Carpal Tunnel Syndrome

• The carpal tunnel contains 9 flexor tendons and the median nerve. The 9 flexor tendons are:

• Flexor pollicis longus
• Flexor digitorum profundus (x4)
• Flexor digitorum superficialis (x4)

Pathophysiology

• Sensory fibers are more sensitive to compression:
  • Early symptoms: paresthesias, pain
• Motor involvement in advanced cases:
  • Weakness of thumb abduction and opposition
  • Functional issues: dropping objects, difficulty opening jars or buttoning shirts
• Late finding: resolution of pain indicating permanent sensory loss

Risk factors and causes of CTS

Fluid retention	Inflammation of structures within/around the carpal tunnel	Space occupying lesions	Other conditions
Pregnancy Menopause Obesity	Repetitive strain injury causing tendinopathy (overuse in jobs such as gardening, assembly line work and use of vibrational power tools) Inflammatory arthropathy (e.g. rheumatoid arthritis)	Ganglion cysts Osteophytes (in osteoarthritis) Previous wrist fractures/ trauma may also mechanically reduce the space within the carpal tunnel	Diabetes mellitus Hypothyroidism Smoking advanced age chronic renal failure alcoholism

Clinical Hallmarks

• Pain and paresthesias in median nerve distribution:
  • Palmar aspect of thumb, index, middle, and radial half of ring finger
• Symptoms can vary widely and occasionally localize to the wrist or the entire hand, or radiate to the forearm or rarely the shoulder.
• Flick sign:
  • Patients wake with symptoms and shake their hand to relieve them
  • 93% sensitivity, 96% specificity for CTS
• Symptom variability:
  • May localize to wrist, entire hand
  • Can radiate to forearm or rarely shoulder
• Provoking factors:
  • Activities with repetitive wrist flexion or hand elevation:
    • e.g. driving, holding a phone
• severe cases:
  • motor fibers are affected, leading to weakness of thumb abduction and opposition.
  • Patients may describe difficulty holding objects, opening jars, or buttoning a shirt. Disappearance of pain is a late finding that implies permanent sensory loss.

Physical Examination

• Unlikely pattern: no symptoms in digits 1–3
• Thenar atrophy
• Durkan’s Test (Carpal Tunnel Compression Test):
  • Press thumbs over carpal tunnel for 30 seconds
  • Positive if pain/paresthesia in median distribution occurs
  • Most sensitive physical test

• Phalen’s Test:
  • Passive wrist flexion (backs of hands together) for 60 seconds
  • Positive if symptoms reproduced
  • Less sensitive than Durkan’s

• Tinel’s Sign:
  • Tapping over volar carpal tunnel elicits tingling

• Hand Symptom Diagram:
  • Classic pattern: symptoms in ≥2 of digits 1–3; excludes palm/dorsum
• Probable pattern: similar, may include palmar symptoms unless limited to ulnar side

A hand symptom diagram can be a useful tool in diagnosing carpal tunnel syndrome.

A. In the classic pattern, symptoms affect at least two of digits 1, 2, or 3. It includes symptoms in the fourth and fifth digits, wrist pain, and radiation of pain proximal to the wrist, but excludes symptoms on the palm or dorsum of the hand.

B. The probable pattern has the same symptom pattern as the classic pattern, except palmar symptoms are possible unless confined solely to the ulnar aspect.

C. In the unlikely pattern, no symptoms are present in digits 1, 2, or 3

DIAGNOSIS

• EMG (electromyography) and Nerve Conduction Velocities
  • sensitivity of 56% – 85%
  • specificity of 94% – 99%
  • May be normal in up to one-third of mild CTS cases
  • Best used to confirm atypical presentations or rule out differentials
  • Mild cases may not require further testing.
  • Indications for nerve conduction studies/EMG:
    • Atypical presentation
    • Persistent numbness, weakness
    • Surgical consideration
  • Severity classification:
    • Mild: sensory changes only
    • Moderate: sensory + motor changes
    • Severe: extensive damage

• ULTRASONOGRAPHY
  • The cross-sectional area of the median nerve is closely correlated with CTS symptoms and severity
  • cross-sectional area > 9 mm2 is 87.3% sensitive and 83.3% specific for CTS.1

• OTHER TESTS
  • Plain radiography may be useful if structural abnormalities, such as bone or joint disease, are suspected.
  • Magnetic resonance imaging is not generally indicated.
  • Laboratory testing for comorbidities, such as diabetes or hypothyroidism, may be considered if there are other signs suggesting disease.

Treatment / Management

Conservative Treatment (first-line for mild CTS):

• Nighttime wrist splinting (neutral position).
• Glucocorticoid injection (e.g., methylprednisolone 20–40 mg + 1% lidocaine):
  • Relief for ~3 months
  • Max: 1 injection per wrist every 6 months.
• Short course oral prednisone (20 mg/day for 10–14 days) if injection not preferred.
• Hand therapy: splinting + exercises (nerve/tendon glides, mobilization).
• NSAIDs, diuretics, oral agents: ineffective.

Surgical Treatment:

• Indicated if:
  • Failed conservative therapy
  • Severe CTS on nerve testing
• Carpal tunnel release (open or endoscopic)
  • Cuts transverse carpal ligament
  • Day procedure with >90% initial success
  • grip strength is expected to return to 100% preoperative levels by 12 weeks postop
  • Long-term success ~60% at 5 years