Learn About Multiple Sclerosis In Humans

Multiple sclerosis (MS) can be thought of as an inflammatory process involving different areas of the central nervous system (CNS) at various points in time. As the name suggests, multiple sclerosis affects many areas of the CNS.

Multiple sclerosis is more common in individuals of northern European descent. Women are more than twice as likely to develop multiple sclerosis as men. Multiple sclerosis usually affects people between the ages of 20 and 50 years, and the average age of onset is approximately 34 years.

The central nervous system is made up of the brain and spinal cord. They process information from our environment and control voluntary muscle movements to allow the body to do certain things.

When you touch something hot, for example, signals are sent from sensory nerve endings in your hand up long nerves in your arm, eventually reaching the spinal cord. From there, the signal is transferred up your spinal cord to your brain, where the information is processed. Your brain then sends a signal back down the spinal cord to the nerves in your arm. These nerves cause the muscles in your arm to contract, pulling your hand away from the heat.

This neural system works efficiently, unless there is a disease process affecting the pathways in the spinal cord and brain. Multiple sclerosis is one of the diseases that can affect these pathways. Signals are transmitted within the central nervous system along pathways.

These pathways are made up of long fibers called nerves. Nerves are capable of transmitting information from the environment to the brain. Everything you see, touch, taste, smell, or feel is transmitted along nerves to your brain.

Nerves also carry information responsible for our alertness, behavior, ability to understand and think rationally, capacity to communicate with others, and feeling and interpreting emotions.

To help transmit all this information in a timely manner, the nerves are covered by a fatty substance called myelin. Myelin insulates the nerves and allows them to transmit information to and from the brain in a fraction of a second.

If the myelin is disrupted in any way, the transmitted information is not only delayed, but it may also be misinterpreted by the brain.

Multiple sclerosis results in destruction of the myelin surrounding the nerves of the CNS. The destruction is thought to be caused by the body's immune system attacking the myelin sheath.

This autoimmune destruction of the myelin sheath leads to areas of demyelination (also known as plaques) in the brain and spinal cord.

These plaques disrupt the transmission of information in the CNS and lead to the symptoms seen in multiple sclerosis.

The symptoms of multiple sclerosis can be different from person to person. Visual, sensory, and motor signs and symptoms are all part of multiple sclerosis. The clinical manifestations are varied, and therefore there is a wide range of symptoms that can appear. Some people have mild cases of multiple sclerosis with little or no disability over the years. Others have more severe types of multiple sclerosis, requiring confinement to a wheelchair or bed.

Still others may live their entire lives symptom-free (some individuals without multiple sclerosis symptoms are found incidentally to have multiple sclerosis lesions by MRI, or individuals in whom an examination of their brain after death unexpectedly reveals that they were affected by the disease). This variability makes it difficult in some cases to diagnose multiple sclerosis. Often the signs and symptoms are mistaken as being psychiatric in origin.

The first symptoms of multiple sclerosis are often visual changes. Large number of people with multiple sclerosis develop optic neuritis (inflammation of the optic nerve, which is an extension of the central nervous system), described as a painful vision loss. If a patient is diagnosed with optic neuritis early, treatment could change the course of the disease.

Before the actual loss of vision, the patient may have visual changes described by many people as blurred or hazy vision, flashing lights, or alterations in color. The tissues around the eye and moving the eye may be painful. Most people recover over several months. Others are left with permanent visual defects. Double vision occurs when the eyes move in different directions and is another common symptom of multiple sclerosis.

Multiple sclerosis commonly affects the cerebellum, the portion of the brain responsible for balance and fine motor coordination. Consequently, people with multiple sclerosis often have difficulty maintaining their balance when walking and performing delicate tasks with their hands. Unexplained dropping of a cup or other object or unusual weakness can occur.

Patients may experience facial pain, a sensation of spinning referred to as vertigo, and sometimes hearing loss. Virtually any area of the body can be involved, making this disease the great imitator of other disorders of the nervous system. The patient may experience painful muscle spasms or loss of strength in one or more of the arms or legs.

The nerve fibers that conduct touch, pain, and temperature sensations are often affected, causing tingling, numbness or electrical-type pain sensations in the chest, abdomen, arms or legs. Multiple sclerosis can involve the nerves responsible for involuntary actions of the bladder and intestines. The pateint may often have constipation and urinary retention. These symptoms lead to other complications, such as infections of the bladder, kidney, or blood.

Most people with multiple sclerosis complain of a constant state of tiredness. Something as simple as carrying groceries up a flight of stairs may become an impossible task for someone with multiple sclerosis.

A peculiar trait of multiple sclerosis is the relationship between higher temperatures and the worsening of symptoms. People often complain of worsening of any of their symptoms after taking a hot shower, or participating in strenuous exercise.

The exact reason this occurs is unknown. Perhaps it is because at higher temperatures nerve conduction decreases, which could lead to further slowing in the transmission of messages in nerves that have already lost myelin.

A physician should be notified if you or someone you know have any of the signs and symptoms associated with multiple sclerosis. Also check with a doctor if you or someone you know have any signs or symptoms that may not be associated but that are of concern. The person may not have multiple sclerosis, but because of the nonspecific nature of this disease, it is best to let a qualified professional make that determination.

Several of the symptoms of multiple sclerosis may send the patient to a hospital's emergency department. If visual changes and painful eye movements are experienced, visit the nearest emergency department. The patient could have optic neuritis, one of the most common early signs of multiple sclerosis.

If the patient experiences personality changes or sudden loss of strength in the arms and legs they should go to the emergency department for evaluation. These symptoms are common with multiple sclerosis, but they can also be signs of other serious diseases, such as stroke, infection, or chemical imbalances.

Diagnosing multiple sclerosis is difficult. The vague and nonspecific nature or this disease mimics many other diseases. Doctors combine history, physical exam, laboratory work, and sophisticated medical imaging techniques to arrive at a diagnosis.

A complete blood count, blood chemistry, urine analysis, and often spinal fluid evaluation are all routine laboratory tests used to rule out other diagnoses and help confirm the diagnosis of multiple sclerosis. An MRI, which creates an image of the brain or the spinal cord, is used to search for changes within the brain or spinal cord that are particular to multiple sclerosis. More often than not, a neurology specialist is required to make a diagnosis.

There are several treatment options for multiple sclerosis. The following is a brief summary of the drugs approved by the FDA to treat multiple sclerosis. For more information, consult your physician.

Substances called interferons are immunomodulatory (meaning they affect the action of the immune system) drugs that have been approved to treat multiple sclerosis. Interferons are also made by the body, mainly to combat viral infections.

Interferons have been shown to decrease relapses by about one-third (if compared to patients receiving placebo) and delay progression of the disease. Common side effects include flu-like symptoms (which tend to disappear with time) and injection site reactions (which can be minimized with analgesics, rotation of injection sites, and local measures to prepare the skin prior to injection).

Interferons include interferon beta-1a (Avonex) which is given once a week as an injection into the muscle interferon beta-1a [(Rebif), which is given three times per week as an injection below the skin)], and interferon beta-1b [(Betaseron), which is given every other day as an injection below the skin].

Glatiramer acetate (Copaxone) is a mixture of amino acids used to treat multiple sclerosis. Glatiramer acetate has been shown to decrease the relapse rates of multiple sclerosis by about one-third (if compared to patients receiving placebo) and appears to also have an effect on the overall progression of multiple sclerosis.

Common side effects with Glatiramer acetate include a sensation of chest tightening following the injection, and injection site reactions which may include rare skin lesions referred to as lipoatrophy. Copaxone is given every day as an injection below the skin.

Natalizumab (Tysabri) is a monoclonal antibody that binds to white blood cells and interferes with their movement from the bloodstream into the brain and spinal cord. White blood cells are thought to play a role in causing the nervous system damage in multiple sclerosis.

Tysabri decreases relapses by about two- thirds (if compared to patients receiving placebo) and reduces the accumulation of disability, but carries a warning for increasing the risk of progressive multifocal encephalopathy (PML), a potentially fatal brain infection. Because of this risk, Tysabri can only be given to patients that have registered for treatment under a controlled drug distribution program.

Several drugs that suppress the immune system and are used to treat cancer have also been used to treat multiple sclerosis, but they may make people with multiple sclerosis very ill, especially if not used with caution. Mitoxantrone (Novantrone) is a chemotherapy agent that has been approved by the FDA to treat multiple sclerosis.

Treatment with mitoxantrone requires monitoring of cardiac function, and there is a fixed limit to the dose that can be administered to patients. It also carries the long-term risk of leukemia. For these reasons, Novantrone is typically reserved for patients with more aggressive forms of multiple sclerosis.

New research and treatment methods are currently being investigated and are expected to offer some hope to people with multiple sclerosis.