1008 Excessive daytime sleepiness in myotonic dystrophy treated with modafinil

Abstract Introduction Physiology of excessive daytime sleepiness (EDS) in myotonic dystrophy type 1 (DM1) remains incompletely understood and best practice treatment approaches are unclear. Report case(s) We present a 73-year-old man with atrial fibrillation, implantable cardioverter defibrillator for inducible ventricular tachycardia, hypertension, severe obstructive sleep apnea (OSA) was referred after recent diagnosis EDS. He presented foot pain, balance issues, falls. A subdural hemorrhage from fall prompted thorough evaluation including electromyography. This showed length-dependent polyneuropathy pattern features subacute chronic denervation change discharges right vastus medialis bilateral tibialis anterior gastrocnemius muscles. Myotonic Syndrome Advanced Evaluation revealed repeat expansion mutation DMPK gene (85 13 CTG repeats). previously diagnosed OSA an AHI 64 titrated onto bilevel. recalled no improvement symptoms noted sleeping 10-12 hours per night feeling rested. However, he takes multiple times day at time. When actively working on tasks feels alert focused. Epworth scale (ESS) 12. Polysomnogram bilevel followed by MSLT demonstrated control mean onset latency 8 minutes 5 REM periods. With relatively little impairment desire intermittent improved wakefulness, started modafinil 200mg daily as needed. reported robust response to without the need additional naps or cardiac complications thus far. Repeat ESS only 10. Conclusion case highlights precision medicine approach subpopulations exist even within specific dystrophy. People DM1 have been similarly but dramatic subjective modafinil. Cochrane Review European Medicines Agency recommendations not supportive its use despite subpopulation clear response. Interestingly, clinical measures do seem predict modafinil, suggesting unmeasured and, potentially, varied pathologies DM1. Support (if any)