Introduction: Considerable evidence supports that magnetoencephalography (MEG) can be a valuable noninvasive tool for presurgical mapping eloquent brain areas. In this study we present the UPMC Brain Mapping Center’s initial experiences with presurgical brain mapping using MEG.
Methods: Between September 2010 and March 2011, ten patients with brain tumors underwent presurgical mapping using MEG. Sensory (median nerve stimulation), motor (index finger lift), auditory, aurally-presented language, and visually-presented language paradigms were used, Single dipoles were chosen to represent each identified average MEG peak, which were then projected on the coregistered MRI.
Results: The results suggest that somatosensory and auditory responses found in all ten patients and were localized to cortical area were robust and repeatable. For primary sensory cortex the peak was found to be at an average time point of 56ms (range: 43.2ms to 65ms), the mean goodness of fit was 96.3% (range: 93.9% to 98%) and the mean confidence volume was 279.3mm³ (range: 3mm³ - 982.1mm³). For primary auditory cortex the peak was found to be at an average time point of 130ms (range: 113.5ms to 160ms), the mean goodness of fit was 95.5% (range: 93.3% to 96.9%) and the mean confidence volume was 42mm³ (range: 6.8mm³ - 77.7mm³). Motor activity was inconsistently localizable, found only in a subset of patients, but when identified the response bore a consistent localization pattern. Language localizations also exhibited a large degree of individual variability, but also depended on which pathway the paradigm targeted (visual or auditory).
Conclusions: The results suggest that while somatosensory and auditory responses are fairly robust and repeatable, motor and language localizations are more challenging. Overall, results presented here represent the successes and pitfalls of our initial experience with pre-surgical planning using MEG.
Patient Care: Use of MEG based mapping can reduce the risk of surgical morbidity for tumors in critical brain locations
Learning Objectives: To understand the concept of magnetoencephalography (MEG)
To understand the advantages brain mapping using MEG