The median nerve (C5–T1) provides motor innervation to forearm flexors and thenar muscles, and sensory innervation to the thumb, index, middle, and radial half of the ring finger. Acute injury most commonly results from lacerations, fractures (especially distal radius), dislocations (lunate/perilunate), crush injuries, and iatrogenic causes. [1-4] Injury severity is classified by the Seddon system — neurapraxia, axonotmesis, and neurotmesis — with management and prognosis varying accordingly. [2][5]
1. History
- Mechanism of injury: laceration (glass, knife), blunt trauma, fracture, dislocation, crush, or iatrogenic (IV access, surgical positioning, casting) [1][3]
- Timing of symptom onset relative to injury — immediate vs. progressive (critical distinction between nerve contusion and acute carpal tunnel syndrome [ACTS]) [6]
- Distribution of numbness/tingling: thumb, index, middle, and radial ring finger; palmar surface
- Weakness: difficulty with pinch grip, thumb opposition, inability to make "OK" sign (anterior interosseous nerve branch) [5]
- Pain: severity, location, progression — worsening pain after reduction or casting is a red flag for ACTS [6-7]
- Hand dominance, occupation, functional demands
- Prior hand/wrist injuries, surgeries, or neuropathy
2. Alarm Features
- Progressively worsening pain and sensory loss after wrist trauma → suspect ACTS, a surgical emergency requiring urgent carpal tunnel release [6-7]
- Rapidly evolving motor deficit (thenar weakness/paralysis)
- Tense swelling of the volar forearm → forearm compartment syndrome
- Open wound with visible nerve transection (neurotmesis)
- Vascular compromise (absent radial pulse, pallor, cool digits)
- Carpal tunnel pressure >40 mmHg on wick catheter measurement [6]
- Complete loss of two-point discrimination (>15 mm) in median nerve distribution [6]
3. Medications
- Acute pain management: NSAIDs (ibuprofen 400–600 mg q6h, ketorolac 15–30 mg IV), acetaminophen
- Neuropathic pain (if persistent): first-line agents include gabapentin (300–1200 mg TID), pregabalin (75–300 mg BID), duloxetine (60 mg daily), or amitriptyline (10–75 mg nightly) [8-9]
- Topical lidocaine 5% patches or capsaicin for localized neuropathic pain [9-10]
- Avoid: tight circumferential casts/splints that may worsen compression; opioids are not recommended as first-line for neuropathic pain [9]
- Anticoagulants and antiplatelet agents may increase hematoma risk contributing to nerve compression
4. Diet
- No specific dietary modifications for acute median nerve injury
- Adequate protein intake and micronutrient support (B vitamins, particularly B12) may support nerve regeneration
- Hydration and nutrition optimization in trauma patients
5. Review of Systems
- Neurologic: numbness, tingling, weakness in other extremities (brachial plexopathy, cervical radiculopathy)
- Vascular: cold digits, color changes, absent pulses
- Musculoskeletal: associated fractures, joint instability, tendon injuries
- Endocrine: diabetes, hypothyroidism (predispose to neuropathy) [11-12]
- Rheumatologic: inflammatory arthritis, connective tissue disease
- Constitutional: fever, weight loss (if considering neoplastic compression)
6. Collateral History and Family History
- Witnesses to mechanism (penetrating vs. blunt, degree of force)
- Occupational exposures: repetitive use, vibration, compression [13]
- Family history of hereditary neuropathy with liability to pressure palsies (HNPP) — increases susceptibility to nerve injury from minor trauma [14]
- History of diabetes or metabolic conditions in family
7. Risk Factors
- Distal radius fractures — ACTS occurs in ~4% of cases; volar plate fixation increases risk [11]
- Lunate/perilunate dislocations — 25% incidence of acute median neuropathy [15]
- Penetrating trauma (lacerations, glass injuries) — most common cause of complete nerve transection [3]
- Iatrogenic injury (surgery, phlebotomy, casting in palmar flexion) — most common etiology in proximal median nerve injuries (48.4%) [1]
- Prolonged immobilization in wrist flexion (Cotton-Loder position) [7]
- Diabetes, obesity, hypothyroidism, pregnancy [11-12]
- Anticoagulation (hematoma-related compression)
8. Differential Diagnosis
- Acute carpal tunnel syndrome vs. median nerve contusion/neurapraxia — distinguished by progressive vs. immediate/nonprogressive symptoms [6-7]
- Cervical radiculopathy (C6–C7): neck pain, dermatomal distribution, reflex changes [16]
- Brachial plexopathy (upper/middle trunk): broader motor/sensory deficits
- Anterior interosseous nerve syndrome: pure motor, no sensory loss, inability to make "OK" sign [5]
- Pronator syndrome: forearm pain with median nerve sensory changes [5][17]
- Forearm compartment syndrome: tense swelling, pain with passive extension
- Tendon laceration (FPL, FDS, FDP): mimics motor loss but sensation intact
- Complex regional pain syndrome (CRPS): may develop after nerve injury [18]
- Peripheral polyneuropathy: symmetric, length-dependent, bilateral [9]
9. Past Medical History
- Prior carpal tunnel syndrome or median nerve surgery
- Diabetes mellitus (increases susceptibility and impairs recovery)
- Previous wrist/forearm fractures or dislocations
- Rheumatoid arthritis, gout (space-occupying lesions in carpal tunnel)
- Thyroid disease, renal failure, amyloidosis
- Pregnancy (third trimester CTS) [11]
- Hereditary neuropathy with liability to pressure palsies
10. Physical Exam
- Inspection: wound (laceration, open fracture), swelling, thenar atrophy (chronic), deformity
- Sensory testing: light touch and two-point discrimination in median nerve distribution (thumb, index, middle, radial ring finger); compare to ulnar territory
- Motor testing:
- Thumb opposition (opponens pollicis) — ask patient to touch thumb to small finger
- Thumb abduction against resistance (abductor pollicis brevis) — most reliable isolated median motor test
- "OK" sign (FPL + FDP to index) — tests anterior interosseous nerve [5]
- Grip strength
- Provocative tests (more relevant for entrapment): Tinel sign (50% sensitivity), Phalen test (68% sensitivity), Durkan compression test (64% sensitivity) [12]
- Vascular exam: radial and ulnar pulses, Allen test, capillary refill
- Compartment assessment: forearm firmness, pain with passive finger extension
- Cervical spine: rule out radiculopathy if mechanism unclear
11. Lab Studies
- Routine trauma labs: CBC, BMP, coagulation studies (if surgical candidate)
- Type and screen if operative intervention anticipated
- Glucose/HbA1c: screen for diabetes (affects prognosis) [12]
- TSH: if hypothyroidism suspected
- B12 with methylmalonic acid: if concurrent polyneuropathy suspected [9]
- ESR/CRP: if inflammatory or infectious etiology considered
- Labs are generally low yield in isolated acute traumatic median nerve injury
12. Imaging
- X-ray (wrist/forearm): first-line to evaluate for fracture, dislocation (distal radius, lunate/perilunate) [7][15]
- CT: for complex fracture characterization, intra-articular involvement
- Ultrasound: point-of-care assessment of nerve continuity, hematoma, foreign body; can identify neuroma, increased cross-sectional area [1][5][12]
- MRI/MR neurography: gold standard for soft tissue detail; identifies nerve discontinuity, denervation edema in muscles, space-occupying lesions; indicated for severe weakness or multiple nerve involvement [5][19]
- Imaging should be performed immediately if severe weakness or multiple nerve involvement is present [5]
13. Special Tests
- Electrodiagnostic studies (NCS/EMG): gold standard for diagnosis, severity grading, and prognosis [5][20-21]
- Optimally performed 3–4 weeks post-injury when Wallerian degeneration is complete and fibrillation potentials become evident [20][22]
- Early studies (within first week) can still provide useful baseline information, including conduction block and pre-existing lesions [20]
- Serial EMG monitors for reinnervation (nascent motor unit potentials) [22]
- Wick catheter pressure measurement: carpal tunnel pressure >40 mmHg supports ACTS diagnosis [6]
- Two-point discrimination testing: >15 mm indicates significant sensory loss [6]
- Semmes-Weinstein monofilament testing: quantitative sensory assessment
The following figure illustrates the temporal evolution of electrodiagnostic findings after acute nerve injury, demonstrating why EMG has limited utility immediately post-injury but becomes progressively more informative over weeks to months:
14. ECG
- Not routinely indicated for isolated median nerve injury
- Obtain if considering tricyclic antidepressants for neuropathic pain (QTc prolongation, conduction abnormalities) [10]
- Baseline ECG before surgery if indicated by patient comorbidities
15. Assessment
Acute median nerve injury severity is classified using the Seddon classification: [2][5]
- Neurapraxia (Sunderland Grade I): demyelination only, axon intact; conduction block at injury site; full recovery expected in days to weeks
- Axonotmesis (Sunderland Grades II–III): axonal disruption with preserved connective tissue framework; Wallerian degeneration occurs distally; recovery possible but slow (~1 mm/day axonal regrowth); may take months to years
- Neurotmesis (Sunderland Grades IV–V): complete nerve disruption including connective tissue; no spontaneous recovery; requires surgical repair [2][5][23]
Key clinical distinction: In ACTS, patients have initially normal sensation that progressively worsens with severe pain, whereas nerve contusion presents with immediate, nonprogressive sensory loss. [6]
16. Treatment Plan
Initial stabilization
- Wound care, hemostasis, tetanus prophylaxis for open injuries
- Fracture/dislocation reduction — urgent closed reduction for distal radius fractures and lunate/perilunate dislocations [7][15]
- Splinting in neutral wrist position (avoid palmar flexion, which increases carpal tunnel pressure) [7]
- Remove constrictive dressings/casts if symptoms worsen
Surgical indications
- ACTS: emergent carpal tunnel release — decompression within 40 hours of symptom onset yields best outcomes (normal two-point discrimination within 96 hours in 80% of patients) [6]
- Sharp laceration/neurotmesis: primary microsurgical epineurial repair, ideally within 72 hours; tension-free repair is the gold standard [2][4][23]
- Nerve gap: nerve autograft (sural nerve most common donor) or bioengineered conduit for gaps <3 cm [2-3]
- Closed injury without recovery: if no clinical or electrophysiologic improvement by 3–4 months, surgical exploration with intraoperative nerve action potential (NAP) recording to guide neurolysis vs. graft repair [3][5][20]
Outcomes of surgical repair (30-year series): neurolysis achieved ≥Grade 3 functional recovery in 95%, suture repair in 86–91%, and graft repair in 68–75%. [3]
Conservative management (neurapraxia/contusion)
- Observation with serial clinical exams
- Splinting in neutral position
- Physical/occupational therapy for range of motion and sensory re-education
- Neuropathic pain management as above [5]
17. Disposition
- Admit: ACTS requiring emergent decompression, open nerve laceration requiring surgical repair, polytrauma, associated vascular injury, compartment syndrome
- Observation: progressive symptoms post-reduction, borderline compartment pressures
- Discharge: stable neurapraxia/contusion with nonprogressive symptoms, closed injury with intact vascular status, reliable follow-up
- Consult hand surgery/microsurgery: all suspected nerve lacerations, ACTS, complete motor/sensory loss, no improvement at 3–4 months [3][5][12]
18. Follow Up / Return Precautions
- Follow-up timing: 48–72 hours for re-evaluation after reduction/splinting; 1–2 weeks for wound check; 3–4 weeks for initial electrodiagnostic studies [20][22]
- Serial EMG: at 3–4 months to assess for reinnervation; absence of recovery by this point warrants surgical referral [5][20]
- Critical window: nerve transfers and reconstruction should ideally occur within 6 months of injury before irreversible motor endplate degeneration [4][20]
Return precautions — instruct patients to return immediately for:
- Worsening numbness or tingling in the thumb, index, or middle fingers
- Increasing pain despite treatment, especially under a cast or splint
- New weakness in the hand (difficulty gripping, pinching)
- Color change, swelling, or coldness of fingers
- Fever, wound drainage, or signs of infection
Expected recovery
- Neurapraxia: days to weeks for full recovery [5]
- Axonotmesis: months to years; axonal regrowth at ~1 mm/day from injury site to target muscle [2][22]
- Neurotmesis: surgical repair required; only ~50% of patients achieve full functional recovery even with microsurgical repair [23]
References
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2. Bioengineered Nerve Conduits and Wraps for Peripheral Nerve Repair of the Upper Limb. — Thomson SE, Ng NY, Riehle MO, et al. The Cochrane Database of Systematic Reviews. 2022.
3. Surgical Management and Outcomes in Patients With Median Nerve Lesions. — Kim DH, Kam AC, Chandika P, Tiel RL, Kline DG. Journal of Neurosurgery. 2001.
4. Median Nerve Injury and Repair. — Pederson WC. The Journal of Hand Surgery. 2014.
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6. Acute Median Neuropathy After Wrist Trauma. The Role of Emergent Carpal Tunnel Release. — Mack GR, McPherson SA, Lutz RB. Clinical Orthopaedics and Related Research. 1994.
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14. Peripheral Neuropathy. — England JD, Asbury AK. Lancet. 2004.
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16. Carpal Tunnel Syndrome: Clinical Features, Diagnosis, and Management. — Padua L, Coraci D, Erra C, et al. The Lancet. Neurology. 2016.
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18. Complex Regional Pain Syndrome: Advances in Epidemiology, Pathophysiology, Diagnosis, and Treatment. — Ferraro MC, O'Connell NE, Sommer C, et al. The Lancet. Neurology. 2024.
19. Magnetic Resonance Neurography of Traumatic Pediatric Peripheral Nerve Injury: Beyond Birth-Related Brachial Palsy. — Deshmukh SD, Samet J, Fayad LM, Ahlawat S. Pediatric Radiology. 2019.
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21. Interpreting Electrodiagnostic Studies for the Management of Nerve Injury. — Pripotnev S, Bucelli RC, Patterson JMM, et al. The Journal of Hand Surgery. 2022.
22. Assessment, management, and rehabilitation of traumatic peripheral nerve injuries for non‐surgeons. — Bateman EA, Pripotnev S, Larocerie-Salgado J, Ross DC, Miller TA. Muscle & Nerve. 2025.
23. Peripheral Nerve Injury and Repair. — Lee SK, Wolfe SW. The Journal of the American Academy of Orthopaedic Surgeons. 2000.