Carpal Tunnel Syndrome

Definition

Compression neuropathy of the median nerve within the carpal tunnel, the most frequent entrapment neuropathy of the upper limb.

Anatomy

  • Roof is the transverse carpal ligament, from scaphoid tubercle and trapezium to pisiform and hook of hamate
  • Contents are the median nerve, flexor pollicis longus and the four FDS and four FDP tendons
  • Palmar cutaneous branch arises proximal to the tunnel, sparing thenar skin sensation
  • Recurrent motor branch is extraligamentous, subligamentous or transligamentous (Lanz)

Aetiology

  • Idiopathic in most
  • Pregnancy, diabetes, hypothyroidism, obesity and rheumatoid arthritis
  • Amyloidosis, acromegaly and long term dialysis
  • Distal radius fracture causing acute carpal tunnel syndrome
  • Vibration exposure

Clinical Features

  • Nocturnal paraesthesia in the thumb, index, middle and radial ring finger
  • Flick sign, shaking the hand to relieve symptoms
  • Weak abductor pollicis brevis and thenar wasting in advanced disease
  • Phalen test, Tinel sign and Durkan carpal compression test
  • CTS-6 clinical diagnostic tool
    • Numbness in the median nerve distribution
    • Nocturnal numbness
    • Thenar weakness or atrophy
    • Positive Phalen test
    • Positive Tinel sign
    • Loss of two point discrimination

Investigations

  • Nerve conduction studies confirm and grade severity, with prolonged distal sensory latency first
  • Electrodiagnosis changes little when clinical probability is already high
  • Ultrasound shows an enlarged median nerve cross sectional area at the tunnel inlet

Differential Diagnosis

Management

  • Night splint. Wrist in neutral for mild or intermittent symptoms
  • Corticosteroid injection. Short term symptom relief, with recurrence frequent
  • Open carpal tunnel release. Persistent symptoms, thenar wasting or denervation, see open carpal tunnel release
  • Endoscopic release. Outcomes comparable to open release
  • No routine splint after release. AAOS guideline advises against postoperative immobilisation
  • Urgent release. Acute carpal tunnel syndrome after distal radius fracture

References

  1. Graham B, Peljovich AE, Afra R, Cho MS, Gray R, Stephenson J, Gurman A, MacDermid J, Mlady G, Patel AT, Rempel D, Rozental TD, Salajegheh MK, Keith MW, Jevsevar DS, Shea KG, Bozic KJ, Adams J, Evans JM, Lubahn J, Ray WZ, Spinner R, Thomson G, Shaffer WO, Cummins DS, Murray JN, Mohiuddin M, Mullen K, Shores P, Woznica A, Linskey E, Martinez Y, Sevarino K. The American Academy of Orthopaedic Surgeons evidence-based clinical practice guideline on management of carpal tunnel syndrome. J Bone Joint Surg Am. 2016, 98(20), 1750-4. PubMed
  2. Padua L, Coraci D, Erra C, Pazzaglia C, Paolasso I, Loreti C, Caliandro P, Hobson-Webb LD. Carpal tunnel syndrome. Clinical features, diagnosis, and management. Lancet Neurol. 2016, 15(12), 1273-84. PubMed
  3. Graham B. The value added by electrodiagnostic testing in the diagnosis of carpal tunnel syndrome. J Bone Joint Surg Am. 2008, 90(12), 2587-93. PubMed

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 19 October 2026.