Definition and Overview
Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy, caused by compression of the median nerve as it passes through the carpal tunnel of the wrist.
The carpal tunnel is a narrow passage at the volar aspect of the wrist, bordered by carpal bones and the flexor retinaculum, through which the median nerve and nine flexor tendons pass. When this space narrows or its contents increase, the median nerve becomes compressed.
The adult prevalence is approximately 3.8%, with women affected about three times more frequently than men [1]. It is most commonly diagnosed in middle-aged women.
Etiology and Pathophysiology
Increased pressure within the carpal tunnel reduces median nerve blood flow, and sustained compression leads to demyelination and axonal damage. Causes of elevated carpal tunnel pressure include:
- Repetitive hand movements and vibrating tool use (occupational exposure)
- Anatomical wrist abnormalities
- Systemic conditions: diabetes mellitus, hypothyroidism, rheumatoid arthritis, obesity, renal failure (dialysis patients)
- Pregnancy (edema from fluid retention)
- Trauma: post-fracture wrist deformity
Symptoms
Typical symptoms include numbness, tingling paresthesia, and pain in the median nerve distribution (thumb, index, middle, and radial half of the ring finger).
- Nocturnal paresthesia: awakening from sleep due to hand numbness is the most characteristic symptom, temporarily relieved by shaking the hand or letting it hang
- Tinel's sign: tapping over the median nerve at the wrist reproduces tingling
- Phalen's test: maintaining maximum wrist flexion for 60 seconds provokes paresthesia
- Advanced cases: thenar eminence weakness and atrophy, impaired fine motor skills
Diagnosis
Nerve conduction study (NCS) is the standard diagnostic test for carpal tunnel syndrome. Diagnosis is based on prolonged distal motor latency and decreased sensory nerve conduction velocity of the median nerve.
Classic symptoms with positive provocative tests strongly suggest the diagnosis, while NCS is used for severity assessment and treatment planning [2]. Ultrasound is useful as an adjunctive diagnostic tool to identify increased cross-sectional area of the median nerve.
Treatment
Conservative Treatment
For mild to moderate cases, conservative treatment is attempted first.
- Nighttime wrist splint: immobilizes the wrist in a neutral position to reduce carpal tunnel pressure. Effective for symptom relief [3].
- Local corticosteroid injection: intra-carpal tunnel corticosteroid injection is effective for short-term symptom relief.
- Activity modification: limiting provocative movements, ergonomic workplace adjustments
- Oral medications: NSAIDs and neuropathic pain medications are used as adjuncts
Surgical Treatment
Surgical decompression is recommended when conservative treatment fails, symptoms are severe, or muscle atrophy is present. Carpal tunnel release involves incising the flexor retinaculum to decompress the median nerve. Symptom improvement is reported in approximately 75-90% of patients after surgery [2][4].
Both open and endoscopic approaches are performed, with the endoscopic approach having a somewhat shorter recovery period.
Prognosis
Earlier treatment initiation is associated with better outcomes. When NCS shows axonal loss or thenar muscle atrophy has progressed, complete recovery after surgery may take longer. Surgical outcomes may be relatively less favorable in patients with diabetes.
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This information is provided for medical educational purposes only and does not replace professional medical advice.
If you are experiencing symptoms, please consult a specialist.
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