Hi boscjo and welcome to NeuroTalk

Avonex, as well as many of the other MS treatments are meant to:

(1) Slow progression. You can still progress even taking Avonex

(2) Decrease the amount and severity of relapses. You can still have relapses on the MS medications.

(3) Decrease lesion load. You can still get lesions on medications.

None of 3 listed above is gauranteed. This disease is a crapshoot. Many of the Disease Modifying Therapies/Disease Modifying Drugs were not meant to help with symptoms, although, there are some who have found that to be true.

The MRI does not give the entire picture of this disease. You can be doing good and the MRI will show an increase in lesions or you can be feeling poorly, MS wise, and there are no changes to the MRI. Sometimes the MRI will match up to how you feel. You can have stable (no changes) MRIs but still progress.

No sure I answered your question directly but, unfortunately, no one really knows if the treatments are helping or if the patient would be doing the same off of treatment. It is truely a leap of faith.