Idiopathic hypersomnia: clinical features and response to treatment.

A recent American Academy of Sleep Medicine publication identified a need for research regarding idiopathic hypersomnia. We describe various clinical and polysomnographic features of patients with idiopathic hypersomnia, with an emphasis on response to pharmacotherapy. A retrospective review of our database initially identified 997 patients, utilizing "idiopathic hypersomnia", "hypersomnia NOS", and "primary hypersomnia" as keywords. The charts of eligible patients were examined in detail, and data were abstracted and analyzed. Response to treatment was graded utilizing an internally developed scale. Eighty-five patients were ultimately identified (65% female). Median (interquartile range) ages of onset and diagnosis were 19.6 (15.5) and 33.7 (15.5), respectively. During a median follow-up duration of 2.4 (4.7) years, 65% of patients demonstrated a "complete response" to pharmacotherapy as assessed by the authors' grading schema. Methylphenidate was most commonly used as a first-line agent prior to December 1998, but subsequently, modafinil became the most common first drug. At the last recorded follow-up visit, 92% of patients were on monotherapy, with greater representation of methylphenidate versus modafinil (51% vs. 32%). Among these patients, methylphenidate produced a higher percentage of "complete" or "partial" responses than modafinil, although statistical significance was not reached (38/40 [95%] vs. 22/25 [88%], respectively, p = 0.291). The majority of patients with idiopathic hypersomnia respond well to treatment. Methylphenidate is chosen more often than modafinil as final monotherapy in the treatment of idiopathic hypersomnia, despite the fact that it is less commonly used initially. Further prospective comparisons of medications should be explored.