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

Highlights

• HH predominates after 50 years of age, but may occur in young adults and children

• Autonomic manifestations may occur bilaterally, but do not meet diagnostic criteria for trigeminal-autonomic headaches.

• Lithium, caffeine, indomethacin and melatonin are first choice drugs for prophylactic treatment of HH.

Abstract

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.

Introduction

Hypnic headache (HH) is a rare headache syndrome first described by Raskin in 1988 [1]. It has also been called ‘clockwise headache’ or ‘alarm-clock headache’ [2]. It is characterized by recurrent nocturnal episodes of headache that periodically awaken the sleeping patient and usually occur in the elderly. Its pathogenesis is unknown [3,4].

This headache is a dull pain that develops only during sleep and awakens the patient. It occurs for 10 or more days per month, for more than three months and lasts >15 min and for up to 4 h after waking up, predominantly in women after the age of 50. There are no autonomic symptoms or restlessness. The headache should not be attributed to another disorder [5,6].

Over the past 30 years, eleven large series of cases (≥10 patients per publication) have been published, totaling >200 patients [5,[7], [8], [9], [10], [11], [12], [13], [14], [15], [16]], and eight major reviews on HH [3,[17], [18], [19], [20], [21], [22], [23]]. According to these case series, HH was diagnosed in 0.07% to 0.1% of all headache patients assessed in headache centers, demonstrating the relative rarity of this condition [3].

In 2014, a major review of the 255 HH cases described since 1988 was published [23] based on case reports and eight major series [5,[7], [8], [9], [10], [11], [12], [13]]. In the last five years, almost a hundred new cases of HH have been described, but no other review was published.

This review summarizes the presently available information on clinical characteristics, pathophysiology and therapeutic options in HH patients reported from 1988 to 2018. Pediatric HH cases are discussed separately.