DEFINITION:
An unequivocal diagnosis by a neurologist of definite Multiple Sclerosis, characterized by well defined neurological abnormalities persisting for a continuous period of at least 6 months or with two separate clinically documented episodes. Neurological abnormalities in this context must be evidenced by the typical symptoms of demyelination of the brain or the spinal cord with resultant impairment and must be confirmed by evidence of multiple areas of demyelination by MRI scanning. Multiple Sclerosis is an extremely difficult condition to diagnose and usually all other possibilities are excluded first. Symptoms vary according to which part of the brain and spinal cord are affected.

INTERPRETATION:
Multiple Sclerosis destroys areas of the fatty myelin sheath covering nerve fibers, thus blocking nerve impulses to and from the brain. Demyelination is typical evidence of Multiple Sclerosis and is required under this definition. This definition has centered around the neurological abnormalities, as opposed to the degree of physical impairment. Benign, Chronic and Acute forms of Multiple Sclerosis are all covered by this definition.