How does the doctor make the diagnosis of carpal syndrome?

Carpal Tunnel?: I assume you mean carpal tunnel syndrome. The diagnosis is made based on history of numbness and tingling in the thumb, index, long finger, as well as 1/2 of the ring finger associated with pain. Their reproduction by phalan's test and tinnel's sign(check for images on the web).

Carpal tunnel sndr: 1.Tingling or numbness in your fingers or hand, especially your thumb and index, middle or ring fingers, but not your little finger. 2.Pain radiating or extending from your wrist up your arm to your shoulder or down into your palm or fingers 3.A sense of weakness in your hands and a tendency to drop objects.