Magnetoencephalography: Clinical application in epilepsy

Abstract

Magnetoencephalography (MEG) has developed to the point that it has now entered routine clinical application. Epilepsy MEG studies show that it can accurately localize spike sources--both ictal and interictal--as compared with both directly. Limitations involve difficulties in detecting complex or deep sources when recording spontaneous cerebral activity. MEG not only provides a novel tool to localize and characterize epileptiform disturbances, it also has an important role in determining the significance of abnormalities seen on both structural and functional imaging. Ultimately, MEG should play a major role in totally noninvasive epilepsy surgery evaluation.

The correlation of magnetoencephalography to intracranial EEG in localizing the epileptogenic zone: A study of the surgical resection outcome

“…MEG has a high temporal resolution (ms), which makes this tool valuable for localizing the epileptogenic zone (EZ) and assessing the spread of epileptic activity. Compared to the electric signals recorded by electroencephalography (EEG), the magnetic signals are minimally distorted, resulting in an improved spatial resolution that can be useful in directing epilepsy surgery resection (Ebersole, 1997;Baumgartner, 2000;Baumgartner and Pataraia, 2006;Pataraia et al, 2002;Knowlton, 2003;Wheless et al, 2004;Wu et al, 2006;Grondin et al, 2006;Ray and Bowyer, 2010). Unlike some pre-surgical procedures, identification of the seizure focus using MEG is not limited by the need for special preparation (e.g., ictal-SPECT) or by the state of recording (e.g., FDG-PET scan).…”

Combination of PET and Magnetoencephalography in the Presurgical Assessment of MRI-Negative Epilepsy

“…During the last 40 years, MEG instruments have evolved from a single-channel portable system to the modern whole head systems with more than 300 channels that are housed in multilayered shielded rooms. Moreover, validated source modeling procedures are now available in several commercial softwares, so that routine clinical use of MSI is now feasible ( 54 – 56 ).…”

Past, Current and Future Clinical Applications of MEG

“…Although there are many different sub-types of epilepsy, many of these manifest themselves as spontaneous, high-amplitude electrical activity and therefore are particularly well suited to detection via MEG. There are a number of excellent reviews of the role of MEG in the diagnosis and pre-surgical evaluation of epilepsy patients (for example da Silva, 2005;Knowlton, 2003;Tovar-Spinoza et al, 2008). As outlined in the introduction, the aim of this chapter is not to exhaustively describe the evidence for the effectiveness of MEG in the diagnosis of epilepsy, but to outline the progression of the analyses and methods used in the study of epilepsy and to highlight where this has been successful.…”