Methylphenidate hydrochloride for excessive daytime sleepiness in a patient with myotonic dystrophy

A 28-year-old man with a history of myotonic dystrophy (MyD) is described. His progressively worsening excessive daytime sleepiness (EDS) was treated with methylphenidate hydrochloride. Polysomonography (PSG), the multiple sleep latency test (MSLT), middle latency-evoked response, and auditory event-related potentials were used to assess the cause of EDS. The PSG detected small numbers of central sleep apneic episodes. Mean sleep latency, which was determined by MSLT, increased from 5 min before treatment to 14 min after treatment. The Pa, P1, and N1 amplitudes at the Cz site increased after treatment, but P3 latency remained unchanged. These observations suggest that EDS and impairment of cognitive and information processing seen in a patient with MyD may be caused by a central nervous system disorder.