Brachial Plexus Injuries

Epidemiology

  • Rule of 7, 70’s
    1. 70% caused by RTA
    2. 70% RTA’s involve bike or motorcycle
    3. 70% of these have multiple injuries
    4. 70% supraclavicular
    5. 70% of these have at least one root avulsion
    6. 70% with root avulsion have avulsion of lower roots (C7-T1)
    7. 70% with lower root injuries have persistent pain

Anatomy & Injury Classification

  • Plexus formed from the C5-T1 roots
  • 30% have contribution from C4 - Prefixed Plexus
  • 30% have contribution from T2 - Post fixed plexus

Roots
- Lie between scaleneus anterior and medius
- Roots are formed by the Dorsal (sensory) roots and Ventral (motor) roots
- Dorsal root ganglion contains only sensory rootlet cell bodies
- Motor cell bodies are within the cord

Pre-ganglionic Injuries
- Proximal to the dorsal root ganglion
- Central Root avulsions (avulsion directly from the cord)
- Intra-dural root avulsions (outside cord but before DRG)
- Poor prognosis for recovery

Postganglionic injuries
- Distal to the dorsal root ganglion
- Better prognosis

Trunks
- Within the posterior triangle of the neck
- C5 & 6 merge > Upper trunk
- Point at which they merge is called ERB’s point
- ERB’s point is where the Suprascapular nerve forms
- C7 > middle trunk
- C8 & T1 > Lower trunk

Divisions
- Trunks divide into Anterior & Posterior divisions below the clavicle
- Posterior divisions form the Posterior cord
- Anterior divisions of the upper and middle trunks form Lateral Cord
- Anterior division of the Lower trunk forms the medial cord

Cords
- Lateral cord ends in the MCN nerve and part of median nerve
- Posterior cord ends as the Axiliary and Radial nerves
- Medial cord ends as the Ulna nerve and the median nerve contribution
- Hence the median nerve is formed by the Lateral and Medial cords

Smaller Branches
- C5 Root
- Phrenic nerve branch
- Long thoracic
- Dorsal Scapular nerve
- Nerve to subclavius
- C6 Root
- Long Thoracic nerve
- C7 Root
- Long Thoracic nerve
- Upper Trunk
- Suprascapular
- Lateral Cord
- Lateral Pectoral nerve (Clavicular head of Pec major)
- Posterior Cord
- Upper Subscapular
- Thoracodorsal
- Lower Subscapular
- Medial Cord
- Medial Pectoral (Sternal head of Pec Major)
- Medial Antibrachial cutaneous
- Medial Brachial cutaneous

Lower Cervical Sympathetic Ganglion

  • Very close to the T1 root > avulsion can cause a Horner’s syndrome
    • Partial Ptosis, Meiosis (Small pupil), Enopthalmos, Anhydrosis

Examination

  • Important to establish if pre or post ganglionic injury for prognosis
  • Which roots (preganglionic)/Trunks affected
  • Individual Muscle Groups
  • Are other important structures involved?
    • Brachial artery
    • Spinal accessory nerve (trapezius) - often needed for nerve grafting
    • Eyes? Horner’s Syndrome

Radiography

  • XR
    • C spine, shoulder, and chest
    • C spine transverse fracture indicates possible root avulsion
    • Clavicle and 1st or 2nd rib fractures may result in plexus injury
    • Diaphragm elevation indicates C5 root injury (phrenic nerve)
  • CT Myelogram
    • Used to diagnose root avulsion - is gold standard for this purpose
    • Best done at 3 weeks onwards
  • MRI
    • Can be done early
    • Identifies mass lesions in non-traumatic plexopathy
  • NCS/EMG
    • Useful for:
      • Localizing injury
      • Assessing recovery
    • Pre vs post ganglionic assessed by testing root level muscles

Management Concepts

  • Always ATLS approach
  • Treat life-threatening injuries first

Surgical Treatment Methods
- Neurolysis
- Nerve repair
- Nerve grafting
- Nerve transfer
- Tendon transfer
- Joint Fusion

Prioritization of Functional Restoration
1. Elbow flexion
2. Shoulder abduction
3. Shoulder stability
4. Hand sensibility
5. Wrist Extension & Finger flexion
6. Wrist Flexion & Finger Extension
7. Intrinsic function

Primary Immediate or Early Surgery
- Direct repair
- Neurolysis
- Nerve Grafting
- Nerve Transfer (Neurotization)

Secondary (Salvage) Procedures – Late Surgery
- Tendon transfer
- Free muscle transfer
- Fusion/Osteotomy
- Amputation (for flail arm)

A Typical Salvage Regime Might Include:
- Fuse Shoulder
- Transfer Pec Major or Lat Dorsi to biceps for elbow flexion
- Transfer medial epicondyle to anterior humerus – restores flexion
- Transfer Lat Dorsi to Infraspinatus (L’Esposito)

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