Carpal tunnel syndrome: hand numbness, diagnosis and treatment

What is the carpal tunnel?

The carpal tunnel is a narrow passage on the palm side of the wrist. Its floor and walls are formed by the small wrist bones, and its roof by a tough band of tissue called the transverse carpal ligament. The tendons that bend the fingers pass through it together with the median nerve, which provides feeling to the thumb, index finger, middle finger and part of the ring finger, and controls some of the thumb muscles.

When space inside the tunnel is reduced or its contents swell, pressure on the nerve rises and it starts to work less well. The result is carpal tunnel syndrome – one of the most frequent causes of hand numbness and a common reason to see an orthopaedic or hand surgeon or a neurologist. It belongs to the wider group of peripheral nerve problems – see neuropathy.

Causes and risk factors

Often no single cause is found. The risk is higher with:

• female sex and age between about 40 and 60;
• pregnancy – fluid retention commonly causes temporary symptoms that usually resolve after birth;
• diabetes, an underactive thyroid and obesity;
• rheumatoid arthritis, other inflammatory conditions and osteoarthritis of the wrist;
• previous wrist fractures;
• prolonged use of vibrating tools and repeated forceful wrist bending;
• a family history of the condition.

Keyboard and mouse use can aggravate symptoms, but the evidence does not clearly show that it causes the condition on its own.

Symptoms

• numbness, tingling or burning in the thumb, index, middle and half of the ring finger (the little finger is usually spared);
• symptoms that wake you at night or are worse in the morning, and ease when you shake the hand;
• numbness when holding a phone, steering wheel or book;
• pain that may spread up into the forearm;
• clumsiness, dropping things and difficulty with buttons;
• in advanced cases, constant numbness and wasting of the muscles at the base of the thumb.

Hand numbness can have other causes, such as a trapped nerve root in the neck from a cervical disc herniation or a generalised neuropathy, so an accurate examination matters.

How is it diagnosed?

The diagnosis is often clear from the typical symptoms and examination. The doctor checks sensation in the fingers and the strength of the thumb muscles, and may perform provocation tests – tapping over the nerve at the wrist (Tinel’s sign) or holding the wrist bent (Phalen’s test).

The most objective test is a nerve conduction study with electromyography – see EMG. It confirms compression, shows how severe it is and helps rule out other causes, and is particularly useful before surgery. Ultrasound of the wrist can show a swollen nerve and causes such as a cyst or inflamed tendon sheaths. Blood tests, for example for blood sugar and thyroid function, may be done if an underlying condition is suspected.

Non-surgical treatment

For mild to moderate symptoms, non-surgical treatment is often enough:

• a night splint that keeps the wrist straight and reduces pressure on the nerve during sleep;
• activity changes – regular breaks, avoiding prolonged wrist bending and forceful gripping, and an ergonomic workstation;
• a steroid injection into the carpal tunnel – often relieves symptoms for weeks to months and can help confirm the diagnosis;
• nerve and tendon gliding exercises guided by a physiotherapist or hand therapist;
• treating underlying conditions – good diabetes control, treatment of an underactive thyroid.

Painkillers and anti-inflammatory tablets usually have limited benefit. In pregnancy, symptoms most often settle within weeks to months after the birth, so surgery during pregnancy is rarely needed.

Carpal tunnel release surgery

Surgery is recommended when symptoms are persistent or severe, when non-surgical treatment has not helped, or when there are signs of nerve damage – constant numbness, weakness or wasting of the thumb muscles, or marked changes on nerve testing.

The operation, called carpal tunnel release (decompression), divides the ligament that forms the roof of the tunnel, giving the nerve more room. It is usually a day-case procedure under local anaesthetic and takes a short time. There are two main approaches:

Night-time symptoms often improve within days. Recovery of feeling and strength after long-standing, severe compression can take months and is sometimes incomplete. Possible complications include scar tenderness, temporary grip weakness and, rarely, infection or nerve injury; recurrence is uncommon.

Recovery after surgery

You are encouraged to move your fingers straight after the operation to reduce swelling and stiffness. The bulky dressing is usually removed after a few days and stitches after around two weeks. Light daily activities are possible quite soon, but heavy gripping and lifting are avoided for several weeks. Return to work depends on your job – often one to two weeks for desk work, longer for heavy manual work.

When to see a doctor

See your GP, an orthopaedic surgeon or a neurologist if finger numbness lasts more than a few weeks, wakes you at night or interferes with work. Do not delay if you have constant numbness, weakness or wasting of the thumb muscles, as prolonged compression can permanently damage the nerve. Call emergency services if sudden arm weakness or numbness comes with facial droop, leg weakness or slurred speech – this may be a stroke.

Treatment abroad and in Türkiye

Carpal tunnel release is a short, routine operation and in most cases can be done close to home. Some patients from Bulgaria and elsewhere in Europe nevertheless plan it at large accredited hospitals in Istanbul, sometimes alongside another orthopaedic procedure. Check the surgeon’s experience in hand surgery, whether nerve conduction tests have been done beforehand, the written plan and how stitch removal and follow-up will be handled at home. Organisers such as New City Clinic in Istanbul coordinate the hospital, surgeon, hotel, transfers and interpreter. For more on the specialty, see orthopaedics and traumatology.