Brain Disease : Multiple Sclerosis : Causes & Diagnosis
Multiple sclerosis is an autoimmune disease that affects the brain and spinal cord (central nervous system).
Causes & Risk Factors
Multiple sclerosis (MS) affects women more than men. The disorder most commonly begins between ages 20 and 40, but can be seen at any age.
MS is caused by damage to the myelin sheath, the protective covering that surrounds nerve cells. When this nerve covering is damaged, nerve impulses are slowed down or stopped.
MS is a progressive disease, meaning the nerve damage (neurodegeneration) gets worse over time. How quickly MS gets worse varies from person to person.
The nerve damage is caused by inflammation. Inflammation occurs when the body’s own immune cells attack the nervous system. Repeated episodes of inflammation can occur along any area of the brain and spinal cord.
People with a family history of MS and those who live in a geographical area with a higher incidence rate for MS have a higher risk of the disease.
Tests & Diagnostics
Symptoms of MS may mimic those of many other nervous system disorders. The disease is diagnosed by ruling out other conditions.
People who have a form of MS called relapsing-remitting may have a history of at least two attacks, separated by a period of reduced or no symptoms.
The health care provider may suspect MS if there are decreases in the function of two different parts of the central nervous system (such as abnormal reflexes) at two different times.
A neurological exam may show reduced nerve function in one area of the body, or spread over many parts of the body. This may include:
- Abnormal nerve reflexes
- Decreased ability to move a part of the body
- Decreased or abnormal sensation
- Other loss of nervous system functions
An eye examination may show:
- Abnormal pupil responses
- Changes in the visual fields or eye movements
- Decreased visual acuity
- Problems with the inside parts of the eye
- Rapid eye movements triggered when the eye moves
Tests to diagnose multiple sclerosis include:
- Lumbar puncture (spinal tap) for cerebrospinal fluid tests, including CSF oligoclonal banding
- MRI scan of the brain and MRI scan of the spine are important to help diagnose and follow MS
- Nerve function study (evoked potential test)