Hypnic headache: A review of 348 cases published from 1988 to 2018.

Hypnic headache (HH) is a rare benign disorder described initially by Raskin in 1988. It is characterized by recurrent nocturnal episodes of headache that periodically awaken the sleeping patient and usually occur in the elderly. This review aimed to describe the clinical features of the HH cases published in the literature from 1988 to 2018. Based on literature search in the major medical databases (LiLacs, SciELO, Bireme, Medline, Embase, Current Contents, Scopus, EBSCO and PubMed), we have analyzed the case reports on HH that have been published from 1988 to 2018. We described 343 adults (69.0% women and 31.0% men) and 5 children (3 girls and 2 boys) diagnosed with HH. Average age for adults and children was, respectively, 58.0 ± 13.1 years (ranging from 15 to 85 years) and 9 years (ranging from 7 to 11 years). The diagnosis was made 7.6 ± 14.2 years (range 0.1 to 39 years) after onset of headache. Pain occurred during nocturnal sleep (94.8%), with an average duration of 90 min, bilaterally located (55.5%), having a dull character (74.4%), and moderate intensity (61.5%). In 94.5% of the patients, headache occurred for 10 or more days per month (mean of 21 days). Autonomic manifestations occurred in 7.6% of the patients, predominantly lacrimation (61.1%) and rhinorrhea (16.7%). Caffeine presented the best therapeutic response in acute treatment. In prophylaxis, lithium, caffeine and indomethacin were effective drugs in 77.8% of the patients. In 56.7% of the patients there was remission with treatment and in 72.7% of them, without recurrence. HH is a rare disease that usually occurs for the first time in older women but may begin in childhood. Lithium and caffeine are effective drugs for pain prophylaxis, but randomized clinical trials are required.