Understanding Carpal Tunnel Syndrome
What is the Carpal Tunnel?
The carpal tunnel is a narrow passageway located at the base of the hand, formed by the transverse carpal ligament (also called the flexor retinaculum). This ligament (see diagram) covers the small wrist bones and creates a tunnel through which the median nerve and flexor tendons (responsible for bending the fingers and thumb) travel from the forearm to the hand. The median nerve provides sensation to part of the hand and controls some muscles crucial for hand movement.
The palm of the hand, showing the median nerve running beneath the flexor retinaculum
What is Carpal Tunnel Syndrome?
Carpal tunnel syndrome (CTS) occurs when the median nerve is compressed within the carpal tunnel. This pressure disrupts normal nerve function and leads to various symptoms.
Symptoms of Carpal Tunnel Syndrome
- Tingling and Numbness: Commonly felt in the part of the hand controlled by the median nerve, often giving the sensation that the entire hand is tingling (see diagram).
- Night-time Symptoms: Many people experience worsening symptoms at night, which can interrupt sleep. Hanging the hand off the bed or shaking it may help relieve symptoms.
- Difficulty with fiddly tasks: As CTS progresses, tingling and numbness may become continuous, affecting hand sensitivity and making tasks like buttoning clothes challenging.
- Weak Pinch Grip: In advanced cases, the muscles at the base of the thumb may weaken, impacting grip strength.
Sensory area for the median nerve
Who is at Risk for Carpal Tunnel Syndrome?
Carpal tunnel syndrome affects many people, often without a clear cause, and is partly influenced by genetic factors. Aging is a common risk factor, as the space in the carpal tunnel naturally decreases over time, increasing the risk of nerve compression. While CTS can develop at any age, it’s rare in children and young adults but becomes more common with age. Additional factors like diabetes, hypothyroidism, arthritis, or wrist injuries can also increase the likelihood of developing CTS.
How is Carpal Tunnel Syndrome Diagnosed?
Diagnosis often involves assessing symptoms and performing a physical examination. Nerve conduction studies may be used to confirm CTS and evaluate its severity. This test involves placing sticky pads on the arm and measuring the speed at which nerve impulses travel, which may feel uncomfortable but isn’t typically painful.
Natural Course of Carpal Tunnel Syndrome
Carpal tunnel symptoms may fluctuate over time, often without progressing immediately. In some cases, addressing underlying conditions such as diabetes or thyroid issues can alleviate symptoms. Pregnancy-related CTS often resolves after childbirth but may return later. However, if symptoms worsen or persist, it’s important to discuss treatment options with a doctor to prevent lasting nerve damage.
Treatment Options for Carpal Tunnel Syndrome
- Splinting: Wearing a wrist splint at night, which keeps the wrist in a neutral position, may help reduce symptoms, though this may not be effective for everyone.
- Steroid Injection: An injection into the carpal tunnel may relieve symptoms temporarily, typically lasting up to three months. While it offers no long-term benefits, it can be a helpful option for those who cannot undergo surgery immediately.
- Surgery: The most effective long-term treatment is a procedure called carpal tunnel release surgery. This involves cutting the transverse carpal ligament to relieve pressure on the median nerve. Typically performed under local anaesthesia, surgery often resolves night-time pain and tingling within days. In severe cases with ongoing numbness or muscle weakness, recovery may be slower or incomplete. Performing light tasks with the hand use is possible shortly after surgery, but full strength and comfort can take months to return as scar tissue reforms over the cut ligament.
Carpal tunnel release surgery has high success rates, with approximately 96% of patients reporting favourable outcomes after one year. However, since the ligament is cut, normal ligament function is temporarily disrupted until it heals with scar tissue. Overall, open carpal tunnel decompression offers excellent results for symptom relief and long-term improvement in most cases.
