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

Local CBF (LCBF) and local partition coefficients (L lambda) 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 less than 0.01) and temporal (p less than 0.05) regions among both groups, but only in Group D were flow values decreased in putamen and thalamus (p less than 0.05). L lambda values were reduced in frontotemporal cortex among both groups but in the thalamus only among Group D (p less than 0.05). Mean white matter flow values were normal in Group I but were reduced in Group D (p less than 0.05). Mean partition coefficients for white matter were reduced in both groups (p less than 0.01) but were lower in Group D (p less than 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.