11th August 2024

Overview of multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated demyelinating condition of the central nervous system, clinically defined as two or more episodes of neurological dysfunction affecting the brain, spinal cord or optic nerves separated in time and space. The hallmark of MS is symptomatic episodes of demyelination occurring months to years apart and affecting different anatomical locations.

The cause of MS is unknown, but it likely involves a combination of genetic factors, making some individuals more susceptible to the disease. Non-genetic triggers such as a preceding viral infection or low vitamin D levels can also cause an autoimmune response against myelinated axons in the CNS.  A characteristic feature of MS is the periventricular infiltration of lymphocytes and macrophages.

There is a marked geographic variation in the incidence of MS with the incidence being lower in equatorial regions, which supports the probability of an environmental trigger. MS classically presents in white women between the ages of 20 and 40.