Adjustable graded augmentation of superior rectus transposition for treatment of abducens nerve palsy and Duane syndrome

Impact of Adding Augmented Superior Rectus Transpositions to Medial Rectus Muscle Recessions When Treating Esotropic Moebius Syndrome

PURPOSE

To describe outcomes after treatment of Moebius syndrome (MBS) esotropia by adjustable bilateral medial rectus recession (BMR) with and without augmented superior rectus transposition (SRT).

DESIGN

Retrospective case series.

METHODS

Patients meeting 2014 diagnostic criteria for MBS and treated at Boston Children's Hospital between 2003 and 2019 were identified via billing records and chart review. Visual acuity, sensorimotor evaluations, strabismus procedures, and other clinical features were recorded. Surgical outcomes for patients treated with strabismus surgery (excluding those with prior surgery elsewhere) were evaluated. The primary outcome measure was postoperative alignment comparing treatment by adjustable BMR vs adjustable BMR+SRT.

RESULTS

A total of 20 patients had MBS, and 12 of these (60%) were male. Fifteen patients (75%) had primary position esotropia, and all had bilateral abduction deficit. Eight of 20 patients met inclusion criteria for primary strabismus surgery outcome. Five had undergone adjustable BMR ranging from 4.5 to 6.5 mm. Three had undergone adjustable BMR+SRT, all with 4-mm medial rectus muscle recessions. Mean preoperative esotropia before treatment by BMR was 39.5 PD (± 15 PD) with mean postoperative esotropia 9 PD (± 7.9 PD) at 6 months. Mean preoperative esotropia before treatment by BMR+SRT was 70.8 PD (± 5.9 PD) with mean postoperative esotropia 2.5 PD (± 3.5 PD) at 6 months. Significantly greater reduction in esotropia resulted from BMR+SRT than from BMR (P = .036).

CONCLUSIONS

BMR proved sufficient to treat esotropia <50 PD and BMR+SRT for greater esotropia in patients with MBS-associated abduction limitation.

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

Various surgical approaches have been described for the management of Duane retraction syndrome (DRS), a type of congenital cranial dysinnervation disorder (CCDD), the goals of which include correcting the primary position deviation and abnormal head posture (AHP), minimizing globe retraction and overshoots and improving the ocular rotations. Vertical rectus transposition (VRT) is one such technique, found more effective in improving abduction and thereby expanding the field of binocular vision, as compared to horizontal muscle surgery. VRT, however, is associated with the risk of inducing vertical deviations and also poses a risk for development of anterior segment ischemia. To overcome these concerns, transposition of only the superior rectus to the lateral rectus was proposed and evaluated to reveal improvement in alignment, AHP and motility comparable to VRT but with lesser surgical time and fewer post-operative complications. With promising results in the management of DRS, superior rectus transposition (SRT) has been extensively studied and has evolved over the last decade with several modifications to further increase the efficiency and reduce the risk of post-operative complications. This article focusses on the pre-operative considerations while planning SRT in DRS, various approaches and surgical techniques described, and the outcomes and complications of SRT in DRS. The role of SRT in the management of other CCDDs may be explored with further studies.

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

Purpose:

To review various types of extraocular muscle transposition procedures for management of strabismus in sixth cranial nerve palsy with little lateral rectus (LR) muscle function, along with their pros and cons.

Methods:

We performed a comprehensive review of transposition procedures in sixth cranial nerve palsy, based on literature published anytime up to March 2021. A thorough search through PubMed and Cochrane databases was performed. All types of clinical studies on different transposition procedures in LR palsy, were included.

Results:

Eighty-six original articles in English, with full text or abstracts available, were included in the review, among which 16 are prospective studies, 48 retrospective, 3 review articles, 1 randomized clinical trial, 17 case reports, and 1 letter. Vertical rectus transposition has demonstrated promising results, especially in abduction improvement and expansion of binocular diplopia-free visual field, albeit the possible adverse effects such as anterior segment ischemia, especially in the presence of medial rectus contracture, and induced vertical deviation may become troublesome. Partial muscle transposition, single muscle transposition, and also transposition without tenotomy have all been introduced to reduce the risk of multiple muscle manipulation and ischemia. On the other hand, different adjustable transpositions are being utilized to manage concomitant or induced vertical deviations.

Conclusion:

Transposition procedures are highly effective in the treatment of esotropia caused by complete LR palsy. Various techniques for vertical muscle transposition have been proposed, with each of them having certain advantages and disadvantages.

Vertical Tropia Following Horizontal Transposition Surgery

Aim

The aim of this study was to determine the prevalence of vertical tropia following horizontal transposition of both vertical rectus muscles (HToVR) in patients with Duane syndrome or sixth nerve palsy.

Methods

This retrospective study included patients with Duane syndrome or sixth nerve palsy who had undergone HToVR muscles. Data collected included: age, gender, diagnosis, laterality, pre-operative angle of deviation, type of surgery and post-operative angle of deviation at one week, three months and six months. Information on the use of botulinum toxin (BT) ipsilateral medial rectus (MR), additional surgery was performed, and the presence of preoperative and postoperative binocular function and any vertical deviation was collected.

Results

There were 11 patients, eight patients with a diagnosis of Duane syndrome and three patients with a diagnosis of sixth nerve palsy. The mean age of the patients was 13 ± 14.79 years (range 5-55 years), four were female. The prevalence of post-operative vertical tropia was 54%. The mean vertical deviation for distance, was 7.6^ ± 2.94 (SD) (range 3^-9^). Stereoacuity was present preoperatively in 5 patients and 8 postoperatively. No patient developed diplopia or received further surgery for the vertical tropia. Of the six patients who had intraoperative BT at the time of the HToVR, four developed a vertical deviation.

Conclusion

The prevalence of vertical deviation following HToVR muscles was 54% in our series. None of the patients with an induced postoperative vertical deviation reported diplopia or required further surgery for it.