Metabolic recovery following human traumatic brain injury based on FDG-PET: Time course and relationship to neurological disability

Objective: Utilizing [F-18]fluoroaeoxyglucose positron emission tomography (FDG-PET), we assessed the temporal pattern and the correlation of functional and metabolic recovery following human traumatic brain injury Design and Subjects: Fifty-four patients with injury severity ranging from mild to severe were studied. Thirteen of these patients underwent both an acute and delayed FDG-PET study Results: Analysis of the pooled global cerebral metabolic rate of glucose (CMRglc) values revealed that the intermediate metabolic reduction phase begins to resolve approximately one month following injury regardless of injury severity. The correlation, in the 13 patients studied twice, between the extent of change in neurologic disability, assessed by the Disability Rating Scale (DRS), and the change in CMRglc from the early to late period was modest (r = -0.42). Potential explanations for this rather poor correlation are discussed. A review of the pertinent literature regarding the use of PET and related imaging modalities, including single photon emission tomography (SPECT) for the assessment of patients following traumatic brain injury is given. Conclusion: The dynamic profile of CMRglc that changes following traumatic brain injury is seemingly stereotypic across a broad range and severity of injury types. Quantitative FDG-PET cannot be used as a surrogate technique for estimating degree of global functional recovery following traumatic brain injury.