Cluster headache: cardiovascular responses to head-up tilt.

Head-up tilt tests were performed in six cluster headache patients in a bout of attacks, but in a pain-free interval at the time of investigation; and in eleven controls matched for age, basal blood pressure, and heart rate. A Doppler servomethod was used for a noninvasive, beat-to-beat blood pressure determination. There were no significant differences between the cluster headache and control groups for heart rate and systolic blood pressure response to the head-up tilt. However, the average diastolic blood pressure seemed to drop more after the tilt in the cluster headache group than in the control group; in particular, in the later part of the test. This might suggest a dysfunction of the baroreflex in cluster headache patients in a bout, also outside of attacks, and most probably of the sympathetically-mediated vasomotor response.