Management of Duane retraction syndrome: A simplified approach

Two novel CHN1 variants identified in Duane retraction syndrome pedigrees disrupt development of ocular motor nerves in zebrafish

Duane retraction syndrome (DRS) is a rare congenital eye movement disorder causing by the dysplasia of abducens nerve, and has highly variable phenotype. MRI can reveal the endophenotype of DRS. Most DRS cases are sporadical and isolated, while some are familial or accompanied by other ocular disorders and systemic congenital abnormalities. CHN1 was the most common causative gene for familial DRS. Until now, 13 missense variants of CHN1 have been reported. In this study, we enrolled two unrelated pedigrees with DRS. Detailed clinical examinations, MRI, and the whole exome sequencing (WES) were performed to reveal their clinical and genetic characteristics. Patients from pedigree-1 presented with isolated DRS, and a novel heterozygous variant c.650 A > G, p. His217Arg was identified in CHN1 gene. Patients from pedigree-2 presented with classic DRS and abnormalities in auricle morphology, and the pedigree segregated another novel heterozygous CHN1 variant c.637 T > C, p. Phe213Leu. A variety of bioinformatics software predicted that the two variants had deleterious or disease-causing effects. After injecting of two mutant CHN1 mRNAs into zebrafish embryos, the dysplasia of ocular motor nerves (OMN) was observed. Our present findings expanded the phenotypic and genotypic spectrum of CHN1 related DRS, as well as provided new insights into the role of CHN1 in OMN development. Genetic testing is strongly recommended for patients with a DRS family history or accompanying systemic congenital abnormalities.

Duane syndrome: An overview on the current management

Duane syndrome is one of the most common restrictive congenital strabismus characterized by variable horizontal duction deficits with globe retraction and shoots on attempted adduction and narrowing of the palpebral aperture. It is now listed as a congenital cranial dysinnervation disorder. The disease is usually unilateral with female preponderance. Basic etiopathogenesis involves dysinnervation of the lateral rectus (LR) due to aplastic/hypoplastic abducens nucleus with a secondary aberrant supply to the LR by the medial rectus (MR) subnucleus of the oculomotor nerve. Diagnosis of the disease is usually clinical. Due to the variable presentation of the disease, surgical management is a challenge and has to be individualized to achieve alignment in the primary gaze, reduction in globe retraction, upshoots and downshoots, and correction of any abnormal head posture. Differential recessions of the lateral and MR muscles are done to correct esotropia or exotropia in the primary gaze. For globe retraction and shoots, Y-split or periosteal fixation of the LR muscles is done depending on the severity.

Bilateral Lateral Rectus Recession in Duane Retraction Syndrome Type II: A Case Report

A two year presented to the clinic with abnormal head posture and right-sided face turn since birth. On examination, he showed a large right face turn of 40° while concentrating on a near target. His ocular motility assessment showed a -4 limitation of adduction in the left eye with 40 prism diopters (PD) exotropia and grade 1 globe retraction of the left eye. He was diagnosed with type II Duane retraction syndrome (DRS) in the left eye and planned for lateral rectus recession of both eyes. Postoperatively, the patient was orthotropic at distance and near in primary gaze with resolved face turn and improvement of limitation of adduction to -2, but some limitation of abduction -1 in the left eye was observed. Herein, we discuss the clinical features, etiologies, tailored evaluation, and management for type II DRS patient.

Advances in the genetics of congenital ptosis

Congenital ptosis, a birth defects presents at birth or by 1 year of age, is characterized by the drooping of the upper eyelid. either in isolation (non-syndromic) or with many different systemic disorders (syndromic). The estimated prevalence of ptosis (congenital & acquired) ranges from 0.79 to 1.99 per 10,000 people in different populations, and it is more prevalent in males. The underlying pathogenesis of congenital ptosis are myogenic and neurogenic, related to the development of muscles and nerves. Although most cases are sporadic, there are familial transmission characteristics, including autosomal dominant, recessive mode and X-linkage inheritance patterns. Moreover, some forms are due to chromosomal aberrations and mutations and deletions in mitochondrial DNA. Genes involved in simple congenital ptosis are ZFHX4 and COL25A1. The clinical aspects of various syndromes involving congenital ptosis are partly caused by single gene mutations. However, the pathogenesis of congenital ptosis is not fully understood. We review the reported epidemiology, genetics and clinical features of congenital ptosis and associated syndromes here.

Solitary median maxillary central incisor with congenital strabismus and autoimmune thyroiditis in a young child

Single median maxillary central incisor (SMMCI) syndrome is rare. It is commonly associated with other midline defects. About 50% of children with SMMCI have short stature, associated with isolated growth hormone deficiency or panhypopituitarism.A 6-year-old girl presented to us with worsening convergent squint, slowing linear growth and a suspected pituitary macroadenoma on neuroimaging. The key findings on examination included a disproportionate short stature, SMMCI, congenital abduction defect and pseudohypertrophy of calf muscles with myopathy. The evaluation showed autoimmune thyroiditis with pituitary hyperplasia. Bone age corresponded to 3 years.Three months after initiation of thyroxine, her myopathy resolved, and the hormone profile and neuroimaging were normal. Autoimmune thyroiditis in association with SMMCI is not reported previously. This case study emphasises the importance of growth monitoring and the exclusion of common treatable conditions.

Efficacy and complications of transposition surgery in Duane esotropia syndrome

OBJECTIVE

To study the long-term efficacy and the complications of several transposition techniques for the treatment of Duane syndrome. These included, full vertical rectus transposition, partial vertical rectus transposition, transposition without muscle disinsertion, and superior rectus transposition.

MATERIAL AND METHODS

A retrospective study of the patients diagnosed with Duane syndrome, and who underwent any of the different transposition techniques associated or not to the medial rectus recession with a follow-up longer than 12 months. A good result was considered a final deviation≤10 prism dioptres (pd) in primary position, anomalous head posture<10°, and an improvement of the abduction without diplopia.

RESULTS

Seven cases were included (6 women, 6 unilateral), and a mean age of 37.71 years. Pre-operative central gaze esotropia of 28±11.68pd decreased to 6±4.62pd at the final visit (P=.009). The anomalous head posture decreased in 6 patients, and the abduction improved one degree from -3.14 to -2.14 (mean). An induced vertical deviation≤8pd was observed in 4 cases. None experienced diplopia at the final visit. The percentage of reoperations was 71.42%. Only 28.57% had a favourable outcome with a single surgery, which increased to 71.42% with further surgeries at the final follow-up. Mean evolution time was 52±31.65 months.

CONCLUSIONS

Vertical rectus transpositions in Duane syndrome with moderate or severe clinical signs have only been effective in a small percentage of the cases. Most of them required further surgeries to resolve the complications or the under-corrections.

Unilateral medial rectus muscle recession combined lateral rectus muscle marginal myotomy for the treatment of Duane's retraction syndrome: A promising surgical procedure

Background:

Duane's retraction syndrome is a congenital eye movement anomaly with narrowing of the palpebral fissure and globe retraction on attempted adduction. There are several surgical approaches to treat the narrowing of the palpebral fissure. The purpose of the present study was to evaluate the efficacy of unilateral medial rectus recession (MRR) muscle combined lateral rectus (LR) muscle marginal myotomy (MM) with unilateral MRR alone in the management of narrowing of the palpebral fissure of patients with Type 1 Duane's retraction syndrome (DRS).

Materials and Methods:

Twenty-eight patients with unilateral DRS Type 1 were randomly divided into two groups (14 eyes of 14 patients in each group). Age ≥5 years with DRS Type 1 with <20 prism diopters in primary position who were candidates for surgery were consecutively enrolled in this randomized controlled trial. Patients were divided into treatment groups to receive unilateral MR recession with simultaneous MM group or with unilateral MR recession alone. The amount of deviation in primary position, abnormal head position, palpebral fissure width (PFW), and up/down shoot was evaluated before and 3 months after the surgery. This study was registered at the Iranian Registry of Clinical Trials under the registration code IRCT20131229015975N3.

Results:

PFW increased within MRR/MM group at the end of the study (8.86 ± 1.51) compared with the baseline (7.79 ± 1.48) (P < 0.001). In contrast, in the MRR/MM group, PFW did not increase statistically significantly within the MRR group at the end of the study (8.14 ± 1.35) compared with the baseline (8.07 ± 1.38) (P = 0.67). Mean ± standard deviation of PFW (mm) in MRR/MM group after surgery (8.86 ± 1.51) was statistically significantly higher than that in the MRR group (8.14 ± 1.35), (P = 0.002).

Conclusion:

The results of our study demonstrate PFW significantly increased after unilateral MRR muscle combined LR muscle MM.

Treatment modalities in Duane's Retraction Syndrome

AIM

To study the different treatment modalities needed in cases of Duane's Retraction Syndrome (DRS).

METHODS

This prospective study undergone in more than four years, in Alexandria, included 238 patients of DRS, including type I, 162 patients (68%), type II 12 patients (5%) and type III 64 patients (27%). Surgery was indicated in 98 (41%) of them, to eliminate abnormal head posture, deviation of the eye in primary position, severe retraction of the globe or cosmetically unacceptable upshoot with attempted adduction.

RESULTS

Type I was the most common and type II was the least. Females were predominant in this study, constituting 125 patients (52.5%), and males 113 patients (47.5%). Left eye was more affected, in 110 patients (46.2%), right eye in 91 patients (38.2%) and bilateral in 37 patients (15.6%). Amblyopia was found in 27 patients (11.3%) and treated in 13 patients under 10 years of age, by patching the normal eye. Ninety-eight patients (41%) were operated, the results were most satisfactory and a nomogram is followed in the surgical plan.

CONCLUSION

The surgical management is needed in less than half of the cases and should be planned for every case individually according to the clinical findings, planned nomogram and modified intraoperatively according to the anatomical findings during surgery.

Reoperation in esotropic Duane retraction syndrome: Long-term motor outcome of superior rectus transposition

AIM

The aim was to evaluate the long-term motor outcome of superior rectus transposition procedure in patients affected by unilateral esotropic Duane retraction syndrome with residual esotropia and anomalous head position.

METHODS

A retrospective analysis of medical records of patients affected by esotropic Duane retraction syndrome who underwent superior rectus transposition procedure as reoperation for residual esotropia and/or residual anomalous head position. Amount of deviation, anomalous head position, duction limitation, globe retraction, presence of upshoot/downshoot, and vertical deviation were analyzed before and after superior rectus transposition procedure.

RESULTS

Twenty patients were selected. All patients underwent unilateral medial rectus recession or bilateral medial rectus recession, for unilateral esotropic Duane retraction syndrome at least 2 years before superior rectus transposition reoperation. Mean age at surgery (superior rectus transposition) was 12 ± 6.8 years, and the follow-up period was 2.7 ± 0.6. Mean deviations at distance and near before surgery were 19.5 ± 5.7 and 15.2 ± 6.8, respectively. Two patients showed upshoot. Head turn was 11.4 ± 5.1°; abduction limitation was -2.6 ± 0.9. After superior rectus transposition, all patients showed an improvement of esotropia at distance and near (8.1 ± 5.7 and 5.1 ± 5.6, respectively; p < 0.05), anomalous head position (5.6 ± 3.9°; p < 0.05), and abduction limitation (-2.3 ± 0.8; p < 0.05). No statistically significant changes occurred in globe retraction. No adduction limitation, vertical deviation, and upshoot/downshoot were present after superior rectus transposition procedure. Results were stable during follow-up.

CONCLUSION

Superior rectus transposition procedure is an effective procedure in esotropic Duane retraction syndrome patients who previously undergone unilateral/bilateral medial rectus recession, with residual esotropia and anomalous head position. It allows improvement of esotropia, head turn, and partial recovery of abduction in a significant percentage of patients (30%) with no vertical complications.