Authors:

Coleman, M., SHIEL, A., Fryer, T., Gelling, L., Menon, D, WILSON, B., Pickard, J.D. & Boniface, S.

Reference:

Year of publication:

2003

CBU number:

5815

Abstract:

Some brain injury patients regain consciousness slowly following withdrawal of sedation. Understanding why recovery is slow (if at all) is very limited. The aim of this study was to investigate the relationship between the integrity of neurometabolic coupling (the homeostatic link between neuronal electrical activity and cerebral metabolism) and patients' behavioural ability. Methods: Five heterogeneous patients (3 female: mean age 58.4, range 41-80 years) were studied 11-30 days after withdrawal of sedation. Each was studied with positron emission tomography (PET) using an 18F-fluorodeoxyglucose protocol. Immediately after, an electroencephalogram (double-banana montage) was obtained (bandpass 0.1-70 Hz). Using in house software spatially normalised maps of the cerebral metabolic rate of glucose utilisation were calculated. The correspondence between neuronal electrical activity and cerebral glucose metabolism was analysed using the method of Leuchter et al., (1999). Behavioural ability was assessed using the WHIM on the day of scanning and four weeks later. Results: The integrity of neurometabolic coupling was strongly related to each patient's behavioural ability on the day of investigation and 4 weeks later. However, when measures of neuronal electrical function or cerebral metabolism were individually compared with WHIM scores, neither showed any association. Conclusions: These findings provide a new insight into the patho-physiological sequelae of coma suggesting the important homeostatic relationship between electrical function and cerebral metabolism may be related to recovery. Such findings highlight the need for neuroprotective strategies, which target the integrity of neurometabolic coupling.