Cortical processing in persistent vegetative state.

to make judgments about awareness or consciousness based on these results; however, it is clear that she not only perceived visual stimuli, but also processed them to recognise content that was not based on primary image attributes such as colour, brightness, size, or movement. Further studies may more closely correlate functional imaging with behavioural assessment, electrophysiological findings, and eventual outcome. Effect of cervical spinal cord stimulation (cSCS) on cerebal glucose metabolism and blood flow in a vegetative patient assessed by positron emission tomography (PET) and single photon emission tomography (SPECT). Regional cerebral blood flow changes related to affective speech presentation in persistent vegetative state. Grady CL. The functional organization of human extrastriate cortex: a PET-rCBF study of selective attentions to faces and locations. Reductions in cerebral blood flow and glucose metabolism have been reported in patients in persistent vegetative state. 1 A few studies have suggested residual cortical activity. Objective assessment of residual cognitive function is difficult because motor responses may be small or inconsistent. We used positron emission tomography to study covert cognitive processing in a patient in a persistent vegetative state. A 26-year-old woman had an acute febrile illness and became comatose. Clinical findings and examination of cerebrospinal fluid were consistent with acute disseminated encephalomyelitis. Magnetic resonance imaging showed hyperintensity in the brainstem, and small foci of hyperintensity in both thalami and in the medial right temporal lobe on T2-weighted images. 4 months after admission, she had a tracheostomy, was fed through a gastrotomy, and was doubly incontinent. Her eyes opened spontaneously and she had sleep-wake cycles. Despite repeated examination, she showed no consistent spontaneous or elicited motor responses or eye movements to suggest she could communicate. Electroencephalograms were consistent with a thalamic lesion, complicated by possible cortical ischaemia. The pons and mid-brain components of the brainstem auditory evoked responses were abnormal on both sides, but a delayed auditory oddball P300 could be detected. Functional imaging studies were undertaken to look for evidence of preserved but covert cortical processing. Face-recognition was tested after a rapid infusion of H 2 15 O. Photographs of faces familiar to the patient were shown on a computer screen. Control images were generated by repixellating the same photographs to remove structure from the images. Subtraction of control from test images showed a significant focus of activation in the right fusiform gyrus (Brodmann's area 37), which spread ventrally to the most dorsal part of …