How Does Scarring Relate to Long-Term Disability in Multiple Sclerosis?

Patients with multiple sclerosis (MS) tend to develop permanent, moderately sized scarring following attacks or relapses, according to a study by the Mayo Clinic published in Neurology.

When these scars form in the areas of the central nervous system (CNS) that control peripheral limb musculature, the damaged nerve fibers are more vulnerable to further deterioration, leading to worsening symptoms and long-term disability within the secondary progressive course of MS.   

In this study, researchers compared 67 patients with MS to 51 patients with aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD) and 38 patients with myelin oligodendrocyte glycoprotein antibody-associated disorder (MOGAD). Like MS, these other diseases also involve autoimmune attacks on the body’s CNS, resulting in inflammation and demyelination.

However, the ability of patients with MS to repair neural lesions caused by attack episodes significantly differed from patients with AQP4-NMOSD and MOGAD. The regeneration capability of the latter 2 diseases is evidenced by less residual scarring on MRI imaging, as well as the lack of slow progressive disability development compared with MS.

AQP4-NMOSD resulted in large areas of inflammation during attacks, leading to severe acute symptoms; however, during recovery from these episodes, smaller scars form in locations that are less critical compared with MS in which moderate scars form in important CNS regions. As the inflammation resolves, long-term residual problems are less likely to occur from the minimal scarring left behind in AQP4-NMOSD.   

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Despite large regions of inflammation during attacks, CNS lesions resulting from MOGAD healed completely over time without leaving any trace of scarring. This corresponds with the excellent prognosis of full recoveries from attacks and lack of gradual progressively worsening long-term disability found in MS. MOGAD may provide clues in the development of treatments, which enhance and expedite nerve remyelination and prevent scar formation for patients with MS.

Former Mayo Clinic fellow Elia Sechi, MD, emphasized the important role of currently available MS medications, which effectively prevent MS attack episodes and, in turn, deter the development of new lesions and the resultant neural scarring. By hindering scar formation, these medications slow the progressive decline and long-term disability of patients with MS. 

Reference

Study may show why multiple sclerosis patients develop progressive disability. News release. Mayo Clinic; July 19, 2021.