Publication date: Oct 11, 2019
Multiple sclerosis (MS) is an autoimmune, acquired T cell-mediated neuro-inflammatory disorder that is marked by axonal degeneration and focal demyelination in the central nervous system (CNS).
In around 10% of patients, the disease is progressive, marked by the slow development of disability from onset.
Figure 1: Mechanisms of demyelination and axon degeneration in MS. The pathological characteristics of MS are demyelination, neuroinflammation, and axonal degeneration.
T2 weighted axial view of MRI brain scan from a patient with relapsing-remitting MS. Multiple white matter T2 hyperintense lesions are shown, in orientation and distribution typical for MS. Since 1865, when MS was first defined by Charcot, researchers and clinicians have considered the risk factors for developing MS. There is evidence of a polygenetic determinant of risk; specific human leukocyte antigen haplotypes bestow higher susceptibility.
Exposure to Epstein Barr virus over the course of an age-linked period of susceptibility is an environmental risk factor for MS. Furthermore, low vitamin D levels are associated with risk of relapse, and studies are evaluating whether vitamin D replacement impacts MS disease course.
The concept of disease activity is vital to the understanding of an inflammatory basis for MS relapses.
MR imaging with the potential to show subclinical CNS inflammation is a powerful tool in the measurement of disease activity (see Figure 3).
In addition, loss of CNS volume (atrophy), estimated between interval scans, is also associated with the slow accrual of disability in progressive disease.
In order to evaluate potential treatment effects on progressive disease, it is vital to measure disability.
Several licensed drug treatments are available for relapsing-remitting MS. These treatments minimize the burden of relapse.
Although there has been progress, no significant randomized control trial evidence is available to indicate that any of these treatments have a considerable effect on long-term disability.