OBJECTIVE AND BACKGROUND: Important elements of cluster headache (CH) pathophysiology may be seated in the posterior hypothalamus. Cranial autonomic features are inherent, but involvement of systemic autonomic control is still debated. We aimed to characterize autonomic function as investigated by baroreflex sensitivity (BRS) in CH patients.

METHODS: Twenty-six active CH patients and an equal number of age-, sex-, and BMI-matched controls underwent head-up tilt table test and BRS was determined by the sequence method.

RESULTS: Compared with controls, patients exhibited a blunted reactivity of RR intervals in response to falls and increases in systolic blood pressure (SBP) (15.3 vs. 20.0 ms/mmHg, P = .0041) in the supine position. Also, compared with controls, BRS was lower in patients having suffered an attack within the past 12 hours (n = 13, 12.5 vs. 22.3 ms/mmHg, P = .0091), opposed to those patients who had not (n = 13, 16.0 ms/mmHg, P = .1523). In the tilted position, the drop in SBP at the carotid sinuses was higher in patients who had recently suffered an attack. Despite this, they exhibited a less marked shortening of RR intervals when compared with patients who had been attack free for longer.

CONCLUSIONS: CH patients exhibit a subclinical blunting of BRS that may be affected by the attacks themselves. The fast RR interval fluctuations used in this method reflects cardiovagal responses, thus the blunted responses are suggestive of dysfunction in the parasympathetic division of the autonomic nervous system or in the central relay of impulses from the baroreceptors.