Carpal Tunnel Syndrome

Author(s): Stephen Kishner, MD, John Faciane, MD, Casey Murphy, MD

Originally published:11/10/2011

Last updated:05/05/2016



Carpal tunnel syndrome (CTS) is the complex of symptoms and signs brought on by dysfunction of the median nerve due to trauma or compression as it travels through the carpal tunnel.


Median nerve compression results from either a decrease in the size of the carpal tunnel, an increase in the size of its contents, or increased susceptibility of the nerve to pressure.

Epidemiology including risk factors and primary prevention

  • Estimated prevalence of 3 to 5% in the general population 1
  • In patients with nerve conduction study (NCS) evidence of CTS in one hand, the contralateral asymptomatic hand will show NCS abnormalities about 50% of the time.2
  • Most frequent compressive focal mononeuropathy seen in clinical practice1
  • Known risk factors include:
    • Obesity
    • Female gender
      • Believed to be secondary to decreased cross-sectional area of carpal tunnel
    • Pregnancy
    • Metabolic
      • Connective tissue diseases (rheumatoid arthritis, amyloidosis)
      • Diabetes mellitus and the metabolic syndrome
    • Neuropathies
    • Familial and congenital CTS
    • Musculoskeletal
      • Wheelchair use
      • Wrist/hand fractures and masses
      • Anatomic “square wrist”
        • Ratio of AP to mediolateral diameter at wrist crease >0.7
      • Workplace factors
      • Prolonged wrist extension/flexion, repetitive and strenuous use of the hands and wrists, and work with vibrating tools predispose to CTS.


  • The carpal tunnel is formed by the flexor retinaculum on the volar surface and carpal bones dorsally.
  • Traversing through this tunnel are the median nerve and 9 flexor tendons of the forearm (flexor pollicus longus and the four flexor digitorum superficialis and four flexor digitorum profundus tendons).
  • Increased median nerve pressure or sensitivity leads to myelin injury secondary to ischemia and mechanical disruption.
    • Pressures are greater in wrist extension than flexion 3
  • Sensory fibers appear to be more sensitive to compression and are routinely affected prior to motor fibers.

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

  • New onset/acute
    • Intermittent numbness, tingling, pain and/or burning in the radial 3-1/2 digits
    • Nocturnal paresthesias
  • Subacute N/A
  • Chronic/stable
    • Sensory symptoms may progress from intermittent to persistent as CTS worsens.
    • Progression leads to weakness of the hand and coordination deficits.
    • Fixed sensory loss is often a late finding.
    • CTS may progress without worsening of symptoms.
    • Late-stage CTS can become difficult to treat and may not respond to even surgical decompression.
    • About one in five patients will show improvement with no intervention other than modifying their hand activities. 1
  • Pre-terminal N/A



Presentation most commonly includes paresthesias affecting the median innervated first 3½ digits, with symptoms worsening at night.4

Although sensory symptoms are usually limited to median-innervated fingers, there exists a wide range of variability in presentation which often includes the hand and proximal extremity.3

May complain of deep aching pain in the hand and wrist

Symptoms may be worsened by activities such as driving or reading.4

Report relief by shaking their hands (flick sign) or by placing them under warm water

(+) flick sign predicted electrodiagnostic abnormality in 93% of cases5

Physical examination

  • Evaluation should include the cervical spine, shoulder, and elbow.
  • Findings may be normal in mild cases.
  • Sensory findings
    • Objective sensory deficits may be detected involving the median-innervated fingers, but sparing the thenar eminence as the palmar cutaneous sensory branch arises proximal to the carpal tunnel.
    • 2-point discrimination is generally affected before pain and temperature.
  • Motor findings
    • Objective weakness can occur in advanced CTS, manifesting as weakness of thumb abduction and opposition.
    • Atrophy of the thenar eminence may be observed.
  • Provocative tests may reproduce patient’s paresthesias into the hand in those with CTS and include:
    • Tinel’s sign 67% sensitive and 68% specific 6
    • Phalen’s test 85% sensitivity and 89% specificity 6
    • Carpal compression test (87-89% sensitive7)
      • A reasonable approach is to screen with the Tinel’s sign and if negative, check the more sensitive carpal compression test.

Functional assessment

A detailed occupational history includes the type of work performed, tools used and the work station design.

The history should also include an assessment of all activities outside of work which may predispose to CTS.

Laboratory studies

Lab tests may be utilized for the diagnosis or exclusion of conditions that predispose to the development of CTS.


  • Ultrasound (US) is becoming increasingly used for the evaluation of CTS, with mounting data on its utility for both the diagnosis of CTS and identification of its underlying causes8
    • Advantages include its tolerance and dynamic capabilities, ability to detect an underlying abnormality (i.e., a mass) and capacity to identify a systemic disease such as rheumatoid arthritis or dialysis-related amyloidosis.
    • However, NCS remains the gold standard as it has a significantly higher specificity for diagnosing CTS than US 9
  • MRI is reserved for unusual cases (i.e., to rule out a mass).

Supplemental assessment tools

  • Electromyography (EMG)
    • EMG and NCS are the gold standard for the diagnosis of CTS.
    • Evaluates for cervical radiculopathy, ulnar neuropathy, brachial plexopathy and proximal median neuropathy
    • The combined sensory index (CSI) has been shown to have the greatest sensitivity and specificity. 10
    • Prolonged median sensory distal latency is usually the first abnormal finding on electrodiagnostic testing, secondary to damage to the myelin sheath.
    • Axon loss may result in a reduction of the median nerve compound motor or sensory action potential amplitude in association with positive findings on EMG.
    • In mild cases there may be an absence of abnormalities with an estimated 15% false negative rate.11

Early predictions of outcomes

  • Symptoms of untreated patients with minimal or mild compression tended to worsen over the first year, while those with initially moderate or severe involvement tended to improve.
  • Factors that have been associated with a failure of conservative therapy include long duration of symptoms (>10months), age >50, constant paresthesias, and impaired 2-point discrimination.
  • In approximately 50% of cases where CTS occurs in one wrist the other will eventually become involved.


  • Controversy remains regarding the role of workplace factors in the development of CTS.
    • Food processing, construction, and manufacturing are occupations that have a higher incidence of CTS.
    • Multiple studies have shown that keyboard use has no association with CTS 12,13,14


Available or current treatment guidelines

The American Academy of Orthopaedic Surgeons (AAOS) provides guidelines for the treatment of CTS.

At different disease stages

New onset/acute

  • Conservative therapy is considered first-line treatment for those with mild to moderate symptoms.
  • Modification of activities that precipitate paresthesias
  • A nocturnal wrist splint or brace which maintains the wrist in neutral to 30° extension often provides significant symptom improvement. Splinted group had improved symptoms regardless of degree of median nerve impairment compared to control group 15
  • Tendon and nerve gliding exercises of the wrist and upper extremity are employed to maintain function and ROM.


  • Corticosteroid injection into the carpal tunnel has proven effective when other conservative measures have failed, although results are rarely sustained.
    • Recent studies have shown 93.7% of patients reported marked improvement of symptoms at 3 months 16 and statistically significant benefit of symptoms at 6 months, as well as improvement in nerve conduction studies and decrease in cross-sectional area (i.e., swelling) of the nerve in the carpal tunnel.


  • NSAIDs, vitamin B6, and oral steroids have been shown not to be of benefit.17
  • Surgery may be indicated when conservative treatment modalities have failed and in those with severe symptoms.
  • The goal of surgery is to expand the carpal tunnel via division of the transverse carpal ligament to relieve pressure on the median nerve.
    • There is no definitive evidence supporting an open or endoscopic approach being more effective than the other.18
    • There is limited evidence that the mini-open technique assisted by the Knifelight instrument is more effective than a standard open release at a follow-up of 19 months but not at 30.18
  • Recurrence of CTS after successful treatment is rare, although some patients experience residual numbness, pain or weakness.
    • If pain and symptoms return then surgery may be repeated.
  • No consensus exists regarding the optimal presurgical or postsurgical rehabilitation and treatment programs.

Pre-terminal or end of life care

Patient & family education

Activity modification

Emerging/unique Interventions


The AMA Guides to the Evaluation of Permanent Impairment


The Carpal Tunnel Questionnaire (CTQ) has demonstrated a greater responsiveness to clinical change following release of the carpal tunnel than the Michigan Hand Outcomes Questionnaire (MHQ).

The combined sensory index electrodiagnostic tool has been shown to effectively establish a correlation with clinical outcomes following surgical intervention for carpal tunnel syndrome.10

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

  • Presentations of CTS will often include symptoms that do not fit a classical median nerve distribution.
  • Anatomical variants may also contribute to symptoms outside of the typical median portion of the hand.
  • A normal physical exam does not rule out CTS.
  • Electrodiagnosis is considered the best diagnostic test for CTS although neuromuscular ultrasound has been shown by many studies to have comparable diagnostic utility.
  • Many non-surgical methods of treatment have proven benefit and warrant trials before surgical decompression.


Cutting edge concepts and practice

Ultrasound guided tenotomy and hydrodissection of the flexor retinaculum has emerged as another potential treatment option for those with electrodiagnostically confirmed CTS.


Gaps in the evidence-based knowledge

Randomized prospective trials should evaluate the effectiveness of ultrasound versus standard surgical techniques.

The optimal timing of surgery in the natural history of CTS has not been established.

No evidence exists regarding the best technique for carpal tunnel injection, and ultrasound guidance has not been proven to improve outcomes.

Outcomes of long-term serial carpal tunnel injection have not been studied.


  1. Stewart JD. Focal Peripheral Neuropathies. Philadelphia, PA: Lippincott, 2000.
  2. Padua L., et al. Incidence of bilateral symptoms in carpal tunnel syndrome. Journal of Hand Surgery (Br) 1998 Oct;23(5):603-6.
  3. Gelberman RH, Hergenroeder PT, Hargens AR, Lundborg GN, Akeson WH. The carpal tunnel syndrome: a study of carpal canal pressures. Journal of Bone and Joint Surgery. 1981:63(2): 380-383.
  4. Stevens JC, Smith BE, Weaver AL, Bosch DP, Deen Jr GH, Wilkens JA. Symptoms of 100 patients with electromyographically verified carpal tunnel syndrome. Muscle and Nerve. 1999 Oct;22(10):1448-1456.
  5. Pryse-Phillips W. Validation of a diagnostic sign in carpal tunnel syndrome. J Neurol Neurosurg Psychiatry 1984;47:870-872.
  6. Bruske J., The Usefulness of the Phalens Test and the Hoffmann-Tinel sign in the Diagnosis of Carpal Tunnel Syndrome. Acta Orthopaedica Belgica. 2002 Apr;68(2):141-5.
  7. Malanga GA, Nadler SF. Musculoskeletal Physical Examination: An Evidence Based Approach. Philadelphia, PA: Elsevier, 2006.
  8. Walker FO, Cartwright MS. Neuromuscular Ultrasound. Philadelphia, PA: Elsevier, 2011.
  9. Kwon BC., et al. Comparison of sonography and electrodiagnostic testing in the diagnosis of carpal tunnel syndrome. Journal of Hand Surgery – American. 2008 Jan;33(1):65-71.
  10. Malladi N, Micklesen PJ, Hou J, Robinson LR. Correlation between the combined sensory index and clinical outcome after carpal tunnel decompression: a retrospective review. Muscle & Nerve. 2010 Apr;41(4):453-457.
  11. American Association of Electrodiagnostic Medicine, American Academy of Neurology, and American Academy of Physical Medicine and Rehabilitation. Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: Summary statement. Muscle & Nerve. 2009; 25: 918-922.
  12. Keith T., et al. Carpal tunnel syndrome and its relation to occupation: a systematic literature review. Occupational Medicine (Oxford). 2007 Jan;57(1):57-66,.
  13. Atroshi I., et al. Carpal tunnel syndrome and keyboard use at work: a population based study. Arthritis & Rheumatism. 2007 Nov;56(11):3620-5.
  14. Stevens JC., et al. The frequency of carpal tunnel syndrome in computer users at a medical facility. Neurology. 2001 Jun;56(11):1568-70.
  15. Werner R., et al. Randomized controlled trial of nocturnal splinting for active workers with symptoms of carpal tunnel syndrome. Arch Phys Med Rehabil. 2005 Jan;86(1):1-7
  16. Agarwal V., et al. A prospective study of the long-term efficacy of local methyl prednisolone acetate injection in the management of mild carpal tunnel syndrome.  Rheumatology (Oxford). 2005 May;44(5):647-50.
  17. Huisstede BM, Hoogvliet P, Randsdorp MS, Glerum S, van Middelkoop M, Koes BW. Carpal tunnel syndrome. Part I: Effectiveness of nonsurgical treatments – a systemic review. Arch of Phys Med and Rehab. 2010;91(7):981-1004.
  18. Huisstede BM, Randsdorp MS, Coert JH, Glerum S, van Middelkoop MV, Koes BW. Carpal tunnel syndrome. Part II: Effectiveness of surgical treatments – a systemic review. Arch of Phys Med and Rehab. 2010;91(7):1005-1024.

Additional Resources

American Academy of Orthopaedic Surgeons (AAOS). Clinical Practice Guideline on the Treatment of Carpal Tunnel Syndrome. September, 2008. (available online)

Beck JA, Malone DG. Ultrasound-guided tenotomy and hydrodissection of the flexor retinaculum in carpal tunnel syndrome (CTS). PM&R. 2010;2(9):S35.

Brininger TL, Rogers JC, Holm MB, Baker NA, Li Z-M, Goitz RJ. Efficacy of a fabricated customized splint and tendon and nerve gliding exercise for the treatment of carpal tunnel syndrome: a randomized controlled trial. Arch Phys Med Rehabil. 2007;88:1429-1435.

Chatterjee JS, Price PE. Comparative responsiveness of the Michigan Hand Outcomes Questionnaire and the Carpal Tunnel Questionnaire after carpal tunnel release. J Hand Surg (Am.) 2009 Feb;34(2):273-80.

Gordon C, Johnson EW, Gatens EF, et al. Wrist ratio correlation with carpal tunnel syndrome in industry. Am J Phys Med Rehabil 1988;67(6):270-2.

Padua L, Padua R, Aprile I, Pasqualetti P, Tonali P, Italian CTS Study Group. Multiperspective follow-up of untreated carpal tunnel syndrome: a multicenter study. Neurology. 2001;56(11):1459.

Piazzini DB, Aprile I, Ferrara PE, et al. A systematic review of conservative treatment of carpal tunnel syndrome. Clin Rehabil. 2007 Apr;21 (4): 299-314.

Rempel D, Tittiranonda P, Burastero S. Hudes M, So Y. Effect of keyboard keyswitch design on hand pain. J Occup Environ Med. 1999;41:111-119.

Rozmaryn LM, Dovelle S, Rothman ER, Gorman K, Olvey KM, Bartko JJ. Nerve and tendon gliding exercises and the conservative management of carpal tunnel syndrome. J Hand Ther. 1998;11:171-179.

Stahl S, Yarnitsky D, Volpin G, Fried A. Conservative therapy in carpal tunnel syndrome. Harefuah. 1996;130(4):241.

Original Version of the Topic:

Michael Mehnert, MD. Carpal Tunnel Syndrome. Publication Date: 2011/11/10.

Author Disclosure

Stephen Kishner, MD
Nothing to Disclose

John Faciane, MD
Nothing to Disclose

Casey Murphy, MD
Nothing to Disclose

Related Articles