What are the signs?

First of all, don't panic and assume that discomfort in your hands, wrists or arms is CTS. The pain may simply be overuse strain caused by doing too much too soon (just like an athlete, you need to train your limbs to go beyond a previously adequate level of conditioning). But don't try to diagnose your own problem; let a doctor do that. Accurately diagnosing and dealing with pain early on will avert more severe problems from developing.
Many people don't associate common early warning signs of CTS, such as awakening at night with numbness in the hand, to job-related stress. The following symptoms may be intermittent at first, but can become persistent if the condition is not treated.
Decreased mobility of the fingers, hand, elbow or shoulder
Decreased hand strength
Dull aching discomfort or pain that occurs most commonly at night or in the early morning
Severe pain that awakens you during the night
Wrist pain that radiates to the forearm, shoulders, neck and chest
Dry skin, swelling or color changes in the hand
Weakness of the thumb
Tingling in all but the little finger
Numbness in the hand, resulting in weakness or clumsiness