Strabismus surgery in Angelman syndrome: More than ocular alignment.

Paola Michieletto,Stefano Pensiero,Laura Diplotti,Manuela Giangreco,Luca Ronfani,Alberto Danieli,Paolo Bonanni,Ahmed Awadein

doi:10.1371/journal.pone.0242366

Paola Michieletto, Stefano Pensiero + Show 6 more

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https://doi.org/10.1371/journal.pone.0242366

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Abstract

PurposeTo report and evaluate strabismus surgery in children with Angelman syndrome, in order to optimize and standardize surgical approach. Other purposes are to understand the possible relation between ocular findings and motor ability, and between improvement in ocular alignment and changes in motor skills in this population.DesignObservational cross-sectional study.MethodsMedical records of pediatric patients with Angelman syndrome, who underwent strabismus surgery, were investigated. Collected data included: genotype, gender, age at the time of surgery, refractive error, pre-operative strabismus, surgical procedure, surgical outcome, gross and fine motor development assessment pre- and post-operatively.ResultsSeventeen subjects, aged 3–15 years, were investigated. Fourteen patients were exotropic, three esotropic. Most patients presented astigmatism. Considering the exaggerated response to standard amounts of surgery and the risk of consecutive strabismus on long term follow-up reported by previous studies in children with developmental delay, a reduction of the amount of strabismus surgery was applied. Post-operatively, all patients presented with a significative reduction of the baseline deviation angle, with all esotropic patients and 7 exotropic patients (59%) achieving orthotropia. The surgical outcomes were variable according to the type and the amount of baseline strabismus, but no case presented with exaggerated surgical response. At baseline, patients showed important delays in all motor abilities, and, post-operatively, presented a significant improvement in walking and fine motor tasks. Pre- and post-operative motor abilities were negatively correlated to astigmatism, anisometropia, and amount of deviation.ConclusionsAccording to our data, the standard nomograms for strabismus surgery may be successfully applied in subjects with Angelman syndrome and exotropia. Our data suggest that the reduction of the deviation angle improves motor skills in strabismic pediatric patients with Angelman syndrome.

Highlights

Angelman syndrome (AS) is a rare genetic neuro-behavioural disorder, affecting between 1/ 15.000 and 1/20.000 people worldwide, with variable expressivity and penetrance [1]
Considering the exaggerated response to standard amounts of surgery and the risk of consecutive strabismus on long term follow-up reported by previous studies in children with developmental delay, a reduction of the amount of strabismus surgery was applied
The standard nomograms for strabismus surgery may be successfully applied in subjects with Angelman syndrome and exotropia

Summary

Introduction

Angelman syndrome (AS) is a rare genetic neuro-behavioural disorder, affecting between 1/ 15.000 and 1/20.000 people worldwide, with variable expressivity and penetrance [1]. It is caused by various inactivating mutations of the UBE3A gene on the 15q11.2–13.3 chromosomal region [2,3,4], including: de novo interstitial deletions of maternally-inherited chromosome 15 (class I, 70–75%, often resulting in more severe phenotypes [5, 6]), paternal uniparental disomy of chromosome 15 (class II, 2–3%), paternal imprinting disorders in chromosome 15 (class III, 3–5%), point mutations in the maternally-inherited UBE3A gene (class IV, 5–10%), and currently unknown genetic mechanisms (class V, 10–15%) [1, 7]. Ophthalmic findings in AS include ametropia (typically astigmatism), strabismus (usually exotropia) and less frequently nystagmus, amblyopia, iris and choroidal hypopigmentation, optic nerve atrophy or optic disk pallor, retinochoroidal atrophy, ptosis and keratoconus [16]

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