Evaluation and Proposal for Optimalization of Neurophysiological Tests in Migraine: Part 1—Electrophysiological Tests

Abstract

Neurophysiological testing has become a valuable tool for investigating brain excitability and nociceptive systems in headache disorders. Previous reviews have suggested that most neurophysiological tests have limited value for headache diagnosis, but a vast potential for exploring the pathophysiology of headaches, the central effects of certain pharmacological treatments and phenotype-genotype correlations. Many protocols, however, lack standardization. This meta-analytical review of neurophysiological methods in migraine was initiated by a task force within the EUROHEAD project (EU Strep LSHM-CT-2004-5044837-Workpackage 9). Most of the neurophysiological approaches that have been used in headache patients are reviewed, i.e. evoked potentials, nociception-specific blink reflex, single-fibre electromyography, neuroimaging methods (functional MRI, PET, and voxel-based morphometry) and the nitroglycerin attack-provoking test. For each of them, we summarize the results, analyse the methodological limitations and propose recommendations for improved methodology and standardization of research protocols. The first part is devoted to electrophysiological methods, the second to neuroimaging techniques and the NTG test.

Altered processing of sensory stimuli in patients with migraine

“…Interictal thalamocortical dysrhythmia causes hyperresponsivity of sensory cortices (3) as well as abnormal pain processing (4). The thalamocortical dysrhythmia itself may be induced by decreased control from brainstem monoaminergic nuclei (5). Cortical hyperresponsivity combined with a decreased mitochondrial energy reserve favours metabolic strain (6).…”

“…3,4 The temporal precision and noninvasiveness of electro physiological methods make them particu larly well suited to study of the cyclic functional brain changes associated with migraine. 5 Investigators using these techniques have demonstrated that the migrainous brain has altered functioning between migraine attacks, and that this brain dysfunction undergoes cyclic changes up to initiation of the attack. 6 Various electrophysiologi cal parameters have been studied in migraine research, including multimodal evoked potentials, steady state visual evoked responses, noxious evoked cortical responses, and nociceptive reflexes.…”

Correlation between habituation of visual-evoked potentials and magnetophosphene thresholds in migraine: A case-control study

“…The brain structures involved in the pathophysiology of migraine include the cerebral cortex, the brainstem, the hypothalamus, the thalamus and the trigeminovascular system. The exact sequence of activation of these structures before, during, and after a migraine attack is still unknown (2,4 (5). A reduced habituation of cortical-evoked responses to repeated stimuli was the first reproducible physiological brain abnormality found interictally in migraine patients (6).…”

Analysis and clinical correlates of 20 Hz photic driving on routine EEG in migraine

“…Mean PD power was numerically higher in CM patients with medication overuse (n=37; 7.48±2.65 μV 2 ) compared to CM without such overuse (n=11; 5.34 ± 3.92μV 2 , p= 0.40).…”

“…These intricate phenomena are responsible for the multifaceted clinical features of the disorder and especially repetition of attacks as part of a cycling ictalinterictal temporal profile [1]. Electrophysiological methods are particularly suited to study the functional and cycling brain changes associated with migraine pathophysiology [2]. Given the increased sensitivity to light between, and even more so during migraine attacks, many studies have focused on the EEG responses induced by repetitive light stimuli: photic driving (PD), steady-state visual evoked responses (SSVEPs), visual evoked potentials, or more recently visual-induced changes in connectivity for various EEG frequency bands [4,5].…”