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Carpal tunnel syndrome

Introduction

  • Compression of the median nerve in the carpal tunnel at the wrist.
  • Most common compressive neuropathy in the upper extremity
  • Incidence: 1-3 cases per 1000 subjects
  • Male : Female 1:8
  • Usually 40 - 50 years old
  • Younger patients usually have associated factors

Aetiology

  • CTS syndrome is more common in females due to the fact that, as a rule, their carpal tunnel is smaller in diameter compared to males. Bilateral involvement is common in females as well.
  • Several factors are associated
    • Pregnancy
    • Rheumatoid arthritis
    • Amyloidosis
    • Hypothyroidism
    • Acromegaly
    • DM
  • Common in menopausal women
  • Occupational risk factors:
    • prolonged use of handheld vibratory tools
    • repetitious flexion and extension of the wrist with forceful gripping
    • There is little/no evidence to support a relationship with keyboarding

Diagnosis

History and Physical:

  • Provacative tests:
    • Tinel's sign: elicit by taping just proximal to the site of impingement
    • Phalen's test: hands flexed at wrist (consider negative if no symptoms after one minute)
    • Modified Phalen's test: hold pressure over carpal tunnel while flexing the wrists (consider negative if no symptoms after one minute)
    • Reverse Phalen's test: Extending wrists in a prayer-like position (consider negative if no symptoms after one minute)
    • Durkan's test: Hold pressure over carpal tunnel (consider negative if no symptoms after one minute)
  • CTS-6 Diagnositc criteria:
    • Numbness and tingling in the median nerve distribution
    • Nocturnal numbness
    • Weakness and/or atrophy of the thenar muscles
    • Tinel sign - reproduction of symptoms with median nerve tapping at wrist
    • Phalen's test - forced palmar flexion may reproduce the pain or tingling
    • Loss of 2-point discrimination
  • Also:
    • Sensation relieved by hanging the arm out the side of the bed or getting up and walking around
    • Pain may radiate up the arm
    • Carpal compression test:
      • When done with Durkan gauge, the test is neither sensitive or specific (0.36 and 0.57, respectively)

Electrodiagnostic Testing:

The role of electrodiagnostic testing is uncertain. Carpal tunnel syndrome is a clinical diagnosis. Electrodiagnostic testing is useful to confirm the diagnosis preoperatively, as a baseline for monitoring unexpected outcomes,  ruling out other conditions such as radiculopathy, and for Workers Compensation cases. If repeat testing is performed on a patient, be sure to send them to the same lab for the study.

X-ray

Plain radiographs are not required in the routine work up of CTS

MRI

MRI and possibly ultrasound can be used postoperatively to evaluate the quality of the release.

Differential Diagnosis

  • Hereditary neuropathy
  • AIN syndrome
  • Pronator teres syndrome
  • Cervical radiculopathy

Treatment

  • Conservative treatment :
  • Resting splint: May minimize symptom severity and functional deficits for up to 3 months
  • Oral steroids: May offer a benefit for up to 8 weeks
  • Local steroids: May provide benefit for 2 weeks to 6 months. A good response to an injection is prognositic of a better response to to surgery compared to those who do not respond to the injection. May be used for therapeutic and prognostic reasons. Long-term benefits have not been shown. Surgical decompression is recommended after an injection no longer provides symptomatic relief.
  • Operative treatment:
    • Open carpal tunnel release (OCTR)
      • Disadvantages;
        • Scar tenderness
        • Higher risk of bowstringing of flexor tendons, particularly when associated with a flexor tendon repair
    • Endoscopic carpal tunnel release (ECTR)
      • Less postoperative pain and shorter return to functional activities than OCTR, however there is no difference in outcomes at one year post op
      • The most significant, proven advantage of ECTR is faster mean return to work (18 days for ECTRcompared to 38 days for OCTR)
      • Disadvantages:
        • There is higher risk of incomplete release, and revision surgery compared to OCTR
        • Visualization is not as good as with the open technique (eg inflamed, hypertrophied tenosynovium in a patient with rheumatoid arthritis may impair visualization)
        • There is higher risk of transient neuropraxia of the digital nerves, however no increased risk of major nerve or vessel injuries.
    • Both OCTR and ECTR are safe and effective methods.

Opponensplasty: Patients with severe weakness and atrophy of the thenar muscles have a low likelihood of regaining their strength. In these cases an opponensplasty may be indicated. Options include:

  • Camitz Procedure: palmaris longus to the abductor pollicis brevis insertion siter (radial collateral ligament).
  • Royle-Thompson Procedure: Ring FDS to  is routed around ulnar border of the palmar fascia, which acts as a pulley. A slip of the superficialis is attached to the neck of the first metacarpal, and another slip is drawn over the MP joint and sutured into the hood mechanism of the proximal phalanx.

Outcomes

  • Reoperation for persistent CTS occurs in less than 5% of cases. The  most common reason for revision is technical error during primary release:
    • incomplete release of flexor retinaculum in 55%
    • nerve adhesion in scar tissue in 32%
    • nerve laceration in 6%
    • no known cause in 7%
  • Thirty percent of patients over the age of 65 who have chronic symptoms will not improve postoperatively.
  • EMG's may not normalize post op but they will improve.
  • MRI and possibly ultrasound can be used postoperatively to evaluate the quality of the release.
  • Pillar pain -

References

JAAOS Articles

Resources on Carpal tunnel syndrome from JAAOS. [Sign Up and build your orthopaedic network].

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