Multiple sclerosis is a chronic autoimmune disease affecting the central nervous system characterized by inflammation, demyelination and axonal injury. It affects approximately 2.5 million people worldwide with a typical diagnosis being established in the age of 20 – 50 years. Women are 2-3 times more likely to get the disease than men and in general it is more common in colder climates although it can affect all ethnic groups1,2,3. Diagnosis is based on the clinical presentation and following the McDonald criteria for imaging and laboratory investigations. Patients are classified into four types of multiple sclerosis although boundaries between the groups can be sliding. The most common type is relapsing-remitting multiple sclerosis (RRMS) which affects approximately 85% of patients. These patients experience worsening of existing symptoms or new symptoms lasting for more than 48 hours – such attacks are called relapses. In between, the patients have periods where they are partially or completely symptom free – called remissions. Patients who start with RRMS may develop a steady progression into secondary progressive multiple sclerosis (SPMS) that over some years progress into manifest disease without clear relapse episodes. Primary progressive multiple sclerosis (PPMS) is relative rare and affect up to 10% of patients. This type of MS is characterized by a steady progressive disease without clear relapses. The last type is progressive relapsing multiple sclerosis (PRMS) and is the rarest form affecting about 5% of patients. This type is characterized by a progressive disease with clear relapse exacerbations of the disease.
1 Gawronski KM et al., Treatment Options for Multiple Sclerosis: Current and Emerging Therapies. Pharmacotherapy. 2010 Sep;30(9):916-27. Link
2 National Multiple Sclerosis Society. Just the facts. Link
3 Kim SE et al., Daclizumab treatment for Multiple Sclerosis. Pharmacotherapy. 2009 Feb;29(2):227-35. Link
4 Polman CH et al, Diagnostic criteria for Multiple Sclerosis: 2005 revisions to the “McDonald Criteria”. Ann Neurol. 2005 Dec;58(6):840-6. Link