Multiple sclerosis

Overview

Multiple sclerosis (MS) is an autoimmune condition that specifically attacks the cells in myelin, the protective sheath around nerves in the brain and spinal cord. When the myelin sheath is damaged, it interferes with the transmission of nerve signals from the brain to other parts of the body. The condition can eventually cause persistent nerve fiber injury or deterioration. The injury may cause symptoms affecting the spinal cord, brain, and eyes.

There are four types of multiple sclerosis: clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), primary progressive MS (PPMS), and secondary progressive MS (SPMS). Depending on the form of MS, some people may experience long periods of remission with no new symptoms.

CIS is characterized by the first episode of MS symptoms but not every person with CIS develops multiple sclerosis. RRMS usually involves experiencing flare-ups, also known as relapses or exacerbations, of new or worsened symptoms. PPMS is characterized by having symptoms that deteriorate gradually over time, with no intervals of relapse or remission. With SPMS, symptoms worsen over time. Relapses or flares may occur with no periods of remission.

The treatment for multiple sclerosis often focuses on managing the condition. Medicines are available to help hasten recovery after attacks, alter the course of the disease, and manage symptoms.

Symptoms

The signs and symptoms of multiple sclerosis vary depending on the type of MS and where the damaged nerve fibers are located. Vision issues, such as optic neuritis characterized by blurriness and pain in one eye, are frequently among the early symptoms of multiple sclerosis. Other common symptoms include:

• Muscle weakness
• Unsteady gait
• Balance or coordination problems
• Vertigo
• Tingling or numbness, particularly in the legs or arms
• Lhermitte sign, or electric-shock sensation associated with specific neck movements, particularly forward bending of the neck
• Spasms in the muscles
• Partial or full vision loss, usually in one eye at a time, often accompanied by pain during eye movement
• Prolonged double vision
• Blurry vision
• Issues with sexual, bowel, or bladder function
• Slurred speech
• Cognitive issues
• Mood changes
• Fatigue

If any signs and symptoms persist, it is advisable to schedule a consultation with a healthcare provider. Immediate consultation may be necessary if an individual experiences heightened sensitivity to heat, a sense of unsteadiness or imbalance, memory problems, numbness or tingling sensations, especially in the arms or legs, unexpected changes in vision, or weakness in the arms or legs.

Causes

The exact cause of multiple sclerosis (MS) remains uncertain, and ongoing research is dedicated to unraveling the underlying factors responsible for this condition.

In the case of multiple sclerosis, the immune system dysfunction kills the fatty material, known as myelin, that coats and protects nerve fibers in the brain and spinal cord. When the protecting myelin is damaged and the nerve fiber is exposed, messages may be slowed or inhibited as they travel along that nerve fiber. However, it is unclear why some people develop MS and others do not.

Several factors are also believed to trigger multiple sclerosis, this includes specific viruses or bacteria exposure, living location, environment, and family history.

Risk factors

Several risk factors are known to contribute to one’s risk of developing multiple sclerosis:

• Age: Both young and old people may be affected. However, it commonly strikes between the ages of 20 and 40.
• Sex: The likelihood of women having relapsing-remitting MS is over two to three times higher compared to men.
• Family history: Having a family member with MS increases one’s risk of the disease.
• Certain infections: Certain studies indicate that exposure to specific infections, like the Epstein-Barr virus, could potentially act as a trigger for the onset of multiple sclerosis later in one’s life.
• Race: People of Asian, African, or Native American heritage have the lowest risk of having MS, while white people, particularly those of Northern European descent, have a higher chance of developing the disease.
• Climate: Exposure to sunlight during pregnancy appears to reduce the risk of MS in children. Thus, the month of birth can potentially influence the likelihood of developing multiple sclerosis. Multiple sclerosis is more prevalent in countries characterized by temperate climates, such as Canada, New Zealand, southeastern Australia, and Europe.
• Vitamin D: Areas farther from the equator had greater incidence of MS, which may be due to less strong sun exposure. People who get less sun have lower amounts of vitamin D, which is a risk factor for MS.
• Genetics: Multiple sclerosis was discovered to be linked to a gene on chromosome 6p21.
• Obesity: Females who experienced obesity during childhood and adolescence are more susceptible to multiple sclerosis.
• Other autoimmune diseases: Having an autoimmune condition increases the likelihood of acquiring multiple sclerosis. These disorders include thyroid disease, pernicious anemia, psoriasis, type 1 diabetes, or inflammatory bowel disease.
• Smoking: Individuals who smoke and experience an initial symptom suggestive of multiple sclerosis have a greater likelihood of developing a subsequent event that confirms the presence of relapsing-remitting MS than nonsmokers.