Not all numbness/tingling, weakness, or pain in the hand is a result of CTS.
Tingling of the hand with the absence of muscular weakness is common, but is not true CTS. There is a palmer (palm side of the hand) branch of the median nerve which passes over the top of the carpal tunnel. The palmer branch of the median nerve is often irritated when consistent pressure is applied to the palm-side of the wrist, e.g. typing on the computer.
When CTS symptoms are present in both hands and wrists, especially occurring at the same time, the symptoms may be stemming from the spine. This condition is a cervicothoracic joint derangement with pain referral. This fancy term means there are altered joint mechanics in the neck and/or upper back region irritating the nerves that send information down the arm. With a joint derangement causing nerve irritation, symptoms can occur anywhere along the path of that nerve.
As an analogy, think of a kinked hose: the issue is a lack of water flowing down the hose, but the source of the problem is the kink itself.
In the case of the neck and upper back causing wrist and hand symptoms, the source is the “kink” of a nerve(s) near the spine and the wrist/hand symptoms are due to the lack of “flow” down the “hose”.
The kinked hose analogy can also be applied to the shoulder, and the low back relative to the legs!