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)