The upper limb tingling coming on when you lie on your back suggests it's mechnical and that you are irritating a nerve. If it's in the palm side of your wrist it is the median nerve. Have u had previous accidents that began this? what is your job? Have a look on the internet at upper limb tension tests (ULTT). They are gentle movements that you can do to get the nerves sliding on their interfaces a bit better. They can get stuck down a bit if there has been trauma. Have you seen a phsiotherapist? Also if it TOS with no known cause then you could pursue the route of traditional chinese medicine. Personally I think this is a great approach as they inspect the whole person to see for disharmony and not just look at the site of pain. Acupuncture and herbs could be the way to go. One question though, do you have metal fillings?