The expansion of chronic white matter lesions in people with relapsing-remitting multiple sclerosis (RRMS) determined the increase in total lesion volume and significantly contributed to disease progression, a study has revealed.
The study, “Expansion of chronic lesions is linked to disease progression in relapsing-remitting multiple sclerosis patients,” was published in the Multiple Sclerosis Journal.
MS is characterized by inflammatory demyelination — loss of myelin, the protective coat of nerve fibers — that presents as new lesions in the white matter of the brain and is the primary cause of nerve fiber (axon) damage.
While new lesion activity is typically measured as changes to the combined volume of new lesions plus the growth of pre-existing (chronic) lesions, recent evidence suggest that mechanisms underlying the formation of new lesions are different from the ones involved in the slow expansion of chronic lesions.
Examination of chronic lesions found an inactive core surrounded by a rim of inflammation, ongoing demyelination, and axon damage. This slow-burning inflammation at the edge of chronic MS lesions may be associated with lesion expansion leading to the progressive loss of axons and worsening disability.
To investigate further, a team led by researchers based at The University of Sydney in Australia examined the incidence and extent of the growth of chronic white matter lesions in 33 people with RRMS followed for five years.
The average age of participants (13 men and 20 women) was 42.6 years, with an average disease duration of 6.5 years. All patients were receiving disease-modifying therapies except one. MRI scans and clinical assessments were conducted in the pre-study period (0 months) to find new lesions, and at 12 months (baseline) and 60 months (follow-up).
Of the 569 lesions identified as chronic at baseline, 261 (46%) were classified as expanding lesions, 236 (42%) were stable, and 72 (12%) were shrinking. Also, 139 new lesions were detected.
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