Hypersomnia and low CSF hypocretin-1 (orexin-A) concentration in a patient with multiple sclerosis showing bilateral hypothalamic lesions.

A 45-year-old Japanese woman with multiple sclerosis (MS) manifested hypersomnia in a relapse of MS. Magnetic resonance imaging revealed new bilateral hypothalamic lesions, and the hypocretin-1 level in the cerebrospinal fluid (CSF) was significantly low. Methylprednisolone pulse treatment successfully resolved the hypersomnia and the left hypothalamic lesion, and it normalized the hypocretin-1 level in the CSF. These findings suggest that the hypothalamic hypocretin (orexin) system may be crucial to maintaining the arousal level and that lesions in the system can cause hypersomnia in MS.