Its sensory component supplies the skin of the palm, thumb, index and middle finger as well as half the ring finger, and, importantly and often forgotten, the bones of the wrist. In the proximal forearm it gives rise to the anterior interosseous nerve which innervates the flexor of the thumb (FPL), the flexor digitorum profundus of the index finger (FDP IF), and the pronator quadratus, and terminates in a sensory branch to the bones of the wrist, i.e., the carpal tunnel. Compression of the proximal median nerve results in weakness of these three muscles, and can cause aching pain in the wrist on the basis of the sensory nerve to the carpal bones. Diagnosis
The most common chief complaint is intermittent pain in the wrist, associated with sustained pronation, frequently misinterpreted by patients and providers as "tendonitis." This is usually accompanied by the perception of "hand weakness," and "dropping things." The characteristic physical finding is tenderness over the proximal median nerve, with ensuing numbness in the hand in less than a minute, and/or numbness in the hand with resisted pronation of the forearm in less than a minute.The flexor pollicis longus and FDP of the index finger are weak, leading to impairment of pinching firmly.
In most of the cases there was an additional annular pulley structure distal to the A1 to be released resolving the triggering: the so-called Av pulley or variable pulley. Therefore, infants and adults need to be treated differently as the main problem is different. Open vs. percutaneous
There are two types of surgery: open surgery which is mentioned above and percutaneous surgery. Unlike open surgery percutaneous surgery is done without exposing the anatomical structures beneath the skin. Research has shown that percutaneous surgery is a good alternative to open surgery. Percutaneous surgery is done with a needle that is inserted in the flexor sheath at the level of the A1 pulley. Before the needle insertion the thumb is placed in extension, whereas when the needle is already inserted the thumb will be put into semi-flexion, so that the needle can be moved and the palmar skin is movable. The A1 pulley will then be cut with the needle longitudinally and parallel to the fibers of the tendon of the flexor pollicis longus muscle. When the release with the needle is done according to the pivot maneuver the chances of incomplete release and damage to the digital nerve nearby will be increased. To prevent any postoperative hematoma and swelling, pressure should be applied for at least 10 minutes after the procedure. Percutaneous surgery has also been proven to be without residual deformities and recurrence after surgery. When the A1 pulley is too thick and long to be released at once, open surgery still can be a solution.