Anatomy
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 major nerves to the hand — the median nerve — is squeezed or compressed as it travels through the wrist.
The carpal tunnel is a narrow passageway in the wrist, about an inch wide. The floor and sides of the tunnel are formed by small wrist bones called carpal bones. The roof of the tunnel is a strong band of connective tissue called the transverse carpal ligament. Because these boundaries are very rigid, the carpal tunnel has little capacity to “stretch” or increase in size.
The median nerve is one of the main 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.
Causes
- Heredity. 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 period of 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 of time can increase pressure on the nerve.
- Pregnancy. Hormonal changes during pregnancy can cause swelling.
- Health conditions. Diabetes, rheumatoid arthritis, and thyroid gland imbalance are conditions that are associated with carpal tunnel syndrome.
Symptoms
Symptoms of carpal tunnel syndrome may include:
- Numbness, tingling, burning, and pain—primarily in the thumb and index, middle, and ring fingers
- Pain or tingling that may travel up the forearm toward the shoulder
- Weakness and clumsiness in the hand—this may make it difficult to perform fine movements such as buttoning your clothes
- Dropping things—due to weakness, numbness, or a loss of proprioception (awareness of where your hand is in space)
- Night-time symptoms are very common. Because many people sleep with their wrists bent, symptoms may awaken you from sleep.
Treatments
Nonsurgical treatments
Bracing or splinting. Wearing a brace or splint at night will keep you from bending your wrist while you sleep. Keeping your wrist in a straight or neutral position reduces pressure on the nerve in the carpal tunnel
Non-steroidal anti-inflammatory drugs (NSAIDs). Medications such as ibuprofen and naproxen can help relieve pain and inflammation.
Activity changes. Symptoms often occur when your hand and wrist are in the same position for too long—particularly when your wrist is flexed or extended.
Steroid injections. Corticosteroid, or cortisone, is a powerful anti-inflammatory agent that can be injected into the carpal tunnel. Although these injections often relieve painful symptoms or help to calm a flare up of symptoms, their effect is sometimes only temporary. A cortisone injection may also be used by your doctor to help diagnose your carpal tunnel syndrome.
Surgical treatments
In most cases, carpal tunnel surgery is done on an outpatient basis. The surgery can be done under general anesthesia, which puts you to sleep, or under local anesthesia, which numbs just your hand and arm. In some cases, you will also be given a light sedative through an intravenous (IV) line inserted into a vein in your arm.
Open carpal tunnel release. In open surgery, your doctor makes a small incision in the palm of your hand and views the inside of your hand and wrist through this incision. During the procedure, your doctor will divide the transverse carpal ligament (the roof of the carpal tunnel). This increases the size of the tunnel and decreases pressure on the median nerve.
After surgery, the ligament may gradually grow back together—but there will be more space in the carpal tunnel and pressure on the median nerve will be relieved.
For most patients, surgery will improve the symptoms of carpal tunnel syndrome. Recovery, however, may be gradual and complete recovery may take up to a year.
If you have significant pain and weakness for more than 2 months, your doctor may refer you to a hand therapist who can help you maximize your recovery.
