Deciding whether to start a DMT before you've received a definite MS diagnosis is a decision that you and your physician can explore together. People who have experienced a clinically isolated syndrome (CIS: one neurological episode, lasting at least twenty-four hours and caused by inflammation in the CNS) may or may not go on to develop MS. However, studies show that those presenting with certain signs or symptoms have a greater chance of developing MS. If a CIS is accompanied by evidence of MS-type lesions on an MRI, the likelihood of having a second neurological episode is greater.

Three large-scale clinical trials have been conducted to determine whether early treatment following a clinically isolated syndrome can delay a second clinical event. The studies involved the use of Avonex, Betaseron, and Rebif (three of the DMTs used in MS) and results indicated that the drugs significantly delayed the onset of a second neurological episode. MRI findings also showed that the brain lesion volume in the patients studied was reduced. It is important to discuss these studies with your doctor and decide which course of action is right for you.