Diseases of the nervous system may be confined to the spinal cord, where they produce very distinctive syndromes. These relate to the special anatomic features of the cord, such as its prominent function in sensorimotor conduction and relatively primitive reflex activity; its long, cylindrical shape; its small cross-sectional size; the peripheral location of myelinated fibers next to the pia; the special arrangement of its blood vessels; and its intimate relationship to the vertebral column. Woolsey and Young estimated that approximately 30 diseases are known to affect the spinal cord, of which half are seen with regularity. These processes express themselves in readily recognizable ways, and, as will be evident, certain diseases preferentially produce special syndromes. This syndromic grouping of spinal cord disorders greatly facilitates clinical diagnosis.
The main syndromes considered in this chapter are idealized patterns of the results of damage within the cord: (1) a complete or almost complete sensorimotor myelopathy that involves most or all of the ascending and descending tracts, effectively a transverse myelopathy causing paralysis and sensory loss marked by a distinct level on the body demarcating normal from absent sensation below (sensory level); (2) a combined painful radicular and transverse cord syndrome; (3) the hemicord (Brown-Séquard) syndrome of paralysis one side of the body and loss of pain and temperature sensation on the other side, usually with a hemisensory level; (4) a ventral cord syndrome of paralysis and loss of pain and temperature below a level, sparing posterior column function; (5) a foramen magnum syndrome of sequential paralysis of the limbs; (6) a central cord or syringomyelic syndrome, in which pain and thermal sensation are lost over several segments of innervation; (7) a syndrome of the conus medullaris of leg weakness, sensory loss in the perinium and sphincter dysfunction; and (8) a syndrome of the cauda equina of pain, variable leg weakness, radicular leg pain and later sphincter dysfunction. In addition, important distinctions and further recognizable patterns are made between lesions within the cord (intramedullary) and those that compress the cord from without (extramedullary). Some of the anatomic and physiologic considerations pertinent to an understanding of disorders of the cord and of the spine can be found in Chaps. 3, 8 (Fig. 8–7), and Chap. 10, on motor paralysis, somatic sensation, and back pain, respectively.
MYELOPATHY CAUSED BY TRAUMA AND OTHER PHYSICAL FACTORS
This syndrome is best considered in relation to trauma, its most frequent cause, but it occurs also from other acute damage including infarction or hemorrhage and with rapidly advancing compressive, necrotizing, demyelinative, or inflammatory lesions. For convenience, we have included in this group radiation myelopathy, which is transverse but evolves subacutely.
Traumatic Injuries of the Spine and Spinal Cord
Throughout medical history, advances in the understanding of spinal cord disease have coincided largely with ...