Episodic hypnic headache?

Hypnic headache is a primary headache disorder, which occurs exclusively during sleep and usually begins after the age of 60 years. It was first described by Raskin in 1988 (1), as a sleep-related headache, that regularly awakened patients at a consistent time of night; the pain was diffuse, persisting for 30–60 min, without autonomic symptoms. Hypnic headache was not included in the first edition of the International Headache Society (IHS) classification. In the second edition this headache was classified in section 4.5, included in the group of ‘Other primary headaches’ (2). At the time of this writing 82 patients with this disorder have been described (3–29). The possible pathophysiology and the pharmacological treatment of this headache have been recently discussed and analysed (30, 31), as well as its relationship with REM sleep (14, 27, 28). A symptomatic case that developed after an ischaemic stroke in the pontine reticular formation was also reported (29). The natural history of hypnic headache is not well known. The review of the published cases suggests that hypnic headache tends to be a chronic unremitting disorder. To better understand the natural history of hypnic headache, we have prospectively followed 4 patients with this disorder since 1998. The first two cases, diagnosed in 1998 and 1999, respectively, were published previously (13, 17); the other two cases, of new description, were first seen in 2000. Hypnic headache was the main diagnosis in 0.09% of all headache patients and notably in 1.4% of geriatric patients (above the age of 65 years) seen in our Headache Centre from 1998 to 2002.