CARPAL TUNNEL SYNDROME
Carpal tunnel syndrome is the most common compression neuropathy in the upper extremity. The median nerve becomes compressed beneath the transverse carpal ligament, which is the roof of the carpal tunnel. The carpal tunnel itself contains nine flexor tendons, their associated synovium, and the median nerve.
The patient most often complains that the hand “goes to sleep.” Activities such as driving the car, holding a book, or blow drying the hair will often exacerbate these symptoms. Night-time wakening is nearly universal as the wrist is pulled into a flexed position during sleep by the strong wrist flexors, and this is often the symptom that encourages the patient to seek medical advice.
The diagnosis of carpal tunnel syndrome is made by a careful clinical history combined with a focused physical examination. Associated conditions including diabetes mellitus, rheumatoid arthritis, gout, hypothyroidism, and pregnancy must be discussed. Physical examination first excludes more proximal nerve compression (cervical, brachial plexopathy, pronator syndrome). The Phalen test and percussion of the median nerve at the carpal tunnel can reproduce paresthesias into the radial three digits. Direct compression over the median nerve (Durkan test) has been shown to be both sensitive and specific for diagnosing carpal tunnel syndrome. Sensory testing should also be performed, as well as evaluation for thenar atrophy signs of more advanced/prolonged median nerve compression. Electrodiagnostic testing is frequently obtained to confirm the diagnosis, grade the severity of median nerve compression/injury, and provide prognostic nformation for recovery after surgical decompression.
Initial treatment consists of night splinting with the wrist in neutral, use of anti-inflammatory medications when appropriate, and modification of activities. The next step in treatment employs injection of corticosteroid into the carpal canal. Eighty percent of patients report symptom improvement after injection lasting on average 3 to 9 months. Failure of conservative measures or patients presenting initially with severe compression/thenar atrophy/dense numbness are considered for surgical release of the carpal tunnel. Surgery can be performed either open or endoscopically with the shared goal of complete release of the transverse carpal ligament and distal antebrachial fascia. Complete relief of night symptoms occurs quickly, while sensory improvement takes longer to recover. Residual numbness is not uncommon in severe cases, and patients must be educated prior to surgical release about this occurrence.