A prospective study recently published in the journal Cephalalgia , the official journal of the International Headache Society, extends the idea behind cluster headache chronicity. The study, entitled "Temporal changes of circadian rhythmicity in cluster headache", was first-authored by Dr. Mi Ji Lee, from the Department of Neurology, Neuroscience Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Cluster headache (CH) is known in the medical literature as the most intense pain experienceable by humans and is popularly known as "suicidal headache". CH consists of a primary headache disorder, classed as a Trigeminal Autonomic Cephalalgia by the 3rd Version of the International Classification of Headaches Disorders - ICHD-3. It is characterized by severe or very severe unilateral orbital, supraorbital and/or temporal pain lasting 15-180 minutes, presenting with at least one of the following autonomic symptoms in the same side of the pain: conjunctival injection and/or lacrimation; nasal congestion and/or rhinorrhea; eyelid edema; forehead and facial sweating; miosis and/or ptosis; and a sense of restlessness or agitation.
Attacks occur with a frequency between one every other day and 8 per day. During part, but less than half, of the active time-course, attacks may be less severe and/or of shorter or longer duration. Attacks occur in series lasting for weeks or months (so-called cluster periods or bouts) separated by remission periods usually lasting months or years. Another hallmark feature of CH is its circadian, or even circannual pattern, with up to 82% of patients reporting CH attacks around the same time each day.
In this study, Dr. Lee's and colleagues investigated prospectively the pattern of circadian rhythmicity in relation to disease course in 175 patients in the active, within-bout period from 15 hospitals in Korea. The prevalence and characteristics of circadian rhythmicity were compared between- and within-patients with different numbers of total lifetime bouts. Patients with ≥ 2-lifetime bouts were categorized as stationary (no change between bouts), developing (becomes more prominent as disease progresses), decreasing (becomes less prominent as disease progresses), and variable (different from bout to bout), with regard the changes in the pattern of circadian rhythmicity during their disease progression.
Circadian rhythmicity was reported in 86 (49.1%) patients for the current bout. Seasonal rhythmicity was more prevalent in patients with circadian rhythmicity compared to patients with no seasonal rhythmicity (66.2 % vs 37.1 %, respectively). The prevalence of circadian rhythmicity was similar between groups (deciles groups) regarding the number of total lifetime bouts, while changes in circadian rhythmicity between bouts throughout the disease course were reported by 45.3% of patients. Patients without circadian rhythmicity showed a more variable pattern compared to patients with circadian rhythmicity (35.2% vs 8.8 %), whereas a stationary pattern was more common among patients with circadian rhythmicity in the current bout (64.7 % vs 40.9 %) compared to those without rhythmicity. Related Stories
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