Hummelsheim procedure combined with medial rectus recession in complete sixth nerve palsy and esotropic Duane Retraction Syndrome

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.

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.

Risk of torsion in superior rectus transposition surgery augmented with posterior scleral fixation sutures

It has been reported that superior rectus transposition combined with medial rectus recession can provide as good results as transposition of both vertical rectus muscles, with no adverse effects on torsion or postoperative vertical misalignment. Further augmentation of transposition surgery can be achieved through the use of posterior fixation sutures, myopexy and botulinum toxin into the medial rectus. We report a patient with complete bilateral traumatic sixth cranial nerve palsies who underwent sequential superior rectus transposition surgery combined with medial rectus recession. The surgery was augmented with a myopexy (posterior suture joining superior and lateral recti with no scleral fixation) in the first eye and with a posterior fixation suture (with scleral fixation) in the second eye. After the second procedure, despite a significant improvement in horizontal alignment, the patient developed 15 degrees of incyclotorsion which was attributed to the scleral fixation suture. The patient underwent removal of the scleral suture and 3 months postoperatively had a significant reduction in incyclotorsion to 8 degrees; however this continued to be a barrier to fusion. Vertical rectus transposition of superior and inferior recti augmented with posterior scleral fixation sutures is one type of conventional surgery for complete lateral rectus palsy. In more recent times, it has become common to transpose the superior rectus alone along with recession of the contracted medial rectus. This procedure can also be augmented with a posterior fixation suture which may or may not be attached to the sclera. Whilst this surgery has gained popularity it is not without risk as demonstrated by our case in which transposition of the superior rectus was associated with postoperative incyclotorsion. In this case a possible explanation may be the use of a the posterior scleral fixation suture as it did not occur when no scleral fixation was used. Furthermore, removal of the posterior scleral fixation suture did reduce the torsion significantly although it did not eliminate it.