He told me, “The immune system in your body attacks and damages the nerve sheath, which could lead to paralysis, blindness or other complications.” I asked, ‘how could it be?’ The doctor answered me that there are a lot of researches, but they could not identify a “cause,” and the only thing we could do is to take drugs to slow the deterioration of the condition, and that we can only sit and wait.
Avicenna defines ’cause’ as the first factor for a change in the body. This may be a positive change towards health or a negative change towards disease. The reasons are six as mentioned

air
Food, drink and medicine
sleep and wakefulness
movement and stillness
Vomiting and congestion – that is, the expulsion of something from the body or its retention in it.
Psychological state such as joy, anger, tension, sadness, etc
Medical institutions and their staff can support the patient with medication, physiotherapy sessions …etc, but the rest of the six reasons remain in the patient’s hands and under his responsibility.
I think of myself and how it’s been about ten years I’ve been dealing with Multiple Sclerosis, I confined my treatment to medication (for about three and a half years) and then focused only on food. By researching and delving into Avicenna’s medicine, we see that there are broader aspects that must be included in the healing process. Perhaps this is the lifestyle change I should be making?!

An excerpt from The Canon of Medicine Book.