Abstracts

In the last decade MEG has proven to be a valid clinical tool when a detailed characterization of eloquent cortex is needed in the presurgical context. In this report we summarize our experience after more than 800 procedures applying MEG to derive maps of language and sensorimotor functions., Our clinical experience using MEG in the last 6 years for presurgical functional mapping is summarized. We describe the clinical procedures applied to derive function-specific maps of activation and our experience in testing the clinical validity of these MEG-derived maps. The results of direct comparison with [ldquo]gold standard[rdquo] procedures for determination of hemispheric dominance (100 cases) and precise localization of language specific cortex (53 cases) are presented. Intra- and extraoperative confirmation of MEG-derived maps of sensorimotor function are described., MEG studies in patient have demonstrated that language mapping using specific activation protocols and data analysis procedures, produces estimates of language laterality that closely match the Wada-derived ones. These promising results are further reinforced by the fact that the MEG-derived brain activation maps were shown to be valid and extremely accurate through comparisons with the results of intraoperative and extraoperative direct cortical stimulation mapping in individual patients. MEG has proven to be a reliable and clinically valid instrument for characterization of receptive language and sensorimotor functions. A reliable procedure for mapping expressive aspect of linguistic function remains to be developed and validated., Direct recordings of neurophysiological signals using MEG can help to identify [ldquo]essential[apos] function-specific cortex and be a valid clinical tool to prevent functional morbidity in patients undergoing brain surgery.,