Amniotic bands may involve the brachial plexus although more frequently they affect the peripheral nerves. Physical examination should include separating the skin folds to search for amniotic bands. The possibility of surgical intervention should be considered if there is a conduction block under the amniotic band.

Neonatal hemangiomatosis may be associated with brachial plexus palsy (Figure 256.1). Brachial plexus palsy results from compression of the brachial plexus by a hemangioma.

Figure 265.1.— [A] Large neck, upper thorax, and scalp hemangioma. [B] right brachial plexus palsy.

Brachial plexus palsy is a rare presentation of late-onset group-B streptococcal osteomyelitis of the cervical spine or superior head of the humerus. (Figure 265.2) Evidence of brachial plexus involvement has been documented by electromyographic findings (fibrilations). The mechanism of injury is probably ischemia.Weakness resolves with treatment of the infection.

Figure 265.2.— Abnormal superior head of the right head of the humerus due osteomyelitis.

Exostosis of the first rib is an unusual cause of brachial plexus palsy in the neonatal period. The mechanism of injury is probably compression of the brachial plexus by the bone tumor.

Brachial plexus palsy may result from compression of the brachial plexus at the level of the neck by a positive pressure apparatus.

Brachial plexus palsy may be due to neoplastic involvement of the plexus. In the two reported cases, weakness was noted a few days after birth and had a progressive course. A mass at the level of the neck was present in one patient. The tumor was considered a rhabdomyosarcoma (Figure 265.3) in one patient and a plexiform neuroma in the other.

Figure 265.3.— [A] Large neck mass. [B] MRI of the cervical spine demonstrating a large mass compressing the plexus.

Lesions in the cauda equina region are caused by tumors or spinal dysraphysm. Magnetic resonance imaging is the investigation of choice for this area (Figure 265.4). Spinal cord dysraphysms are usually associated with cutaneous stigmata.

Figure 265.4.— MRI of the spine demonstrates a lipoma of the conus medullaris and the cauda equina.