Carpal tunnel syndrome involves pressure on the median nerve in the wrist, causing pain and numbness.
The carpal tunnel is a narrow passage on the palm side of the wrist, bounded by small wrist bones and a tough ligament, through which the median nerve and the tendons that bend the fingers all pass. Carpal tunnel syndrome occurs when the median nerve becomes compressed within this tunnel, most often because the tissues around it have thickened or the space has narrowed.
It is the most common nerve entrapment condition in the body. Because the median nerve supplies sensation to the thumb, index, middle and part of the ring finger, and also controls some of the small muscles at the base of the thumb, carpal tunnel syndrome can affect both sensation and fine hand function if left untreated for a long period.
In many cases, no single cause is identified, and the condition arises simply from the tunnel being naturally narrow or the tissue within it thickening slightly with age. Recognised contributing factors include repetitive or sustained wrist movements, particularly prolonged gripping or vibrating tools, pregnancy, due to fluid retention narrowing the tunnel, and medical conditions such as diabetes, an underactive thyroid, and rheumatoid arthritis.
A previous wrist fracture that has altered the shape of the tunnel, and being overweight, are also recognised contributing factors. It is common in people with no obvious risk factor at all.
The characteristic symptoms of carpal tunnel syndrome are:
Shaking or moving the hand often provides brief relief of symptoms, which many people notice before ever being formally assessed.
Assessment includes a history of symptoms and their pattern, examination of hand sensation and strength, and typically a nerve conduction study to confirm the diagnosis and assess its severity.
Mild to moderate carpal tunnel syndrome is often managed initially without surgery: a wrist splint worn at night to keep the wrist in a neutral position, activity modification, and a corticosteroid injection into the carpal tunnel, which can provide meaningful, though sometimes temporary, relief.
Surgery, carpal tunnel release, is recommended when symptoms are more significant, persistent despite non-surgical treatment, or when there is weakness or muscle wasting. It is a common and generally straightforward day surgery procedure that involves dividing the ligament forming the roof of the tunnel to relieve pressure on the nerve.
The outlook for carpal tunnel syndrome is generally very good. Mild and intermittent symptoms often respond well to splinting alone, particularly when the diagnosis is made early.
For patients who proceed to surgery, most experience substantial or complete relief of numbness and tingling, often within weeks. Grip and pinch strength recover more gradually. In longstanding cases with established muscle wasting at the base of the thumb, some weakness may persist even after successful surgery, which is why earlier treatment tends to give the best overall results.
Carpal tunnel syndrome is one of the most common nerve conditions affecting the hand, and it is very treatable at every stage. Mild cases often respond well to splinting, while more established or progressive symptoms are effectively treated with a straightforward day surgery procedure. Persistent numbness or tingling in the thumb, index and middle fingers, especially at night, is worth having assessed.
For a comparison with a similar nerve condition affecting the elbow, see carpal tunnel vs cubital tunnel syndrome.
