pre- and post-operatively, the largest measured angle was used for the calculations, usually resulting with the angle for distance, except in young infants, where measurements were made at near fixation using the Krimsky test. RESULTS: Fifteen patients met the inclusion criteria for the study, of them 9 (60.0%) had also medial rectus muscle recession at the time of surgery. Mean follow-up period was 21.4±23.2mo (range 1.5-82mo). Preoperative mean esotropia was 51.3±19.7 prism diopter (PD; range 20-90 PD). Postoperative mean deviation on final follow-up was 7.7±20.2 PD (range -40 to 35 PD; P=0.018). In all patients with preoperative abnormal head position, improvement was noted. Ten (66.7%) patients had improvement in abduction and 10 (66.7%) patients reported improvement in their diplopia, by final follow-up. The addition of medial rectus recession was correlated with a larger change in postoperative horizontal deviation compared to baseline (P=0.026). Two (13.3%) patients developed a vertical deviation in the immediate postoperative period which had resolved in one of them. CONCLUSION: Half-width VRT augmented with posterior fixation suture, with or without medial rectus muscle recession, is an effective and safe procedure for esotropia associated with sixth cranial nerve palsy. A major improvement in the angle of deviation is expected. Most patients will have improvement in their abnormal head position and diplopia.