Birth Trauma: Peripheral Nerve Injury

Brachial plexus injury

Brachial plexus injury occurs most commonly in large babies, frequently with shoulder dystocia or breech delivery. Incidence for brachial plexus injury is 0.5-2.0 per 1000 live births. Most cases are Erb palsy; entire brachial plexus involvement occurs in 10% of cases.

Traumatic lesions associated with brachial plexus injury are fractured clavicle (10%), fractured humerus (10%), subluxation of cervical spine (5%), cervical cord injury (5-10%), and facial palsy (10-20%). Erb palsy (C5-C6) is most common and is associated with lack of shoulder motion. The involved extremity lies adducted, prone, and internally rotated. Moro, biceps, and radial reflexes are absent on the affected side. Grasp reflex is usually present. Five percent of patients have an accompanying (ipsilateral) phrenic nerve paresis.

Klumpke paralysis (C7-8, T1) is rare and results in weakness of the intrinsic muscles of the hand; grasp reflex is absent. If cervical sympathetic fibers of the first thoracic spinal nerve are involved, Horner syndrome is present.

No uniformly accepted guidelines for determining prognosis exist. Narakas developed a classification system (types I-V) based on the severity and extent of the lesion, providing clues to the prognosis in the first 2 months of life. According to the collaborative perinatal study (59 infants), 88% of cases resolved in the first 4 months, 92% resolved by 12 months, and 93% resolved by 48 months. In another study of 28 patients with upper plexus involvement and 38 with total plexus palsy, 92% spontaneously recovered.

Residual long-term deficits may include progressive bony deformities, muscle atrophy, joint contractures, possible impaired growth of the limb, weakness of the shoulder girdle, and/or Erb engram flexion of the elbow accompanied by adduction of shoulder.

Workup consists of radiographic studies of the shoulder and upper arm to rule out bony injury. The chest should be examined to rule out associated phrenic nerve injury. Electromyography (EMG) and nerve conduction studies are occasionally useful. Fast spin-echo MRI can be used to evaluate plexus injuries noninvasively in a relatively short time, minimizing the need for general anesthesia. MRI can define meningoceles and may distinguish between intact nerve roots and pseudomeningoceles (indicative of complete avulsion). Carefully performed, intrathecally enhanced CT myelography may show preganglionic disruption, pseudomeningoceles, and partial nerve root avulsion. CT myelography is more invasive and offers few advantages over MRI.

Management consists of prevention of contractures. Immobilize the limb gently across the abdomen for the first week and then start passive range of motion exercises at all joints of the limb. Use supportive wrist splints. Best results for surgical repair appear to be obtained in the first year of life. Several investigators recommend surgical exploration and grafting if no function is present in the upper roots at 3 months of age, although the recommendation for early explorations is far from universal. Complications of brachial plexus exploration include infection, poor outcome, and burns from the operating microscope. Patients with root avulsion do not do well. Palliative procedures involving tendon transfers have been of some use. Latissimus dorsi and teres major transfers to the rotator cuff have been advocated for improved shoulder function in Erb palsy. One permanent and 3 transitory axillary nerve palsies have been reported from the procedure.

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• Birth Injury - United Cerebral Palsy in Philadelphia

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