Multiple sclerosis (MS) is a potentially disabling disease of the central nervous system (brain and spinal cord). The Multiple Sclerosis International Federation (MSIF) estimates that about 2.8 million people worldwide have MS with the highest prevalence found in the northern hemisphere .
MS is an autoimmune condition. The immune system mistakenly attacks the myelin sheaths (the layers that surround and protect the nerves). The underlying nerves may also be affected. As a result, messages travelling along the nerves become slowed or disrupted (pathological substrate) [1,2].
MS symptoms vary widely and may include fatigue, blurred vision, weak limbs, numbness or tingling sensations, bladder dysfunction, difficulty with balance and co-ordination and problems with thinking, learning, and planning. Depending on the type of MS, symptoms may come and go (relapsing MS or relapsing-remitting MS) or steadily worsen over time (progressive MS) (types of MS) [1,2].
The exact cause of MS remains unclear, but most experts think a combination of genetic and environmental factors are involved [1,2].
Most people are diagnosed between the ages of 20 and 40 years, although onset may well occur earlier or later in life. MS affects two to three times as many women as men (see figure), suggesting a role of hormones in the disease process [1-3].
The female to male ratio of MS has changed over the years (US data)