Asymmetrical Reduction of the Nociceptive Flexion Reflex Threshold in Cluster Headache

Abstract

The nociceptive flexion reflex (NFR) of the lower limbs (RIII reflex) was examined bilaterally in 54 cluster headache (CH) patients suffering from episodic CH (ECH) and chronic CH (CCH). Fifteen ECH patients were examined in both remission and active phases. The RIII reflex threshold (Tr) and the threshold of pain sensation (Tp) were significantly reduced on the symptomatic side in patients with episodic CH during the bout. During the active phase of episodic CH an inverse correlation was found between the severity of CH (ratio: number of cluster periods/years of illness duration) and the Tp, which may suggest a role for secondary central sensitization in pain pathways. The lower Tr and Tp on the symptomatic side is in keeping with previous observations exploring pain mechanisms using different methods (i.e. corneal reflex, pain pressure threshold). On the whole, these data tie in with the view of an impairment of the pain control system, which parallels the periodicity of the disorder in the episodic form.

Impaired Circadian Rhythmicity of Nociceptive Reflex Threshold in Cluster Headache

“…The data obtained in the present study agree with another study in a large population of patients with CH 28,29 where a decrease in the RIII threshold on the symptomatic side during a cluster period has been shown. The data obtained in the present study agree with another study in a large population of patients with CH 28,29 where a decrease in the RIII threshold on the symptomatic side during a cluster period has been shown.…”

Pathophysiology of Pain Perception

“…Sandrini et al (1991) investigated the trigeminal pain sensitivity by means of the electrically elicited corneal reflex in 21 patients with cluster headache. Similar results were recendy reported by Sandrini et al (2000), who found lower nociceptive reflex thresholds of the lower limbs only on the symptomatic side in patients with cluster headache. This reduction vanished during the remission.…”

Widespread Hypersensitivity to Pressure Pain in Men With Cluster Headache During Prolonged Remission Is Not Related to the Levels of Depression and Anxiety

“…Our findings are consistent with central sensitization and could be attributable to plastic changes in central pain pathways induced by repetitive CH attacks during the active cluster periods. In addition, our results may reflect a primary dysfunction of the endogenous inhibitory pain modulatory systems, which is thought to occur in CH . There is ample evidence supporting a fundamental role of the hypothalamic region in the pathogenesis of CH.…”