Demyelination is a condition in which the myelin sheath that covers and protects nerves in the brain and spinal cord becomes damaged. Demyelination is not a stand-alone disease and is considered a category of a disease in which demyelenation occurs, such as multiple sclerosis.
Definition
The myelin sheath is a natural fatty protein made by the body to surround and protect the nerves in the brain and the spinal cord. Myelin is like the insulation on the outside of an electrical wire, the wire being like the nerves in our bodies.
What it does
The process of demyelination is still not completely understood but it has been discovered that the body's own immune system plays a part. The immune system cells known as macrophages and T-cells, or acquired immune system cells are often found at the site of demyelinated nerves. Once demyelnation sets in the nerve impulses that naturally occur begin to slow and eventually stop altogether. When these impulses, or messages, cease to transmit there can be a number of neurological problems.
Multiple Scerlosis
Multiple sclerosis, also known as MS, is the most common disease that involves demyelination. In patients with MS, their immune systems begins attacking the myelin and/or the cells that produce it. What can happen to the myelin sheath and the uncovered nerves is called sclerosis, which is the scarring of the tissue. This scarring is what can cause the nerve signals to slow resulting in slower natural impulses and responses in muscle coordination, strength and the five senses. Sometimes the damage can be so bad that the signals stop completely and the natural impulses and responses become uncontrollable or non-existent. Currently, there is no cure for multiple sclerosis. Treatment is primarily based on the management of symptoms and the controlling the body's autoimmune responses. Autoimmune medications are prescribed and the patient usually has a physical therapy routine to help build and maintain strength that is needed for every day tasks.
Eye Disorders
There are several other disorders in which demyelenation can occur. One type are disorders of the eye. Optic neuritis occurs when the bundle of nerves in the eye, known as the optic nerve, becomes inflamed resulting in the loss vision. The inflammation can be caused by MS, bacterial infections, diabetes or drug abuse and results in the destruction of myelin. Devic disease is a condition in which the optic nerve and the spinal cord become inflamed, causing damaged via demyelentation which can result in pain blindness, weakened muscles or paralysis. The symptoms are very similar to those of MS, but can be cured with intravenous steroids and methylprednisolone.
Spinal Cord Related Disorders
Because the spinal cord is protected by the myelin sheath, disorders of the spinal cord can be caused by demyelenation. In patients with transverse myelitis the spinal cord becomes inflamed, which can destroy myelin. Causes of transverse myelitis include lyme disease, measles, herpes simplex, Epstein-Barr, influenza, HIV, hepatitis A, rubella and bacterial pneumonia. Causes have also been known to remain unknown. Acute disseminated encephalomyelitis is another condition that is often the result of demyelenation of the brain and spinal cord, which can lead to seizures, delirium and comas. Signs of this condition come on fairly quickly and sometimes lead to a misdiagonsis of multiple sclerosis.
Tags: spinal cord, myelin sheath, brain spinal, brain spinal cord, immune system