FUNCTIONAL AND METABOLIC ANALYSIS OF CEREBRAL-ISCHEMIA USING MAGNETOENCEPHALOGRAPHY AND PROTON MAGNETIC-RESONANCE SPECTROSCOPY

The details of the relationship between brain function and metabolism in brain infarcts have not been studied. Using magnetoencephalography (MEG) and proton magnetic resonance spectroscopic imaging (H-1 MRSI), we localized sources of abnormal magnetic activities in ischemic brain regions and biochemical changes in suspected lesions showing patholog ical characteristics. Twelve patients with ischemic stroke were examin ed and the results of MEG and H-1 MRSI were superimposed onto the corr esponding MR images. The signal intensities of N-acetyl (NA) and lacta te (Lac) were measured in the lesions with highly concentrated dipoles of slow wave activity. Eleven of 12 cases had increased slow wave act ivity in the cortical areas adjacent to the infarcts; 1 case was exclu ded because the infarct was too small (<1 cm in diameter). The signal intensity of NA in the regions with the highest slow wave activity was significantly reduced and was well correlated with the dipole density of slow waves. Though Lac was mildly accumulated in the lesions, the Lac level had no correlation with slow wave magnetic activity. The rem aining and metabolically active cortical tissue showing NA signal prod uced the abnormal slow wave activity under lactic acidosis (mild accum ulation of Lac).