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Carpal tunnel syndrome

Last updated: October 30, 2020

Summary

Carpal tunnel syndrome (CTS) is a peripheral neuropathy caused by chronic or acute compression of the median nerve by the transverse carpal ligament. It is characterized by both sensory disturbances (pain, tingling, and numbness) and motor symptoms (weakness and clumsiness of the thumb) in the area innervated by the median nerve distal to the carpal tunnel. Several occupational and non-occupational risk factors (e.g., manual labor, age, sex, diabetes) have been associated with the syndrome. The presence of clinical symptoms and signs of CTS (e.g., the hand elevation test, carpal compression test, and Phalen test) should raise suspicion, but the diagnosis must be confirmed with specific neurological tests (e.g., EMG, ENG). Conservative management (i.e., immobilization with a splint, local steroid injections, and ultrasound therapy) may be effective in patients who only experience mild to moderate symptoms. Surgical release of the transverse carpal ligament with decompression of the median nerve is indicated in acute cases or patients with moderate to severe symptoms (atrophy of the thenar eminence).

Epidemiology

  • Most common entrapment neuropathy in the upper extremity (90% of all cases) [1]
  • The prevalence and yearly incidence of CTS may change according to several occupational and non-occupational factors.

Epidemiological data refers to the US, unless otherwise specified.

Etiology

The following risk factors are associated with CTS: [2]

Pathophysiology

Clinical features

Mild to moderate

  • Symptoms develop in the areas innervated by the median nerve: palmar surface of the thumb, index, and middle fingers, and radial half of the ring finger. [7][9]
  • Symptoms worsen at night.
  • Usually, there is no loss of sensation of the palmar surface of the thenar eminence, because it is innervated by the superficial branch of the median nerve, which arises 5–7 cm proximal to the carpal tunnel and is, therefore, not compressed.

Sensory innervation of the thenar eminence is not affected in CTS.

Moderate to severe

Motor symptoms in addition to the symptoms mentioned above: [9]

  • Weakened pinch and grip; : Patients often complain of dropping objects.
  • Severe, sustained median nerve compression may lead to thenar atrophy and, subsequently, impaired thumb opposition.

The "pope's blessing" (inability to flex the first three digits when making a fist) is not a symptom of CTS. It is only seen in proximal lesions of the median nerve

Subtypes and variants

Tarsal tunnel syndrome [10]

Diagnostics

Provocative tests

There is no agreement as to which provocative test should be used to support the diagnosis of CTS. Several authors suggest combining two or more provocative tests to improve the specificity of the diagnosis. [9][11]

  • Hand elevation test: : The hand is held above the head of the patient for approx. two minutes. The test is considered positive if the symptoms of CTS (paresthesia and numbness) are reproduced. This test is easy to perform in a clinical setting and has higher sensitivity and specificity than all other tests. [12]
  • Carpal compression test: By applying moderate compression with the finger directly over the proximal edge of the carpal tunnel, the examiner may elicit paresthesia in the median nerve distribution.
  • Phalen test: The examiner actively or passively holds the patient's wrist in full flexion (90°). The test is positive if paresthesia occurs or worsens in the areas innervated by the median nerve within one minute. This finding is considered highly specific (approx. 85%) for the diagnosis of CTS.
  • Tinel sign: Percussion or tapping with the fingertips over the carpal tunnel leads to shooting pain and/or tingling in the areas innervated by the median nerve.

Electrophysiological tests

There is strong evidence against the use of clinical signs alone to diagnose CTS because of their questionable sensitivity and specificity. Thus, electrodiagnostic studies (particularly NCS) are essential for diagnosis.

Treatment

Mild to moderate symptoms [14]

Moderate to severe symptoms (or no response to conservative treatment)

References

  1. Ibrahim I, Khan WS, Goddard N, Smitham P. Carpal Tunnel Syndrome: A Review of the Recent Literature. Open Orthop J. 2012; 6 : p.69-76. doi: 10.2174/1874325001206010069 . | Open in Read by QxMD
  2. Geoghegan JM, Clark DI, Bainbridge LC, Smith C, Hubbard R. Risk factors in carpal tunnel syndrome. J Hand Surg Br. 2004; 29 (4): p.315-320. doi: 10.1016/j.jhsb.2004.02.009 . | Open in Read by QxMD
  3. Palmer KT. Carpal tunnel syndrome: The role of occupational factors. Best Pract Res Clin Rheumatol. 2011; 25 (1): p.15-29. doi: 10.1016/j.berh.2011.01.014 . | Open in Read by QxMD
  4. Ablove RH, Ablove TS. Prevalence of Carpal Tunnel Syndrome in Pregnant Women. WMJ. 2009; 108 (4): p.194-196.
  5. Haddiya I, Yacoubi H, Bentata Y. Why does Carpal Tunnel Syndrome Still Occur in our Chronic Hemodialysis Patients?. Journal of Nephrology & Therapeutics. 2018; 08 (03). doi: 10.4172/2161-0959.1000310 . | Open in Read by QxMD
  6. Karne SS, Bhalerao NS. Carpal Tunnel Syndrome in Hypothyroidism. J Clin Diagn Res. 2016; 10 (2): p.OC36-OC38. doi: 10.7860/JCDR/2016/16464.7316 . | Open in Read by QxMD
  7. Ghasemi-rad M, Nosair E, Vegh A, Mohammadi A, Akkad A, Lesha E et al.. A handy review of carpal tunnel syndrome: From anatomy to diagnosis and treatment. World J Radiol. 2014; 6 (6): p.284-300. doi: 10.4329/wjr.v6.i6.284 . | Open in Read by QxMD
  8. Aroori S, Spence RAJ. Carpal tunnel syndrome. Ulster Med J. 2008 .
  9. Rutkove SB. Overview of lower extremity peripheral nerve syndromes. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/overview-of-lower-extremity-peripheral-nerve-syndromes?search=tarsal%20tunnel%20syndrome&source=search_result&selectedTitle=1~25&usage_type=default&display_rank=1#H450886655.Last updated: February 20, 2020. Accessed: August 3, 2020.
  10. Ma H, Kim I. The Diagnostic Assessment of Hand Elevation Test in Carpal Tunnel Syndrome. J Korean Neurosurg Soc. 2012; 52 (5): p.472-475. doi: 10.3340/jkns.2012.52.5.472 . | Open in Read by QxMD
  11. Ahn DS. Hand elevation: a new test for carpal tunnel syndrome. Ann Plast Surg. 2001; 46 (2): p.120-124.
  12. Kohara N. [Clinical and electrophysiological findings in carpal tunnel syndrome].. Brain Nerve. 2007; 59 (11): p.1229-1138.
  13. Clinical Practice Guideline On The Treatment Of Carpal Tunnel Syndrome. http://www.aaos.org/research/guidelines/CTSTreatmentGuideline.pdf. Updated: September 1, 2008. Accessed: December 23, 2016.
  14. Aboong MS. Pathophysiology of carpal tunnel syndrome. Neurosciences (Riyadh). 2015; 20 (1): p.4-9.
  15. Concannon MJ, Brownfield ML, Puckett CL. The incidence of recurrence after endoscopic carpal tunnel release. Plast Reconstr Surg. 2000; 105 (5): p.1662-1665.