Nociceptive blink reflex and pain-related evoked potentials in hypnic headache.

Background: Central facilitation of trigeminal pain processing and deficient habituation was observed in different headache and facial pain disorders. This overactivation seems to be primarily associated with chronic pain states.

Objective: To investigate the function of the trigeminal nociceptive system in patients with hypnic headache (HH).

Methods: Fifteen HH patients according International Classification of Headache Disorders II criteria and 15 age- and gender-matched healthy controls were investigated using the nociceptive blink reflex (nBR) and trigeminal pain-related evoked potentials (PREP).

Results: nBR and PREP responses showed no significant differences comparing HH patients and healthy controls. Moreover, no habituation deficit was detected in HH patients.

Conclusion: Central facilitation and change in habituation do not seem to be a crucial part in the pathophysiology of HH despite the chronic nature of this disease. Facilitation or habituation deficit does not seem to be exclusively related to chronic pain disorders in general. Further research is needed to illuminate the pathophysiology of HH.