Type 4 Duane syndrome

Acquired Synergistic Divergence: Contrary to Current Literature

Current literature reports synergistic divergence as a rare, congenital ocular motility pattern associated with adduction palsy. Its mechanism has been likened to Duane's syndrome, and some suggest it be referred to as Duane's Type 4 (Gupta et al. 2010; Schliesser et al. 2016; Wilcox et al. 1981; Khan et al. 2016). There are no published reports of synergistic divergence as an acquired condition, making this case report seemingly the first of its kind. This case report describes an 18-year-old female who presented to clinic in 2013 with symptoms of diplopia and left eye turning outwards. Orthoptic assessment and MRI confirmed a third nerve palsy secondary to cavernous sinus schwannoma. Further monitoring showed progression of the cranial nerve palsy but a stable schwannoma and no aberrant regeneration noted in five years of follow up. The patient was treated with multiple botulinum toxin injections and had squint correction surgery in 2017. Seven months later, synergistic divergence was first noted and remained stable in all following assessments. While the aetiology of acquired synergistic divergence in this case is unclear, we can be confident it is unlikely to be of congenital origin as it was not noted until adulthood and after five years of investigations. This report will discuss possible aetiologies of acquired synergistic divergence and, contrary to current literature, suggest clinicians should consider the possibility that synergistic divergence can be acquired, though is likely to be even rarer than its congenital form.

Synergistic divergence: case series and literature review

Background

To present the data of a series of patients with synergistic divergence, to propose a different modality of surgical correction and to perform a literature review of such a rare entity.

Methods

A retrospective study was performed on all patients who presented with unilateral or bilateral synergistic divergence to the Ophthalmology Department, Cairo University, during the period from January 2007 to July 2016. The demographic data, the results of sensorimotor examination, the surgical procedures performed and the ophthalmological as well as the systemic findings of all patients were collected and tabulated. PubMed was searched for patients with features of synergistic divergence.

Results

Thirteen patients with features of synergistic divergence were identified. The mean age of the patients was 8.9±10.1 years (range 1–40 years). Only one case was orthotropic in the primary position. Lateral rectus orbital wall fixation combined with 8–10 mm medial rectus resection was done in 10 patients. The mean follow-up was 6.6±7.7 months. Exotropia was significantly reduced in all patients. All patients had complete disappearance of synergistic divergence after surgery. A total of 78 patients with features of synergistic divergence were identified from PubMed. Surgery was done for 37 patients. Synergistic divergence disappeared in patients who had lateral rectus extirpation or orbital wall fixation.

Conclusion

Synergistic divergence is a challenging rare condition. We propose that lateral rectus orbital wall fixation combined with medial rectus resection both improves the alignment in primary position and eliminates the synergistic divergence in such patients.

Surgical treatment of Duane retraction syndrome

Purpose

Surgical treatment in Duane retraction syndrome (DRS) can be very challenging even for the strabismus specialists because of a wide spectrum of diversity in clinical manifestations. The purpose of this article is to review these different surgical treatments.

Methods

A comprehensive search was performed using PubMed database with the different keywords of "Duane retraction syndrome" and "surgery". Articles were selected from original English papers published since 2000. The full text of the selected articles was reviewed, and some articles were added based upon the references of the initial articles. We also provided selected case examples about some of these procedures.

Results

125 articles were found in the initial search of which 37 articles were mostly related to the topic of this review. The number finally increased to 59 articles after considering the relative references of the initial articles. Different surgical methods performed on horizontal and vertical rectus muscles (recession, resection, transposition, Y splitting, periosteal fixation and posterior fixation suture) are reviewed. Careful selection of the surgical technique is important to achieve optimal results.

Conclusion

With accurate diagnosis of patients with DRS and proper surgical management, several adverse situations associated with this syndrome (amblyopia, abnormal head posture, upshoot, downshoot, and muscle underaction) can be prevented.