it is impossible to predict whether your SFN will lead to disability. It will depend on the cause, whether the cause can be treated, it also depends on the individual person, some will experience spread of areas affected and worsening symptoms, some will plateau and not get worse, some will get worse very slowly, some will get better. The best thing you can do is to provide your body with the best conditions possible to heal, such as nutrients, vitamins, healthy life style, treating or avoiding the underlying cause or causes.