Augmented superior rectus muscle transposition in management of defective ocular abduction

Abstract

Background Superior rectus muscle transposition (SRT) is one of the proposed transposition techniques in the management of defective ocular abduction secondary to chronic sixth nerve palsy and esotropic Duane retraction syndrome (Eso-DRS). The aim of the current study is to report the outcomes of augmented SRT in treatment of Eso-DRS and chronic sixth nerve palsy. Methods a retrospective review of medical records of patients with Eso-DRS and complete chronic sixth nerve palsy who were treated by augmented full tendon SRT combined with medial rectus recession (MRc) when intraoperative forced duction test yielded a significant contracture. Effect on primary position esotropia (ET), abnormal head posture (AHP), limitation of ocular ductions as well as complications were reported and analyzed. Results a total of 21 patients were identified: 10 patients with 6th nerve palsy and 11 patients with Eso-DRS. In both groups, SRT was combined with ipsilateral MRc in 18 cases. ET, AHP and limited abduction were improved by means of 33.8PD, 26.5°, and 2.6 units in 6th nerve palsy group and by 31.1PD, 28.6°, and 2 units in Eso-DRS group respectively. Surgical success which was defined as within 10 PD of horizontal orthotropia and within 4 PD of vertical orthotropia was achieved in 15 cases (71.4%). Significant induced hypertropia of more than 4 PD was reported in 3 patients (30%) and in 2 patients (18%) in both groups, respectively. Conclusion augmented SRT with or without MRc is an effective tool for management of ET, AHP and limited abduction secondary to sixth nerve palsy and Eso-DRS. However, this form of augmented superior rectus muscle transposition could result in high rates of induced vertical deviation.

A Review of Transposition Techniques for Treatment of Complete Abducens Nerve Palsy

“…Theoretically, single muscle transposition may induce a significant vertical or torsional diplopia. SRT procedure with or without augmentation sutures has induced vertical deviation, in 7%–28% of cases, 12 27 61 64 66 67 68 69 which is comparable to VRT. Although transposition may reduce SR vertical force, it might not change the muscle force vector (nearly 23° into abduction).…”

Superior Rectus Transposition in the Management of Duane Retraction Syndrome: Current Insights

“…Lateral transposition of the superior rectus muscle would also be expected to intort the eye, raising concern over induced torsional diplopia. While studies analysing torsion 22 , 41 , 43 , 45 using double Maddox rod or by direct fundus observation, before and after SRT have reported post-operative intorsion, clinically significant torsional diplopia was nearly absent in these studies. This can be possibly explained by the patient’s fusion capacity (<8 PD) or by modelling of the orbital forces to prevent diplopia.…”

“…In addition, in these studies, MR recession was limited to less than 5–5.5 mm to prevent an adduction deficit. 32 , 41 …”

“…Both hypertropia 28 , 44 , 45 and hypotropia 8 , 17 , 41 have been observed following SRT, although there is a greater tendency for the development of hypodeviation. Escuder et al 43 observed that the onset of vertical diplopia was generally within the first few days or weeks after the surgery and did not develop beyond 3 months.…”

“…Vertical misalignment in the affected lateral gaze has also been reported following SRT. 8 , 40 , 41 Mehendale et al noted clinically insignificant hypotropia in attempted abduction in several cases after surgery. However, as explained by Rhiu et al, 48 this finding was present pre-operatively in all of them.…”