The term obstetric brachial plexus palsy refers to an injury to all or to a portion of a child's brachial plexus nerve network occurring at the time of delivery.

Injuries to the brachial plexus during childbirth are usually the result of excessive lateral traction on the head so that the head is pulled away from the shoulder. This force produces four distinct types of nerve injuries: an avulsion, a rupture, a neuroma and a neuropraxia.

An avulsion is the most severe form of injury, where the nerve root actually gets torn away from the spinal cord. In a nerve rupture, the nerve is torn but not at the level of the spinal cord. In a neuroma, the nerve has torn and healed but the scar tissue exerts pressure on the nerve and prevents it from properly conducting nerve signals to the muscles. Neuropraxia or stretch occurs when a nerve has been damaged but not torn. Of the four types of nerve injuries, neuropraxia is the most common form of brachial plexus injury.

The following conditions are known risk factors for obstetric brachial plexus palsy:

    • Cephalopelvic disproportion - a condition in which there is a disproportion between the size of the fetal head and the maternal pelvis such that the maternal pelvis is inadequate for passage of the fetal head during delivery.
    • A large or a macrosomic baby (a baby with a birth weight more than 4.0kg).
    • Instrumental delivery (especially from use of forceps during delivery).
    • Breech delivery.
    • Delivery of a premature - a premature baby is one delivered before 37 completed weeks of gestation. They are at an increased risk of developing brachial plexus injuries because of their fragile bodies.
    • Shoulder dystocia.
    • Primigravida - first timers have an untried pelvis and as such, there is a possibility of nerve injury occurring during delivery.
    • Prolonged labour.
    • Congenital anomalies - including hydrocephalus.

Brachial plexus injuries during childbirth include:

    • Erb-Duchenne Palsy

        This is also less commonly known as obstetric brachial plexus palsy. It involves injury to the 5th, 6th and sometimes the 7th cervical nerve roots. It results in paralysis of the deltoid and infraspinatus muscles as well as the flexor muscles of the forearm. The affected extremity is held straight and internally rotated with the elbow extended and the wrist and fingers flexed. Moro, biceps and radial reflexes are absent on the affected extremity however, grasp reflex remains intact.

    • Klumpke's Palsy

        Klumpke's palsy is rare. It results from injury to the 7th, 8th cervical and 1st thoracic nerve roots. It is characterized by weakness of the intrinsic hand muscles; grasp reflex is absent in the affected extremity. If the cervical sympathetic fibers of the 1st thoracic nerve are involved, Horner syndrome will also be present.

Other conditions may complicate brachial plexus injury and they include:

    • Fracture of the clavicle
    • Fracture of the humerus
    • Subluxation of the cervical spine
    • Cervical cord injury
    • Facial nerve palsy
    • Phrenic nerve palsy

Managing obstetric brachial plexus palsy:

    • Most cases of obstetric brachial plexus injury resolve spontaneously in a little as 4 months or as much as 2 year after delivery.
    • X-rays to exclude fractures and examination for phrenic nerve paresis are important.
    • Other investigations that could be carried out include MRI, electromyography, nerve conduction studies and CT myography.
    • To prevent contractures, the affected arm should be immobilized across the upper abdomen for 7 days after which, physiotherapy using wrist splits should be commenced.
    • Surgery should be considered if movement does not return after 3 months and electrophysiology results indicate a poor prognosis.

brachial plexus injury


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