Multiple sclerosis

MS is a chronic immune-mediated disease, characterized by demyelinating lesions in the brain and spinal cord.

Demyelinating lesions are thought to result from migration of autoreactive lymphocytes across the blood-brain barrier, which triggers a cascade of inflammation with T- and B-cell clonal expansion and activation of microglia, leading to the development of characteristic plaque Genetic factors (HLA-DRB1 haplotype) and environmental factors (viruses, low vitamin D, distance from the equator) have been implicated.

The prevalence of MS varies markedly geographically. In the US, MS has an estimated prevalence of 149.2 persons per 100,000 population. Incidence has been estimated at 17.3 cases per 100,000 person-years in Western Europe.

The clinical manifestations of MS are wide ranging. Common presenting features include weakness, paresthesia or focal sensory loss, optic neuritis, diplopia, ataxia and vertigo. Autonomic dysfunction is common, and may manifest as bladder, bowel and sexual symptoms. Other manifestations can include painful muscle spasms, trigeminal neuralgia, fatigue and depression, subtle cognitive difficulties, psychiatric disturbances and seizures.

MS typically follows a relapsing and remitting course, but it can be progressive from disease onset, or can become progressive after initial remissions. The interval between relapses is variable. The latent phase between the first manifestation of MS and the first relapse can be many years.