Quantitative EEG responses to ischaemic arm stress in migraine

EEG Changes in Migraine-Can EEG Help to Monitor Attack Susceptibility?

Migraine is a highly prevalent brain condition with paroxysmal changes in brain excitability believed to contribute to the initiation of an attack. The attacks and their unpredictability have a major impact on the lives of patients. Clinical management is hampered by a lack of reliable predictors for upcoming attacks, which may help in understanding pathophysiological mechanisms to identify new treatment targets that may be positioned between the acute and preventive possibilities that are currently available. So far, a large range of studies using conventional hospital-based EEG recordings have provided contradictory results, with indications of both cortical hyper- as well as hypo-excitability. These heterogeneous findings may largely be because most studies were cross-sectional in design, providing only a snapshot in time of a patient's brain state without capturing day-to-day fluctuations. The scope of this narrative review is to (i) reflect on current knowledge on EEG changes in the context of migraine, the attack cycle, and underlying pathophysiology; (ii) consider the effects of migraine treatment on EEG features; (iii) outline challenges and opportunities in using EEG for monitoring attack susceptibility; and (iv) discuss future applications of EEG in home-based settings.

Application of EEG in migraine

Migraine is a common disease of the nervous system that seriously affects the quality of life of patients and constitutes a growing global health crisis. However, many limitations and challenges exist in migraine research, including the unclear etiology and the lack of specific biomarkers for diagnosis and treatment. Electroencephalography (EEG) is a neurophysiological technique for measuring brain activity. With the updating of data processing and analysis methods in recent years, EEG offers the possibility to explore altered brain functional patterns and brain network characteristics of migraines in depth. In this paper, we provide an overview of the methodology that can be applied to EEG data processing and analysis and a narrative review of EEG-based migraine-related research. To better understand the neural changes of migraine or to provide a new idea for the clinical diagnosis and treatment of migraine in the future, we discussed the study of EEG and evoked potential in migraine, compared the relevant research methods, and put forwards suggestions for future migraine EEG studies.

No indications for altered EEG oscillatory activity in patients with chronic post-burn itch compared to healthy controls

A large proportion of patients with burn injuries develop chronic itch, which impacts quality of life. The underlying pathophysiological mechanisms are poorly understood. This cross-sectional pilot study investigates whether altered cortical oscillatory processes are involved in chronic post-burn itch. Continuous electroencephalography (EEG) data were recorded during rest and stimulation of non-injured skin, inducing itch (histamine and electrical) and cold-pressor task pain for 15 adults with chronic post-burn itch and 15 matched healthy controls. Quantitative metrics comprised oscillatory power and peak frequencies in theta, alpha, and beta bands. No statistical differences between patients and healthy controls were found in oscillatory activity during rest or stimulation, with Bayesian analysis suggesting equivocal evidence. However, post-traumatic stress symptoms and duration of chronic itch may be associated with changes in oscillatory activity. A lack of differences in cortical oscillatory processing and itch levels at non-injured sites, suggests that itch symptoms have a localised character in this sample of patients with post-burn itch. For future studies, a biopsychological approach with integration of peripheral and central nervous system techniques, linear and non-linear EEG analysis, injured and non-injured stimulation sites, and incorporation of individual characteristics is recommended. Insight into pathophysiological mechanisms underlying chronic post-burn itch could improve diagnostics and treatments.

Effect of attention bias modification on brain function and anxiety in patients with irritable bowel syndrome: A preliminary electroencephalogram and psycho-behavioral study

BACKGROUND

Gastrointestinal symptoms of irritable bowel syndrome (IBS) show a reciprocal relationship with anxiety. In this intervention-based study, we investigated the utility of attention bias modification (ABM) therapy in patients with IBS. We hypothesized that IBS-related electroencephalographic abnormalities would be normalized after ABM therapy.

METHODS

Seventeen patients with IBS and 13 healthy subjects completed five ABM intervention sessions over a 2-month period. Each session included 128 ABM trials, resulting in a total of 640 trials across the intervention period. For each trial, subjects viewed a pair of facial expression images and were instructed to indicate the position of the neutral face as quickly and accurately as possible by pressing one of two buttons on a button box. Electroencephalography data (alpha and beta power percentages) were collected during the 1st and 5th sessions.

KEY RESULTS

Generalized estimating equations of relative alpha power revealed a significant effect of period was identified at O2 (P=.036). Paired t tests revealed that ABM significantly increased relative alpha power at O2 in patients with IBS. Generalized estimating equation of relative beta power revealed a significant effect of the group × period interaction was identified at Pz (P=.035). Paired t tests revealed that ABM significantly decreased relative beta power at Pz in patients with IBS.

CONCLUSIONS & INFERENCES

Attention bias modification may normalize brain function related to attention and anxiety in patients with IBS.

Quantitative EEG in patients with alcohol-related seizures

BACKGROUND

To investigate whether quantitative electroencephalography (QEEG) recorded within a few days after a generalized seizure can improve the discrimination between alcohol-related seizures (ARSs), seizures in epilepsy and other seizures. In addition, we wanted to evaluate the influence of various external factors on QEEG, e.g., drug use, time from seizure occurrence, and alcohol intake.

METHODS

An ARS was defined by (i) scores ≥8 in the Alcohol Use Disorders Identification Test (AUDIT) and (ii) no history of epilepsy. Twenty-two ARS patients, 21 epileptic patients with seizures (ES), 30 AUDIT-negative patients with seizures (OS), and 37 well-controlled epileptic outpatients (EPO) were included. EEG from 79 sciatica patients (SC) served as an additional control group. EEG was recorded in relaxed wakefulness with eyes closed. Spectral analysis of ongoing resting EEG activity was performed. For the main analysis, spectral band amplitudes were averaged across 14 electrodes.

RESULTS

Major quantitative EEG abnormalities were mainly seen in the ES group. AUDIT score correlated negatively with QEEG band amplitudes in patients with seizures unrelated to alcohol, but not in the ARS group. Recent alcohol intake correlated negatively with delta and theta amplitude. We could not confirm that beta activity is increased in ARS subjects.

CONCLUSIONS

A QEEG with slightly reduced alpha amplitude supports a clinical diagnosis of ARS. An abnormally slow QEEG profile and asymmetry in the temporal regions indicates ES. QEEG predicted the clinical diagnosis better than standard EEG.

Interictal quantitative EEG in migraine: a blinded controlled study

Abnormal electroencephalography (EEG) in migraineurs has been reported in several studies. However, few have evaluated EEG findings in migraineurs during a time period when neither the last attack nor the next attack may interact with the results. We, therefore, compared interictal EEG in migraineurs and headache-free subjects with a design controlled for interference by pre-ictal changes. Pre-ictal EEG findings in the painful cranial side during the next attack after registration were also investigated. Correlations between clinical variables and EEG are reported as well. Interictal EEGs from 33 migraineurs (6 with and 27 without aura) and 31 controls were compared. Absolute power, asymmetry and relative power were studied for delta, theta and alpha frequency bands in parieto-occipital, temporal and fronto-central areas. EEG variables were correlated to attack frequency, headache duration, attack duration, pain intensity, photo- and phonophobia. Compared with controls, migraineurs had increased relative theta power in all cortical regions and increased delta activity in the painful fronto-central region. Absolute power and asymmetry were similar among groups. In age-adjusted analyses, headache intensity correlated with increased delta activity. In this blinded controlled study, we found globally increased relative theta activity in migraineurs. A slight interictal brain dysfunction is probably present between attacks.

Voxel-based morphometry reveals gray matter abnormalities in migraine

BACKGROUND

Migraine is generally considered a functional brain disorder lacking structural abnormalities. Recent magnetic resonance imaging (MRI) studies, however, suggested that migraine may be associated with subtle brain lesions.

OBJECTIVE

We evaluated the presence of global or focal gray or white matter alterations in migraine patients using voxel-based morphometry (VBM), a fully automated method of analyzing changes in brain structure. VBM data also were used to evaluate possible differences between episodic and chronic migraine.

METHODS

Twenty-seven migraine right-handed patients and 27 healthy controls were selected for the study. Sixteen patients fulfilled the International Headache Society criteria for episodic migraine and 11 for chronic migraine. MRI scans were analyzed with MATLAB 6.5 and SPM2 software, using VBM method.

RESULTS

In comparison with controls, migraineurs presented a significant focal gray matter reduction in the Right Superior Temporal Gyrus, Right Inferior Frontal Gyrus, and Left Precentral Gyrus. Chronic migraine patients, compared to episodic, showed a focal gray matter decrease in the bilateral Anterior Cingulate Cortex, Left Amygdala, Left Parietal Operculum, Left Middle and Inferior Frontal Gyrus, Right Inferior Frontal Gyrus, and bilateral Insula. Considering all the migraine patients, a significant correlation between gray matter reduction in anterior cingulate cortex and frequency of migraine attacks was found.

CONCLUSIONS

Our study shows that migraine is associated with a significant gray matter reduction in several of the cortical areas involved in pain circuitry. In addition, we found a significant correlation between frequency of migraine attacks and signal alteration in the Anterior Cingulate Cortex. Our data provide new insight into migraine pathophysiology and support the concept that migraine may be a progressive disorder.

Effect of alpha-helical CRH on quantitative electroencephalogram in patients with irritable bowel syndrome

Patients with irritable bowel syndrome (IBS) may have a higher tone of corticotropin-releasing hormone (CRH) in the brain. We tested our hypothesis that peripheral administration of CRH antagonist, alpha-helical CRH(9-41) (alphahCRH), improves decreased alpha power spectra and increased beta power spectra of electroencephalogram (EEG) in IBS patients. A barostat bag was inserted to the descending colon of 10 normal controls and 10 IBS patients. The EEG power spectra and topography were measured during baseline period and colonic distention period with the administration of saline followed by the administration of 10 microg kg(-1) of alphahCRH. IBS patients showed a significantly lower alpha power percentage and a higher beta power percentage than normal controls during baseline. Colonic distention induced a decrease in the alpha power percentage and an increase in the beta power percentage in both groups without difference between groups. After the administration of alphahCRH, changes in the EEG power spectra in response to colonic distention were blunted and the differences in the EEG power spectra between IBS patients and controls vanished. Peripheral administration of alphahCRH almost normalized EEG activities in IBS patients. Our data strongly suggest that CRH plays an important role in IBS.

Neurophysiological reactivity before a migraine attack

Migraine patients are characterized by increased amplitudes and reduced habituation of the contingent negative variation (CNV) response, especially before a migraine attack. As shown previously, migraine provoking and precipitating agents can cause CNV abnormalities. However, it is unclear whether the temporal relation to the migraine attack determines how the brain reacts to a migraine precipitant. In this study, experimentally-induced achievement stress, one of the typical precipitants for migraine, was examined for its effects upon the CNV response. CNV was recorded during conditions of rest and stress, both before and after a migraine attack, as well as during a headache-free interval. The neurophysiological reactivity to stress in migraineurs was compared with those of healthy subjects. Before a migraine attack, migraine patients demonstrated significantly more pronounced neurophysiological reactivity to stress: the amplitude of the early CNV component was more increased and its habituation was more reduced in the stress condition, especially 1-3 days before an attack compared with changes of CNV amplitudes and habituation under stress obtained after an attack, during the headache-free interval, or in healthy controls. The study demonstrates that the brain of migraine patients is characterized by increased susceptibility to migraine provoking agents before an actual attack.