Complete Brachial Plexus Palsy
Weakness involving the whole arm (Figure 215.1) is the initial presentation in most neonates with brachial plexus injury. Most neonates with total arm monoparesis immediately after a brachial plexus trauma will later develop a segmental syndrome. Neonates with transient weakness of the whole arm usually begin to improve within one week of the injury.

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Figure 215.1.— [A] Total brachial plexus palsy with thumb amputation and cutaneous scars in the shoulder areas. [B] Left Horner syndrome. The mother had chickenpox during pregnancy.

Complete brachial plexus palsy may be associated with Horner syndrome (Figure 215.1), sympathetic arm abnormality or facial nerve palsy. Tongue weakenss has also been reported. The presence of Horner syndrome in a neonate with flacid arm weakness localizes the lesion to the brachial plexus. The presence of total flaccid arm monoparesis and ipsilateral facial weakness raises the possibility of an upper motor neuron lesion. Neonates with total flaccid arm monoparesis and ipsilateral, predominantly lower quadrant facial weakness should probably have an MRI of the brain because of the possibility of a central nervous system lesion. Neonates with total arm monoparesis and contralateral lower quadrant facial weakness are likely to have a facial nerve branch injury in conjunction with a brachial plexus lesion. Neonates with total arm monoparesis and encephalopathy, seizures, or gaze preference should undergo MRI of the brain because of the possibility of a central nervous system lesion. Sympathetic arm abnormalites lead to lighter skin color and colder arm (Figure 215.2).

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Figure 215.2.— [A] Total left brachial plexus palsy. [B] Infrared photograph demostrating hot right arm and cold left arm.

Peripheral nerve lesions are unlikely to produce total arm weakness. Nevertheless, the possibility of a circular amniotic band high in the arm should always be considered in a neonate with total arm monoparesis and every skin fold in the arm should be scrutinized for this possibility. A circular amniotic band may compress the musculocutaneous, radial, ulnar, and medial nerves and produce clinical findings similar to those of a complete brachial plexus palsy but without involvement of brachial plexus proximal nerves.