Ocular motor function in relation to gross motor function in congenital and childhood myotonic dystrophy type 1

Authors

  • Eva Aring,

    1. Department of Ophthalmology, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
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  • Anne-Berit Ekström,

    1. Department of Paediatrics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
    2. Department of Paediatrics, Northern Älvsborg County Hospital, Trollhättan, Sweden
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  • Mar Tulinius,

    1. Department of Paediatrics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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  • Anders Sjöström

    1. Department of Ophthalmology, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
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Eva Aring
Department of Ophthalmology
The Queen Silvia Children’s Hospital
Sahlgrenska University Hospital/East
416 85 Gothenburg
Sweden
Tel: + 46 31 3434720
Fax: + 46 31 845113
Email: eva.aring@vgregion.se

Abstract.

Purpose:  To assess ocular motor function in congenital and childhood myotonic dystrophy type 1 (DM1) and correlate the results with cytosine-thymine-guanine (CTG) repeat size, severity of the disease, myotonia and skeletal muscle function.

Methods:  A cross-sectional investigation into strabismus, versions/ductions, saccades, smooth pursuit movements and ptosis was performed on 49 individuals with a confirmed diagnosis of DM1, all diagnosed at <18 years of age and with >40 CTG expansion repeats. The results were correlated with myotonia as well as Hammersmith motor ability scale (HMA). In addition, the ocular results were compared to results from an age and- sex-matched control group.

Results:  Ocular motor abnormalities were seen in 82%; the most frequent findings were altered conjugate eye movements and ‘pseudoptosis’ while blepharoptosis was rare. Strabismus was most common in the severe congenital subgroup, with a frequency 14 times higher than in the control group. Positive correlations were seen between CTG repeat size and affected eyelids, and between myotonia and affected eyelids; both these findings were most prominent in the mild congenital group. CTG repeat size was also correlated with version/duction defects, and most obviously in the childhood group. Low HMA scores were associated with high occurrence of strabismus and version/duction defects.

Conclusion:  Abnormalities of ocular motor function are frequently present. CTG repeat size correlates positively with altered versions/ductions and eyelid pathology. Gross motor dysfunction correlates with strabismus and defect versions/ductions, and eyelid pathology indicates involvement of myotonia.

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