Diseases of the nervous system may be confined to the spinal cord where they produce a number of 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 a number of readily recognized ways and, as will be evident, certain diseases preferentially produce special syndromes. This syndromic grouping of the spinal cord disorders, which is in keeping with the general plan of this book, greatly facilitates clinical diagnosis.
The main syndromes considered in this chapter are (1) a complete or almost complete sensorimotor myelopathy that involves most or all of the ascending and descending tracts (transverse myelopathy); (2) a combined painful radicular and transverse cord syndrome; (3) the hemicord (Brown-Séquard) syndrome; (4) a ventral cord syndrome, sparing posterior column function; (5) a high cervical–foramen magnum syndrome; (6) a central cord or syringomyelic syndrome; (7) a syndrome of the conus medullaris; and (8) a syndrome of the cauda equina. In addition, an important distinction is 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, 9 (Figs. 9-5 and 9-7), and Chap. 11, on motor paralysis, somatic sensation, and back pain, respectively. The typical spinal cord syndromes are represented most perfectly by tumor compression that originates in an adjacent vertebral body; this important process is therefore described as a model in the introductory section and again in a later part of the chapter.
This syndrome is best considered in relation to trauma, its most frequent cause, but it occurs also as a result of other acute damage including infarction or hemorrhage and with rapidly advancing compressive, necrotizing, demyelinative, or inflammatory lesions. Each of these categories of acute spinal cord disease is discussed in the following pages. 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 recorded medical history, advances in the understanding of spinal cord disease have coincided largely with periods of warfare. The first thoroughly documented study of the effects of sudden total cord transection was by Theodor Kocher in 1896, based on his observations of 15 patients. During World War I, Riddoch, and later Head and Riddoch, gave what are now considered the classic descriptions of spinal transection in humans; ...