What is Carpal Tunnel Syndrome?

Carpal Tunnel Syndrome is a common condition that causes pain, numbness and tingling in the hand and arm. The condition occurs when one of the primary nerves to the hand, the median nerve, is squeezed or compressed as it travels through the wrist, causing the hand to stop working as efficiently, resulting in altered feeling and loss of dexterity and strength.

Carpal Tunnel Syndrome patients most commonly describe altered feelings or pins and needles in their hand, but more classically, the thumb, index, middle and half the ring finger. The symptoms can occur at any time but worsen at night. Patients often describe having to shake their hands to resolve the hand and arm symptoms caused by a pinched nerve in the wrist. In most patients, carpal tunnel syndrome worsens over time, so early diagnosis and treatment are important. However, if pressure on the median nerve continues, it can lead to nerve damage and worsening symptoms. Surgery to take pressure off the median nerve may be recommended to prevent permanent damage.

Carpal Tunnel Syndrome is very common and becomes particularly common as we age. It can also be caused by repetitive wrist activities, particular occupations and medical conditions including pregnancy, hypothyroidism, trauma or injury, ganglion or tumour, certain metabolic diseases and inflammatory conditions such as Rheumatoid Arthritis. Most are idiopathic, which means that there is no specific cause but comes on with age.

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Anatomy, Cause and Symptoms

The Carpal Tunnel is a narrow passageway in the wrist, about an inch (2.5 cms) wide. The floor and sides of the tunnel are formed by small wrist bones called carpal bones. The tunnel's roof is a strong band of connective tissue called the flexor retinaculum. Because these boundaries are very rigid, the carpal tunnel has little capacity to "stretch" or increase size.

The median nerve is one of the primary nerves in the hand. It originates as a group of nerve roots in the neck. These roots come together to form a single nerve in the arm. The median nerve goes down the arm and forearm, passes through the carpal tunnel at the wrist, and goes into the hand. The nerve provides feeling in the thumb and index, middle, and ring fingers. The nerve also controls the muscles around the base of the thumb. The nine tendons that bend the fingers and thumb also travel through the carpal tunnel. These tendons are called flexor tendons.

Carpal Tunnel Syndrome is caused by a compressed nerve in the carpal tunnel, usually due to high pressure. There are many potential causes of Carpal Tunnel Syndrome, although the commonest is termed "idiopathic." meaning that no single cause is found. Age and gender are the two most common risk factors for Carpal Tunnel. There are, however, certain factors that increase the risk of developing carpal tunnel syndrome. They include congenital abnormalities, repetitive motion of hand and wrists, fractures and sprains, hormonal imbalance, and other medical conditions such as hypothyroidism, rheumatoid arthritis, diabetes, obesity, gout, overactive pituitary gland, or the presence of a cyst or tumour in the canal.

Other risk factors for carpal tunnel syndrome include:

Heredity: This is likely an important factor. The carpal tunnel may be smaller in some people, or there may be anatomic differences that change the amount of space for the nerve and these traits can run in families.
Repetitive hand use: Repeating the same hand and wrist motions or activities over a prolonged time may aggravate the tendons in the wrist, causing swelling that puts pressure on the nerve.
Hand and wrist position: Doing activities that involve extreme flexion or extension of the hand and wrist for a prolonged period can increase pressure on the nerve.
Pregnancy: Hormonal changes during pregnancy can cause swelling.
Health conditions: Diabetes, rheumatoid arthritis, and thyroid gland imbalance are associated with carpal tunnel syndrome.

In most cases, the symptoms of carpal tunnel syndrome begin gradually without a specific injury. Many patients find that their symptoms come and go at first. Night-time symptoms are very common because many people sleep with their wrists bent. Symptoms may be so severe they may awaken you from sleep. During the day, symptoms often occur when holding something for a prolonged time with the wrist bent forward or backward, such as when using a phone, driving, or reading a book. However, as the condition worsens, symptoms may occur more frequently or may persist for longer periods of time. Many patients find that moving or shaking their hands helps relieve their symptoms.