A voxel based correlation analysis of fronto-thalamic glucose metabolism in traumatic brain injury: relationship with conscioussnes and cognition

Autores UPV
Año
CONGRESO A voxel based correlation analysis of fronto-thalamic glucose metabolism in traumatic brain injury: relationship with conscioussnes and cognition

Abstract

Objective: To study the correlation between frontal and thalamic glucose metabolism in a sample of severe traumatic brain injury (TBI) patients with different neurological outcome. Methods: We studied 49 patients who had suffered a severe TBI, and ten healthy control subjects, with PET using 18F-FDG as tracer. All the patients were divided into the following three groups according to their level of consciousness and cognition: group A) (n=17), patients in a vegetative or a minimally conscious state; group B) (n=12), patients in post-traumatic amnesia (PTA); and group C) (n=20) patients who have emerged from PTA. SPM5 software implemented in MATLAB 7 was used for spatial pre-processing and analysis and to determine the quantitative differences between TBI patients and age-matched normal controls. FDG-PET images were spatially normalized to a standard template and two automated region of interest masks were generated around the thalamus and the frontal lobes (orbitofrontal, dorsolateral and frontomedial). The groups were parametrized with one sample voxel- wise T-test. Principal Component Analysis (PCA) was used to obtain an intensity- estimated-value by subject. Last step was applying correlation of PCA values between thalamus and frontal lobes. Results: Frontal and thalamic metabolism was related to the neurological status of our patients with most severe patients showing most severe hipometabolism. We also found a significant correlation between thalamic and frontal lobe metabolism in all our patients (group C 0.72, group B 0.77 and group A 0.64). In healthy control subjects we obtain a lower correlation (0.32) Conclusions: Voxel-based analysis demonstrates a functional connectivity between frontal cortex and thalamus, with decreasing metabolism in both areas, depending on the neurological outcome. Differences in thalamocortical metabolism correlations between patients and controls may be related to the loss of information due to focal or diffuse lesions generated after TBI, which may reduce the functionality of the system as a whole.