Significance of white matter abnormalities in patients with closed head injury

Neuroimaging in patients with closed head injury (CHI) may frequently reveal abnormalities of white matter. Because white matter abnormalities may be seen in patients aged over 40 years even without CHI, the significance of these abnormalities in patients with CHI is questionable and needs to be assessed in the context of relevance to clinical outcome. The aims of this study were to determine the relative incidence of white matter abnormalities in a group of patients with CHI, and to assess the impact (if any) of these abnormalities on clinical outcome. Sixty-three patients with CHI underwent neuroimaging with magnetic resonance imaging (MRI) and regional cerebral blood flow (rCBF) single photon emission tomography (SPET) approximately 6 months after trauma. Seven patients had white matter abnormalities on MRI scanning. There are no rCBF SPET criteria for defining abnormal perfusion to the white matter. The SPET scans ranged from normal (one patient) and abnormal perfusion to frontal, temporal or parietal lobes in these patients (n = 6). Patients were assessed for outcome after undergoing appropriate rehabilitation programmes with indices of reintegration into the community, activities of daily living, disability, and their cognitive ability to perform tasks. This assessment was conducted 2 years after initial trauma. Of these seven patients with abnormal MRI of the white matter, one performed poorly and six had moderate to good clinical outcome. When individual lobar perfusion is considered, abnormal perfusion to the frontal or temporal lobes was significantly associated with poorer outcome (P < 0.005). In conclusion, white matter abnormalities detected by MRI are frequently associated with cortical perfusion defects identified by SPET (6/7 or 86%). However, when these white matter abnormalities were accompanied by perfusion defects in the frontal and temporal lobes, these were statistically significant in predicting poorer outcome.