Carpal Tunnel Syndrome

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Carpal tunnel syndrome (CTS) is a common entrapment neuropathy caused by compression of the median nerve as it passes through the carpal tunnel in the wrist, leading to pain, numbness, and weakness in the hand.

Aetiology

CTS occurs due to increased pressure on the median nerve within the carpal tunnel.

Common Causes:

  • Repetitive hand movements: typing, manual labour, or excessive wrist use.
  • Inflammatory conditions: rheumatoid arthritis, tenosynovitis.
  • Endocrine disorders: hypothyroidism, diabetes mellitus.
  • Pregnancy: fluid retention leading to swelling in the carpal tunnel.
  • Trauma: wrist fractures, dislocations.
  • Obesity: increased pressure in the carpal tunnel.

Pathophysiology

  • The median nerve supplies sensation to the thumb, index, middle, and half of the ring finger.
  • Compression of the median nerve leads to impaired nerve conduction.
  • Prolonged compression results in demyelination and eventual axonal degeneration.

Risk factors

  • Female sex (higher prevalence due to smaller carpal tunnel size).
  • Occupational strain (repetitive wrist movements).
  • Pregnancy (fluid retention causing swelling).
  • Diabetes mellitus (increased nerve susceptibility).
  • Hypothyroidism (soft tissue swelling).
  • Rheumatoid arthritis (synovial inflammation).
  • Obesity.

Signs and symptoms

CTS primarily affects sensation and motor function in the median nerve distribution.

Typical Features:

  • Numbness and tingling: affects the thumb, index, middle, and half of the ring finger.
  • Night-time symptoms: symptoms often worsen at night, waking patients from sleep.
  • Weakness and clumsiness: difficulty gripping objects, dropping things.
  • Thenar muscle wasting: in advanced cases, atrophy of the thenar muscles.

Provocative Tests:

  • Tinel’s sign: tapping the median nerve at the wrist elicits tingling.
  • Phalen’s test: holding wrists in flexion for 60 seconds reproduces symptoms.

Investigations

  • Clinical diagnosis: based on characteristic symptoms and physical examination.
  • Nerve conduction studies (NCS): confirms slowing of conduction across the carpal tunnel.
  • Electromyography (EMG): assesses for muscle denervation in severe cases.
  • Ultrasound: can show median nerve swelling.
  • Blood tests: check for underlying conditions (e.g., thyroid function, HbA1c for diabetes).

Management

1. Conservative Management (First-Line):

  • Wrist splinting: especially at night to keep the wrist in a neutral position.
  • Activity modification: avoid repetitive wrist movements.
  • NSAIDs: short term use for pain relief.
  • Weight management: if obesity is a contributing factor.

2. Pharmacological Management:

  • Corticosteroid injection: provides temporary relief in moderate cases.

3. Surgical Management (For Severe or Persistent Cases):

  • Carpal tunnel release surgery: cutting the transverse carpal ligament to relieve pressure on the median nerve.
  • Indicated if symptoms persist despite conservative treatment or if there is thenar muscle wasting.

4. Follow-Up and Monitoring:

  • Assess symptom progression and function.
  • Consider referral to physiotherapy for hand exercises post-surgery.
NeurologymypanotesCarpal Tunnel Syndrome, CTS