Hypnic headache: a rare type of primary headache disorder

Abstract

Introduction: Headaches are a common complaint that most people experience many times during their lives. Headaches affect people of all ages, races and socioeconomic status. Headaches are broadly classified as 'primary' or 'secondary'. Primary headaches are benign, not caused by an underlying disease or structural problems. Secondary headaches may be caused by problems elsewhere in the head or neck. Hypnic headache, first described by NH Raskin (Raskin, 1988). It is a rare type of primary headache that occurs only at night during sleep. HHS affects people older than 50 years (Evers and Goadsby, 2003; Stefan and Peter, 2005). Hypnic headache usually starts 3-4 hours after sleep onset. As a result, the patient starts to wake up (Headache Classification Subcommittee of the International Headache Society [IHS], 2018). Because of the tendency to occur at the same time each night, hypnic has been called the 'alarm clock' headache (Newman et al., 1990). Hypnic headache is included in the International Headache Society classification (International Classification of Headache Disorders II edition, 2004). The headache is usually unilateral and occurs more than 15 nights per month (International Headache Society Classification ICHD 3-beta, n.d.). It is commonly dull in character and lasts for 15-240 minutes. It does not make the patient restless, unlike cluster headache (International Headache Society Classification ICHD 3-beta, n.d.). After waking up, most patients engage in some activity like eating, drinking, showering and reading (Diener et al., 2012). Hypnic headache usually not associated with trigeminal autonomic symptoms. A few cases of hypnic headache are available in the literature. According to some studies, bedtime coffee is helpful for HHS. Lithium carbonate, indomethacin and flunarizine have been used to treat the disease. Methods: A 70-year-old male patient had been suffering from headaches during nocturnal sleep for the last year. The headache started 3-4 hours after falling asleep, and he awoke almost every night. After waking up, he kept himself busy with walking, reading and religious activities and the headache gradually resolved. His headache persisted for 30-40 minutes. He then returned to bed. The patient reported that the headache was dull in nature and located in the left temporal and occipital regions and was not associated with photophobia, phonophobia, nausea, vomiting, tearing or leg discomfort. The patient had no history of early morning or daytime headaches, sleep disorders, snoring or sleep apnoea. He had no history of head trauma, fainting, unconsciousness, weakness, limb paralysis, seizures or non-epileptic seizures. He is a non-smoker and non-alcoholic. On general examination, his heart rate was 70 beats per minute, his blood pressure was 138/68 mm Hg, and he had an absence of anaemia, jaundice or oedema. Both lung fields were clear, and no abnormality was detected on neurological examination. Serological investigations, complete blood count, fasting blood glucose and lipid profiles were within normal limits. His computed tomography (CT) brain scan was normal with no cerebral atrophy or volume loss compatible with age. The patient had been treated previously by several general practitioners with paracetamol, diclofenac sodium and tramadol hydrochloride. He had used these drugs either singly or in combination; however, there was no significant improvement. The patient is a little scared and depressed regarding his nocturnal headache. At our facility, he was treated with indomethacin (50 mg/day) and flunarizine (10 mg/day) in divided doses and responded well. Results: Hypnic headache is usually not associated with nausea, vomiting, runny nose, tearing, photophobia or phonophobia. Some patients may report autonomic symptoms (Newman et al., 1990; Diener et al., 2012; Patsouros et al., 2004). Nocturnal hypertension may cause a similar headache syndrome (Caminero et al., 2010). The diagnosis is mainly clinical and underlying causes must be excluded. The exact cause of hypnic headache is unknown, ut the condition may be linked to rapid eye movement sleep (Dodick, 2000; Pinessi et al., 2003). Some patients report improvement with a cup of coffee before sleep (Diener et al., 2012) or that drinking a cup of black coffee before bed is effective in treating headaches (Holle and Obermann, 2012; Mathew and Wilson, 1985) Indomethacin is useful if the headache is unilateral (Diener et al., 2012; Dodick, 2004; Patsouros et al., 2004; Pinessi et al., 2003). Lithium appears to be the most effective treatment option, which has been associated with increased plasma levels of melatonin (Bordini et al., 2016; Chazot et al., 1987; Dodick, 2000; Treiser et al., 1981). Melatonin deficiency may explain the occurrence of hypnic headaches in biologically predisposed subjects (Dodick et al., 1998). Another hypothesis is impaired serotonin metabolism because lithium also increases the release of serotonin (Chazot et al., 1987). Conclusion: Hypnic headache is a very rare type of primary headache that occurs during sleep. It should be diagnosed only after other secondary causes of headache have been excluded. Caffeine, lithium carbonate, flunarizine and indomethacin have been used to treat patients with hypnic headache. Lack of study and awareness about these disorders can lead to delays in diagnosis and treatment.