Can you explain what Benign MS is?

Benign MS refers to people with milder forms of the disease than the majority of people with MS. The concept remains controversial for a number of reasons. These include the following:

1. Commonly used definitions of MS disability focus on impaired muscle function or movement and do not fully consider the effects of cognitive impairment. We've known for many years that cognitive impairment is a greater limitation to gainful employment and independence than impaired muscle function.
2. Many definitions of benign MS focus on early features of the disease, primary relapse rates and inter-attack interval (the duration of time between relapses) during the first 5-10 years. [None really incorporate MRI data since this is not available in most natural history databases.] Those with few early relapses or a long inter-attack interval without treatment are said to have a greater likelihood of benign MS. While this is often true, it is also clear that some people develop progressive disease later in the course of their MS, despite very few relapses early in the disease.
3. More modern definitions include a low level of disease activity  on serial MR imaging studies in younger relapsing MS  patients (under age 40) not on disease modifying therapy (DMT). This is a rare population, not because this does not occur, but because few patients or physicians make the decision not to go on DMTs and observe the disease off of therapy for any significant period of time. 
4. Most definitions of benign MS are based on an analysis of patients after 20-30 years of disease. When this is done approximately 20 % of people with MS look benign after 30 years. The problem with this approach is that people with MS are often only 40-60 years old after 20 to 30 years of the disease. They still have a significant remaining lifespan during which the disease can continue to worsen. This is one of my pet peeves about discussions concerning the concept of benign MS; we have very few useful studies on the behavior of MS with people over age 65 (geriatric MS).

Despite these reservations the concept of benign MS does serve a purpose when making treatment decisions. Our current treatments work best in younger people (those under 45 to 50) with evidence of ongoing inflammatory disease; few people with these characteristic are found to have benign MS by anyone's definition.

​Revere P (Rip) Kinkel, MDProfessor of Clinical Neurosciences
Director of the Multiple Sclerosis Program
Clinical Neurosciences Director
University of California San Diego