Generally, multiple sclerosis (MS) follows one of four courses:

• Relapsing-remitting, where you have alternating periods of active disease when symptoms flare up and periods when symptoms fade. This cycle can occur for many years. The disease does not advance during the remissions
• Secondary progressive, where active symptoms of MS become steadily progressive, with ongoing damage to the central nervous system. Symptoms usually get worse as the disease progresses.
• Primary progressive is where the disease is progressive from the start, although damage to the central nervous system occurs at different rates in different people. This course of MS is not very common.
• Progressive relapsing, which is a rare course of MS that causes steady damage to nerves when symptoms first appear and continues to cause damage to the central nervous system even when you are not experiencing symptoms.