Adult Brachial Plexus Injury — Comprehensive Review

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1. ANATOMY

• Supraclavicular = roots + trunks (higher energy, worse prognosis)
• Infraclavicular = divisions + cords + branches

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2. CLASSIFICATION OF NERVE INJURY

2A. Seddon Classification (3 classes)

2B. Sunderland Classification (5 degrees) — More granular

Key concept: Axon regenerates at ~1 mm/day (≈1 inch/month). Motor endplates degenerate irreversibly at 12–18 months → creates a surgical deadline for motor recovery.

2C. Topographic Classification

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3. MECHANISMS AND COMMON INJURY PATTERNS

• Motorcycle/motor vehicle accidents (most common — violent traction)
• Penetrating trauma (stab, GSW, iatrogenic)
• Stretch injuries ("burners/stingers" in athletes)
• Scapulothoracic dissociation

• C5–C6 (upper trunk): 15%
• C5–C7: 20–35%
• C8–T1 (lower trunk): 10%
• Pan-plexus (complete): 50–75% in high-energy trauma

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4. SIGNS & SYMPTOMS

4A. Upper Plexus Injury — Erb's Palsy (C5–C6)

• "Waiter's tip" posture: arm adducted, internally rotated, elbow extended, forearm pronated
• Loss of: shoulder abduction/external rotation, elbow flexion, forearm supination
• Sensory loss: lateral arm, forearm, thumb
• Deltoid, biceps, brachioradialis, supraspinatus, infraspinatus weakness

4B. Middle Trunk (C7)

• Weak wrist/finger extension
• Triceps weakness
• Sensory loss: middle finger

4C. Lower Plexus Injury — Klumpke's Palsy (C8–T1)

• Clawing of the hand (intrinsic minus)
• Loss of: hand grip, intrinsic hand muscles, wrist/finger flexors
• Sensory loss: medial forearm and hand (ulnar distribution)
• Horner syndrome if T1 preganglionic (ptosis, miosis, anhidrosis, enophthalmos)

4D. Pan-Plexus Injury (C5–T1)

• Flail, anesthetic upper limb
• Complete motor paralysis shoulder → hand
• Pain is common (especially with root avulsions — neuropathic/deafferentation pain)

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5. SIGNS OF PREGANGLIONIC INJURY (Root Avulsion)

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6. CLINICAL EXAMINATION

History

• Mechanism (high vs. low energy)
• Associated injuries (vascular — axillary/subclavian; fractures — clavicle, scapula, rib, cervical spine; pneumothorax)
• Time from injury
• Dominant hand, occupation, patient age

Physical Examination — Systematic Approach

• Posture of arm (Erb's tip vs. clawing)
• Muscle wasting (particularly deltoid, thenar, hypothenar)
• Scapular winging

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7. INVESTIGATIONS & EVALUATION

Imaging

• Cervical spine: transverse process fractures → suggest root avulsion
• Chest PA + lateral: hemidiaphragm elevation → phrenic nerve injury
• Inspiratory/expiratory CXR: paradoxical diaphragm movement
• Shoulder + clavicle: fractures, scapulothoracic dissociation

• Demonstrates pseudomeningocele at avulsed root sleeve
• Detects intradural root injury
• Still preferred over MRI in many centres for avulsion

• Demonstrates: peripheral neuroma, pseudomeningocele, nerve edema (STIR hyperintensity), fascicular discontinuity
• Differentiates preganglionic vs. postganglionic injury
• Preferred for infraclavicular lesions and cord/branch-level injury

Electrodiagnostics

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8. TREATMENT

8A. Decision Framework

INJURY
  ├── Penetrating / sharp laceration → Immediate exploration (within 72 hours)
  ├── Vascular injury requiring repair → Simultaneous nerve exploration
  ├── Progressive neurologic deficit → Urgent surgery
  ├── Closed traction injury
  │     ├── High-energy + complete → Surgery 3–12 weeks
  │     ├── Low-energy + incomplete → Observe 3 months; surgery if plateau
  │     └── Gunshot wound → Observe; most recover without surgery
  └── Beyond 6 months → Less predictable nerve repair outcome

• Early: <3 days — sharp transection, vascular compression
• Subacute: ~3 weeks — ragged lacerations (propeller, chainsaw)
• Delayed: 3–6 months — closed injuries with no recovery
• Late: >1 year — tendon/muscle transfer (nerve repair no longer viable)

1. Elbow flexion (most functionally critical)
2. Shoulder stability and abduction/external rotation
3. Wrist/finger flexion (hand sensation)
4. Finger extension
5. Hand intrinsics (last priority, poorest outcome)

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8B. NEURORRHAPHY (Primary Nerve Repair)

1. Preparation: Debride nerve ends sequentially until healthy, bleeding fascicles appear (no gap, no tension)
2. Alignment: Align epineurial blood vessels as topographic landmarks
3. Epineural repair: 8-0, 9-0, or 10-0 monofilament nylon interrupted sutures through epineurium — most common technique
4. Grouped fascicular repair: Additional internal epineurial sutures between identifiable fascicular groups — reserved for large nerves with clear fascicular topography
5. Tension-free: Critical; tension causes ischemia, scarring, failed regeneration

• Sharp laceration with minimal zone of injury
• Short gap after neuroma-in-continuity resection
• Must be tension-free

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8C. NERVE GRAFTING (Cable/Interpositional Graft)

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8D. NEUROTIZATION (Nerve Transfer)

• Coaptation is closer to target muscle → shorter regeneration distance → faster recovery
• Distal nerve contains purer motor or sensory fascicles
• Essential when no proximal stump exists (avulsion)

1. Intraplexal (intra-extraplexal) — donor from within the plexus
2. Extraplexal — donor from entirely outside the plexus (cranial nerves, intercostals, phrenic, contralateral C7)

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KEY NEUROTIZATION PROCEDURES

• Donor: Ulnar nerve fascicle to FCU (± median nerve fascicle to FDS)
• Recipient: Musculocutaneous nerve → biceps motor branch (± brachialis branch)
• Purpose: Elbow flexion
• Approach: Medial arm incision
• Outcome: ~90% M3+ biceps recovery; gold standard for C5–C6 injury

• Purpose: Shoulder abduction + external rotation
• Donor: Descending branch of CN XI (spinal accessory)
• Recipient: Suprascapular nerve
• Outcome: ~70% regain useful shoulder abduction (MRC ≥3)
• Can be performed via dorsal (posterior) or anterior approach

• Donor: Motor branch of radial nerve to long/medial head of triceps
• Recipient: Axillary nerve (anterior branch → deltoid)
• Purpose: Shoulder abduction and forward elevation
• Triceps function is maintained because redundant branches are used

• Donor: 3rd–5th intercostal nerves (motor branches)
• Recipient: Musculocutaneous nerve (elbow flexion) or nerve to chest free muscle flap
• Purpose: Elbow flexion; useful when ulnar/median nerve not available
• Requires patient to practice breathing movements to activate biceps initially
• Can provide 3–4 intercostal nerves; each contributes ~1,000–1,500 motor axons

• Donor: Phrenic nerve (C3–C5)
• Recipient: Suprascapular nerve or musculocutaneous nerve
• Purpose: Shoulder/elbow function in pan-avulsion
• Caution: Assess pulmonary function first; sacrifice causes hemidiaphragm paralysis

• Donor: Contralateral C7 root (entire or posterior division)
• Recipient: Injured plexus (via sural nerve graft tunneled across midline)
• Purpose: Pan-plexus avulsion — restore wrist/finger flexion or extension
• Most axon-rich transfer (>18,000 axons in C7)
• Transient ipsilateral donor-side deficits; usually recover within months
• Used in total avulsion when no ipsilateral donors available

• For late presentations (>12–18 months) when target muscles are fibrotic
• Gracilis muscle most commonly used
• Transferred with its vascular pedicle (anastomosed to thoracodorsal or serratus vessels)
• Neurotized directly by donor nerve (intercostal, spinal accessory, contralateral C7)
• Restores elbow flexion or finger flexion in selected cases

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Summary Table — Common Nerve Transfers

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8E. NEUROLYSIS

• External neurolysis: Release of nerve from surrounding scar tissue; preserves internal architecture
• Internal neurolysis: Separation of fascicles within nerve; controversial — may increase intraneural scarring
• Indication: Neuroma-in-continuity with positive intraoperative NAP (viable axons crossing) → neurolysis only; do not resect

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8F. TENDON AND MUSCLE TRANSFERS

• Elbow flexion: Latissimus dorsi/pectoralis minor transfer, Steindler flexorplasty, free gracilis FFMT
• Shoulder stabilization: Trapezius transfer, glenohumeral fusion (arthrodesis)
• Wrist extension: BR to ECRB; ECU to ECRB
• Isolated C8–T1 injury: early tendon transfers preferred (too distal for nerve repair to succeed in time)

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9. INVESTIGATION–GUIDED DECISION PATHWAY

Supraclavicular injury
  ↓
EMG/NCS at 4–6 weeks (baseline)
  ↓
Horner's + paraspinal denervation + normal SNAPs
  → Preganglionic avulsion
  → CT myelography / MRI for pseudomeningocele
  → Nerve transfer (neurotization) — no direct repair possible
  ↓
No signs of avulsion + recovery plateau at 3 months
  → Explore; intraoperative NAP
     ├── NAP positive → Neurolysis
     └── NAP negative → Resect + Cable graft / Nerve transfer

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10. REHABILITATION & POST-OPERATIVE PROTOCOLS

10A. Pre-Operative Rehabilitation

• Goal: Prevent contractures, maintain passive ROM, protect denervated skin
• Gentle passive ROM exercises for all joints from day 1
• Resting splints in functional position (wrist neutral, MCP 70° flexion, IP extended)
• Patient and family education on skin protection (denervated skin insensate to heat/pressure)
• Pain management: gabapentin/pregabalin for neuropathic pain

10B. Acute Post-Operative Phase (0–6 weeks)

• Immobilization for 3 weeks in position of least tension (shoulder in slight adduction; elbow at ~90° flexion if upper plexus)
• Gradual mobilization from week 3 (avoid sudden passive stretching)
• Edema management: compression garments, elevation
• Wound care and scar management after 6 weeks

• Similar immobilization to direct repair
• No neuromuscular re-education needed in initial phase
• Focus on passive ROM maintenance

• Immobilization typically minimal (coaptation under no tension)
• Crucial difference: The patient must learn to use a new cortical movement pattern to activate the donor nerve
• E.g., after Oberlin transfer, patient must squeeze hand (ulnar activation) to contract biceps initially

10C. Regeneration Phase (6 weeks – 6 months)

• Serial clinical examinations every 6–8 weeks tracking advancing Tinel sign
• EMG monitoring at 3, 6, 9, 12 months
• Gravity-eliminated active-assisted ROM when first voluntary contraction detected
• Progressive gravity-resisted strengthening once MRC grade 2 achieved
• Neuromuscular re-education:
  • Biofeedback EMG: Electrode on target muscle; audio/visual feedback for activation
  • NMES (Neuromuscular electrical stimulation): Activate weakly recovering muscle; may enhance motor end plate maintenance
  • Mental imagery and cortical remapping (especially after nerve transfer)

10D. Motor Re-Education for Nerve Transfers

10E. Recovery Phase (6–18 months)

• Progressive resistance training
• Functional bimanual activities (occupational therapy)
• Work hardening / vocational rehabilitation
• Upper limb prosthetics assessment if reconstruction fails
• Splints tailored to residual deficits (cock-up wrist splint for wrist drop, dynamic MCP extension splint for intrinsic minus hand)

10F. Pain Management (Ongoing)

• First-line: Gabapentin, pregabalin, amitriptyline
• Opioids: short-term, titrated
• TENS (transcutaneous electrical nerve stimulation)
• DREZ (dorsal root entry zone) lesioning: surgical last resort for intractable avulsion pain

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11. PROGNOSIS

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Quick Summary Chart

ADULT BRACHIAL PLEXUS INJURY
│
├── CLASSIFY
│   ├── Seddon: Neurapraxia / Axonotmesis / Neurotmesis
│   ├── Sunderland: Grades I–VI
│   └── Location: Pre/postganglionic; Supra/infraclavicular
│
├── DIAGNOSE
│   ├── Clinical: Motor/sensory mapping, Horner, Tinel, reflexes
│   ├── Imaging: CXR, CT myelography (avulsion), MR neurography
│   └── EDX: EMG + NCS + SSEPs at 4–6 weeks
│
├── TREAT (Timing-driven)
│   ├── <72 hrs: Sharp transection → Neurorrhaphy
│   ├── 3–12 weeks: High-energy closed → Exploration + NAP-guided resection + Graft
│   ├── 3–6 months: Plateau → Nerve transfer / neurotization
│   └── >12 months: Tendon/muscle transfer; FFMT
│
└── REHABILITATE
    ├── Pre-op: ROM, splinting, education
    ├── Post-op 0–6 wks: Immobilize, edema control, passive ROM
    ├── 6 wks–6 months: Biofeedback, NMES, cortical re-education
    └── 6–18 months: Strengthening, functional training, vocational rehab

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