Beyond the headache: autonomic reflex dysfunction and heightened sensory sensitivity contribute to orthostatic intolerance in migraine

Our overarching objective was to determine whether autonomic reflex dysfunction and heightened sensory sensitivity contribute to orthostatic intolerance (OI) in patients with migraine. Adults with migraine (N = 30) underwent autonomic function tests summarized as the Composite Autonomic Severity Score (CASS) and vagal/adrenergic baroreflex sensitivity (BRS-V/A). Postural orthostatic tachycardia syndrome (POTS) and orthostatic hypotension/hypertension were diagnosed during tilt table testing. A cold pressor test (CPT) evaluated sympathetic vasomotor function. Participants completed the Migraine Disability Assessment (MIDAS), the 2011 Fibromyalgia (FM) Survey Criteria, and chronic overlapping pain condition (COPC) screening. The number of headache days per month correlated with CASS (p = 0.001), BRS-V (p < 0.001), and the CPT (p = 0.003) in the expected direction, with increasing autonomic nervous system (ANS) reflex dysfunction correlating with increasing number of headache days. During tilt testing, OI was prevalent (25/30; 83%) and was reported by all patients with chronic migraine. An abnormal cardiovascular response to tilt was present in 63%; POTS was the most common etiology (56.2%). Patients reporting OI during tilt table testing despite a normal cardiovascular response (33%) had higher FM scores (15.8 ± 3.6 vs. 7.5 ± 4.6; p < 0.01) and a greater prevalence of non-headache COPCs (88.8% vs. 20.0%, p = 0.02) than asymptomatic patients. Increased headache frequency correlates with increasing ANS reflex dysfunction. The high prevalence of OI in patients with migraine may be due to both autonomic reflex dysfunction and an abnormal cardiovascular response to tilt (i.e., concordant OI) and heightened sensory sensitivity (i.e., discordant OI).