Hypersomnia caused by isolated angiitis of the CNS.

A 42-year-old woman presented gradual development of hypersomnia and memory disturbance. T2-weighted and FLAIR MRI scans revealed a high intensity abnormality in the hypothalamus. Stereotactic brain biopsy specimen revealed prominent infiltration of the lymphocytes in the vessel walls. Since there was no evidence of systemic angiitis, the diagnosis of isolated angiitis of the CNS (IAC) was made. Polysomnographic study showed decreased REM sleep and increased stage I sleep. Orexin A in the CSF was decreased. Hypersomnia and a decrease of the CNS orexin A improved after corticosteroid therapy. Hypersomnia can be an initial symptom of IAC if it involves the hypothalamus.