Benign MS is a term used to describe a variation of relapsing-remitting MS (RRMS) where relapses are very mild, where there are very long periods between relapses and/or only a few relapses ever occur. It is thought that 5-20% of people with MS have benign MS.
The first attack often affects vision or another sense, but the person remains active. Usually, subtle damage is occurring despite the lack of relapses.
If someone with MS has remained mostly functional for 15 years, they are generally considered to have benign MS.
Its numbers are probably overestimated because we don’t connect it to subtle problems like fatigue and cognitive, social, and/or psychological issues.