The pupils of migraine patients : preliminary results

Aim To date there is no consensus whether there is a sympathetic or a parasympathetic disturbance in migraine; most pupillometric studies point towards a sympathic hypofunction. (1-4) By testing migraine patients both during an attack and in the headache free interval, we wanted to compare whether a potential sympathetic dysfunction increases during an attack by using apraclonidine 1%, an alpha adrenergic agonist. Methods We used infrared pupillometry to measure the dark adapted and light adapted pupil diameter. The minimal diameter, latency, amplitude, constriction and redilatation velocity of the light reflex were measured as well. We studied 31 controls and 42 migraine patients interictally, after a migraine-free period of at least 15 days. None of the migraine patients took prophylactic medication. Fourteen migraine patients were also studied ictally; they were not allowed to take any attack-aborting medication before or during the test. Results We found no differences between migraine patients with and without aura. None of the parameters correlated with the headache side in patients with unilateral migraine. We found no significant difference between migraine patients and controls, neither interictally, nor ictally. The pupil parameters of migraine patients did not differ significantly between and during the attack. However after administration of apraclonidine 1%, migraine patients had a longer latency compared to controls. This increase in latency was more pronounced ictally (right: P = 0.046, left: P = 0.023) than interictally (right: P = 0.075, left: P = 0.021). Conclusion We assume there is a subtle pupillary sympathetic hypofunction in migraine patients which is unmasked after administration of apraclonidine 1%. The sympathetic hypofunction creates a sympathetic hypersensitivity that causes the prolonged latency. References 1. Ophthalmic Physiol Opt. 2005;25(3):240-5. 2. Psychiatry 1990;53:121-5. 3. Headache 1985;25:40-8. 4. Clin Auton Res. 2003;13:16-21