Carpal Tunnel Syndrome Explained

Carpal tunnel syndrome is the most common nerve compression disorder of the upper limb. The symptoms are recognisable but the point at which they stop being a nuisance and start indicating nerve damage is less obvious. This sets out what causes it, what the symptoms mean, and where surgery fits.

What carpal tunnel syndrome is

Carpal tunnel syndrome occurs when the median nerve, which runs through a narrow passage in the wrist called the carpal tunnel, becomes compressed. The tunnel is formed by bones and the transverse carpal ligament, creating a protected pathway for the median nerve and flexor tendons. When inflammation, swelling or structural change narrows this space, the nerve is compressed and the characteristic symptoms appear.

The role of the median nerve

The median nerve carries both sensory and motor function in the hand. It provides sensation to the thumb, index, middle and part of the ring finger, and controls the muscles at the base of the thumb that enable pinching and gripping. Compression or irritation of this nerve affects hand function directly.

What causes it

Repetitive motion

Repetitive wrist and hand movements are the most common contributor. Typing, sewing, playing musical instruments and using hand tools can strain the flexor tendons and cause swelling. Over time this reduces the space in the tunnel.

Underlying medical conditions

Certain conditions predispose to carpal tunnel syndrome by increasing inflammation or exerting direct pressure on the nerve:

• Rheumatoid arthritis — chronic inflammation in the wrist joint narrows the tunnel.
• Diabetes — diabetic neuropathy makes the median nerve more susceptible to damage.
• Hypothyroidism — hormonal imbalance leads to fluid retention.
• Pregnancy — hormonal change causes swelling that temporarily narrows the tunnel.

Wrist trauma

Fractures or dislocations of the wrist can deform the structure of the carpal tunnel and place pressure on the nerve. Acute injuries may produce sudden, severe symptoms that require immediate attention.

Anatomical predisposition

A naturally smaller carpal tunnel or inherited wrist structure increases the likelihood of developing the condition. Family history often plays a role.

Weight and lifestyle

Excess weight adds pressure on the wrist structures. Smoking and a sedentary lifestyle can worsen nerve-related problems over time.

Symptoms

Tingling or numbness

The most common symptom is tingling or numbness in the thumb, index, middle and half of the ring finger. It may be intermittent at first and become persistent as the condition progresses.

Pain

Pain often starts in the wrist and radiates up the forearm or into the shoulder. It can be sharp, aching or burning, and is commonly worse at night.

Weakness or clumsiness

Grip weakens, making it difficult to hold objects, type or perform fine tasks. Some people drop items because of sudden loss of strength.

Shock-like sensations

Shock-like or burning sensations shooting through the fingers or wrist indicate significant nerve irritation and accompany more advanced cases.

Muscle wasting

Without treatment, prolonged compression can cause wasting of the muscles at the base of the thumb. This is a sign of long-standing damage.

How it is diagnosed

History and examination

A detailed history of symptoms and risk factors helps establish likelihood. During examination the following may be used:

• Tinel’s sign — tapping over the median nerve to elicit tingling.
• Phalen’s test — sustained wrist flexion to reproduce symptoms.

Nerve conduction studies

Electrodiagnostic tests measure the speed of electrical signals travelling through the median nerve. Slowed conduction confirms compression.

Imaging

MRI or ultrasound can show swelling, structural abnormality or other problems within the tunnel. These are used in complicated or advanced cases.

Non-surgical treatment

Non-surgical measures can be effective in mild to moderate disease.

Wrist splints

Splints hold the wrist in a neutral position, reducing pressure on the nerve. Night splints are particularly useful for symptoms that wake the patient.

Activity modification

Avoiding or adjusting repetitive wrist movements reduces strain on the tendons. Ergonomic workstations, keyboards and wrist rests help minimise pressure.

Physical and occupational therapy

Therapists teach stretching and strengthening exercises to improve wrist mobility and reduce swelling. Soft tissue mobilisation and posture correction may also be used.

Medication

Non-steroidal anti-inflammatory drugs relieve pain and swelling. Corticosteroid injection into the carpal tunnel provides temporary relief where inflammation is significant.

When surgery is indicated

Surgery becomes appropriate when conservative treatment fails to relieve symptoms, or where there is evidence of significant nerve damage. The aim is to reduce pressure on the median nerve and restore hand function.

Open carpal tunnel release

An incision in the palm gives access to the transverse carpal ligament, which is divided. This enlarges the tunnel and relieves pressure on the nerve. Recovery typically takes a few weeks and results are generally durable.

Endoscopic carpal tunnel release

A less invasive alternative using a small camera and specialised instruments through small incisions. This allows quicker recovery, less scarring and less post-operative discomfort.

Recovery and rehabilitation

Timeline

Most patients return to light activities within one to two weeks. Full recovery, including restoration of strength and flexibility, may take six to twelve weeks.

Therapy

Rehabilitation exercises reduce stiffness, improve range of motion and restore hand function. Splints or braces may be used to support recovery.

Preventing recurrence

Ergonomic practice, maintaining a healthy weight and avoiding sustained repetitive hand motion reduce the chance of recurrence.

Risks of surgery

Carpal tunnel release has a high success rate, but the recognised risks are:

• Infection — proper wound care reduces this risk.
• Scarring — scars are typically small and fade, but can be tender in some cases.
• Nerve damage — rarely, surgery can cause temporary or permanent nerve problems.
• Persistent symptoms — a small proportion of patients have incomplete resolution.

Prevention

Ergonomic practice

Ergonomic tools, neutral wrist positions and regular breaks reduce strain.

Stretching

Stretching the wrist and forearm before and after repetitive tasks helps maintain flexibility and reduce tension.

General health

Maintaining a healthy weight, managing chronic conditions and avoiding smoking support nerve health.

Conclusion

Carpal tunnel syndrome is common and, treated appropriately, manageable. Understanding the cause, recognising the symptoms that indicate nerve damage and acting before muscle wasting occurs is what determines the outcome.