Page 309 Guide to Pain Management in Low-Resource Settings

Diagnostic and Prognostic Nerve Blocks 297

trying to determine the cause of cervicogenic headache to ultimately synapse on the celiac ganglia. Th e greater,
and/or neck pain. By blocking the atlantoaxial, atlanto- lesser, and least splanchnic nerves provide the major
occipital, cervical epidural, and greater and lesser occip- preganglionic contribution to the celiac plexus. Th e
ital nerve blocks on successive visits, the pain manage- greater splanchnic nerve has its origin from the T5–T10
ment specialist may be able to diff erentiate the nerves spinal roots. Th e nerve travels along the thoracic para-
subserving the patient’s headache and/or neck pain. vertebral border through the crus of the diaphragm into
the abdominal cavity, ending on the celiac ganglion of
Intercostal nerve block its respective side. Th e lesser splanchnic nerve arises
Th e intercostal nerves arise from the anterior division from the T10–T11 roots and passes with the greater
of the thoracic paravertebral nerve [7]. A typical inter- nerve to end at the celiac ganglion. Th e least splanchnic
costal nerve has four major branches. Th e fi rst branch nerve arises from the T11–T12 spinal roots and passes
is the unmyelinated postganglionic fi bers of the gray through the diaphragm to the celiac ganglion.
rami communicantes, which interface with the sympa- Interpatient anatomical variability of the celiac
thetic chain. Th e second branch is the posterior cutane- ganglia is signifi cant, but the following generalizations
ous branch, which innervates the muscles and skin of can be drawn from anatomical studies of the celiac gan-
the paraspinal area. Th e third branch is the lateral cu- glia. Th e ganglia vary in number from one to fi ve and
taneous division, which arises in the anterior axillary range in diameter from 0.5 to 4.5 cm. Th e ganglia lie an-
line. Th e lateral cutaneous division provides the major- terior and anterolateral to the aorta. Th e ganglia located
ity of the cutaneous innervation of the chest and ab- on the left are uniformly more inferior than their right-
dominal wall. Th e fourth branch is the anterior cutane- sided counterparts by as much as a vertebral level, but
ous branch supplying innervation to the midline of the both groups of ganglia lie below the level of the celiac
chest and abdominal wall. Occasionally, the terminal artery. Th e ganglia usually lie approximately at the level
branches of a given intercostal nerve may actually cross of the fi rst lumbar vertebra.
the midline to provide sensory innervation to the con- Postganglionic fi bers radiate from the celiac
tralateral chest and abdominal wall. Th is fact has spe-
ganglia to follow the course of the blood vessels to in-
cifi c import when utilizing intercostal block as part of
nervate the abdominal viscera. Th ese organs include
a diagnostic workup for the patient with chest wall and/
much of the distal esophagus, stomach, duodenum,
or abdominal pain. Th e 12th nerve is called the subcos-
small intestine, ascending and proximal transverse co-
tal nerve and is unique in that it gives off a branch to
lon, adrenal glands, pancreas, spleen, liver, and biliary
the fi rst lumbar nerve, thus contributing to the lumbar
system. It is these postganglionic fi bers, the fi bers aris-
plexus.
ing from the preganglionic splanchnic nerves, and the
Selective blockade of intercostal and/or sub-
celiac ganglion that make up the celiac plexus. Th e dia-
costal nerves thought to be subserving a patient’s pain
phragm separates the thorax from the abdominal cav-
can provide the pain management specialist with use-
ity while still permitting the passage of the thoracoab-
ful information when trying to determine the cause of
dominal structures, including the aorta, vena cava, and
chest wall and/or abdominal pain. By blocking the inter-
costal nerves and celiac plexus on successive visits, the splanchnic nerves. Th e diaphragmatic crura are bilateral
pain management specialist may be able to diff erenti- structures that arise from the anterolateral surfaces of
ate which nerves are subserving the patient’s chest wall the upper two or three lumbar vertebrae and disks. Th e
and/or abdominal pain. crura of the diaphragm serve as a barrier to eff ectively
separate the splanchnic nerves from the celiac ganglia
Celiac plexus block and plexus below.
Th e sympathetic innervation of the abdominal viscera Th e celiac plexus is anterior to the crus of the
originates in the anterolateral horn of the spinal cord diaphragm. Th e plexus extends in front of and around
[8]. Preganglionic fi bers from T5–T12 exit the spinal the aorta, with the greatest concentration of fi bers ante-
cord in conjunction with the ventral roots to join the rior to the aorta. With the single-needle transaortic ap-
white communicating rami on their way to the sym- proach to celiac plexus block, the needle is placed close
pathetic chain. Rather than synapsing with the sympa- to this concentration of plexus fi bers. Th e relationship
thetic chain, these preganglionic fi bers pass through it of the celiac plexus to the surrounding structures is as