Reduced hypothalamic gray matter in narcolepsy with cataplexy.

OBJECTIVES: Narcolepsy with cataplexy is associated with a loss of hypocretin. The question is, if there is an autoimmune or neurodegenerative process selectively killing the hypothalamic hypocretin-containing neurons or if these cells survive but fail to produce hypocretin. To support one of these hypothesis we aimed to detect structural changes in the hypothalamus of narcoletic patients.

MATERIALS AND METHODS: Nineteen narcoleptic patients were compared to 16 healthy controls. We used voxel-based morphometry (VBM), an unbiased MRI morphometric method with a high sensitivity for subtle changes in gray and white matter volumes to investigate hypothalamic region in this condition.

RESULTS: Classical MRI protocol revealed no structural abnormalities, but using VBM we found significant reduction in hypothalamic gray matter volumes between patients and controls.

CONCLUSIONS: VBM showed hypothalamic gray matter loss in narcolepsy with cataplexy. This suggest that functional abnormalities of hypocretin neurons in narcolepsy are associated with structural changes of hypothalamus.