Neural injury and recovery near cortical contusions: a clinical magnetic resonance spectroscopy study

Abstract

OBJECT: Proton magnetic resonance (MR) spectroscopy can detect neural metabolic alterations noninvasively after traumatic brain injury (TBI) even in areas that appear normal. Unlike metabolic depression in diffuse TBI, focal metabolic alterations near cortical contusions in humans have not been previously investigated in a longitudinal study. The object of this study was to identify these alterations and examine their course. METHODS: At 1 week and 1 month after mild to moderate TBI involving cortical contusion, 30 patients underwent 1H MR spectroscopy examination that focused bilaterally on normal-appearing frontal and temporal white matter. Levels of N-acetylaspartate (NAA), choline (Cho) compounds, and creatine (Cr) were measured to obtain two metabolite ratios, NAA/Cr and Cho/Cr. The ratios were compared with those of 11 healthy individuals. At 1 week after TBI, the NAA/Cr ratio was significantly lower near cortical contusions than it was in white matter remote from the injury or in controls, while the Cho/Cr ratios did not differ significantly. At 1 month, the decreased NAA/Cr ratios near contusions had increased significantly from 1 week, as had the Cho/Cr ratio. CONCLUSIONS: Metabolic depression reflecting neural injury was apparent in subjacent normal-appearing white matter at 1 week after cortical contusion; this had normalized substantially at 1 month.