Erb-Duchenne Palsy

Snapshot

• A G1P1 woman gives birth to a boy at 41 weeks gestational age via vaginal delivery. Labor was prolonged due to shoulder dystocia which required a forceps delivery. The child’s APGAR scores were 8 and 9 at 1 and 5 minutes, respectively. The child’s weight at birth is 9 pounds 8 ounces. On exam, the baby’s left upper extremity is notable for arm adduction, elbow extension, and forearm pronation. 

Introduction

• Clinical definition
  • lesion in the upper trunk (C5-C6) of the brachial plexus leading to the characteristic “waiter’s tip” deformity 
• Epidemiology
  • incidence
    • most common neonatal brachial plexus palsy
    • approximately 1 per 1000 live births
  • risk factors
    • obstetric
      • large for gestational age
      • shoulder dystocia
      • forceps delivery
      • breech presentation
      • prolonged labor
• Etiology
  • excess traction on head away from the ipsilateral shoulder
    • this motion puts tension on the upper trunk of the brachial plexus
  • common clinical scenarios
    • obstetric complication
      • traction on head away from the shoulder during a difficult delivery (e.g., shoulder dystocia)
    • trauma
      • falling on the shoulder with head bent away from the affected shoulder
• Pathoanatomy
  • normal anatomy
    • brachial plexus diagram 
    • upper trunk of brachial plexus 
      • C5 and C6 nerve roots 
      • important nerve branches and the muscles they innervate
        • axillary nerve
          • deltoid
          • teres minor
        • musculocutaneous nerve
          • biceps brachialis
          • brachialis
          • coracobrachialis
        • suprascapular nerve
          • infraspinatus
          • supraspinatus
  • injury anatomy
    • lesion in the upper trunk will weaken muscles innervated by the axillary, musculocutaneous, and suprascapular nerves resulting in weak
      • arm abduction
        • deltoid
        • supraspinatus
      • arm external rotation
        • teres minor
        • infraspinatus
      • forearm supination
        • biceps brachialis
      • forearm flexion
        • biceps brachialis
        • brachialis
• Associated conditions
  • clavicle fracture
  • humerus fracture
  • shoulder dislocation
• Prognosis
  • unfavorable
    • concomitant Horner syndrome
    • C7 involvement
• cord avulsion

Presentation

• Symptoms
  • infant unable to move affected upper extremity
• Physical exam
  • “waiter’s tip” deformity
    • arm is adducted
      • abductor weakness
        • deltoid and supraspinatous are strong abductors at the shoulder
    • arm is internally rotated
      • external rotator weakness
        • infraspinatus and teres minor are external rotators 
    • forearm is pronated
      • supination weakness
        • biceps brachialis is a strong supinator of the forearm
    • elbow is extended
      • flexion weakness
• biceps brachialis and brachialis are strong flexors at the elbow

Imaging

• Radiographs
  • indication
    • radiographs are not routinely performed unless another diagnosis is being considered
      • fracture
      • dislocation
• Magnetic resonance imaging (MRI)
  • indication
    • MRI is not routinely performed unless another diagnosis is being considered
      • preferred modality to fully characterize the lesion
• preoperative planning

Differential

• Klumpke palsy 
  • distinguishing factors
    • lesion in C8-T1 nerve roots (lower trunk) caused by upward traction of arm
    • presents with “claw hand” due to impaired lumbrical muscles
      • extension of metacarpophalangeal (MCP) joints
      • flexion of proximal and distal interphalangeal joints
• Radial head subluxation 
  • distinguishing factors
    • subluxation of the radial head relative to the radiocapitellar joint
    • occurs in children 2-5 years of age due to excess traction on the arm
• elbow held in slight flexion and pronation

Treatment

• Nonoperative
  • observation and daily passive exercises
    • indications
      • most cases of Erb-Duchenne palsy will resolve with conservative management
• complete recovery may take up to 2 years

Complications

• Joint contracture
• Hemidiaphragm
  • concomitant injury to the phrenic nerve