What is multiple sclerosis?
Multiple sclerosis (MS) is a disease of the nervous system in which the protective myelin sheath that surrounds the nerves in the brain and spinal cord is broken down. This breakdown causes scarring and prevents impulses being sent along the affected nerves. Currently, there is no cure for MS and management of the disease centers around relieving the symptoms. MS is the most common disease of the nervous system (neurological disease) affecting young adults. The average age at which people are diagnosed is between 20 and 40 years. Women are twice as likely as men to be affected by the disease. MS may progress continually over time but in many cases it follows a pattern of alternating periods of relapse (symptom flare-up) and remission (recovery)—called relapsing-remitting MS. MS does not usually reduce life expectancy except in the most severe cases and it is not hereditary or infectious.
What causes MS?
It is thought that there are probably many factors involved in MS and although a cause has not yet been identified, an abnormal immune response is suspected. The body’s own immune system mistakes the myelin sheath surrounding the nerves for a foreign body and attacks it. It is generally believed that there is a genetic susceptibility to MS but as yet the gene responsible has not been identified. Some experts believe that symptoms of MS may be triggered by exposure to a viral infection. No particular virus has been identified, although it has been suggested that a common childhood virus (eg, measles or chickenpox) may act as a trigger. The incidence of MS is higher in temperate countries such as Europe and North America but there are no proven theories yet as to why this may be.
What are the symptoms of MS?
The symptoms of MS can vary greatly depending on the site of the myelin sheath damage. Areas of nerve damage are referred to as plaques. It is not possible to accurately predict the course of MS in any one person, but in many cases the first five years of a person’s illness will indicate whether the disease will be continuous or relapsing-remitting. The disease may present initially as visual problems, pain at the back of the eye (optic neuritis) or face pain. People may find it difficult to concentrate, become forgetful or experience anxiety, depression or mood swings. Symptoms may also include: fatigue; weakness or difficulty walking; numbness or tingling; giddiness or balance problems; speech problems; or problems with bladder or bowel control leading to incontinence. Sexual function or sensation can also be affected. The symptoms of MS may be made worse by factors such as heat and humidity, exercise, fever or overexertion. In most people with MS, symptoms will come and go. Periods of remission may last any length of time, sometimes many years. The reason why remission occurs is not yet understood.