Two Cases Report And Literature Review Of Hypnic Headache

Hypnic headache is a rare episodic headache syndrome first described by Raskin in 1988. It has also been called'clockwise headache'or'alarm-clock headache'. More than 90 similar cases have been reported and our found two cases from 2006 to 2007. Now we will report the cases and review the literature of Hypnic Headache.Hypnic headache syndrome is a rare, recurrent, late-onset headache disorder that usually begins after age of 60 years and occurs exclusively during sleep. Headache attacks occur predominantly during nighttime sleep, but may also occur during daytime nap. The frequency of patients with hypnic headache is not really known. It was reported as the main diagnosis in 0.07% of all headache patients and 0.1% of all headache outpatient clinic. The mean age at onset is 62 years.There is a slight female prepon- derance– about3 : 2.The pathophysiology of hypnic headache is speculative because there have been no experimental studies. Not surprisingly, it has been debated whether hypnic headache is a particular subtype of cluster headache. However, only the time features of hypnic headache support this hypothesis. There is no strict unilaterality and no obligatory cranial paraympathetic activation in hypnic headache, as is usually observed for the trigeminal-autonomic cephalalgias. The strict association with sleep, the onset at a consistent time each night and the efficacy of drugs that can impact circadian rhythms, such as lithium and melatonin, strongly suggest that HH may be a chronobiological disorder.The observation that in many patients HH onset is reported at the same time each night suggests that pain onset may be further controlled by a time-related mechanism, possibly located in suprachiasmatic nucleus(SCN), the hypothala- mic area considered to be the human biological clock. Because of the age-related impairment of SCN, lead to impairment of melatonin secretion and induce headache.The relation of hypnic headache with REM-sleep, findings from polysomnographic studies. The possibility that hypnic headache is a REM sleep-related disorder caused by a derangement of a brainstem neural network that regulates sleep-wake rhythms.Intermittent increases of intracranial pressure occurring during sleep are more pronounced during REM phases. Some patients the headache usually aggrava- ted by prostration and alleviated by orthostatism, so a possible involvement of raised intracranial pressure in hypnic headache pathogenesis cannot be excluded.Other authors have described headache due to arterial hypertension, which might also occur during REM sleep. However, there is no relations of body position and blood pressure in our two case. All of the hypothesis can not to explain overall the cases, and the physiology of hypnic headache is complicated.The diagnose of hypnic headache is main according to clinical manifestation, and International Headache Society made the diagnostic criteria for hypnic headache in 2004: A. Dull headache fulfilling criteria B–D; B. Develops only during sleep, and awakens patient; C. At least two of the following characteristics: 1. occurs >15 times per month; 2. lasts≥15 min after waking; 3. first occurs after age of 50 years; D. No autonomic symptoms and no more than one of nausea, photophobia or phonophobia; E. Not attributed to another disorder. This two cases of patients with headache characteristics consistent with the standards, the diagnosis of hypnic headache is set up.Acute medication in the attack was tested only in a few patients. Notably, subcutaneous sumatriptan and oxygen inhalation, the drugs of first choice for the treatment of cluster headache attacks, were not effective. Only acetylsalicylic acid showed, on average, a moderate efficacy in stopping acute hypnic headache attacks.The best prophylactic treatment is lithium, whereas indomethacin,and flunarizine exhibit variable results. Beta-blockers, amitriptyline and steroids are only rarely effective. Some patients benefit from melatonin. Caffeine (a cup of coffee) in the evening is a good option because it does not disrupt nocturnal sleep in such patients. The long-term use of lithium is limited because of the severity side effect. Nondrug therapy, such as sleep behavior therapy or physiotherapy,was not reported.The first case in the first five days after treatment, headaches disappeared, the results is obvious, and lasted about three months. But the recurrence of headaches after application flunarizine failed to achieve satisfactory results, Patients due to poor sleep after a period of time, headaches was mitigation. there is two Hypothesis:1.the treatment of sleep limitation can effect on hypnic headache;2. hypnic heafache have the Ease– Recurrence course of disease, but they need long term follow-up. The second case with flunarizine, the effect of treatment is general. however, the effect is obvious after adding indomethacin. The therapeutics of hypnic headache is need to control investiga- tion.Since the limited number of cases , no systematic observation and no experimental studies, so the pathogenesis is speculative, diagnostic Criteria is nonspecific, and have on specific treatment. In the future study need to do polysomnography for patients, finding rule of headache attack; monitor the level of melatonin in body, revealing the relationship of neuroendocrine and headache; undertake functional imaging studies, searching structural abnorma- lities of activation and scatter of headache. On the therapeutics aspact, make controlled experiment, to identify the dependability of all the treatment.