Carpal Tunnel Syndrome

Basics

• Compression neuropathy of median nerve due to increased pressure in carpal tunnel.
• Carpal tunnel boundaries: dorsal - carpal bones; palmar - transverse carpal ligament.
• Contains 9 flexor tendons and median nerve.
• Dominant hand more commonly affected; >50% bilateral.
• High socioeconomic impact with ~600,000 carpal tunnel release surgeries annually.
• Affects mostly females (3:1 to 10:1), age 40-60 years.
• Increased incidence in pregnancy (20-45%) and chronic hemodialysis (2-31%).

Epidemiology

• Incidence up to 276 per 100,000.
• Prevalence ~3% overall (4% women, 2% men).
• Higher prevalence in diabetics (14% without neuropathy, 30% with neuropathy).

Etiology and Pathophysiology

• Combination of mechanical trauma, inflammation, ischemia to median nerve.
• Acute CTS may occur from trauma requiring urgent decompression.
• Chronic CTS causes:
• Idiopathic (edema and fibrous hypertrophy without inflammation).
• Anatomic (persistent median artery, ganglion cyst, space-occupying lesion).
• Systemic (obesity, diabetes, hypothyroidism, RA, amyloidosis, scleroderma, renal failure).
• Exertional (repetitive hand use, vibratory tools).
• Familial cases reported; increased risk if first-degree relative affected.

Risk Factors

• Repetitive wrist flexion/extension postures.
• Use of vibratory tools (motorcycle riding).
• Systemic: pregnancy, RA, hypothyroidism, obesity, renal failure, hemodialysis.
• Neuropathic: diabetes, alcoholism, vitamin deficiencies.
• Higher risk with migraine headaches.

Prevention

• No proven prevention.
• Recommend frequent breaks during repetitive work or exposure to vibration.

Associated Conditions

• Diabetes, obesity, pregnancy, hypothyroidism.
• Osteoarthritis of small hand/wrist joints.
• Hyperparathyroidism, hypocalcemia.
• Hemodialysis.

Diagnosis

History

• Nocturnal pain, numbness, tingling in thumb, index, long, and radial half of ring finger.
• Symptoms relieved by shaking/rubbing hand (positive Flick sign; sensitivity 93%, specificity 96%).
• Hand weakness during tasks (e.g., opening jars).
• Symptoms triggered by activities such as driving, phone use, repetitive maneuvers.

Physical Exam

• Durkan compression test (compression over carpal tunnel for 30 sec): 87% sensitivity, 90% specificity.
• Phalen sign (wrist flexion held 60 sec): 68% sensitivity, 73% specificity.
• Tinel sign (tapping median nerve): 50% sensitivity, 77% specificity.
• Square-sign test (wrist width/height ≥0.7): 53% sensitivity, 80% specificity.
• Hand elevation test (hands above head 1-2 min): 85% sensitivity, 95% specificity.
• Loss of two-point discrimination, decreased pain sensation.
• Thenar muscle wasting is a late sign (16% sensitivity, 94% specificity).

Differential Diagnosis

• Cervical spondylosis (double crush syndrome).
• Peripheral neuropathy.
• Brachial plexopathy (upper trunk).
• CNS disorders (MS, stroke).
• Thoracic outlet syndrome.
• Pronator syndrome, anterior interosseous syndrome.
• Ulnar nerve compression.
• Musculoskeletal wrist disorders: trauma, arthritis, ganglion cyst, tenosynovitis, Raynaud’s.

Diagnostic Tests

• Questionnaires: CTS-6, Kamath and Stothard, Katz and Stirrat diagram.
• Labs: TSH, HbA1c, ESR to exclude secondary causes.
• Imaging: wrist X-rays (degenerative changes), limited role for MRI.
• Ultrasound: median nerve cross-sectional area ≥11.5 mm, sensitivity 87%, specificity 91%.
• Electrodiagnostic studies: sensitivity 85%, specificity 95%; used for unclear cases or alternative diagnoses.

Treatment

General Measures

• Immobilization by splint/brace/orthosis.
• Local corticosteroid injection improves outcomes.
• Surgical treatment provides better functional improvement at 1 year.
• Nonoperative trial recommended for mild to moderate cases.
• Surgery considered early for moderate to severe disease.

Medication

• First line: night splinting (12 weeks), local corticosteroid injection.
• NSAIDs: conflicting evidence.
• Oral corticosteroids: less effective than injection; limited long-term benefit.
• Gabapentin (300 mg daily) effective symptom management.
• Hand therapy improves function.

Surgery

• Carpal tunnel release (CTR): complete division of transverse carpal ligament.
• Outpatient procedure under local/regional anesthesia.
• Incisional healing ~2 weeks; additional 2 weeks before strength-demanding tasks.
• Endoscopic CTR associated with quicker recovery but slightly higher transient nerve injury risk.

Complementary Medicine

• No evidence supporting vitamin B6.
• Acupuncture may be as effective as short-term oral steroids.
• Chiropractic therapy lacks supportive data.

Admission

• Outpatient treatment.

Ongoing Care

• Follow-up 4-12 weeks to monitor nonoperative treatment progress.
• Rehabilitation exercises have limited evidence.
• Recurrence after surgery: 7-20%.

Prognosis

• 85% respond to conservative therapy but many relapse within 4 years.
• Thenar wasting and positive Phalen test predict poorer conservative outcomes.
• Severe CTS may have persistent symptoms post-surgery; numbness and weakness may be permanent.

Complications

• Median nerve or recurrent branch injury.
• Pillar pain (6-36% prevalence) post-CTR.

Clinical Pearls

• Paresthesias localize to thumb, index, long, and radial half of ring finger.
• Thenar atrophy indicates advanced nerve damage.
• Durkan test superior to Tinel and Phalen.
• Flick sign has highest diagnostic accuracy.
• Steroid injection plus night splinting mainstay for mild/moderate CTS.
• Surgical release >90% effective long-term.

References

1. Ashworth NL, Bland JDP, Chapman KM, et al. Local corticosteroid injection versus placebo for carpal tunnel syndrome. Cochrane Database Syst Rev. 2023;2(2):CD015148.
2. Ostergaard PJ, Meyer MA, Earp BE. Non-operative treatment of carpal tunnel syndrome. Curr Rev Musculoskelet Med. 2020;13(2):141-147.