Carpal tunnel syndrome is caused by the compression of the median nerve in the carpal tunnel at the wrist. The carpal tunnel consists in an inextensible tunnel, through which the median nerve enters the hand. This tunnel measures about 4-7 cm and is delimited inferiorly by carpal bones and superiorly by a ligament, the transverse carpal ligament.
In case of prolonged and repeated use of the hand, the median nerve is compressed inside the carpal tunnel, causing a chronic and recurrent nerve ischemia. This condition requires a prompt decompression of the median nerve by section of the transverse carpal ligament. This procedure is able to release the nerve and to allow the proper neural vascularization.
Symptoms of carpal tunnel syndrome consists in a lack of sensitivity of the area innervated by the median nerve (associated with tingling and pain). In severe cases, a loss of strength of the thenar muscles could be observed.
However, the carpal tunnel syndrome could affect theoretically each sensitive area and muscle innervated by the median nerve in the hand. In detail:
- Sensitivity: Palmar surface of the first three fingers, radial half of the fourth and corresponding hand palm. Dorsally the median nerve innervates only the skin over the distal phalanx of the same fingers. When affected, the symptoms are tingling, loss/absence of sensitivity and pain. This usually rises at night, waking the patient.
- Muscles: some lumbricals, the opponent, abductor pollicis brevis and flexor pollicis brevis. A loss of grip and pinch strength could be observed.
The diagnosis of carpal tunnel syndrome is primarily clinical and is based on the symptoms and clinical tests. Electrodiagnostic study tests the ability of the nerve to transmit an electrical stimulus of low intensity and it is essential to define objectively the disease.
The surgery is performed under local anesthesia and requires a palmar incision of 2.5 cm. Absorbable sutures are employed. A drainage (consisting of a soft silicone tube) is applied and maintained for 24 hours. The procedure lasts 10-15 minutes and it is performed as an outpatient procedure.
What to expect
Symptoms regress completely if surgery is performed within a reasonable time from the onset of symptoms (usually 6-10 months). In case of late intervention, a residual deficit of sensitivity and strength could be observed.
Recovery of daily activities is gradual and requires 3 weeks. Sports and heavy manual activities are allowed after 4-6 weeks.