Carpal Tunnel Syndrome

Carpal tunnel syndrome is a common problem where increased pressure on the median nerve in the wrist leads to numbness, tingling, and pain.  Severe cases can result in weakness and severe disability.

Anatomy and Causes

The carpal tunnel is a space in the wrist.  The “arch” of the tunnel is made up of a row of small bones called the carpal bones.  The palm or volar side of the arch consists of a thick ligament called the transverse carpal ligament.  Multiple important structures travel through the carpal tunnel including the flexor tendons to your fingers and thumb as well as the median nerve.  This nerve provides sensation to the thumb, index, and middle fingers, and usually provides sensation to half of the ring finger (though not all nerves have read the textbook and there can be some variation).  Swelling inside the carpal tunnel or thickening of the transverse carpal ligament can put pressure on the nerve, resulting in symptoms.

Symptoms and Associations

Symptoms of carpal tunnel syndrome are due to compression of the median nerve.  Early symptoms frequently include numbness, tingling, or “pins and needles” sensations  in the hand at night or with gripping activities such as driving.  Patients frequently describe having to shake their hands awake.  Difficulties with small tasks such as buttoning a collar are also common.  Numbness and tingling present throughout the day often signifies worsening damage to the median nerve.  Weakness with pinch and loss of muscle bulk at the base of the thumb can also signify severe disease.  Persistent numbness and tingling and loss of muscle mass can signify prolonged pressure on the nerve, which can result in permanent damage to the nerve itself.

Carpal tunnel can sometimes be associated with other conditions including diabetes, rheumatoid arthritis, amyloidosis, hypothyroidism, and gout.

Treatment

Treatment for carpal tunnel is aimed at reducing pressure on the median nerve to relieve symptoms and to prevent ongoing damage to the nerve.  In some cases, nerve studies can be useful to help isolate the location of nerve symptoms and quantify their severity.

Non-operative

The first line treatment for carpal tunnel syndrome includes wearing night splints and modifying activities.  Splints for carpal tunnel are designed to hold the wrist in a position which maximizes the amount of space available for the median nerve.  Splinting is appropriate for mild carpal tunnel syndrome.  Occasionally steroid injections into the carpal tunnel can be used to reduce swelling around the nerve.  These can be useful both as a diagnostic tool and to improve symptoms, though the improvement is usually temporary.

Operative

Carpal tunnel surgery involves making an incision over the palm of the hand or wrist and releasing the ligament over the carpal tunnel to create more space for the nerve.  This is a low-risk surgery and is done as an outpatient procedure with no requirement to stay overnight in the hospital.  Night-time symptoms improve immediately for many patients.  Patients with severe symptoms before surgery usually continue to improve for at least a year after surgery, though severely injured nerves may not recover completely.