[Hypnic headache: a new case].

INTRODUCTION: Hypnic headache is a condition characterized by nocturnal episodes of headache which periodically waken the sleeping patient. They usually occur in persons over 55 years of age and are thought to be due to some type of disturbance of biological rhythm. CLINICAL CASE: A 70 year old woman, with no relevant past history, complained that during the previous 12-14 months she had been woken from sleep by episodes of headache. The headache was diffuse, non-pulsatile and very intense. The duration was variable, from 15 to 45 minutes and usually disappeared without requiring analgesics. The pain was not associated with autonomic or ocular disorders, nausea, vomitting or focal neurological signs. Both general and neurological examinations were completely normal. No alterations were seen on cranial CT. Treatment with lithium was started and there was marked improvement in the frequency of headaches. CONCLUSIONS: Hypnic headache is an unusual disorder characterized by episodes of holocranial, or rarely hemicranial, headache of moderate-severe intensity and periodic occurrence. Typically the headache wakes the patient whilst he is asleep ('alarm clock') and there are no autonomic or neurological alterations of any type associated with the episode. The condition usually affects persons over 55 years of age, and it has been related to changes in biological rhythms. This presumed alteration of biological pacemakers has been based on the periodicity of the episodes and the response to lithium.