Carpal tunnel syndrome is a condition caused by a nervous tightening at the front of the wrist that sometimes causes numbness, paraesthesias, and pain in the forearm, hand, and fingers. There is a space on the anterior surface of the wrist known as the carpal canal where the median nerve and nine tendons pass from the forearm to the hand. Carpal tunnel syndrome occurs when increased pressure within the canal causes nerve compression, which is very sensitive. When compression is high enough, it causes changes in nerve function, which causes numbness, paraesthesias, and pain in the hand and fingers.
Usually the cause is unknown. Pressure on the nerve can happen in many ways. Tendon sheath edema, known as tenosynovitis, can increase pressure within the canal. Bone dislocations, fractures and arthritis may narrow the carpal canal, but are not as frequent. Fluid retention during pregnancy may in some cases lead to canal edema and symptoms of carpal tunnel syndrome, which usually subside after delivery. Some diseases such as hypothyroidism, rheumatoid arthritis, diabetes, and renal failure may be associated with carpal tunnel syndrome.
Signals and symptons
The symptoms of carpal tunnel syndrome are usually pain, numbness, tingling or a combination of the three in one or both hands. Sleeping and tingling affect the thumb, forefinger, middle and part of the ring in most situations. Symptoms usually manifest at night, but may appear during daily activities, such as driving or reading a newspaper. Patients sometimes notice that they have decreased grip strength and may drop objects from their hand. In the most severe cases, tenderness may be completely absent and the muscles of the thumb base atrophied (tenar eminence atrophy).
A detailed history of the type of hand activity, any previous trauma and previous symptoms are important. A hand x-ray may be ordered to check for other causes of symptoms, such as arthritis or an underlying fracture. In some cases laboratory studies may be necessary if a symptom-associated disease is suspected. An electromyogram (EMG) is usually performed to confirm the diagnosis of carpal tunnel syndrome and to exclude any compression of the median nerve at a level other than the wrist, such as the forearm, shoulder, or cervical spine.
Non Surgical Treatment
Elimination of symptoms can sometimes be achieved without surgery. Shifting activity to reduce repetitive and tiring use of the hand or keeping the wrist in a neutral position can help decrease edema within the canal, creating more room for the nerve. Wearing a splint at night can lessen the complaints that prevent sleep. Oral anti-inflammatory medicines or injected directly into the carpal canal can help reduce edema and pressure within the canal.
When symptoms are very intense or do not improve, surgery may be necessary to widen the carpal canal. The pressure on the nerve is decreased by opening the ligament that forms the roof of the canal on the palmar side of the hand. The technique for this surgery can be varied (open or arthroscopic), but the goals are the same – to increase the space within the canal and to decrease the pressure on the nerve. After surgery the painful sensation around the scar may persist for a few weeks or months. The numbness and tingling may disappear quickly, but it may take some time for wrist and hand mobility to return to normal. The symptoms of carpal tunnel syndrome may in some cases come back, and the resumption of heavy and repetitive work may cause recurrence.