March 16, 2010

Although most relapses in MS resolve either partially or fully, and progression of disability tends to occur gradually over time, some people with MS as well as doctors are concerned about the risk of a very severe relapse that doesn't resolve. This concern can affect treatment decisions -- for instance, it could influence someone away from stopping treatment even if they have other reasons for discontinuing it. A pair of researchers at the Marshfield Clinic in Wisconsin decided to help quantify the odds of having this type of severely disabling attack. They examined their clinic's database to count how many MS patients there had experienced a relapse that left them permanently disabled with an EDSS of 6.0 or greater.

Out of 1,078 relapsing-remitting patients who had 2,587 recorded relapses, only seven had a relapse leaving them with an EDSS of 6 or more that did not improve with time. For two of these patients, this relapse was a first MS attack that left them partially paralyzed. The other five patients who had confirmed MS at the time of the relapse also had partially paralyzing attacks that left them unable to walk without assistance. Their EDSS scores prior to the attack ranged from 2.5 to 4.0. Two of these five had been on interferon beta at the time. The research team found no characteristics that set these seven patients apart from the other 1,071, such as disease duration or past relapse features.

A couple of limitations of this study are that (1) due to the clinic's location, it didn't include many African-Americans, and (2) it assessed disability in terms of the EDSS scale, which is weighted toward walking ability. However, the results provide initial evidence that severe relapses resulting in permanent disability are quite rare. The fact that some of the patients left with disability were on treatment at the time suggests that concern about these types of relapses shouldn't dictate decisions about treatment.