Altered processing of sensory stimuli in patients with migraine

Higher, faster, worse? An event-related potentials study of affective picture processing in migraine

BACKGROUND

Migraine is a disorder of periodic disabling headache. Facilitated cortical responsivity has been suggested as one predisposing factor. Although the underlying mechanisms of migraine attack onsets are not fully understood, facilitated cortical responsivity has been suggested as one predisposing factor. Here, we investigate if enhanced cortical responsivity is reflected in altered event-related potentials during processing of complex pictures.

METHOD

Altogether, 16 migraine patients and 16 healthy volunteers participated in this study. Each patient had a diagnosed migraine and was headache- and medication-free for the study. Participants watched positive, negative and neutral pictures from the international affective picture system. An electroencephalogram was recorded during picture presentation. Afterwards, participants were asked to rate the pictures for valence and arousal.

RESULTS

Migraine patients showed significantly more negative-going early event-related potential components from 100 ms to 180 ms to all picture categories over occipital regions as well as more positive-going late potentials over central regions. Patients and controls did not differ in valence and arousal ratings for the international-affective picture system.

DISCUSSION

Patients with migraine seem to react cortically more intensely to all kinds of pictorial stimuli, regardless of emotional content. This facilitated processing may be related to the high cortical responsivity shown in various other event-related potential studies and might contribute to the recurring intense headache attacks.

Migraine is associated with altered processing of sensory stimuli

Migraine is associated with derangements in perception of multiple sensory modalities including vision, hearing, smell, and somatosensation. Compared to people without migraine, migraineurs have lower discomfort thresholds in response to special sensory stimuli as well as to mechanical and thermal noxious stimuli. Likewise, the environmental triggers of migraine attacks, such as odors and flashing lights, highlight basal abnormalities in sensory processing and integration. These alterations in sensory processing and perception in migraineurs have been investigated via physiological studies and functional brain imaging studies. Investigations have demonstrated that migraineurs during and between migraine attacks have atypical stimulus-induced activations of brainstem, subcortical, and cortical regions that participate in sensory processing. A lack of normal habituation to repetitive stimuli during the interictal state and a tendency towards development of sensitization likely contribute to migraine-related alterations in sensory processing.

Effect of sleep deprivation on the electrophysiological signature of habituation to noxious laser stimuli

BACKGROUND

Sleep deprivation induces hyperalgesia. However, this pro-nociceptive effect is not reflected at the electrophysiological level, since sleep restricted subjects show amplitude reduction of Laser-evoked Potentials (LEP). We aimed to explore the contribution of habituation to this paradoxical LEP amplitude decline.

METHODS

We compared LEP's of 12 healthy students (23.2 ± 1.1 years) after habitual sleep (HS) and a night of total sleep deprivation (TSD). Twelve repetitive laser stimulus blocks (each comprising twenty stimuli) were applied under three attention conditions ('focusing' - 'neutral' - 'distraction' condition). Stimulus blocks were split in part 1 (stimulus 1-10) and part 2 (stimulus 11-20). The contribution of habituation to the TSD-induced LEP amplitude decline was studied by calculating the percentage amplitude reduction of part 2 as compared to part 1. Individual sleepiness levels were correlated with (1) averaged LEP's and (2) the degree of habituation.

RESULTS

TSD induced hyperalgesia to laser stimuli (p < 0.001). In contrast, depending on the attention condition, the P2 amplitude of the N2P2-complex was significantly reduced ('focusing': p = 0.004; 'neutral': p = 0.017; distraction: p = 0.71). Habituation of the P2 amplitude to radiant heat was increased after TSD ('focusing': p = 0.04; 'neutral': p < 0.001; distraction: p = 0.88). TSD had no significant effect on N1 amplitudes (p > 0.05). Individual sleepiness correlated negatively with averaged P2 amplitudes (p = 0.02), but not with the degree of habituation (p = 0.14).

CONCLUSION

TSD induces hyperalgesia and results in attention-dependent enhanced habituation of the P2 component. Increased habituation may--to a substantial degree--explain the TSD-induced LEP-amplitude decline. For this article, a commentary is available at the Wiley Online Library.

Targeting pericranial nerve branches to treat migraine: Current approaches and perspectives

BACKGROUND

Migraine is a highly prevalent neurological disorders and a major individual and societal burden. Migraine is not curable at the present time, but it is amenable to acute symptomatic and preventive pharmacotherapies.

SUMMARY

Since the latter are frequently unsatisfactory, other treatment strategies have been used or are being explored. In particular, interventions targeting pericranial nerves are now part of the migraine armamentarium. We will critically review some of them, such as invasive and noninvasive neurostimulation, therapeutic blocks and surgical decompressions.

CONCLUSIONS

Although current knowledge on migraine pathophysiology suggests a central nervous system dysfunction, there is some evidence that interventions targeting peripheral nerves are able to modulate neuronal circuits involved in pain control and that they could be useful in some selected patients. Larger, well-designed and comparative trials are needed to appraise the respective advantages, disadvantages and indications of most interventions discussed here.

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

Chronic migraine (CM) is a disabling neurological condition affecting 0.5-2 % of the population. In the current third edition of the International Classification of Headache Disorders, medication overuse is no longer an exclusion criterion and CM is diagnosed in patients suffering from at least 15 headache days per month of which at least eight are related to migraine. CM is difficult to treat, and preventive treatment options are limited. We provide a pathogenetic model for CM, integrating the latest findings from neurophysiological and neuroimaging studies. On behalf of the Belgian Headache Society, we present a management algorithm for CM based on the international literature and adapted to the Belgian situation. Pharmacological treatment options are discussed, and recent data on transcranial and invasive neuromodulation studies in CM are reviewed. An integrated multimodal treatment programme may be beneficial to refractory patients, but at present, this approach is only supported by a limited number of observational studies and quite variable between centres.

New insights into pathophysiology of vestibular migraine

Vestibular migraine (VM) is a common disorder in which genetic, epigenetic, and environmental factors probably contribute to its development. The pathophysiology of VM is unknown; nevertheless in the last few years, several studies are contributing to understand the neurophysiological pathways involved in VM. The current hypotheses are mostly based on the knowledge of migraine itself. The evidence of trigeminal innervation of the labyrinth vessels and the localization of vasoactive neuropeptides in the perivascular afferent terminals of these trigeminal fibers support the involvement of the trigemino-vascular system. The neurogenic inflammation triggered by activation of the trigeminal-vestibulocochlear reflex, with the subsequent inner ear plasma protein extravasation and the release of inflammatory mediators, can contribute to a sustained activation and sensitization of the trigeminal primary afferent neurons explaining VM symptoms. The reciprocal connections between brainstem vestibular nuclei and the structures that modulate trigeminal nociceptive inputs (rostral ventromedial medulla, ventrolateral periaqueductal gray, locus coeruleus, and nucleus raphe magnus) are critical to understand the pathophysiology of VM. Although cortical spreading depression can affect cortical areas involved in processing vestibular information, functional neuroimaging techniques suggest a dysmodulation in the multimodal sensory integration and processing of vestibular and nociceptive information, resulting from a vestibulo-thalamo-cortical dysfunction, as the pathogenic mechanism underlying VM. The elevated prevalence of VM suggests that multiple functional variants may confer a genetic susceptibility leading to a dysregulation of excitatory–inhibitory balance in brain structures involved in the processing of sensory information, vestibular inputs, and pain. The interactions among several functional and structural neural networks could explain the pathogenic mechanisms of VM.

Contact heat evoked potentials and habituation measured interictally in migraineurs

BACKGROUND

A lack of habituation of different evoked potential modalities in migraine patients in-between attacks has been suggested.

METHODS

This study investigates cortical response after painful stimuli evaluated by contact heat evoked potentials (CHEPs) and quantitative sensory testing (QST) during the migraine-free interval. We enrolled 22 migraine patients and 22 healthy subjects.

RESULTS

Cortical potentials after contact heat stimulation of the cheeks and the volar forearm at a temperature of 51°C showed significantly reduced A-δ-amplitudes in patients and healthy controls. When the subjects' attention was drawn to an arithmetic task, a partial lack of habituation of amplitude could be seen in migraine patients. QST did not show any difference between migraineurs and controls.

CONCLUSION

Our findings can be primarily deemed to demonstrate that patients and healthy controls show significantly lower amplitudes while performing the calculation task. Without performing the calculation task we could not show the expected lack of habituation in migraineurs. Yet, while performing the calculation task our results partly suggest that hypothesis.

Calcitonin gene-related peptide (CGRP): a new target for migraine

Migraine is a neurological disorder that manifests as a debilitating headache associated with altered sensory perception. The neuropeptide calcitonin gene-related peptide (CGRP) is now firmly established as a key player in migraine. Clinical trials carried out during the past decade have proved that CGRP receptor antagonists are effective for treating migraine, and antibodies to the receptor and CGRP are currently under investigation. Despite this progress in the clinical arena, the mechanisms by which CGRP triggers migraine remain uncertain. This review discusses mechanisms whereby CGRP enhances sensitivity to sensory input at multiple levels in both the periphery and central nervous system. Future studies on epistatic and epigenetic regulators of CGRP actions are expected to shed further light on CGRP actions in migraine. In conclusion, targeting CGRP represents an approachable therapeutic strategy for migraine.