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Visual function in children with merosin-deficient and merosin-positive congenital muscular dystrophy
E Mercuri1, S Anker, J Philpot
1Department of Paediatrics, Royal Postgraduate Medical School, University College, London, United Kingdom.
Insights
Children with congenital muscular dystrophy (CMD) show normal clinical visual function, even with white matter changes. However, visual evoked potentials may be abnormal in merosin-deficient CMD, indicating potential neurophysiological changes.
Area of Science:
- Neurology
- Ophthalmology
- Genetics
Background:
- Congenital muscular dystrophy (CMD) is a group of inherited neuromuscular disorders.
- Visual impairments are sometimes associated with certain subtypes of CMD.
- The relationship between clinical visual function, merosin status, and neuroimaging in classical CMD requires further elucidation.
Purpose of the Study:
- To investigate visual function abnormalities in children diagnosed with classical congenital muscular dystrophy.
- To determine if visual function deficits correlate with merosin status or magnetic resonance imaging (MRI) findings.
- To compare clinical visual assessments with neurophysiological measures like visual evoked potentials (VEPs).
Main Methods:
- Twenty children (aged 5-17 years) with classical CMD underwent assessments of visual acuity, stereopsis, and visual fields.
- Merosin status and brain MRI findings were analyzed.
- Visual evoked potential (VEP) data were obtained for 14 participants.
Main Results:
- All 20 children exhibited normal clinical visual function across all tested parameters, irrespective of merosin status or MRI results.
- VEPs were normal in merosin-positive CMD but abnormal in merosin-deficient CMD.
- Despite white matter changes in the occipital lobes on MRI and abnormal VEPs, clinical visual function remained normal in merosin-deficient CMD.
Conclusions:
- Classical congenital muscular dystrophy does not present with clinical visual function abnormalities.
- Merosin deficiency in CMD may be associated with subclinical neurophysiological visual pathway changes, as indicated by VEPs.
- Further research is necessary to understand the nature of white matter changes and the discrepancy between clinical and neurophysiological findings in merosin-deficient CMD.
Abstract:
This study evaluates whether abnormalities of visual function are present in children with congenital muscular dystrophy and whether these, if present, are associated with merosin status or magnetic resonance imaging (MRI) findings. Twenty children (age range 5-17 years) with a diagnosis of classical congenital muscular dystrophy were assessed on visual acuity, stereopsis, and visual fields and the results compared with merosin status and MRI findings. Visual-evoked potential results were available for 14 of 20 children. All 20 children revealed normal results on all the clinical tests assessing visual function, irrespective of their merosin status or of MRI findings. Visual-evoked potentials were normal in the children with merosin-positive congenital muscular dystrophy but were abnormal in those with merosin deficiency. Unlike the other forms of congenital muscular dystrophy, which are associated with structural brain changes and eye involvement, visual function was always normal in the classical form of congenital muscular dystrophy. Interestingly, visual function was normal also in the group of children with merosin-deficient congenital muscular dystrophy who manifested white matter changes involving the occipital lobes on MRI and abnormal visual evoked potentials. Further studies are needed to specify the nature of the white matter changes observed with MRI and the reason for the dissociation between clinical and neurophysiologic findings.
