Demyelinating disease causes the myelin sheaths that cover nerve cells in the brain and spinal cord to deteriorate. When myelin sheaths deteriorate, the nerves can't properly transmit impulses. Demyelination of the nerves can occur in the nerves that affect the peripheral nerves or the central nervous system. CNS demyelination affects the brain, optic nerve and spinal cord.
Types
Demyelinating disease of the CNS takes many forms. Multiple sclerosis, the most common demyelinating disease of the CNS, can cause symptoms ranging from mild to severe. This disease affects some 400,000 Americans, according to the National Multiple Sclerosis Society. A number of demyelinating diseases affect the eye. Optic neuritis, neuromyelitis optica and Leber's hereditary optic neuropathy affect the optic nerve. Adrenoleukodystrophy and adrenomyeloneuropathy are rare metabolic diseases that cause adrenal gland dysfunction. Transverse myelitis can lead to muscle weakness
Symptoms
Symptoms depend on the disease location, but can affect any part of the CNS. Seizures, headaches, delirium, confusion or slurred speech can occur. Muscle weakness, paralysis, trouble with balance, difficulty walking and tremors affect some individuals with demyelination disorders. Pain, numbness or tingling affect some with the disease. Vision and hearing problems and bladder problems can also occur. People with adrenoleukodystrophy and adrenomyeloneuropathy may have developmental problems and mental deterioration. Symptoms may start suddenly and may wax and wane, the "Merck Manual" states.
Causes
Some demyelinating diseases, such as Tay-Sachs disease, adrenoleukodystrophy and adrenomyeloneuropathy, are hereditary. Other demyelination diseases may be caused by autoimmune disease, infection, nutritional deficiencies and low oxygen levels from disorders such as carbon monoxide toxicity. Viruses may trigger immune reactions such as acute disseminated encephalomyelitis, a disease similar to Guillain-Barre syndrome, which causes temporary paralysis of the peripheral nerves.
Treatment
Diagnosis and treatment of demyelination diseases depend on the specific disease. MRI can often diagnose plaques or scarring caused by multiple sclerosis, but a normal MRI occurs in 5 percent of people with MS in early stages, the National Multiple Sclerosis Society states, and doesn't rule out MS or other demyelinating diseases. Corticosteroid medications help decrease inflammation in some cases. Drugs called disease-modifying agents are also used for some forms of the disease, including multiple sclerosis.
Complications
Some forms of CNS demyelination can lead to early death or disability. Demyelination disorders tend to progress over time. Most people with multiple sclerosis have a normal or near-normal life expectancy, the National Multiple Sclerosis Society states. Hereditary demyelination disorders such Tay-Sachs disease can end in early death.
