These "carpal tunnel thumb tests" should be part of a complete carpal tunnel exam. More precisley we are testing for thumb weakness and muscle shrinkage called thumb atrophy (pronounced AT-trophy). Both of these tests are very good at detecting thumb weakness which may indicate carpal tunnel syndrome (CTS). See HOW CTS IS DIAGNOSED.
Check out both of the carpal tunnel thumb tests I use:
With the palm up and hand resting on table or examiners hand, the patient is instructed to raise his/her thumb perpendicular (or straight-up) from the palm as the examiner applies downward pressure to the end of the thumb.This test isolates an important muscle in the thumb that is stimulated by the median nerve.
The examiner should compare results to the patient's other thumb.If there is not good resistance against the examiner's pushing down effort (i.e. the doctor can push the thumb back down easily,than there is a problem)
Also,having done this many,many times over the years on different people,you kind of learn how much resistance you should expect.
This is the second carpal tunnel thumb test I do.With this one I have the person try and pinch (with thumb and index finger-like an "Okay" sign) a Piece of paper.Now as I try and pull the paper,the person should increase their pinching effort.As this is being done, I palpate or feel their thumb muscle(Thenar muscle).The thumb muscle should be tight and firm,because the person is contracting or flexing this muscle as they pinch harder and harder to prevent the paper from slipping.If this thumb muscle is kind of soft or "mushy"...when the person is trying to forcefully pinch,then there is a problem.The median nerve supplying this muscle may have been compressed or damaged a long time.
This resulting damage is called Thenar atrophy (Thee-nar At-trophy). Note however, that a normal key pinch test (i.e. you have a firm thumb muscle) doesn't mean you don't have CTS.
Thenar atrophy takes a long time to occur and is a late sign of chronic and severe carpal tunnel syndrome.
These two simple thumb tests should be part of a complete carpal tunnel exam.
Carpal tunnel causes
EMG test for CTS
How CTS is diagnosed