Neurology · Peripheral Neuropathy
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Carpal tunnel syndrome results from median nerve compression at the wrist within the carpal tunnel.
Patients classically present with paresthesias and nocturnal pain involving the first three digits and the radial half of the fourth digit.
Physical examination reveals thenar eminence atrophy in chronic, severe cases due to denervation of the abductor pollicis brevis.
The Phalen maneuver and Tinel sign are the classic provocative clinical tests used to support the diagnosis.
Nerve conduction studies and electromyography (EMG) are the gold standard diagnostic tests to confirm the diagnosis and assess severity.
First-line management for mild to moderate cases includes nocturnal wrist splinting and ergonomic modification.
Conditions such as pregnancy, hypothyroidism, diabetes mellitus, and rheumatoid arthritis are classic associated risk factors.
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A 45-year-old female presents with a 3-month history of numbness and tingling in her right hand that is worse at night and wakes her from sleep. She works as a data entry clerk and reports that the symptoms involve her thumb, index, and middle fingers. On physical exam, she has weakness with thumb opposition and a positive Tinel sign at the wrist. There is visible atrophy of the thenar eminence. Sensation is spared over the thenar eminence itself.
What is the most appropriate next step in management for this patient?
Surgical decompression (carpal tunnel release)
The patient exhibits signs of advanced carpal tunnel syndrome, specifically thenar atrophy, which indicates significant nerve damage and warrants surgical intervention rather than conservative management.
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Etiology / Epidemiology
Common in repetitive wrist motion, pregnancy, diabetes, and hypothyroidism.
Clinical Manifestations
Paresthesias in the median nerve distribution; Thenar atrophy is a late finding.
Diagnosis
Electromyography (EMG) and Nerve Conduction Velocity (NCV) are the gold standard.
Treatment
Wrist splinting is first-line; surgical decompression for refractory cases.
Prognosis
Untreated cases lead to permanent thenar muscle wasting and loss of function.
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Epidemiology & Etiology
Most common entrapment neuropathy, frequently affecting middle-aged women. Strong associations include obesity, rheumatoid arthritis, and amyloidosis. Occupational risk is highest in jobs requiring repetitive flexion/extension.
Pertinent Anatomy
The median nerve passes through the carpal tunnel beneath the transverse carpal ligament. Compression occurs due to increased pressure within this confined space, affecting the first three digits and the radial half of the fourth.
Pathophysiology
Chronic compression leads to focal demyelination and eventual axonal loss of the median nerve. Increased interstitial pressure impairs venous outflow, causing edema and further nerve ischemia. Prolonged ischemia results in the classic nocturnal paresthesias reported by patients.
Clinical Manifestations
Patients report numbness and tingling in the thumb, index, and middle fingers, often worse at night. Phalen's maneuver and Tinel's sign are classic physical exam findings. Thenar muscle atrophy indicates severe, chronic nerve damage requiring urgent intervention.
Diagnosis
Nerve conduction studies demonstrate slowed conduction velocity across the carpal tunnel. Diagnostic criteria include distal sensory latency > 3.5 ms or motor latency > 4.2 ms. Clinical diagnosis is supported by positive Phalen's and Tinel's tests.
Treatment
Wrist splinting (neutral position) at night is the initial treatment. Corticosteroid injections provide temporary relief for acute flares. Avoid repetitive wrist flexion during recovery. Surgical carpal tunnel release is indicated for persistent symptoms or objective motor weakness.
Prognosis
Early intervention prevents permanent thenar atrophy. Post-surgical recovery is generally excellent, though patients with severe preoperative nerve damage may have incomplete sensory recovery.
Differential Diagnosis
Cervical radiculopathy (C6-C7): neck pain and dermatomal distribution
Pronator teres syndrome: proximal forearm tenderness
Diabetic polyneuropathy: symmetric, stocking-glove distribution
De Quervain's tenosynovitis: positive Finkelstein's test
Thoracic outlet syndrome: vascular symptoms and ulnar nerve involvement