Proton MR spectroscopic findings correspond to neuropsychological function in traumatic brain injury.

BACKGROUND AND PURPOSE Traumatic brain injury (TBI) causes substantial irreversible damage to neurons. Our aim was to investigate whether proton MR spectroscopic measures of diffuse cellular integrity were related to neuropsychological dysfunction after TBI.

METHODS Twelve patients with TBI (mean, 53 +/- 23 days postinjury) and 14 control subjects were included in the study using paired MR spectroscopy and neuropsychological assessment. N-acetylaspartate (NAA), creatine, and choline were measured in normal-appearing occipitoparietal white and occipital gray matter using short-echo quantitative spectroscopy. A composite measure of neuropsychological function was calculated from z-scored individual tests probing the major functional domains commonly impaired after head trauma.

RESULTS Patients with TBI displayed reduced NAA in white matter and elevated choline in gray matter, suggestive of neuronal injury and inflammation, respectively. NAA and creatine in white and gray matter were significantly associated with composite neuropsychological function and many individual neuropsychological tests. Gray matter choline, although abnormal, was not related to neuropsychological function.

CONCLUSION The concordance between neurometabolic levels and behavioral function supports the hypothesis that diffuse axonal injury is an important contributor to brain dysfunction after TBI.