Carpal Tunnel Syndrome
Carpal tunnel syndrome occurs when the median nerve, which runs from the forearm into the hand, becomes compressed at the wrist. The median nerve controls sensations to the palm side of the thumb and fingers (although not the little finger), as well as impulses to some small muscles in the hand that allow the fingers and thumb to move. The carpal tunnel itself is a narrow passageway of ligament and bones at the base of the hand where the median nerve and tendons pass through. Carpal tunnel syndrome is the most common and widely known type of compressive neuropathy.
Symptoms
Symptoms start gradually, frequently with burning, tingling, or itching numbness in the palm of the hand and the fingers, especially the thumb, index and middle fingers. Other times there may be a sensation of uselessness or swelling of the hand. Symptoms often first appear during the night or early morning upon awakening. Often times shaking the hand will releive the symptoms. In more severe cases the tingling may continue during the day. Decreased grip strength may make it difficult to form a fist, grasp small objects, or perform other manual tasks. In chronic and/or untreated cases, the muscles at the base of the thumb may waste away, with some sufferers not being able to decipher between hot and cold by touch.
Causes
A variety of factors typically lead to carpal tunnel syndrome, often causing an increase in pressure on the median nerve as it traverses through the carpal tunnel. The nerve itself is usually not diseased. Predisposing factors include congential abnormalities, trauma, injury to the wrist, rheumatoid arthritis, pregnancy, hypothyroidism, diabetes work related overuse or cyst or tumor in the carpal tunnel. Other times there is no identified cause.
Women are tthree times more likely to develop carpal tunnel syndrome, perhaps because the carpal tunnel itself is smaller in women. The dominant hand usually is affected first and produces more severe symptoms.
Diagnosis
Early diagnosis and treatment are important to avoid permanent damage to the median nerve. A complete history and physical examination of the hands, arms, shoulders, and neck can help determine whether the symptoms are related to daily activities or to an underlying disorder. Often times laboratory testing and/or x-rays may be performed if the cause is not readily identified.
In either unclear cases or with severe disease electrodiagnostic testing may be used to confirm the diagnosis. A nerve conduction study measures nerve impulses. Electromyography, through the measurement of electrical activity through muscle can determine the severity of damage to the median nerve.
Ultrasound imaging can visualize an enlarged median nerve which is suggestive of carpal tunnel syndrome or identify a foreign object (cyst or tumor) causing compression of the nerve.
Treatment:
Treatments for carpal tunnel syndrome should begin as early as possible. If the cause is due to an underlying condition such as diabetes or arthritis, it should be treated first.
Initial treatment generally involves resting the affected hand and wrist for at least 2 weeks, avoiding activities that may worsen symptoms. Wrist immobilizers or splints can avoid further damage from twisting or bending. If there is inflammation, applying cool packs can help reduce swelling.
Non-surgical treatments
Medication –
- Nonsteroidal anti-inflammatory drugs, such as aspirin, ibuprofen, and other nonprescription pain relievers, may ease the symptoms of pain and inflammation that have been present for a short time or have been caused by strenuous activity.
- Corticosteroids (such as prednisone) or the drug lidocaine can be injected directly into the wrist or taken by mouth to relieve pressure on the median nerve and provide immediate, temporary relief for mild or intermittent symptoms.
- Additionally, some studies show that vitamin B6 (pyridoxine) supplements may ease the symptoms of carpal tunnel syndrome.
Exercise – Stretching and strengthening exercises can be helpful in people whose symptoms have resolved. It is recommended that these exercises be supervised by an experienced physical therapist, who is trained to use exercises to treat physical impairments. Similarly an occupational therapist, trained in evaluating people with physical impairments can help to build skills to improve their health and well-being.
Alternative therapies – Acupuncture and chiropractic care have benefited some patients but their effectiveness remains unproved. An exception is yoga, which has been shown to reduce pain and improve grip strength among patients with carpal tunnel syndrome.
Surgery
Carpal tunnel release is one of the most common surgical procedures in the United States. Generally recommended if symptoms last for 6 months, surgery involves severing the band of tissue around the wrist to reduce pressure on the median nerve. Surgery is done under local anesthesia and is done as an outpatient procedure. There are two generaly approaches: open release surgery or endoscopic.
Although symptoms may immediately be relieved after surgery, full recovery from carpal tunnel surgery can take months. Complications from surgery include infection, nerve damage, stiffness, and pain at the scar. Patients should undergo physical therapy after surgery to restore wrist strength. Some patients may need to adjust occupational duties or even change jobs after recovery from surgery.
Recurrence of carpal tunnel syndrome following treatment is rare. The majority of patients recover completely.
Prevention:
At the workplace, workers can do on-the-job conditioning, perform stretching exercises, take frequent rest breaks, wear splints to keep wrists straight, and use correct posture and wrist position. Wearing fingerless gloves can help keep hands warm and flexible. Workstations, tools and tool handles, and tasks can be redesigned to enable the worker’s wrist to maintain a natural position during work. Jobs can be rotated among workers. Employers can develop programs in ergonomics, the process of adapting workplace conditions and job demands to the capabilities of workers. However, research has not conclusively shown that these workplace changes prevent the occurrence of carpal tunnel syndrome.