Multiple sclerosis is a central nervous system disorder marked by decreased nerve function with initial inflammation of the protective myelin nerve covering and eventual scarring. Symptoms and severity of symptoms vary widely and may progress into episodes of crisis alternating with episodes of remission.

An MRI (magnetic resonance imaging) of the brain creates a detailed image of the complex structures in the brain. An MRI can give a three-dimensional depiction of the brain, making location of problems such as tumors or aneurysms more precise.

The nerves that branch off the central nervous system (CNS) provide messages to the muscles and organs for normal function. When there is CNS damage, the function of these organs and tissues may be compromised. In multiple sclerosis, the demyelinization of nerve cells may lead to bowel incontinence, bladder problems and/or sexual dysfunction.

The central nervous system is comprised of the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.

Myelin is the layer that forms around nerves. Its purpose is to speed the transmission of impulses along nerve cells.