[Hypnic headache: a report of four cases]

Hypnic headaches are an uncommon type of primary headache of short duration, related to sleep, which have usually been described in elderly persons. Although not currently included in the International Headache Society's classification, criteria have been established for its diagnosis. They include: frequency of more than 15 days per month for at least one month, the headache wakens the patient when asleep, it lasts for between 5 and 60 minutes, may be generalized or unilateral, with no associated autonomic disorder or causative aetiological agent.

We describe four clinical cases, three women aged 43, 52 and 65 years old and one 68 year old man. They complained of moderate to severe headaches which were unilateral, daily, woke them up at night, lasted for some hours and had no associated autonomic symptoms. On clinical investigations (cephalic CAT and MR scans) organic disease, as a cause, was ruled out. Different acute and prophylactic treatments were tried, but only lithium carbonate (400 mg at night) led to full improvement of symptoms. When this treatment was stopped the headache reappeared in some patients.

Although some patients did not fulfil the diagnostic criteria described by Dodick et al in a previous series of cases, the night time presentation with no associated autonomic disorder and good response to lithium carbonate were in favour of the diagnosis of hypnic headaches