Chapter 31 Lumbosacral plexopathies

Abstract

Publisher Summary This chapter describes lumbosacral plexopathies. The lumbar plexus and the sacral plexus provide innervation for the lower limb, hip girdle, and much of the pelvic floor. When these two plexuses, and the lumbosacral trunk that links them, are considered as a single entity, the resulting lumbosacral plexus (or pelvic plexus) probably becomes the largest peripheral nervous system (PNS) structure. Virtually every element of the brachial plexus can be assessed with nerve conduction studies (NCSs) except the sensory fibers derived from the C5 root. In contrast, no reliable sensory NCS is available to assess the lumbar plexus (L2–L4 root origin), and the sensory NCSs that assess the superior half of the sacral plexus (L5, S1 root origin) frequently are compromised by various factors. Unlike brachial plexopathies, a significant number of lumbosacral plexopathies are bilateral, including those because of neoplasms (estimated to be bilateral in 25% of cases), radiation, and diabetic amyotrophy.