Not necessarily.
Your Dx sounds exactly like mine, and the small non-myleinated nerves as well as the large myleinated ones area affected, except that mine is axonal which means the axons are being attacked as well.
Testing should be done (see lizajane.com for a list) to determine cause, but it may be that you will be idiopathic without a cause being found. Be prepared for that. The treatment(s) are still the same, primarily.