Carpal tunnel syndrome is compression of the median nerve as it passes through the carpal tunnel in the wrist. Symptoms include pain and paresthesias in the median nerve distribution. Diagnosis is suggested by symptoms and signs and is confirmed by nerve conduction velocity testing. Treatments include ergonomic improvements, analgesia, splinting, and sometimes corticosteroid injection or surgery.
(See also Overview and Evaluation of Hand Disorders.)
Carpal tunnel syndrome is very common and most often occurs in women aged 40 to 59 (1). Risk factors include rheumatoid arthritis or other wrist arthritis (sometimes the presenting manifestation), diabetes mellitus, hypothyroidism, acromegaly, immunoglobulin light chain, cardiac or dialysis-associated amyloidosis, and pregnancy-induced edema in the carpal tunnel. Activities or jobs that require repetitive flexion and extension of the wrist may contribute, but rarely. Most cases are idiopathic.
Reference
1. Ibrahim T, Majid I, Clarke M, Kershaw CJ. Outcome of carpal tunnel decompression: the influence of age, gender, and occupation. Int Orthop. 2009;33(5):1305-1309. doi:10.1007/s00264-008-0669-x
Symptoms and Signs of Carpal Tunnel Syndrome
Symptoms of carpal tunnel syndrome include pain of the hand and wrist with tingling and numbness, classically distributed along the median nerve (the palmar side of the thumb, the index and middle fingers, and the radial half of the ring finger) but possibly involving the entire hand. Typically, the patient wakes at night with burning or aching pain and with numbness and tingling and shakes the hand to obtain relief and restore sensation. Thenar atrophy and weakness of thumb opposition and abduction may develop late.
Diagnosis of Carpal Tunnel Syndrome
Clinical evaluation
Sometimes imaging tests
Sometimes nerve conduction testing
The diagnosis of carpal tunnel syndrome is strongly suggested by the Tinel sign, in which median nerve paresthesias are reproduced by tapping at the volar surface of the wrist over the site of the median nerve in the carpal tunnel. Reproduction of tingling with wrist flexion (Phalen sign) or with direct pressure on the nerve at the wrist in a neutral position (median nerve compression test) is also suggestive. The median nerve compression test is positive if symptoms develop within 30 seconds. The 6-item carpal tunnel syndrome symptom scale (CTS-6) is a diagnostic aid that uses 6 clinical criteria (1, 2). A score ≥ 12 correlates with a high probability of carpal tunnel syndrome.
Clinical differentiation from other types of peripheral neuropathy may sometimes be difficult. MRI or ultrasound of the carpal tunnel are noninvasive tests that can confirm changes in or around the median nerve that are associated with carpal tunnel syndrome, although they cannot offer specific information on nerve function.
If symptoms are severe or the diagnosis is uncertain, nerve conduction testing should be done on the affected arm for diagnosis and to exclude a separate or coexistent peripheral polyneuropathy or more proximal compressive neuropathy.
Diagnosis references
1. Grandizio LC, Boualam B, Shea P, et al: The Reliability of the CTS-6 for Examiners With Varying Levels of Clinical Experience. J Hand Surg Am. 2022;47(6):501-506. doi:10.1016/j.jhsa.2022.01.024
2. Graham B: The value added by electrodiagnostic testing in the diagnosis of carpal tunnel syndrome. J Bone Joint Surg Am. 2008;90(12):2587-2593. doi:10.2106/JBJS.G.01362
Treatment of Carpal Tunnel Syndrome
Splinting
Treatment of underlying disorders
Sometimes corticosteroid/anesthetic injection
Sometimes surgical decompression
Treating any underlying disorders (eg, diabetes, rheumatoid arthritis, hypothyroidism) may help relieve symptoms.
If bothersome symptoms persist or recur or if hand weakness and thenar wasting develop, the carpal tunnel can be surgically decompressed by using an open or endoscopic technique.
Neutral Wrist Splint
Key Points
Although carpal tunnel syndrome has many risk factors, most cases are idiopathic.
Typical symptoms include wrist and hand pain with tingling and numbness along the palmar side of the thumb, the index and middle fingers, and the radial half of the ring finger.
Reproducing symptoms with wrist flexion or pressure over the median nerve can provide helpful diagnostic clues.
Treat first with ergonomic corrections, then try splinting and analgesics, corticosteroid injection, and, for weakness, muscle wasting, and/or severe unresponsive symptoms, surgical decompression.
