Autonomic function in migraine patients: ictal and interictal pupillometry

Pupillometric investigations into migraine have suggested that an autonomic disturbance is part of the pathogenesis of that condition. This observation is controversial, however, which may reflect that the putative sympathetic hypofunction is either subtle or transient. In this study, we assessed the sympathetic function of migraine patients and controls during both a symptom-free phase and a migraine attack, and challenged patients with apraclonidine to reveal small changes in autonomic function.

Infrared pupillometry was used to measure pupillometric parameters in 37 controls and 46 migraine patients in the interictal phase of disease. Fifteen migraine patients were also studied during a migraine attack. In addition, 26 controls and 18 migraine patients were tested interictally both with and without apraclonidine. Of these 18 migraine patients, seven were also tested with and without apraclonidine during a migraine attack.

We found no significant differences between migraine patients and controls in the interictal phase. Additionally, no differences in pupil parameters were detected during the migraine attack. However, after administration of apraclonidine, migraine patients had a longer latency of the light reflex compared with controls. This increase in latency was more pronounced ictally (oculus dexter: P = .046, oculus sinister: P = .023) than interictally (oculus dexter: P = .075, oculus sinister: P = .021).

We conclude that there is evidence for a subtle pupillary sympathetic hypofunction in migraine patients, observed as a prolonged latency to light reflex, which is revealed after the administration of apraclonidine.