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Caudal anesthesia was first described at the turn of last century by
two French physicians, Fernand Cathelin and Jean-Athanase Sicard. The
technique predated the lumbar approach to epidural block by several
years.1 Caudal anesthesia, however, did not gain in
popularity immediately following its inception. One of the major reasons
caudal anesthesia was not embraced arose from the wide variety of
arrangements of sacral bones encountered in the general population and the
consequent high failure rate associated with attempts to locate the sacral
hiatus. The failure rate of 5% to 10% made caudal epidural anesthesia
unpopular until a resurgence of interest occurred in the 1940s led by
Hingson and colleagues, who used it primarily in obstetrical anesthesia.
Caudal epidural anesthesia has many applications, including surgical
anesthesia in children and adults, as well as the management of acute and
chronic pain conditions. Success rate of 98% to 100% can be achieved
in infants and young children before the age of puberty, as well as in lean
adults.1 The technique of caudal epidural block in pain
management has been greatly enhanced by the use of fluoroscopic guidance and
epidurography, in which high success rates can be attained. Unfortunately,
clinical indications, and especially therapeutic interventions for the
relief of chronic pain in individuals with failed back surgery syndrome, are
often most prevalent in patients with difficult caudal landmarks. It has
been suggested that traditional lumbar peridural block should not be
attempted employing an approach requiring needle placement through a spinal
surgery scar, due to the likelihood of tearing the dura and the possibility
of inducing hematoma formation over the cauda equina when blood from the
procedure gets trapped between the layers of scar and connective
tissues.2 Under these circumstances, it is recommended
that fluoroscopically guided caudal epidural block be performed in lieu of
the traditional approach. The second resurgence in popularity of caudal
anesthesia has paralleled the increasing need to find safe alternatives to
conventional lumbar epidural block in selected patient populations, such as
individuals with failed back surgery syndrome.
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The sacrum is a large triangularly shaped bone formed by the fusion of
the five sacral vertebrae. It has a blunted, caudal apex that articulates
with the coccyx. Its superior, wide base articulates with the fifth lumbar
vertebra at the lumbosacral angle (Figure 15–1A–D). Its dorsal
surface is convex and has a raised interrupted median crest with four
(sometimes three) spinous tubercles representing fused sacral spines.
Flanking the median crest, the posterior surface is formed by fused laminae.
Lateral to the median crest, four pairs of dorsal foramina lead into the
sacral canal through intervertebral foraminae, each of which transmits the
dorsal ramus of a sacral spinal nerve (see Figure 15–1B). Below the fourth
(or third) spinous tubercle an arched sacral hiatus is identified in the
posterior wall of the sacral canal, due to the failure of the fifth pair of
laminae to meet, exposing the dorsal surface of the fifth sacral ...