Neuroimaging correlates of cognitive and functional outcome after traumatic brain injury

Magnetic resonance imaging (MRI) may provide an estimate of the severity of diffuse axonal injury by quantitative measurements of atrophy of white mat ter tracts (such as corpus callosum) and of ventricular enlargement (partic ularly the third ventricle). However, most MRI studies failed to reveal con sistent relationships between the pattern of neuropsychological impairments and the site and extent of focal structural lesions after traumatic brain injury. Functional neuroimaging techniques, such as positron emission tomog raphy or functional MRI, may reveal areas of cerebral dysfunction in region s that look structurally intact on MRI. Studies using these techniques have suggested that the cognitive and behavioural disturbances of traumatic bra in injury could be related to a defective activation of a prefrontal-cingul ate network. Curr Opin Neurol 13:665-669. (C) 2000 Lippincott Williams & Wi lkins.