Blink reflex habituation in migraine and chronic tension-type headache.

ΑBSTRACT: R1 and R2 blink reflex latencies were investigated blind in 55 patients with chronic tension-type headache, 55 patients with migraine, and 55 headache-free controls. Standard electrical stimulation of the supraorbital nerve was applied and the response was recorded from the ipsilateral orbicularis oculi muscles. There were no R1 or R2 latency differences between the three groups. During migraine attacks we observed a statistically significant reduction of R2 amplitude and area. The main finding of our study was the elicitation of the late R2" response at different interstimulus intervals in migraine patients compared to the tension-type headache and control groups. This could be considered an indication of habituation mechanism hyperexcitability, although further investigation is needed to confirm these findings and establish the neurophysiologic basis. This study suggests that blink reflex studies can be used routinely as a non-evasive and inexpensive method for the evaluation of headache patients.