Multiple Sclerosis – Causes, Signs and symptoms

Multiple Sclerosis

Also called: MS


Multiple sclerosis (MS) is a neurological disorder that is typically characterized by symptoms that grow progressively more severe with time. Some patients may experience only one or a few attacks of symptoms. Others will have life-changing symptoms as they cope with increasing debilitation and paralysis.

The National Multiple Sclerosis Society estimates that 400,000 Americans and 2.5 million people worldwide have the disease.

MS is believed to be an autoimmune disorder, in which the body’s immune system attacks the myelin that surrounds nerves in the brain and spinal cord. Normally the myelin helps conduct signals along the length of the neurons (nerve cells). In patients with MS, the myelin degrades and is replaced with scar tissue, a process termed sclerosis. The loss of myelin causes the nerve signals to move more slowly or become distorted or blocked.

Scientists do not completely understand why the immune system begins to attack the body’s nerves. There is some evidence of a genetic link that may make some people more susceptible to an unknown environmental trigger. Many researchers believe the trigger is a virus or bacteria, but other factors are also suspected.

There are four types of MS that are generally recognized. They differ in how the symptoms progress. Relapsing-remitting MS patients experience attacks of symptoms that may last weeks or months before a period of remission. After several years, it may develop into secondary-progressive MS with constant symptoms that become more severe and lack significant periods of remission. Primary-progressive MS is similar to secondary-progressive MS, but is not preceded by a period of relapse and remission. Patients with progressive-relapsing MS experience symptoms that continually get worse, as well as periodic attacks of more severe symptoms.

A physician may suspect that a patient has MS based on the patient’s symptoms and the results of a neurological examination. To confirm the diagnosis, a combination of tests are required. These are likely to include imaging tests (e.g., MRI), an analysis of cerebrospinal fluid (spinal tap) and an evoked potential study.

There is a great deal of ongoing research concerning MS. Much of it is focused on trying to discover the causes of the disease. It is hoped that finding the cause will lead to ways to prevent and cure the disabling disease.

About multiple sclerosis

Multiple sclerosis (MS) is a non-contagious, neurological disorder that may cause symptoms that range from mild to severe and can change a patient’s life. As the disease progresses, most patients maintain their ability to walk, though many require the assistance of a cane or similar device. A third of MS patients may be eventually paralyzed by the disease. The disease also causes increasing levels of fatigue and some people experience vision loss. The average life span of patients with MS is slightly shorter than the rest of the population, but does not differ significantly.

MS is a common neurological disease. The National Multiple Sclerosis Society estimates that 400,000 Americans and 2.5 million people worldwide have the disease. In the United States, the disease was reported as the cause of death for 3,124 people in 2002 (the latest year for which figures are available), according to the Centers for Disease Control and Prevention.

The average age of diagnosis of MS is roughly age 30. Symptoms may first appear at any point throughout a person’s life, although they usually start between the ages of 20 and 50.

It is a disease that is twice as likely to develop in women than men and is more common in Caucasian people than other races. In addition, it occurs more frequently in people who live farther from the equator, with the highest rates of MS in northern Europe, southern Canada, northern United States, New Zealand, southeast Australia and Russia.

The symptoms of MS result from the loss of myelin from neurons (nerve cells) in the brain and spinal cord, although scientists are unsure why this occurs. Myelin is a fatty material that forms a layer around the neurons of the central nervous system. It is believed to help conduct the electrical nerve signal from one end of the neuron to the other. MS causes myelin to degrade and it may be replaced by scar tissue, a process that is called sclerosis. Without myelin, nerve signals move more slowly and they may be distorted or blocked by the scar tissue or other damage to the neuron.

Types and differences of multiple sclerosis

Multiple sclerosis (MS) is a neurological disorder that primarily affects movement and vision, as well as other senses. There are several types of the disease that are classified according to the pattern of progression. While different patients will experience different patterns of progression, MS is usually classified as one of the following:

  • Relapsing-remitting MS. Patients experience symptoms during attacks that may last weeks to months. These periods are followed by a remission stage when symptoms may partially or completely fade. Some patients experience only one or two attacks in their lifetime, but others face worsening relapses with shorter and less frequent remission stages. It is the most common form of MS and is diagnosed in 85 percent of patients according to the National Multiple Sclerosis Society (NMSS). It is most often diagnosed in patients between 25 and 29 years of age.

  • Secondary-progressive MS. Half of patients with the relapsing-remitting form of MS will develop this form within 10 years of the initial diagnosis. It is characterized by initial periods of distinct attacks followed by worsening symptoms that may or may not fluctuate in intensity. People with secondary-progressive MS do not usually have remissions, although they may experience temporary improvements or plateaus in their condition.

  • Primary-progressive MS. This form of MS is characterized by a slow progression of disease with symptoms that continue to grow more severe. Patients do not usually experience distinct attacks or periods of remission. According to the NMSS, it is diagnosed in approximately 10 percent of patients, and usually only occurs in patients who are in their 40s or older.

  • Progressive-relapsing MS. This rarest form of MS affects an estimated 5 percent of patients with the disease according to NMSS. They experience continuous symptoms that get progressively worse in conjunction with attacks of more severe symptoms.

Potential causes of multiple sclerosis

Little is known about what causes multiple sclerosis (MS). Most scientists believe it is an autoimmune disorder, which is when the immune system produces a reaction that attacks the body’s own tissues. In the case of MS, the reaction is directed against the myelin sheath of nerve cells (neurons). What may be causing this immune response is not completely understood.

Many researchers believe MS may result from a combination of genetic and environmental factors. While there seems to be a slightly higher rate of incidence when a close family member has the disease, there is no distinct pattern of inheritance to establish a genetic cause. Instead, genetics are suspected of making a person more susceptible to unknown factors that trigger the disease. There are many theories as to what the trigger for MS may be, including:

  • Viral or bacterial disease. Some scientists think a virus or bacteria infection may trigger the body’s immune system to mistakenly attack the myelin around nerve cells. Antibodies to the Epstein-Barr virus, which causes infectious mononucleosis, have been found in nearly 100 percent of MS patients (in general, they are found in up to 90 percent of adults). They are also found more frequently in children who develop MS than in other children. Other infectious agents being studied include Chlamydia pneumoniae (a cause of pneumonia) and the microorganisms that cause measles and canine distemper.
  • Environmental pollution. The occurrence of apparent clusters (disease occurrence at a rate higher than expected) of MS has resulted in investigations into potential causes of the disease. Sometimes these clusters have occurred near potential sources of industrial contamination leading some scientists to speculate that environmental pollutants may trigger MS. No definitive evidence to support this theory has been found.
  • Vitamin D deprivation. People who live farther away from the equator and are exposed to less sunlight are more likely to develop MS. Because sunlight is needed by the body to make vitamin D, some scientists believe that reduced levels of the vitamin may be a cause of the disease.

Signs and symptoms of multiple sclerosis

The signs and symptoms of multiple sclerosis (MS) vary from patient to patient in severity and frequency. They are likely to include:

  • Double vision or vision loss
  • Numbness, tingling or weakness in one or more limbs
  • Unsteady walking
  • Sensitivity to heat
  • Partial or complete paralysis
  • Sensation of an electric shock when bending the neck
  • Lack of coordination
  • Fatigue
  • Dizziness
  • Muscle stiffness or spasticity
  • Slurred speech
  • Bladder, bowel or sexual dysfunction
  • Forgetfulness

Many people with MS also experience depression, which may be related to the nature of the disease or a consequence of living with a chronic illness. People with MS may also experience pain or develop trigeminal neuralgia, ataxia and seizures.

Depending on the form of MS, the symptoms may come in periodic attacks followed by remission or may progressively become worse.

Pregnancy and the resulting changes in hormones can affect the occurrence of MS symptoms. Attacks usually occur less frequently during the second and third trimester, though they may be more severe following birth.

Diagnosis methods for multiple sclerosis

Multiple sclerosis (MS) presents various difficulties for diagnosis. MS may be suspected based on the occurrence of its symptoms, but some symptoms may also be caused by other diseases. In addition, the symptoms of MS are often temporary and may fade before patients are examined. If this occurs, it is recommended that patients relate their medical history, including what symptoms have been experienced, as well as the frequency, severity and timing of symptoms.

The physician is likely to perform a neurological examination. This may indicate signs or symptoms of which the patient was unaware, such as lack of coordination. The examination will test the patient’s reflexes, muscle strength and tone, sense of touch, vision, gait, posture, coordination, balance and mental skills.

A number of techniques are available to help confirm suspected MS based on the patient’s medical history and the results of the neurological exam. These include:

  • MRI (magnetic resonance imaging). This technique uses magnetic fields and radio waves to allow physicians to see MS-related damage in the brain and spinal cord. The procedure takes about an hour and provides more detailed images than CAT scans (computed axial tomography) and other imaging techniques.

  • Spinal tap. Cerebrospinal fluids from the spinal column may be extracted using a needle and analyzed for indicators of MS. These may include abnormal levels of white blood cells, proteins and glucose (blood sugar) in the spinal fluid. The process takes about 45 minutes.

  • Evoked potential study. These tests measure the electrical signals that travel from the sensory organs to the brain and may be used to detect abnormal functioning of the central nervous system. During the test, electrodes are attached to the scalp to measure the patterns of brain activity that occur following stimulation of the senses. The results are compared to normal patterns. Slow or abnormal brain activity may be an indication of MS. The tests usually take about 45 minutes.
  • Nerve conduction velocity. A measure of the electrical activity of nerves. Electrodes on the surface of the skin send and detect electricity as it moves through the nerves. Slower than normal results may be indicative of nerve damage. To prepare for this test, it may be recommended that patients avoid caffeine and smoking for three hours, and anti-inflammatory medications for 24 hours.

A definitive diagnosis of MS relies on evidence of changes in multiple parts of the central nervous system. These changes must include the degradation of myelin into scar tissue as well as at least two separate attacks of symptoms.

Treatment and prevention of multiple sclerosis

To date, there is no method to cure or prevent multiple sclerosis (MS). Years of research have allowed physicians to develop several forms of treatment for the disease. Medications have been developed that help various aspects of MS. These include:

  • Treating symptoms, such as muscle relaxants to relieve muscle spasms.

  • Altering the progression of the disease, including reducing the frequency, length and severity of attacks.

Medications are most effective when used in the early stages of the disease.

In addition to medications, other forms of treatment for both the physical and psychological impact of MS include physical therapy, individual counseling and support groups.

Ongoing research regarding multiple sclerosis

Multiple sclerosis (MS) is a common neurological disorder and is the subject of continuing medical research. Scientists involved in the research are investigating many aspects of the disease, including its causes and potential prevention methods.

Research into the causes of MS is multifaceted. Studies are underway to investigate possible genetic factors that may be involved in the disease and how genetic engineering may be able to prevent MS. Scientists also are examining how viruses, bacteria and pollution may trigger MS. If these triggers can be identified, then there may also be ways to address them. Additionally, stem cell research is in development for MS. It is currently focused on repairing the damage inflicted on body tissue by MS rather than on preventing the disease.  

Another topic of research interest is the blood brain barrier. The membrane around the brain typically serves to control the passage of nutrients and waste products between the central nervous system and the blood. If this barrier malfunctions, it may allow the passage of chemicals into the brain that may be involved in MS.

Questions for your doctor regarding MS

Preparing questions in advance can help patients to have more meaningful discussions with healthcare professionalsregarding their condition. Patients may wish to ask their doctor the following multiple sclerosis-related questions:

  1. Why do you think I have multiple sclerosis?
  2. What tests will you use to diagnose multiple sclerosis?
  3. What type of multiple sclerosis do I have?
  4. Are my symptoms going to get worse over time?
  5. What can I expect as the disease progresses?
  6. How will you treat my multiple sclerosis?
  7. Will treatment make my symptoms easier to live with?
  8. How will multiple sclerosis affect my pregnancy?
  9. If I have multiple sclerosis, could my family members get it too?
  10. Will any of the research being done on multiple sclerosis affect me?
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