Habituation of the nociceptive blink reflex in episodic and chronic cluster headache.

Background: Analysis of habituation patterns in patients with primary headache disorders allows the detection of changes to the excitability level of the trigeminal nociceptive system. Previous studies demonstrated a habituation deficit to painful stimuli in migraine and it was suggested that similar observations could be made in cluster headache (CH).

Methods: Habituation of the "nociceptive" blink reflex (nBR) (R2 response) was studied in 66 CH patients (18 episodic CH inside bout, 28 episodic CH outside bout, 20 chronic CH) as well as in 30 healthy controls in a case-control study design.