Blood pressure during nocturnal sleep in headache

AIM: Interactions between blood pressure control, sleep and headache have been largely studied, although not well understood. We designed a study trying to simultaneously evaluate all three aspects in the same subjects. We particularly concentrated on the observation of physiological blood pressure circadian rhythm, and the presence of cutaneous allodynia correlated to headache. Objective of the study was to investigate blood pressure during nocturnal sleep in patients that underwent a blood pressure 24 hours monitoring, and at the same time the presence of headache and of sleep behavioural alterations. METHODS: Blood pressure 24 hours monitoring was performed by an ambulatory blood pressure (ABP) monitor (Space Labs) with its ad hoc software. Headache diagnosis was made according to ICHD-II criteria. Presence of allodynia and sleep behavior were evaluated through semi-structured ad hoc questionnaires. RESULTS: A total of 195 subjects were included, of which 122 without headache (mean age 60.4±11.6 years, 78 men and 44 women) and 73 with history of headache, (mean age 54.2±12.5 years, 18 men and 55 women). Fifty-one headache patients had migraine (mean age 52.6±11.7 years, 11 men and 40 women) and 22 tension type headache (TTH - mean age 58.0±13.5 years, 7 men and 15 women). Allodynia was found in 30 out of 73 headache patients: 23 out of 51 in the migraine group and in 7 out of 22 in the tension-type one. The physiological reduction of blood pressure during night (dipping) was more conserved among headache patients (34 dippers out of 73 subjects, 46,6%) with respect to subjects without headache (40 dippers out of 122, 32,8%) and that this border-line difference was more strongly significant comparing allodynic subjects (19 dippers out of 30, 63.3%) with both non-headache (40 dippers out of 122, 32.8%, P<0.001) and non-allodynic (15 out of 43, 34.9%, P<0.05) ones. No significant difference was observed between headache patients and subjects without headache in terms of mean systolic and diastolic pressure, neither between migraine and TTH. CONCLUSION: Allodynic headache patients seem to maintain a more physiologic pressure circadian rhythm. While considering the possibility of selection bias, the hypothesis of an allostatic function of headache and allodynia in patients with unbalanced blood pressure could be made.