One of our 3 arm and hand nerves, the "Medianusnerv"("lying in the middle" in Latin) , runs over the wrist into the palm and takes over the sensitive supply of the first three fingers (fingers I-III) as well as the muscular supply in the ball of the thumb. In the wrist area, it runs through a narrow channel formed by the bony carpus and a ligament lying above it, the Carpal tunnel. If, for example, there is increased water retention or slight swelling in the carpal tunnel during pregnancy or due to overuse, the median nerve comes under pressure. Since the arm is held still during the night and thus the fluid in the carpal tunnel is not removed, the affected person initially notices a (painful) falling asleep of the first three fingers, especially during the night. Often he wakes up from this, runs cold water over the wrists or shakes them out to make it better. This also goes well for a while. However, if the compression of the nerve continues for months, damage to the nerve can occur. The fingertips I - III remain numb even during the day and in extreme cases, the strength during grasping movements with the thumb diminishes. The pain can radiate into the affected arm, so that it comes again and again to the incorrect assessment, e.g. that the complaints are the cause of a herniated disc in the cervical vertebrae.
The diagnosis of carpal tunnel syndrome can be made quite quickly and reliably by determining the Nerve conduction velocity (NLG) of the median nerve.
Therapeutically, one first tries to make the complaints disappear by splinting the wrist at night, sometimes with the administration of a decongestant medication. This may be useful for pregnant women in whom the carpal tunnel only comes under pressure during pregnancy. However, if discomfort recurs with increased strain on the affected hand, a minor surgical procedure in which the ligament constricting the canal is split is the solution. This operation, performed by an experienced hand surgeon under local or regional anaesthesia, has a very low complication rate and can be performed even in old age.
The endoscopic method, in which a probe is inserted through an opening in the skin at the wrist, as in a gastroscopy, and the ligament is cut with a small knife attached to it, is gentler at first glance, but in my observation has a greater risk of injuring the nerve in the process.
Usually, the patient must then rest the affected hand for about four weeks, after which he or she can increasingly put weight on it again.