This question has been raised twice now at ISNVD, by neurologists Dr. Burks and Dr. Zivadinov: is CCSVI treatment a disease-modifying treatment or is it for symptom management?
This is looking at CCSVI treatment's effect on MS, not on CCSVI syndrome itself. It does appear to have an effect on CCSVI symptoms, which overlap with some MS symptoms, so it is reasonable to consider it in a symptom-management category.
It is also reasonable to consider it disease-modifying. If research shows that CCSVI treatment reduces lesion seen on MRIs, that would be a success for it as a disease-modifying treatment.