Dec 08, 2008
Multiple Sclerosis (MS) is an acquired inflammatory, demylenating disease of the Central Nervous System (CNS). MS is a leading cause of disability in young adults. It strikes people in the prime of their lives, usually between 20 and 40 years of age. It is estimated that more than 400,000 individuals, two-thirds of whom are female, in the United States are afflicted by the disease, at a national cost of nearly $10 billion per year.
In MS, cells of the immune system invade the CNS and destroy myelin (the fatty material that insulates the neurons in the brain and spinal cord), leading to demyelination of the axon and damage to the axon itself. In response, other CNS cells produce a hardened sclerotic lesion (plaque) around the multiple demyelinated sites. Not all lesions are associated with neurological dysfunction and, depending on their location, areas of demyelination may not cause clinical symptoms or signs. Such lesions are referred to as "silent lesions."
Etiology of MS
The cause of MS remains unknown. Both genetic and environmental factors have been implicated in the disease. Some combination of genetic susceptibility and one or more environmental triggers appears to be the most likely explanation.
Clinical Features of MS
Sensory complaints occur in 20-50% of patients and are often the earliest symptoms of MS that bring the patient to the doctor. Symptoms such as disturbances in feeling in the extremities or in the trunk occur because sensory pathways in the spinal cord are impaired. These disturbances, commonly called paresthesias, include tingling, crawling sensations, tight-band feelings, and feelings of swelling. Another common complaint is an electric sensation that goes down the back and legs with head and neck motion; this is called Lhermitte’s sign.
Optic neuritis occurs as the presenting symptoms in 15-20% of patients with MS. It rarely involves both eyes simultaneously, but may appear on one side followed by a later appearance on the other. Optic neuritis usually starts with blurred vision, which is followed by vision loss, most often in one spot (scotoma), but sometimes in the entire field of vision. Complaints often include dimming of vision, photophobia, and pain that is aggravated by eye movement.
Corticospinal tract involvement, particularly spasticity, occurs with the initial attack of MS in 30-40% of patients and is present in about 60% of patients with progressive disease. Spasticity occurs when opposing groups of muscles that are responsible for maintaining an upright posture, such as the calf, thigh, buttock, groin, and occasionally the back, contract and relax at the same time. Most patients complain of heaviness, stiffness, or pain in an extremity. Usually the legs are more involved than the arms.
Gait and balance disturbances are common in patients with MS and are the initial complaint in about 15% of cases. They are more common in patients with progressive disease, with 50% reporting extremity ataxia (shaky movements or unsteady gait) or intention tremors.
Bladder dysfunction, which occurs in almost two-thirds of patients within their disease course, can be a very disabling feature of MS. Symptoms include urinary frequency, urgency, hesitancy, and incontinence. Retention or the inability to empty the bladder completely increases the risk for, and the frequency of, urinary tract infection.
Constipation is common in patients with MS and is often aggravated by the patients’ reluctance to drink water because of associated urinary problems. Constipation can be prevented by adequate fluid intake and a high fiber intake. Fecal incontinence is less frequent and usually occurs from diarrhea resulting from other illness (laxative overdose or diet).
Fatigue, the single most common complaint of people with MS, is often one of the most debilitating symptoms. It occurs in as many as 75% of patients with MS and interferes with work or family and social life. Fatigue from MS commonly occurs late in the afternoon when the body and environmental temperature rise and often subsides in the early morning when temperatures fall. It can also occur as a result of over-activity or over-work. Relief of fatigue may be achieved by cooling off and resting.
Heat is a common aggravating factor in MS. With a one-degree elevation in temperature, new symptoms may appear or old ones may reappear. The elevation in temperature may be due to environmental heat, fever from an infection, or exercise. Although heat does not bring on an attack, it is a good idea for patients with MS to stay indoors during the hottest part of a summer day and to avoid heat from sunbathing, saunas, or hot showers.
Cognitive and Emotional Dysfunction:
Cognitive and emotional changes are common in MS, affecting approximately one-half of patients with MS. Of this group, approximately 40% have mild dysfunction, and 10% severe dysfunction. There is controversy as to whether MS-related cognitive problems are a reaction to the emotional distress of the disease or are caused by the lesions themselves. The most common cognitive deficits involve memory, reasoning, verbal fluency, and speed of information processing. Cognitive dysfunction can significantly affect the patients’ employment or everyday activities, and it is important that these symptoms are discussed and treated.
Natural Course of MS
The natural course of MS is highly variable and it is impossible to predict the nature, severity, or timing of progression in a given patient; however, there are a few guidelines to follow. For instance, a patient with numbness or tingling (sensory problems) tends to have a better prognosis than those with spasticity or paralysis (balance or coordination problems). Another factor that influences prognosis is age of onset. Disease progression tends to be more rapid in patients who experience their first symptoms after age 40. Other factors predictive of rapid progression include male gender, frequent attacks, and burden of disease as detected by magnetic resonance imaging (MRI). The course of MS over the first 5 years can provide a clue to the progression of the disease over the next 10 years. In a series of patients, 90% of those with minimal disability 5 years after disease onset were still ambulatory at 15 years.
Classifications of MS
Clinically definite MS is further categorized according to disease course. Relapsing-remitting MS is characterized by symptoms that develop over a period of a few hours to a few days, followed by recovery and a stable course between relapses. Approximately 80% of patients are initially diagnosed with relapsing-remitting MS. Almost 50% of patients with relapsing-remitting MS eventually develop secondary-progressive (SP) MS characterized by gradual neurological deterioration with or without superimposed acute relapses. If there is continual disease progression from onset with only minor fluctuation the classification becomes primary-progressive (PP). PP-MS occurs in approximately 10% of patients, mainly those who are older than 40 years at onset. Progressive-relapsing MS, a rare form of the disease, is characterized by gradual neurological deterioration from the onset of symptoms and subsequent superimposed relapses.
Diagnosis and Treatment of MS
A diagnosis of MS should be confirmed by a qualified neurologist, who would subsequently recommend appropriate treatments accordingly.
Despite being told that none of these drugs is a cure for MS and that therapy is unlikely to reverse existing disabilities, patients with MS often hope that their disabilities will disappear and that no further exacerbation will occur. Failure to achieve these outcomes is likely to be very discouraging, therefore patients and their families require continual support and understanding. Education is crucial to maintaining patient compliance with treatment. In addition to the patient-support program provided by each drug supplier, the individual health care provider will be looked to for guidance on all aspects of treatment.
Source: E. Torage Shivapour, M.D.
University of Iowa Hospitals and Clinics, Department of Neurology