Hypersomnolence secondaire à une dystrophie myotonique de type 1 sans myotonie clinique

We report the case of Ms D., 22 years old, with a severe hypersomnolence associated with chronic diarrhea, depression and polyalgia. Decreased mean sleep latency and REM sleep dysregulation were found in neurophysiological investigation. Myotonia was absent from clinical examination but was objectivated in electromyogram. We confirmed the diagnosis of myotonic dystrophy type 1 (MD1) with gene-sequencing of DMPK. Hypersomnolence with REM sleep dysregulation can be the main manifestation of MD1. Clinical myotonia can lack and, in this case, electromyogram can be used.