Multiple sclerosis is a demyelinating disease that affects the motor neurones of the central nervous system (CNS). It is an autoimmune disease in which the body's own immune system destroys the myelin sheaths surrounding the axons of CNS motor neurones. Symptoms can include fatigue, difficulty when walking, blurred vision, numbness and muscle spasms or paralysis.
In the demyelinated regions of these neurones, the propagation of action potentials between successive nodes of Ranvier via saltatory conduction is much slower than in unaffected neurones. Demyelination is progressive and extensive, possibly affecting regions across the entirety of the CNS.