Neurophysiological studies in chronic paroxysmal hemicrania and hemicrania continua.

To explore the possible involvement of the pain control system, pain pressure threshold (PPT), nociceptive flexion reflex (RIII), blink and corneal reflexes have been studied for pain perception assessment in 12 patients with chronic paroxysmal hemicrania (CPH) and 12 patients with hemicrania continua (HC). PPT was found to be reduced in HC and CPH when separately compared to controls. In addition, a significant reduction of subjective pain perception (Tp) which was most marked on the symptomatic side, has been demonstrated after sural nerve stimulation in CPH. The RIII reflex threshold on the symptomatic side was significantly reduced when patients were compared to controls. No major differences between CPH and HC as regards blink reflex latencies were found; nor was any such difference observed when comparing the two headache groups to controls. The corneal reflex thresholds were found significantly reduced bilaterally in CPH, irrespective of whether the treatment was given or not.