Dr. Sonia Lasaosa, MD, et al. studied the supposed link between the lack of a nocturnal decrease in blood pressure, which is seen in individuals with obstructive sleep apnea, and the occurrence of cluster headaches. For the study, 30 patients with episodic cluster headaches were given blood pressure cuffs to monitor their ambulatory blood pressure. These readings were then used to determine the average blood pressure during sleep, average blood pressure during wakefulness, and the decrease in blood pressure during sleep. During normal sleep there is a 10% – 20% “nocturnal dip” in blood pressure, while a dip of less than 10% is considered abnormal. Of the 30 participants in the study, 15 experienced the abnormal lack of dipping, a frequency which was higher than expected. Previous studies have shown that a reduction in mean oxygen saturation due to changes in circadian blood pressure rhythm may be the triggering factors which lead to cluster headaches. The high incidence of the abnormal lack of dipping in patients with episodic cluster headaches supports the hypothesis of a possible relationship between obstructive sleep apnea and cluster headaches. Ambulatory blood pressure monitoring has also proved to be an effective technique which could alert neurologists to the potential risk of cardiovascular disease and the need to check for sleep apnea syndrome in patients with cluster headaches.
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