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Multiple Sclerosis (MS)

What is Multiple Sclerosis? Multiple sclerosis (MS) is an autoimmune disorder of the central nervous system. MS affects over 2 million people worldwide, predominantly females. MS can occur at any age. However, the age of onset is generally between 20 to 40 years. Those of European and African American ancestry have been found to have a higher prevalence of disease than those of East Asian and African descent, with an increasing prevalence in populations living further north.

What Causes MS?

The exact cause of the development of the disordered immune function in MS has not been elucidated. However, it is likely to be caused by interactions between several risk factors:

  • Genetic predisposition– There is a 35-75% chance of developing MS in those with affected biological relatives. There is also a strong correlation with inheritance of HLA-DRB1*15:01, and more than 150 polymorphisms associated with immune function are also implicated.
  • Environmental factors– Exposure to EBV, Vitamin D deficiency, and smoking have shown evidence of correlation in the development of disease, likely through influence on the functioning of the immune system.
  • Immune factors– Dysregulation of the immune system leading to inappropriate activation of TH1 and TH17 is hypothesized to play a role in the development of MS.

The symptoms of MS are the result of focal inflammation and injury to the blood-brain barrier and myelin causing the development of plaques, and microscopic injury to various parts of the neurons leading to neurodegeneration.

What are the Symptoms of MS?

As MS is characterized by lesions in different parts of the brain and at different times, several symptoms may manifest in MS, which may differ from person to person.

Classic symptoms of MS include:

  • Visual changes, such as loss of vision and diplopia, 
  • Vertigo and trouble with balance.
  • Trouble speaking or swallowing.
  • Motor difficulties, such as weakness, tremor, and spasticity of limbs
  • Sensory changes, such as loss of sensation and paresthesias.
  • Urinary or bowel incontinence difficulties.
  • Changes in cognition, including memory, concentration, and executive function.
  • Psychiatric symptoms, such as depression and anxiety.

The disease course of MS can also vary. Progression of MS is described as four possible phenotypes:

  • Clinically isolated syndrome
  • Relapsing-remitting
  • Secondary progressive
  • Primary progressive

Source: Dobson, R., & Giovannoni, G. (2018). Multiple sclerosis – a review. European Journal of Neurology, 26(1), 27–40. https://doi.org/10.1111/ene.13819