This chapter is focused on injuries of extracranial, cranial, intracranial, spinal cord, and peripheral nervous system structures, with emphasis on those disorders that appear to be related primarily to mechanical trauma. Extracranial hemorrhage consists of three major lesions: caput succedaneum, subgaleal hemorrhage, and cephalhematoma. These lesions are generally not serious, except for several uncommon complications. Skull fracture, the principal bony lesion of the newborn, may be linear, be depressed, or consist of occipital osteodiastasis. Intracranial hemorrhage, not unexpectedly, may result from mechanical factors, although among all types of intracranial hemorrhage, trauma per se is a prominent pathogenetic factor principally only for epidural and some cases of subdural hemorrhage. Subdural hemorrhage is discussed in Chapter 22. Spinal cord injury is the most serious CNS parenchymal lesion related primarily to mechanical factors. Two major sites of injury are upper to mid-cervical, occurring mainly in cephalic deliveries and relating primarily to torsional factors, and lower cervical to upper thoracic, occurring mainly in breech deliveries and relating primarily to longitudinal or lateral tractional factors. MRI has proven valuable for both diagnosis and prognosis. Improvements in obstetrical practice have led to declines in incidence. Management is difficult, but new pharmacological, cellular, and rehabilitative interventions are on the horizon. Traumatic injury to peripheral nervous system structures is particularly dominated by brachial plexus injury. The mechanical forces underlying most cases are usually some combination of exogenous factors, such as downward lateral traction involving delivery of the head in a breech delivery or of the shoulder in cephalic deliveries and endogenous factors, such as very strong maternal expulsion forces. Other injuries to peripheral nervous system structures individually are uncommon but collectively are relatively common.
