Multiple Sclerosis (MS)
also known as “disseminated sclerosis” or “encephalomyelitis disseminata”, is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms. Disease onset usually occurs in young adults, and it is more common in women. It has a prevalence that ranges between 2 and 150 per 100,000. MS was first described in 1868 by Jean-Martin Charcot.
- MS affects the ability of nerve cells in the brain and spinal cord to communicate with each other effectively. Nerve cells communicate by sending electrical signals called action potentials down long fibers called axons, which are contained within an insulating substance called myelin. In MS, the body’s own immune system attacks and damages the myelin. When myelin is lost, the axons can no longer effectively conduct signals. The name multiple sclerosis refers to scars (scleroses—better known as plaques or lesions) particularly in the white matter of the brain and spinal cord, which is mainly composed of myelin. Although much is known about the mechanisms involved in the disease process, the cause remains unknown. Theories include genetics or infections. Different environmental risk factors have also been found.
- Almost any neurological symptom can appear with the disease, and often progresses to physical and cognitive disability. MS takes several forms, with new symptoms occurring either in discrete attacks (relapsing forms) or slowly accumulating over time (progressive forms). Between attacks, symptoms may go away completely, but permanent neurological problems often occur, especially as the disease advances. There is no known cure for multiple sclerosis. Treatments attempt to return function after an attack, prevent new attacks, and prevent disability. MS medications can have adverse effects or be poorly tolerated, and many people pursue alternative treatments, despite the lack of supporting scientific study. The prognosis is difficult to predict; it depends on the sub-type of the disease, the individual’s disease characteristics, the initial symptoms and the degree of disability the person experiences as time advances. Life expectancy of people with MS is 5 to 10 years lower than that of the unaffected population.
A person with MS can suffer almost any neurological symptom or sign, including
- changes in sensation such as loss of sensitivity or tingling
- pricking or numbness (hypoesthesia and paresthesia)
- muscle weakness, clonus, muscle spasms, or difficulty in moving
- difficulties with coordination and balance (ataxia)
- problems in speech (dysarthria) or swallowing (dysphagia)
- visual problems (nystagmus, optic neuritis including phosphenes, or diplopia)
- fatigue
- acute or chronic pain
- bladder and bowel difficulties.
- Cognitive impairment of varying degrees and emotional symptoms of depression or unstable mood are also common. Uhthoff’s phenomenon, an exacerbation of extant symptoms due to an exposure to higher than usual ambient temperatures, and Lhermitte’s sign, an electrical sensation that runs down the back when bending the neck, are particularly characteristic of MS although not specific. The main clinical measure of disability progression and symptom severity is the Expanded Disability Status Scale or EDSS.
Symptoms of MS usually appear in episodic acute periods of worsening (called relapses, exacerbation, bouts, attacks, or “flare-ups”), in a gradually progressive deterioration of neurological function, or in a combination of both. Multiple sclerosis relapses are often unpredictable, occurring without warning and without obvious inciting factors with a rate rarely above one and a half per year. Some attacks, however, are preceded by common triggers. Relapses occur more frequently during spring and summer. Viral infections such as the common cold, influenza, or gastroenteritis increase the risk of relapse. Stress may also trigger an attack. Pregnancy affects the susceptibility to relapse, with a lower relapse rate at each trimester of gestation. During the first few months after delivery, however, the risk of relapse is increased. Overall, pregnancy does not seem to influence long-term disability. Many potential triggers have been examined and found not to influence MS relapse rates. There is no evidence that vaccination and breast-feeding, physical trauma, or Uhthoff’s phenomenon are relapse triggers.
Causes of MS: Most likely MS occurs as a result of some combination of genetic, environmental and infectious factors, and possibly other factors like vascular problems. Epidemiological studies of MS have provided hints on possible causes for the disease. Theories try to combine the known data into plausible explanations, but none has proved definitive.