Access Keys:
Skip to content (Access Key - 0)

Carpal Tunnel Syndrome

Introduction

  • Carpal Tunnel Syndrome occurs when median nerve gets squished in the wrist causing pain, numbness, tingling and in more severe cases, weakness and clumsiness of the hands
  • Most common compressive neuropathy in the upper extremity

Anatomy

  • The median nerve arises from the C6,C7,C8 and T1 segments of the spinal cord
  • Roots  from C6 and C7 provide sensory fibers which transmit sensation from the radial 3.5 fingers  (i.e. thumb to medial ½ ring finger)
  • Roots from C8 and T1 provide motor fibers which supply muscles in the
    • Forearm
      • Pronator teres
      • Flexor carpi radialis
      • Palmaris longus
      • Flexor digitorum superficialis
      • Pronator quadrates
    • Hand
      • Abductor pollicis brevis
      • Flexor pollicis brevis
      • Opponens pollicis
      • 1st and 2nd lumbricals
  • As it enters the wrist, the median nerve passes through the carpal tunnel a space enclosed by the transverse carpal ligament on the palmar side and carpal bones on the other 3 sides
  • Median nerve shares this tunnel with 9 flexor tendons
  • The carpal tunnel is smaller in diameter compared to males

Pathogenesis

  • Inflammation or thickening of flexor tendons can result in increased pressure in the carpal tunnel
  • Studies investigating the compression of human nerves show
    • Swelling and thickening of vessel walls in the endoneurium and perineurium
    • Vascular proliferation
    • Thinning of the myelin
    • Nerve fiber degeneration and regeneration
  • Damage to the myelin or vessels supplying the nerve cause
    • Decreased conduction velocity
    • Possibly, axonal loss
  • As a result, signals transmitted by the median nerve would be slowed or eventually
  • Sensory fibers seem to be more sensitive to compression than motor fibers perhaps explaining why sensory findings often precede motor findings in CTS
  • Early in the disease
    • There is no structural changes in the nerve
    • Neurologic symptoms are
      • Reversible
      • Intermittent
  • Prolonged episodes of increased pressure in the carpal tunnel can lead to
    • Segmental demyelination of the nerve
    • Increased frequency
    • Increased severity of symptoms
  • Prolonged ischemia can result in axonal injury and potentially irreversible nerve dysfunction
  • Macroscopically, surgical reports describe an "hourglass" shaped deformity of the median nerve in the carpal tunnel which may reflect thinning of the nerve under the transverse carpal ligament and/or swelling of the nerve distal or proximal to transverse carpal ligament

Risk factors

  • Associated with
    • Aromatase inhibitor use
    • Obesity
    • Pregnancy; due to fluid accumulation
    • Diabetes
    • Rheumatoid arthritis
    • Hypothyroidism
    • Amyloidosis
    • Connective tissue disease
    • Median mononeuropathy
    • Acromegaly; due to tendon sheath enlargement
    • Trauma to wrist
  • It is not caused by work, any more than running after the bus causes heart disease
  • Occupation may precipitate symptoms in patients with underlying disease
    • Prolonged use of hand-held vibratory tools
    • Repetitious flexion and extension of the wrist with forceful gripping
    • There is little/no evidence to support a relationship with keyboarding

Prevention

  • Studies suggest splinting may alter the underlying course of CTS

Nutritional factors

  • AAOS gudelines state that there is insufficient evidence to recommend for or against nutritional supplements or specific supplementation with vitamin B6 as treatment for carpal tunnel syndrome

Natural History

  • Incidence : 1-3 cases per 1000 people per year
  • Prevalence : 50 cases per 1000 people in the general population
  • Male : Female 1:8
    • Bilateral involvement is common in females
    • More common in menopausal women
  • Usually 40 - 50 years old
  • Younger patients usually have associated factors

Clinical Presentation

  • Symptoms usually include burning, numbness or tingling on the palmar side of the thumb, index finger, middle finger and radial half of ring finger sparing the little finger
  • Symptoms amy relieve by hanging the arm at the side of the bed or walking around
  • Pain may radiate up the arm
  • "Classic symptoms" in sensory distribution of the median nerve have
    • 61% sensitivity
    • 71% specificity
  • Patients often report worsening of symptoms at night. Nocturnal symptoms have
    • 51-77% sensitivity
    • 27-68% specificity
  • Loss of two point discrimination in fingers supplied by the median nerve occurs in later stages of disease and has low sensitivity and high specificity
  • 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
      • Low sensitivity and specificity (36% and 57%, respectively)

Diagnositc criteria

  • Numbness and tingling in the median nerve distribution
  • Nocturnal numbness
  • Weakness and/or atrophy of the thenar muscles
  • Tinel sign
  • Phalen's test
  • Loss of 2-point discrimination

Late presentation

Denervation of the muscles of the hand supplied by the median nerve causes

  • Decreased grip strength
  • Decreased strength in opposition of the thumb resulting from

Differential Diagnosis

  • More Proximal Lesion of Median Nerve
    • Can be caused by dislocation of ulna
    • Findings in hand would be similar
    • Distinctive features : weakness of muscles of the forearm supplied by median nerve
  • Radiculopathy
    • C6 or C7 radiculopathy could look similar with similar findings in the hand
    • Distinctive features
      • Neck pain
      • Muscle weakness and sensory findings proximal to the carpal tunnel
  • Ulnar neuropathy
    • Has similar description of numbness and tingling in the fingers
    • Distinctive features : patients would describe funny feelings in the little finger and ulnar side of the ring finger
  • Pronator teres syndrome
  • Hereditary neuropathy
  • AIN syndrome

Psychosocial impact of disease

  • The psychosocial impact of the disease depends on the
    • Patient's occupation
    • Lifestyle
    • Disease severity
  • Decreased grip strength and increased clumsiness and frequency of dropped objects can be a significant source of impairment for people accustomed to working with their hands

Imaging and Diagnostic Studies

Carpal tunnel syndrome is a clinical diagnosis

X-Ray

  • Can be used to rule out possible causes of increased pressure within the carpal tunnel such as fracture to the carpal bones or distal radius
  • Imaging studies are not routinely used to evaluate CTS

Ultrasound

  • Ultrasound has shown that patients with CTS have increased cross sectional area of the median nerve compared to controls
  • However, there is no cut off point for diagnosis of CTS

MRI

  • MRI can be used postoperatively to evaluate the quality of the release

Electrodiagnostic studies

  • Nerve conduction studies measure conduction velocity of the median nerve in the carpal tunnel
  • The role of electrodiagnostic testing is uncertain
  • Electrodiagnostic testing is useful to
    • Confirm the diagnosis preoperatively, as a baseline for monitoring unexpected outcomes
    • Rule out other conditions such as radiculopathy, and for Workers Compensation cases
    • If repeat testing is necessary for a patient, be sure to send them to the same lab
  • Mild CTS may not show any alterations in conduction
  • Demyelination can occur with increased compression, resulting in conduction block or slowed conduction across the wrist
  • EMG's may not normalize post op but they will improve
  • In a 2002 systematic review of prospective studies
    • The sensitivity of nerve conduction studies for CTS ranged from 56 - 85%
    • The specificity ranged from 94 – 99%

Treatment

Non-operative

  • Vitamin B6 does not significantly improve overall symptoms compared with placebo
  • Wrist splint : Immobilise the wrist to avoid positions which increase carpal tunnel pressure
  • NSAIDs
    • Relieve pain
    • Decrease inflammation
  • Oral steroids
  • Steroid injection
    • Injection of corticosteroids into the carpal tunnel to decrease inflammation
    • Have been shown to be better than placebo injections
    • A good response to an injection is prognositic of a better response to surgery compared to those who do not respond to the injection
    • May be used for therapeutic and prognostic reasons
    • Surgical decompression is recommended when injection no longer provides relief

Surgery

  • Cut fascial covering of carpal tunnel to decrease pressure
  • Options
    • Open carpal tunnel release (OTCR)
    • Endoscopic carpal tunnel release (ETCR)
      • No difference in outcomes at 1 year post op
      • Less postoperative pain
      • Shorter return to functional activities
      • The most significant, proven advantage of ECTR is faster mean return to work (18 days for ECTR vs. 38 days for OCTR)

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 : transfer of palmaris longus tendon to the abductor pollicis brevis insertion site
    • Royle-Thompson Procedure
      • Transfer of ring FDS to thumb
      • Tendon is routed around ulnar border of the palmar fascia to act as a pulley
      • A slip of the superficialis is attached to the neck of the first metacarpal
      • Another slip is drawn over the MP joint and sutured into the hood mechanism of the proximal phalanx

Re-operation

  • 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%

Outcome

  • Wrist splints
    • 80% patients report that a wrist splint alleviates symptoms within days
    • May minimize symptom severity and functional deficits for up to 3 months
  • Oral steroids : May offer a benefit for up to 8 weeks
  • Steroid injection
    • Improves symptoms in 75% of patients
    • May provide benefit for 2 weeks to 6 months
    • Long-term benefits have not been shown
  • Surgery
    • Both OCTR and ECTR are safe and effective methods
    • Pain relief occurs within days
    • It takes several months for hand strength to return to preoperative levels
    • 70% of patients are either completely or partially satisfied with results
    • 79-90% patients report being free of nocturnal pain after surgery
    • 30% of patients over the age of 65 with chronic symptoms will not improve postoperatively

Complications

  • Untreated, the syndrome can progress to
    • Permanent sensory loss
    • Paralysis of the thenar muscles
  • Steroid injections
    • Infection
    • Rupture of tendons
    • Irritation of nerves
    • Possible systemic toxicity (hyperglycemia or hypertension)
  • Surgery
    • General
      • Infection
      • Bleeding
      • Ligation of the median nerve
    • OTCR
      • Scar tenderness
      • Higher risk of bowstringing of flexor tendons, particularly when associated with a flexor tendon repair
    • ETCR
      • Visualization is not as good as with the open technique
      • The risk of major nerve or vessel injuries is not increased
      • There is higher risk of
        • Incomplete release
        • Revision surgery
        • Transient neuropraxia of the digital nerves

References


Peer Review

OrthopaedicsOne Peer Review Workflow is an innovative platform that allows the process of peer review to occur right within an OrthopaedicsOne article in an open, transparent and flexible manner. Learn more

Instructions for Authors

Read our Instructions for Authors to learn about contributing or editing articles on OrthopaedicsOne.

Content Partner

Learn about becoming an OrthopaedicsOne Content Partner.

Academic Resources

Resources on Carpal Tunnel Syndrome from Pubget.

Error rendering macro 'rss' : The RSS macro is retrieving an HTML page.
Related Content

Resources on Carpal Tunnel Syndrome and related topics in OrthopaedicsOne spaces.

Page: Mallet finger (baseball finger) (OrthopaedicsOne Articles)
Page: Carpal instability (OrthopaedicsOne Articles)
Page: Carpal Tunnel Syndrome (OrthopaedicsOne Articles)
Page: Elbow instability (OrthopaedicsOne Articles)
Page: Hamate fractures (OrthopaedicsOne Articles)
Page: Scaphoid fractures (OrthopaedicsOne Articles)
Page: Thoracic outlet syndrome (OrthopaedicsOne Articles)
Page: Tibial shaft stress fracture (OrthopaedicsOne Articles)
Page: Head injuries (OrthopaedicsOne Articles)
Page: Neck injuries (OrthopaedicsOne Articles)
Showing first 10 of 488 results