Role of Thalamus and White Matter in Cognitive Outcome after Head Injury

Abstract

Local CBF (LCBF) and local partition coefficients (LΛ) were measured by xenon-enhanced computed tomography among 15 patients with remote cerebral trauma resulting from severe head injury. Results were compared with similar measures among age-matched normal volunteers (N = 20). The patients were divided into two groups according to different outcomes based on serial cognitive testing: Group I (N = 10) improved but Group D (N = 5) deteriorated throughout a mean interval of 10 years of follow-up. Initial LCBF measurements were performed at mean intervals of 6.8 years after injury. Cortical LCBF values were decreased in frontal (p < 0.01) and temporal (p < 0.05) regions among both groups, but only in Group D were flow values decreased in putamen and thalamus (p < 0.05). LΛ values were reduced in frontotemporal cortex among both groups but in the thalamus only among Group D (p < 0.05). Mean white matter flow values were normal in Group I but were reduced in Group D (p < 0.05). Mean partition coefficients for white matter were reduced in both groups (p < 0.01) but were lower in Group D (p < 0.05). Reduced perfusion of frontotemporal gray matter is consonant with neuropathological reports following severe brain trauma of neuronal atrophy, gliosis, and infarction affecting these regions. Group comparisons between patients who cognitively improved versus those that deteriorated demonstrate an association between reductions of CBF in putamen, thalamus and subcortical white matter and impaired cognition after severe head injury.