Neuronal metabolic changes in the cortical region after subcortical infarction: a proton MR spectroscopy study

Objectives-To investigate whether proton magnetic resonance spectroscopy (H-1 MRS) can detect neuronal metabolic changes in the cortical region in patients with cortical dysfunction after subcortical infarction. Methods-Fifteen patients with subcortical large (diameter greater than or equal to 20 mm) infarcts were studied; nine patients with cortical dysfunction (group A), and six without (group B). Seven patients with lacunar infarction served as controls. Infarct volume was measured on T2 weighted images with an image analyser. H-1 MRS data were obtained in three regions; high signal intensity area on T2 weighted image, overlying cortex with a normal T2 MRI appearance, and contralateral homologous cortical region. Results-Infarct volume was not different between groups A and B. N-acetylaspartate (NAA)/creatine+phosphocreatine (Cr) ratios in the cortical region overlying subcortical infarcts in group A were significantly lower than those in group B and the control group (p=0.002). The NAA/Cr ratios in the overlying cortex were significantly lower than those in the contralateral normal cortex in group A on the initial (p=0.015) and follow up (p=0.028) H-1 MRS, but these differences were not found in group B and the control group. Conclusions-The results support the idea that the cerebral cortex is a responsible location for cortical dysfunction after subcortical infarctions. H-1 MRS can be used as a sensitive method for the detection of a neuronal metabolic damage, which is not demonstrated by conventional MRI.