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📋 Condition Guide2024-01-15

Carpal Tunnel Syndrome: Causes, Symptoms, and Treatment

Carpal tunnel syndrome (CTS) is the most common peripheral nerve compression disorder. It occurs when the median nerve is compressed at the wrist, causing numbness, tingling, and weakness in the hand — especially at night.

Educational content only. This article is not medical advice. Always consult a qualified orthopedic surgeon or physician for diagnosis and treatment.

What Is Carpal Tunnel Syndrome?

Carpal tunnel syndrome (CTS) occurs when the median nerve — which runs through a narrow passageway in the wrist called the carpal tunnel — becomes compressed. The carpal tunnel is formed by the wrist (carpal) bones on three sides and the transverse carpal ligament (flexor retinaculum) on the fourth (palm) side.

Nine flexor tendons also pass through this tunnel alongside the median nerve. When tunnel pressure increases — from inflammation, swelling, or structural changes — the nerve is compressed, causing the characteristic symptoms of CTS.

CTS affects approximately 3–6% of adults and is the most common cause of hand numbness and weakness. It's more common in women and peaks between ages 40–60.

Median Nerve Distribution

The median nerve provides sensation to:

  • Thumb
  • Index finger
  • Middle finger
  • Half of the ring finger (the side closest to the middle finger)

It also powers the thenar muscles — the muscles at the base of the thumb responsible for opposition (the motion of touching your thumb to your fingertips).

Causes and Risk Factors

  • Repetitive hand/wrist use: Typing, assembly work, vibrating tools
  • Wrist position: Prolonged wrist flexion or extension increases tunnel pressure
  • Anatomical factors: Smaller carpal tunnel, wrist fracture causing anatomical change
  • Medical conditions: Diabetes, rheumatoid arthritis, hypothyroidism, pregnancy (fluid retention)
  • Obesity
  • Female sex (women have smaller carpal tunnels on average)
  • Age (most common 40–60)
  • Pregnancy: Hormonal fluid retention often causes CTS; usually resolves after delivery

Symptoms

Classic Presentation

  • Numbness and tingling in the thumb, index, and middle fingers — the median nerve distribution
  • Symptoms worse at night and with activities keeping the wrist bent (driving, reading)
  • Wrist shaking provides temporary relief (the "flick sign")
  • Symptoms often awaken patients from sleep

Progressive Cases

  • Constant numbness (loss of sensation)
  • Weakness: Difficulty pinching, opening jars, holding objects
  • Thenar wasting: Loss of muscle bulk at the base of the thumb — indicates chronic, severe compression

Diagnosis

Clinical tests:

  • Phalen's test: Holding wrists fully flexed for 60 seconds — positive if tingling develops in median nerve distribution (sensitivity ~68%)
  • Tinel's sign: Tapping over the carpal tunnel at the wrist crease — positive if tingling shoots into fingers
  • Durkan's compression test: Direct pressure over the carpal tunnel for 30 seconds
  • Hand diagram: Patients shade where they feel numbness — classic CTS pattern strongly suggests diagnosis

Nerve conduction studies (NCS)/EMG: The gold standard diagnostic test, measuring median nerve conduction velocity across the wrist. Confirms diagnosis, grades severity, and rules out alternative diagnoses.

X-ray/MRI: Rarely needed; may be used to identify structural causes.

Treatment

Conservative Treatment

  • Wrist splinting: The first-line treatment — wearing a neutral wrist splint at night prevents the wrist from bending and reduces tunnel pressure during sleep. Many patients with mild-moderate CTS achieve adequate symptom control with nighttime splinting alone.
  • Activity modification: Ergonomic keyboard placement, wrist rests, taking breaks from repetitive tasks
  • Corticosteroid injection: A corticosteroid injected into the carpal tunnel reduces inflammation; typically provides 1–3 months of significant relief. Effective as a bridge to surgery or long-term in mild cases.
  • NSAIDs: Limited evidence but may help with acute flares
  • Physical/occupational therapy: Nerve gliding exercises, ergonomic training

Surgical Treatment (Carpal Tunnel Release)

Surgery is recommended when:

  • Conservative treatment fails
  • Significant or worsening neurological deficit
  • Thenar muscle weakness or wasting (advanced compression)

Carpal tunnel release divides the transverse carpal ligament to decompress the median nerve. Can be performed:

  • Open carpal tunnel release: Small palm incision, direct visualization of the ligament
  • Endoscopic carpal tunnel release: 1–2 small wrist incisions, camera-guided ligament division; faster return to activity, equivalent outcomes

Both procedures are highly effective (85–90% success rate) and typically performed under local anesthesia as outpatient procedures.

Recovery Timeline

  • Surgery: Local anesthesia, 15–30 minute procedure, go home same day
  • Grip strength: Takes 3–6 months to return to full strength
  • Numbness: Typically improves within weeks to months; thenar weakness may take 6–12 months to recover
  • Return to work: Light work in days; heavy manual work 4–6 weeks

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