Cauda Equina Syndrome After Continuous Spinal Anesthesia

TLDR

The authors hypothesize that maldistribution combined with a high local anesthetic dose causes neurotoxic injury and recommend using a lower concentration and a maximum dose ceiling to establish the block. To reduce neurotoxicity, they suggest limiting concentration, setting a dose ceiling, increasing spread when focal sensory block indicates maldistribution, and abandoning the technique if maneuvers fail. Four cases of cauda equina syndrome after continuous spinal anesthesia were observed, all showing focal sensory block and requiring higher-than-usual local anesthetic doses for adequate analgesia.

Abstract

Four cases of cauda equina syndrome occurring after continuous spinal anesthesia are reported. In all four cases, there was evidence of a focal sensory block and, to achieve adequate analgesia, a dose of local anesthetic was given that was greater than that usually administered with a single-injection technique. We postulate that the combination of maldistribution and a relatively high dose of local anesthetic resulted in neurotoxic injury. Suggestions that may reduce the potential for neurotoxicity are discussed. Use of a lower concentration and a "ceiling" or maximum dose of local anesthetic to establish the block should be considered. If maldistribution of local anesthetic is suspected (as indicated by a focal sensory block), the use of maneuvers to increase the spread of local anesthetic is recommended. If such maneuvers prove unsuccessful, the technique should be abandoned.