A longitudinal study of cerebral glucose metabolism, MRI, and disability in patients with MS

Objective: To study the time-related changes in cerebral metabolic rate of glucose (CMRglc) in MS patients and to correlate these with changes in MRI lesion load and disability. Background: Measurements of MRI lesion load and neurologic disability are used widely to monitor disease progression in longitudinal studies of MS patients, but little is known about the associated changes in cerebral neural function. Methods: The authors studied 10 patients with clinically definite MS who underwent serial measurements of CMRglc, MRI T2-weighted total lesion area (TLA), and clinical evaluation of disability (Expanded Disability Status Scale [EDSS]) over a period of approximately 2 years (three examinations). CMRglc was calculated using PET and 18-fluorodeoxyglucose (FDG). Results: The global cortical CMRglc decreased with time (p < 0.001) and the most pronounced reductions of CMRglc were detected in frontal and parietal cortical areas. There was a statistically significant increase of disability (p < 0.01) and TLA (p < 0.05) measurements during the study, but changes in CMRglc were not correlated to changes in TLA and EDSS. Conclusions: Global cortical cerebral metabolism in MS is decreased significantly during a 2-year observation period, suggesting a deterioration of cortical activity with disease progression. The time-related changes of cortical CMRglc are statistically stronger than changes in TLA measurements and neurologic disability, and might be a useful secondary measure of treatment efficacy.