Some people may have gradual development of tingling sensation in the thumb, index and  the middle fingers. This might go on to loss of sensation in the fingers.  As a result people drop things and find it difficult to use their fingers in day to day work.  As the problem develops, they may have acute pain in the hand waking up people from their sleep during nights. This is because of compression of the nerve supplying sensation to the fingers at the level of the wrist.  The wrist architecture is 
unique in that the 8 small bones which make the wrist form an arch bound by a tight strap like ligament called flexor retinaculum. In this small tunnel nine tendons and the median nerve(the nerve of thumb index and middle fingers) pass through.  When the space in the tunnel gets narrowed due to swelling of the tissue or any space occupying lesion the nerve gets compressed.  The blood supply to the nerve gets reduced and that results in pain and later loss of function.  This could be easily treated by release of the ligament.  If it is done early it results in full recovery. 

Cause
There can be many causes of carpal tunnel syndrome. Jobs that require excessive bending of the wrist tend to increase the pressure around the median nerve in the wrist. Similarly, sleeping with your wrist in an acutely bent position will increase pressure on the median nerve and cause carpal tunnel syndrome. Diabetes, alcoholism, hypothyroidism, and obesity are also predisposing factors towards developing carpal tunnel syndrome.

Treatment
The common treatment for Carpal Tunnel Syndrome is release of the tight ligment called the flexor retinaculum at the level of the wrist.  When the liagment is divided longitudinally the nerve is released.  Done early this gives excellent results. 
If there is no contraindication, initially  injection of steroid could be tried.