Carpal tunnel syndrome

Background

Anatomy of the carpal tunnel, showing the median nerve passing through the tight space it shares with the other tendons.

Transverse section at the wrist. The median nerve is colored yellow. The carpal tunnel consists of the bones and transverse carpal ligament.

Nerves of the left upper extremity showing the median nerve distribution. Area of nerve compression is at wrist.

• Also known as "Median Mononeuropathy"
• Most common focal mononeuropathy
• Results from compression of median nerve at wrist where it traverses the carpal tunnel
• Median nerve provides sensation to the palmar aspect digits 1-3 and radial side of 4th
• Etiology: repetitive wrist flexion/extension, trauma, edema

Risk factors

• Female sex
• Rheumatoid arthritis and other connective tissue diseases
• Diabetes mellitus
• Amyloidosis
• Obesity
• Pregnancy
• Hypothyroidism

Clinical Features

History

• Pain, paresthesia, and numbness in distribution of median nerve
  • Palmar aspect of thumb, index, middle, and radial aspect of ring finger
• Awakening at night with burning pain and tingling in hand

Physical

• Sensation testing
  • Most specific - splitting of 4th digit in which medial aspect of 4th digit normal and lateral aspect abnormal
  • Most sensitive - abnormal sensation of distal palmar tip of 2nd digit
• LOAF muscle weakness as compared to other hand - Lumbricals, with thumb Opposition, Abduction, Flexion
• Tinel sign - poorly sensitive and specific
  • Tapping on palmar aspect of wrist reuslts in electric shock sensation shooting into hand
  • SN 0.50 and SP 0.77
• Phalen maneuver
  • Holding wrists in flexion for 60 seconds evokes or worsens symptoms
  • SN 0.68 and SP 0.73
• Durkan sign
  • Manual compression of carpal tunnel reproduces symptoms after 30 seconds
  • SN 0.64 and SP 0.83
  • More sensitive and specific than Tinel and Phalen in earlier studies
• Hand Elevation Test
  • Performed by having patient elevated both hands above the head
  • Positive if paresthesia, numbness, or dull pain felt within two minutes
  • SN 0.87 and SP 0.89
• May see atrophy of thenar eminence in advanced cases

Severe atrophy of the bilateral thenar eminences from untreated carpal tunnel syndrome

Differential Diagnosis

By Type of Lesion

Proximal Lesion

• Spinal cord lesion
• Cervical radicular pain
• Thoracic outlet syndrome
• Multiple Sclerosis (MS)

Distal Lesion

• Ulna neuropathy

Systemic condition

• Raynaud syndrome
• Pregnancy (Main)
• B12 deficiency
• Diabetic neuropathy
• Hypothyroidism
• Hypocalcemia

Upper extremity peripheral nerve syndromes

Median Nerve Syndromes

• Carpal tunnel syndrome
• Pronator teres syndrome
• Anterior interosseous neuropathy

Ulnar Nerve Syndromes

• Ulnar neuropathy

Radial Nerve Syndromes

• Radial neuropathy at the spiral groove (ie. "Saturday night palsy")
• Posterior interosseous neuropathy

Proximal Neuropathies

• Suprascapular neuropathy
• Long thoracic neuropathy
• Axillary neuropathy
• Spinal accessory neuropathy
• Musculocutaneous neuropathy

Other

• Brachial plexopathy
  • Parsonage-Turner syndrome
• Cervical radiculopathy

Management

• See this American Academy of Orthopedic Surgeons clinical decision tool for treatment options and disposition - CTS guidelines
• Behavioral modification
• Wrist splint with wrist in neutral position
• NSAIDs (although not clearly effective)
• Diuretics (if edema is significant contributor to patient's symptoms)

Splint in neutral position

Disposition

• Discharge

See Also

• Radial neuropathy at the spiral groove