Hypnic headache is a separate form of primary chronic cephalgia that occurs during sleep in patients aged 50 years and older. A distinctive feature of the disease is the absence of similar attacks in the waking state. This variant of cephalgia is diagnosed taking into account clinical features after the exclusion of organic brain damage using instrumental studies (Echo-EG, MRI, UZDG). The main pharmaceuticals used in the treatment of hypnic headache are lithium salts, sleeping pills, caffeine, indomethacin, melatonin.
Headache (cephalgia) is one of the most common complaints among patients of various age categories. Primary cephalgias (tension headache, migraine) prevail at a young age, secondary pains due to various intracranial pathologies (tumors, cerebrovascular diseases, arachnoiditis, etc.) are more common in the elderly. The only variant of primary cephalgia that occurs exclusively in the older age group is hypnic headache (HH). The peak incidence occurs at the age of 50-60 years, women get sick a little more often than men. The prevalence of pathology is at the level of 1.1%. Due to the peculiarities of its occurrence in the literature on neurology and among patients, hypnic cephalgia has received the synonymous name “alarm clock” headache.
Provoking etiofactors are unknown. Most researchers assume that the disease is based on a specific disorder of the regulation of circadian rhythms. Cephalgic paroxysms occur during sleep, accompanied by rapid movements of the eyeballs (REM sleep phase). Since the regulation of the alternation of sleep-wake cycles is carried out by the suprachiasmal hypothalamic nucleus, its dysfunction is considered the pathogenetic basis of hypnotic seizures. A likely explanation is changes in the interrelationships of the suprachiasmal nucleus with the noceptive structures of the brain responsible for pain.
Hypnic cephalgia develops paroxysmally at night. The patient wakes up from a headache, cannot fall asleep until the end of the attack. In 10% of cases, patients note that paroxysms can occur during daytime sleep. Usually the pain is dull, moderately pronounced. Complaints of intense pain syndrome are presented by 20% of patients. The hypnic form of cephalgia is diffuse, in 60% of cases it covers both halves of the head. Sometimes migraine-like symptoms are observed: nausea, increased susceptibility to light and sounds, but phonophobia and photophobia do not reach significant severity.
The minimum duration of cephalgic paroxysm is 15 minutes, the maximum is 3 hours. On average, the headache lasts 0.5-1 hour. The number of seizures varies from 1 episode per week to 6 during the night, the hypnotic attack begins 2-6 hours after falling asleep. After its completion, patients are able to fall back into sleep. HH has a long-term chronic course. Having appeared once, paroxysms accompany the patient until the end of life.
Hypnic cephalgia is a relatively benign pathology, not accompanied by serious complications. Frequent hypnotic attacks that occur several times a night negatively affect the quality of life of the patient. Such a course of HH can lead to sleep deprivation. Shortened to 4-5 hours of sleep negatively affects the ability to work, provokes problems with concentration, daytime sleepiness, increased emotional lability, irritability, memory impairment for current events. Sleep deprivation increases the risk of diabetes, obesity, stomach ulcers, fibromyalgia.
Since hypnic headache is a rare pathology, many practicing neurologists and therapists are insufficiently informed about the criteria for its diagnosis. A characteristic feature of the older patients is the presence of a burdened premorbid background (arterial hypertension, coronary heart disease, chronic gastrointestinal pathology). As a result, hypnic paroxysms are attributed to nocturnal attacks of hypertension, manifestations of an abusive headache, symptoms of impaired venous outflow from the cranial cavity (venous DEP).
A thorough study of clinical symptoms, the exclusion of any intracranial organic pathology capable of provoking such cephalgia allows to diagnose HH. Diagnostic criteria were developed in 2003. According to the International Classification of Headaches, there are four signs of the hypnic form of the disease. There is a dull headache that occurs only in a dream, leading to awakening. Cephalgic attacks are characterized by at least two of these signs: they debut at the age of over 50 years, appear more than 15 times within a month, have a duration of more than 15 minutes. Headache is not accompanied by vegetative symptoms. There are no other causes of cephalgic paroxysms.
In order to confirm the latter criterion, instrumental examinations are carried out to detect sleep disorders, organic cerebral pathology. According to the indications, consultations of a cardiologist, a vertebrologist, a somnologist are appointed. The list of necessary examinations includes:
- Echoencephalography. Intracranial pressure is measured using a special ECHO-EG. The study is necessary to exclude intracranial hypertension.
- Assessment of cerebral circulation. It is carried out with the help of ultrasound of the vessels of the head and neck, duplex scanning. Many patients have various hemodynamic abnormalities due to their age. In the absence of headaches during the waking period, their presence does not exclude the diagnosis of HH.
- Polysomnography. Performed in conjunction with the consultation of a somnologist. Polysomnography makes it possible to exclude various somnological disorders: sleep apnea syndrome, nocturnal seizures, parasomnia.
- Tomography. MRI of the brain visualizes morphological changes in cerebral tissues. It allows you to diagnose brain tumors, cysts, inflammatory foci, detect the area of a stroke, lacunar infarcts.
Differential diagnosis of HH is performed with nocturnal migraine paroxysms, bundle headache, venous form of dyscirculatory encephalopathy. Migraine is characterized by the presence of daytime attacks along with nocturnal ones. Bundle cephalgia is characterized by vegetative coloration of paroxysms, high intensity of pain, psychomotor agitation of the patient. Venous DEP occurs with a predominance of night and morning cephalgic paroxysms. A test with a tilt of the head helps to conduct a differential diagnosis.
A unified method of therapy for hypnic cephalgia has not been developed. Clinical studies of the effectiveness of pharmaceuticals used in the treatment of HH have not been conducted. The main means used in therapy are:
- Lithium preparations (lithium carbonate). They affect the noceptive system, increase the nocturnal production of melatonin. They are assigned for the night.
- Hypnotics (zopiclone). The positive effect of medications is associated with a regulating effect on the structure of sleep, an increase in the threshold of awakening. Atypical benzodiazepines (clonazepam) have a similar effect.
- Other pharmaceuticals. Successful attempts of treatment with indomethacin, verapamil, gabapentin, prednisone are described in the literature. The effectiveness of taking caffeine and melatonin preparations before bedtime was noted.
Prognosis and prevention
The hypnic form of headache is characterized by a benign chronic course. Therapeutic measures can reduce the likelihood of another night paroxysm, but do not lead to recovery. After manifestation, the disease continues for the entire period of the patient’s life. Preventive measures have not been developed, since the etiofactors provoking the disease are unknown.