Carpal Tunnel Syndrome

• Carpal tunnel syndrome is caused by compression of the medial nerve as it travels through the carpal tunnel in the wrist, causing pain and numbness in the median nerve distribution on the hand
• Flexor retinaculum


  A fibrous band that wraps across the front (palmar side) of the wrist, also known as the transverse carpal ligament
• Carpal tunnel

  A passageway from the forearm to the hand between the carpal bones and the flexor retinaculum where the median nerve and flexor tendons of the forearm travel through
• Compression of the carpal tunnel

  Result of either swelling of the contents (e.g., swelling of the tendon sheaths due to repetitive strain) or narrowing of the tunnel
• Palmar digital cutaneous branch of the median nerve


  Responsible for sensory innervation of the palmar aspects and full fingertips of the thumb, index and middle finger, and the lateral half of the ring finger
• The palmar cutaneous branch of the median nerve provides sensation to the palm but does not travel through the carpal tunnel, so it is not affected by carpal tunnel syndrome
• Median nerve

  Supplies motor function to the three thenar muscles responsible for thumb movements: Abductor pollicis brevis (thumb abduction), Opponens pollicis
• Median nerve


  Supplies motor function to the three thenar muscles
• Thenar muscles

  • Abductor pollicis brevis (thumb abduction)
  • Opponens pollicis (thumb opposition – reaching across the palm to touch the tips of the fingers)
  • Flexor pollicis brevis (thumb flexion)
  • Adductor pollicis (thumb adduction)
• Adductor pollicis is innervated by the ulnar nerve
• Risk Factors

  • Repetitive strain
  • Obesity
  • Perimenopause
  • Rheumatoid arthritis
  • Diabetes
  • Acromegaly
  • Hypothyroidism
• Tom Tip: 'When preparing for the PACES exam, the link between bilateral carpal tunnel syndrome and acromegaly came up several times...'
• Presentation of carpal tunnel syndrome

  Gradual onset of symptoms, often worse at night, intermittent initially
• Sensory symptoms of carpal tunnel syndrome

  • Numbness
  • Paraesthesia (pins and needles or tingling)
  • Burning sensation
  • Pain
• Affected areas of sensory symptoms

  • Thumb
  • Index and middle finger
  • The lateral half of ring finger
• Motor symptoms of carpal tunnel syndrome

  • Weakness of thumb movements
  • Weakness of grip strength
  • Difficulty with fine movements involving the thumb
  • Wasting of the thenar muscles (muscle atrophy)
• Special tests for carpal tunnel syndrome

  • Phalen’s test
  • Tinel’s test
• Phalen’s test


  Involves fully flexing the wrist and holding it in this position...
• Tinel’s test


  Involves tapping the wrist at the location where the median nerve travels through the carpal tunnel...
• Positive test for carpal tunnel syndrome

  When this position triggers sensory symptoms of carpal tunnel, with numbness and paraesthesia in the median nerve distribution
• TOM TIP: Tinel’s test involves tapping a tin can to remember the difference between Phalen’s and Tinel’s test
• Questions in the Kamath and Stothard carpal tunnel questionnaire (CTQ)

  • Do symptoms wake you at night?
  • Do you have trick movements (e.g., shaking the hand) to improve symptoms?
  • Is your little finger affected?
• A high score on the carpal tunnel questionnaire may replace the need for nerve conduction studies to confirm the diagnosis
• Nerve conduction studies

  A small electrical current is applied by an electrode (nerve stimulator) to the median nerve on one side of the carpal tunnel. Recording electrodes over the median nerve on the other side of the carpal tunnel record the electrical current that reaches them. This demonstrates how well signals are passing through the carpal tunnel along the median nerve
• Management options for carpal tunnel syndrome

  • Rest and altered activities
  • Wrist splints that maintain a neutral position of the wrist can be worn at night (for a minimum of 4 weeks)
  • Steroid injections
  • Surgery
• Carpal tunnel syndrome surgery

  Usually performed as a day case procedure under local anaesthetic. Can be performed by open (with a vertical incision at the wrist) or endoscopic (keyhole) surgery. The flexor retinaculum (AKA transverse carpal ligament) is cut to release the pressure on the median nerve
• Last updated

  August 2021