Hypothalamic gray matter volume loss in hypnic headache

Objective Hypnic headache (HH) is a rare primary headache disorder characterized by strictly nocturnal headache attacks that mostly occur at the same time at night. The pathophysiology of this disease is poorly understood, but hypothalamic involvement was suspected as the hypothalamus represents the cerebral management center of sleep regulation and pain control. Methods Fourteen patients with HH and 14 age‐matched and gender‐matched healthy controls were investigated using magnetic resonance imaging–based voxel‐based morphometry. Results We detected gray matter volume decrease in the posterior hypothalamus of HH patients. Additional gray matter decrease was observed in brain areas known to be associated with cerebral pain processing, including the cingulate cortex, operculum, and frontal lobe, as well as in the temporal lobe. Interpretation Our data confirm the hypothesized involvement of the posterior hypothalamus in the pathophysiology of HH and emphasize the importance of this structure for sleep regulation and pain control. ANN NEUROL 2010