Perinatal Brachial Plexus Palsy

Perinatal Brachial Plexus Palsy is a topic covered in the Select 5-Minute Pediatrics Topics.

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Basics

Description

  • The brachial plexus contains sensory and motor nerves to the upper extremities, stemming from the cervical and thoracic spine (commonly C5–T1 roots).
  • The brachial plexus contains a consistent pattern of nerves that innervate predictable muscles and skin regions.
  • Brachial birth palsy is a proximal stretch, avulsion, or rupture type injury and may involve
    • C5–C6 (Erb palsy), most common, best prognosis
    • C5–C7, less common, worse prognosis
    • C5–T1, least common, flail extremity and worst prognosis

Epidemiology

  • There is no predominance of gender, but variations in clinical care, preventive measures, and birth weight may explain estimates of incidence to range from 0.4 to 4 per 1,000 live births.
  • Incidence drops from 0.2% with vaginal delivery to 0.02% after cesarean section as there is a probable mechanical basis for the plexopathy.
  • Erb palsy is the most commonly encountered plexus injury.

Risk Factors

  • Large size for gestational age, multiparity, prolonged labor, breech position, difficult delivery—especially when forceps- or vacuum-assisted
  • Diabetic mothers and/or neonatal birth weight >4.5 kg
  • Although there is no genetic basis per se, previous delivery leading to obstetric palsy is a risk factor.

General Prevention

  • Careful positioning of the upper extremity during childbirth and conversion to cesarean section when necessary
  • Prevention of long-term disability and contracture can be minimized with exercise of the child’s joints and functioning muscles every day beginning at 3 weeks of age.

Pathophysiology

  • Seddon and Sunderland have described classification systems to describe degree of injury.
    • Neuropraxia
      • Mildest form, interruption of conduction, axons continuous
      • Good recovery
    • Axonotmesis
      • Axonal degeneration with loss of axonal continuity
      • Nerve intact. Epineurium and perineurium intact.
    • Neurotmesis
      • Most severe, nerve is completely contused. Axonal discontinuity
      • Nerve may be grossly intact, but epineurium, perineurium, and axons disrupted. Recovery difficult to predict.

Etiology

  • Downward mechanical force on the shoulder during difficult delivery can lead to stepwise stretch injury leading to transient or permanent damage or total avulsion of nerve roots.
  • Upward mechanical force, that is, after face delivery, leads to C8–T1 injury (Klumpke).
  • Avulsion injury carries the worst prognosis, particularly if proximal to the cell body of the motor nerve (preganglionic), as these injuries cannot spontaneously recover.

Associated Injuries

  • Horner syndrome, phrenic nerve injury, and long thoracic nerve injury (winged scapula) may be observed and are associated with preganglionic injury and a poor prognosis.

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