1/4. Residual cerebral activity and behavioural fragments can remain in the persistently vegetative brain.This report identifies evidence of partially functional cerebral regions in catastrophically injured brains. To study five patients in a persistent vegetative state (PVS) with different behavioural features, we employed [(18)F]fluorodeoxyglucose-positron emission tomography (FDG-PET), MRI and magnetoencephalographic (MEG) responses to sensory stimulation. Each patient's brain expressed a unique metabolic pattern. In three of the five patients, co-registered PET/MRI correlate islands of relatively preserved brain metabolism with isolated fragments of behaviour. Two patients had suffered anoxic injuries and demonstrated marked decreases in overall cerebral metabolism to 30-40% of normal. Two other patients with non-anoxic, multifocal brain injuries demonstrated several isolated brain regions with relatively higher metabolic rates, that ranged up to 50-80% of normal. Nevertheless, their global metabolic rates remained <50% of normal. MEG recordings from three PVS patients provide clear evidence for the absence, abnormality or reduction of evoked responses. Despite major abnormalities, however, these data also provide evidence for localized residual activity at the cortical level. Each patient partially preserved restricted sensory representations, as evidenced by slow evoked magnetic fields and gamma band activity. In two patients, these activations correlate with isolated behavioural patterns and metabolic activity. Remaining active regions identified in the three PVS patients with behavioural fragments appear to consist of segregated corticothalamic networks that retain connectivity and partial functional integrity. A single patient who suffered severe injury to the tegmental mesencephalon and paramedian thalamus showed widely preserved cortical metabolism, and a global average metabolic rate of 65% of normal. The relatively high preservation of cortical metabolism in this patient defines the first functional correlate of clinical- pathological reports associating permanent unconsciousness with structural damage to these regions. The specific patterns of preserved metabolic activity identified in these patients do not appear to represent random survivals of a few neuronal islands; rather they reflect novel evidence of the modular nature of individual functional networks that underlie conscious brain function. The variations in cerebral metabolism in chronic PVS patients indicate that some cerebral regions can retain partial function in catastrophically injured brains.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
2/4. coma vigil masquerading as psychiatric illness.A patient is described who had the hyperpathic variety of akinetic mutism (coma vigil), which was mistaken for a dissociative state. The case discussion emphasizes the importance of differentiating neuropsychiatric syndromes from those which are purely psychiatric in nature in order that appropriate treatment may be given.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
3/4. Computed tomographic findings in akinetic mutism.Brain-injured children who progress from coma to a sleeplike state of akinetic mutism are often misinterpreted by their parents as having improved. In children with akinetic mutism caused by extensive destruction of the cerebral gray matter, the computed tomographic scan may demonstrate the irreversible nature of the pathologic changes.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
4/4. Epileptic akinetic mutism: following temporal lobectomy for Rasmussen's syndrome.A girl aged 9 years with Rasmussen's encephalitis previously treated by left temporal lobectomy suddenly developed prolonged attacks of extremely rapid respirations associated with poverty of body movements and greatly reduced facial movements with loss of speech. Her comprehension appeared intact and she responded to certain requests. Her eye gaze behaviour suggested a high degree of vigilance. The attacks would last from minutes to hours and were repeated up to a dozen times daily. In the context of the stress generated by the illness and other family problems the attacks had been mistaken for an hysterical elaboration. Their ictal nature was confirmed by EEG/video monitoring. Possible links with other developmental language disorders associated with epilepsy are discussed, including a model of autism.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |