Understanding Multiple Sclerosis (MS)

What is MS?

Multiple sclerosis (MS) is a neurodegenerative disorder caused by the immune system mistakenly attacking the myelin sheath, a protective coating around nerve fibers. This results in inflammation, which further damages the myelin sheath, as well as the nerve cells themselves and the cells that produce myelin.

What are the types of MS?

There are four types of MS, broadly classified based on disease progression.

Clinically isolated syndrome

Clinically isolated syndrome represents a single event, the first episode of neurological symptoms that typically precedes relapsing forms of MS. On its own, a single event is not enough to define MS, unless patients have evidence of several lesions in their brains. That’s what the “multiple” refers to in “multiple sclerosis.”

Relapsing-remitting multiple sclerosis

Relapsing-remitting multiple sclerosis (RRMS) is the most common type of MS. Patients experience attacks of increasing neurological symptoms, called exacerbations or relapses, followed by periods of partial or complete recovery, called remissions. At various times, patients may have active, not active, or worsening neurological symptoms.

Secondary progressive multiple sclerosis

Secondary progressive multiple sclerosis (SPMS) is the secondary stage of MS that follows RRMS. Patients may have relapsing-remitting episodes initially, but then they experience a steady worsening of neurological symptoms over time that may be accompanied by occasional relapses.

Primary progressive multiple sclerosis

Primary progressive multiple sclerosis (PPMS) affects about 15% of MS patients. Instead of periods of relapses followed by remission, people with PPMS experience a steady decline in neurological function without relapses from the onset of symptoms.