When the nerves or tendons inside the carpal tunnel swell or become inflamed (carpal tunnel syndrome), pressure on the nerve causes pain, numbness, tingling, or weakness in the fingers and wrist. The nerve most commonly affected in carpal tunnel syndrome is the median nerve, which provides motor and sensory function to the hand. Most physicians recommend trying non-surgical treatments (such as: splinting the wrist, using anti-inflammation medications) before recommending surgery.