Brachial Plexus Palsy (Perinatal)
- 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 flaccid upper extremity paralysis caused by traction injury of the brachial plexus during birth.
- It can produce a proximal stretch, avulsion, or rupture type injury. Classifications are as follows:
|Common Terminology||Affected Nerve Roots||Paralysis|
|Erb palsy (type I)||C5–C6||Bicep and deltoid|
|Extended Erb (type II)||C5–C7||Same + triceps and wrist extensor (wrist flexion = waiter’s tip)|
|Pan plexus (type III)||C5–T1||Entire limb (flail arm)|
|Pan plexus with Horner syndrome (type IV)||C5–T1 and sympathetic chain||Flail arm + Horner syndrome (ptosis, miosis, and anhidrosis)|
- 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.
- 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.
- 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.
- Seddon and Sunderland have described classification systems to describe degree of injury.
- Mildest form, interruption of conduction
- The myelin sheath is disrupted, but the axons and surrounding connective tissue remain intact.
- Good recovery
- The myelin sheath and the axon are both interrupted and the surrounding connective tissue remain undamaged.
- Most severe
- There is a complete disruption of the myelin sheath, axon, and surrounding connective tissue (epineurium and perineurium).
- Nerve may be grossly intact; recovery difficult to predict
- Lesions also can be classified according to their relation to the dorsal root ganglion (preganglionic or postganglionic).
- Preganglionic lesions occur proximal to the dorsal root ganglion and involve avulsion from the spinal cord. Implementation of nerve transfer is usually a better strategy for these lesions.
- Downward mechanical force on the shoulder during delivery can lead to stepwise stretch injury, resulting in either transient or permanent damage or total avulsion of nerve roots.
- Upward mechanical force (i.e., after face delivery) is less frequent and leads to isolated lower plexus palsy (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.
Commonly Associated Conditions
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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