Median nerve compression at the wrist; nocturnal hand paresthesias and thenar weakness; managed with splinting, steroid injection, or surgical release.
Also known as: CTS, carpal tunnel, median nerve entrapment
Overview
Compressive neuropathy of the median nerve at the level of the carpal tunnel beneath the transverse carpal ligament. Most common upper-extremity entrapment neuropathy.
Epidemiology
Affects ~3-5% of adults; women > men 3:1. Peak incidence 45-60. Bilateral involvement common (often worse in the dominant hand).
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Amyloidosis (consider in atypical or bilateral disease, especially with carpal tunnel as harbinger of cardiac amyloid)
Acromegaly
Hemodialysis (beta-2 microglobulin amyloid)
Repetitive hand or wrist activities (modest association)
Vibrating tool use
Wrist fracture (Colles)
Pathophysiology
Increased pressure within the carpal tunnel — from synovial swelling, tendon thickening, fluid retention, or space-occupying lesion — compresses the median nerve, producing initial sensory symptoms in the median distribution (thumb, index, middle, lateral half of ring finger). Persistent compression causes axonal damage with thenar atrophy and weakness.
Clinical presentation
Symptoms
Numbness and tingling in the thumb, index, middle, and radial half of the ring finger
Nocturnal symptoms that wake the patient and are relieved by shaking the hand (flick sign)
Symptoms worsened by activities requiring sustained wrist flexion (driving, holding a phone or book)
Hand clumsiness, dropping objects
Pain may radiate proximally to the forearm or shoulder
Signs / physical exam
Diminished sensation in median nerve distribution (sparing the thenar eminence palm — supplied by the palmar cutaneous branch that runs SUPERFICIAL to the carpal tunnel)
Thenar atrophy and weakness of thumb abduction and opposition (advanced disease)
Positive Tinel sign (percussion over median nerve at wrist reproduces symptoms)
Positive Phalen sign (1 minute of wrist flexion reproduces symptoms)
Positive carpal compression test (Durkan) — sensitive and specific
Differential diagnosis
Cervical radiculopathy (C6-C7) — Neck pain, dermatomal pattern, positive Spurling test; weakness in larger muscle distribution
Pronator teres syndrome (proximal median nerve) — Forearm pain, weakness in pronation; sensory loss extends to thenar eminence palm (palmar cutaneous branch — spared in CTS)
Anterior interosseous nerve syndrome — Pure motor; weakness of FPL, FDP to index, pronator quadratus ('OK sign')
Brachial plexus lesion (thoracic outlet) — More diffuse arm symptoms, often ulnar predominant
Peripheral neuropathy (diabetes, alcohol) — Symmetric stocking-glove distribution
Cervical syringomyelia — Cape-like dissociated sensory loss
Diagnostic workup
Labs
Screen for contributing conditions if atypical: A1c, TSH, CBC, CMP
Consider workup for amyloidosis (especially bilateral CTS in elderly men or those with cardiac/renal involvement): SPEP/UPEP, free light chains, transthyretin
Imaging
Generally NOT needed
Ultrasound of median nerve at the wrist — increased cross-sectional area
Local corticosteroid injection — substantial short-term benefit; many patients have lasting relief but surgery often eventually required for definitive resolution
Carpal tunnel release (open or endoscopic) — first-line for severe disease (thenar atrophy, persistent weakness, denervation on EMG) and second-line for refractory mild-to-moderate disease
Definitive treatment; most patients have rapid symptom relief, though established axonal damage may not fully reverse
Complications
Permanent median nerve damage with thenar atrophy and persistent weakness
The palmar cutaneous branch of the median nerve runs SUPERFICIAL to the carpal tunnel — sensory loss extending into the thenar palm suggests a proximal lesion (pronator teres syndrome or radiculopathy), not CTS.
Nocturnal symptoms and the 'flick sign' are highly suggestive of CTS.
Severe CTS with thenar atrophy is a surgical referral, not a splinting decision.
Bilateral CTS in elderly men should raise concern for amyloidosis — sometimes precedes cardiac amyloid by years.
Pregnancy-related CTS typically resolves within months of delivery — conservative management preferred.
References
AAOS 2016 — AAOS Clinical Practice Guideline on the Management of Carpal Tunnel Syndrome (2016, 2024 update)
AAN 2002 — Practice Parameter for Electrodiagnostic Studies in CTS (Jablecki et al., Neurology 2002)
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