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


CONCLUSIONS
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.
Aring
Eva
E
Department of Ophthalmology, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden. eva.aring@vgregion.se
Ekström
Anne-Berit
AB
Tulinius
Mar
M
Sjöström
Anders
A
D000293:Adolescent; D001763:Blepharoptosis / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005133:Eye Movements; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009223:Myotonic Dystrophy / Q000235:genetics / Q000503:physiopathology*; D009759:Nystagmus, Pathologic / Q000503:physiopathology*; D009801:Oculomotor Muscles / Q000503:physiopathology*; D011698:Pursuit, Smooth; D012438:Saccades / Q000502:physiology; D013285:Strabismus / Q000503:physiopathology*; D019680:Trinucleotide Repeat Expansion / Q000235:genetics; D055815:Young Adult