As hard as we’re working to solve the mystery, we still don’t know.
Most cases don’t seem to run in families. Exposure to chemicals in the environment might play a role. For most people, the exact cause isn’t known.
Some patients connect the onset of their symptoms to a trauma such as an accident, surgery or extreme emotional distress. Most neurologists don’t think there’s a direct link, but they do believe that a traumatic event might cause symptoms to start a little earlier.