Abnormal brain processing of cutaneous pain in patients with chronic migraine

Abstract

Syndromes with chronic daily headache include chronic migraine (CM). The reason for the transformation of migraine into chronic daily headache is still unknown. In this study, we aimed to evaluate heat pain thresholds and event-related potentials following CO(2)-laser thermal stimulation (LEPS) in hand and facial regions in patients with CM, to show changes in nociceptive brain responses related to dysfunction of pain elaboration at the cortical level. The results were compared with findings from normal control subjects and from subjects who suffer from migraine without aura. The effects of stimulus intensity, subjective pain perception and attention were monitored and compared with features of the LEPS. Twenty-five CM patients, 15 subjects suffering from migraine without aura and 15 normal control subjects were enrolled in the study. LEPS amplitude variation was reduced in CM patients with respect to the perceived stimulus intensity, in comparison with migraine without aura patients and control subjects. In both headache groups, the distraction from the painful laser stimulus induced by an arithmetic task failed to suppress the LEPS amplitude, in comparison with control subjects. These results suggest an abnormal cortical processing of nociceptive input in CM patients, which could lead to the chronic state of pain. In both headache groups, an inability to reduce pain elaboration during an alternative cognitive task emerged as an abnormal behaviour probably predisposing to migraine.

Cortical Excitability in Chronic Migraine

“…By contrast, in a group of 25 CM patients, a trend for an excessive increase in LEP N2-P2 amplitudes was detected at baseline [9]. This is less pronounced when the stimulus becomes painful and with increasing disease duration.…”

“…However, LEPs are abnormally modulated by heterotopic conditioning stimuli such as remote capsaicin application [8] and by distraction [9,10].…”

Diagnosis, pathophysiology and management of chronic migraine: a proposal of the Belgian Headache Society

“…rs connectivity caudate-insula; % putamen-insula [132] % activation dorsolateral pons [47] %% iron content PAG and globus pallidus (T2) [29,31] ! central pain modulation [133,134] no % of posterior circulation infarcts [104] Medication overuse headache ! metabolism and tissue density orbitofrontal cortex [48,50] !…”

Effects of remote cutaneous pain on trigeminal laser-evoked potentials in migraine patients

“…In addition, no correlation was found between the effects of remote pain on trigeminal LEPs and Another explanation for the observed results is an altered cognitive processing of pain. In previous studies, migraine patients showed a defect in the attentive modulation of LEPs during an alternative cognitive task [4], so the direction of attention to the remote tonic pain induced by capsaicin may not be able to reduce the level of arousal and emotion toward the painful laser stimulation at the trigeminal level. In a further study, migraine patients did not show trigeminal N2-P2 complex reduction and changes of their cortical representation within the anterior cingulate cortex observed in non-migraine patients during homotopical painful stimulation concurrent with laser stimuli [11].…”

“…The diffuse noxious inhibitory control (DNIC) allows that the activity of pain-transmitting neurons in the spinal dorsal horn and in trigeminal nuclei can be inhibited by noxious stimuli applied to body areas very remote from the excitatory fields of these neurons [4,5]. Recently a reduced effect of remote noxious stimuli on pain threshold tested by electrocutaneous stimuli administered either to the forearm (extra-cranial site) or to the temple (cranial site) was observed in chronic tension-type headache, suggesting a deficient DNIC-like pain inhibitory mechanisms in this type of chronic headache [6].…”