In the past decade, a heterogeneous group of neurologic and
orthopaedic disorders have been categorized collectively as
lumbosacral disease or cauda equina syndrome. Although much
remains to be learned in regard to individual components, new
information concerning diagnosis, therapy, and prognosis has
been presented in the literature. This chapter is a review of
current information pertaining to lumbosacral disease with
emphasis on newer aspects of classification and therapy. The
lumbosacral plexus is formed by the fourth through seventh
lumbar nerves and all sacral nerves. Disease that affects any of
the vertebrae from the caudal end of L4 through the sacrum may
cause signs recognizable as motor or sensory abnormality in the
nerves of the pelvic limbs and perineal region, autonomic
functional abnormalities of the pelvic viscera, or both. Because
of the variability of the location of the cauda equina,
occasional lesions cranial to L4-5 produce signs of lumbosacral
disease. The lumbosacral plexus is characteri