Transcranial Magnetic Stimulation Combined with EEG Reveals Covert States of Elevated Excitability in the Human Epileptic Brain

Kimiskidis, Vasilios Κ.; Koutlis, Christos; Tsimpiris, Alkiviadis; Kälviäinen, Reetta; Ryvlin, Philippe; Kugiumtzis, Dimitris

doi:10.1142/s0129065715500185

Cited by 25 publications

(17 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The combined use of TMS and EEG has shown great promise in studies of the brain in health and in disease by informing us about cortical excitability, connectivity, and dynamic state [2,12,13,[35][36][37][38]. However, artifacts, especially those from scalp muscles, have limited the use of this technique to areas of the head with no musculature or to latencies where muscle artifacts no longer disturb the analysis.…”

Section: Discussionmentioning

confidence: 99%

“…Futhermore, it found that connectivity is drastically weakened in lowered states of consciousness such as deep sleep [5] or coma [11][12]. More recently, progress has been made in developing TMS-EEG for diagnostic purposes, in particular in the case of epilepsy [13]. However, we are still in many cases limited to stimulating areas away from cranial muscles or to studying responses at latencies when the TMS-evoked muscle activity has ceased.…”

Section: Tms-eegmentioning

confidence: 99%

See 1 more Smart Citation

Dealing with artifacts in TMS-evoked EEG

Ilmoniemi

Hernandez-Pavon

Mäkelä

et al. 2015

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Tms-eegmentioning

confidence: 99%

Dealing with artifacts in TMS-evoked EEG

Ilmoniemi

Hernandez-Pavon

Mäkelä

et al. 2015

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

View full text Add to dashboard Cite

show abstract

“…Furthermore, several groups have identified EEG correlates of the paired-pulse TMS-EMG metrics that are abnormal in patients with epilepsy 20,21 . Of particular relevance, previous studies have also suggested that abnormal stimulation-evoked EEG activity is seen in patients with epilepsy 22-25 .…”

Section: Introductionmentioning

confidence: 92%

A Multimodal Imaging- and Stimulation-based Method of Evaluating Connectivity-related Brain Excitability in Patients with Epilepsy

Shafi

Whitfield-Gabrieli

Chu

et al. 2016

JoVE

View full text Add to dashboard Cite

Resting-state functional connectivity MRI (rs-fcMRI) is a technique that identifies connectivity between different brain regions based on correlations over time in the blood-oxygenation level dependent signal. rs-fcMRI has been applied extensively to identify abnormalities in brain connectivity in different neurologic and psychiatric diseases. However, the relationship among rs-fcMRI connectivity abnormalities, brain electrophysiology and disease state is unknown, in part because the causal significance of alterations in functional connectivity in disease pathophysiology has not been established. Transcranial Magnetic Stimulation (TMS) is a technique that uses electromagnetic induction to noninvasively produce focal changes in cortical activity. When combined with electroencephalography (EEG), TMS can be used to assess the brain's response to external perturbations. Here we provide a protocol for combining rs-fcMRI, TMS and EEG to assess the physiologic significance of alterations in functional connectivity in patients with neuropsychiatric disease. We provide representative results from a previously published study in which rs-fcMRI was used to identify regions with abnormal connectivity in patients with epilepsy due to a malformation of cortical development, periventricular nodular heterotopia (PNH). Stimulation in patients with epilepsy resulted in abnormal TMS-evoked EEG activity relative to stimulation of the same sites in matched healthy control patients, with an abnormal increase in the late component of the TMS-evoked potential, consistent with cortical hyperexcitability. This abnormality was specific to regions with abnormal resting-state functional connectivity. Electrical source analysis in a subject with previously recorded seizures demonstrated that the origin of the abnormal TMS-evoked activity co-localized with the seizure-onset zone, suggesting the presence of an epileptogenic circuit. These results demonstrate how rs-fcMRI, TMS and EEG can be utilized together to identify and understand the physiological significance of abnormal brain connectivity in human diseases.

show abstract

“…We suggest that relaxing the pre-ictal state detection problem to a pro-ictal (high seizure susceptibility) state detection problem might prove crucial, followed by a biological and theoretical characterization of such pro-ictal states. Some experimental (Badawy et al, 2009;Kimiskidis et al, 2015) and theoretical evidence already exists, on which future work can build. Furthermore methods of deriving model parameters from data have been developed (Freestone et al, 2011;Ullah and Schiff, 2009), enabling the possibility of model-based design of patient-specific closed-loop stimulation protocols for the pro-ictal state.…”

Section: Figurementioning

confidence: 99%