A new study published in the November 4, 2009, issue of Neurology®, the medical journal of the American Academy of Neurology says that patients with multiple sclerosis (MS) who have relapses within the first five years of onset appear to have more severe disability in the short term compared to people who do not have an early relapse.

The study is one of the first to examine how MS relapses affect people during different time periods of the disease.

Research shows that 85 percent of people with MS begin by having the relapsing-remitting form of the disease and the majority of these people later develop secondary progressive MS. A relapse is defined in the study as worsening of neurological symptoms for more than 24 hours, without a fever or infection. Because relapse-related symptoms often improve within a few weeks, it's been unclear how much disability comes from relapses, and how much from progression.

For the study, scientists reviewed the medical records of 2,477 people with MS who experienced relapses in British Columbia, Canada. The study looked at whether the participants had disability severe enough to require the use of a cane for walking and whether this was related to relapses occurring within five years, five to 10 years, or more than 10 years after onset of symptoms. The participants were followed for an average of 20 years. During that time, the group experienced 11,722 relapses.