Impact of inflammation on brain volume in multiple sclerosis.

Objective: To study changes in brain volume measured monthly in patients treated for relapsing multiple sclerosis due to loss of tissue and the appearance of inflammation.

Design And Patients: The results from T2/fluid-attenuated inversion recovery axial images from 13 consecutive monthly 3-T brain magnetic resonance imaging tests conducted on 74 patients diagnosed with relapsing multiple sclerosis in the BECOME study were used to calculate whole brain volumes using automated software analysis tools. The patients had been randomized to receive treatment with interferon beta-1b or glatiramer acetate. Ongoing inflammation was studied by counting the number of combined active lesions and measuring the volume of gadolinium enhancement. A mixed-effects model was used to analyze brain volumes over time.

Results: There was a significant decrease in brain volume over time but there was no difference in its rate of change by age, sex, frequency of ongoing inflammation, multiple sclerosis type, or randomized treatment assignment. The mean rate of brain volume change per month from multivariable models was -1.1 cm(3) (95% CI, -1.5 to -0.6) and during times of magnetic resonance imaging activity, it increased transiently by an average of 1.2 cm(3)/lesion (95% CI, 0.7 to 1.7) and 7.1 cm(3)/1 cm(3 )of gadolinium volume. In a model with both measures, combined active lesions were independent predictors of brain volume but gadolinium volume was not.

Conclusion: Two major changes in brain volume occur in patients with relapsing multiple sclerosis, a steady decrease likely due to tissue loss with overlapping transient increases due to the appearance of inflammation.