Guide to Pain Management in Low-Resource Settings

What are important and useful 
specifi c diagnostic nerve blocks?
Early proponents of regional anesthesia such as La-
bat and Pitkin [3] believed it was possible to block just 
about any nerve in the body. Despite the many technical 
limitations these pioneers were faced with, these clini-
cians persevered. Th
  ey did so, not only because they be-
lieved in the clinical utility and safety of regional nerve 
block, but because the available alternatives to render 
a patient insensible to surgical pain at their time were 
much less attractive. Th
 e introduction of the muscle 
relaxant curare in 1942 by Dr. Harold Griffi
  th changed 
this construct [2], and in a relatively short time, region-
al anesthesia was relegated to the history of medicine, 
with its remaining proponents viewed as eccentric at 
best. Just as the Egyptian embalming techniques were 
lost to modern man, many regional anesthesia tech-
niques that were in common use were lost to today’s 
pain management specialists.
What we have left are those procedures which 
have stood the test of time for surgical anesthesia. For 
the most part, these were the nerve blocks that were not 
overly demanding from a technical viewpoint and were 
reasonably safe to perform. Many of these techniques 
also have clinical utility as diagnostic nerve blocks. Th
 ese 
techniques are summarized in Table 2. Th
  e more com-
monly used diagnostic nerve blocks are discussed below.
Neuroaxial diagnostic nerve blocks
Diff erential spinal and epidural blocks have gained 
a modicum of popularity as an aid in the diagnosis of 
pain. Popularized by Winnie [9], diff erential spinal and 
epidural blocks have as their basis the varying sensitivity 
of sympathetic and somatic sensory and motor fi bers to 
blockade by local anesthetics. While sound in principle, 
these techniques are subject to some serious technical 
diffi
  culties that limit the reliability of the information 
obtained. Th
 ey include:
1) Th
  e inability to precisely measure the extent that 
each type of nerve fi ber is blocked;
2) Th
 e possibility that more than one nerve fi ber 
type is simultaneously, blocked leading the clinician to 
attribute the patient’s pain to the wrong neuroanatomi-
cal structure;
3) Th
  e impossibility of “blinding” the patient to the 
sensation of warmth associated with sympathetic block-
ade as well as the numbness and weakness that accom-
pany blockade of the somatic sensory and motor fi bers;
4) Th
 e fact that in clinical practice, the construct 
of temporal linearity, which holds that the more “sensi-
tive” sympathetic fi bers will become blocked fi rst,  fol-
lowed by the less sensitive somatic sensory fi bers  and 
lastly by the more resistant motor fi bers, breaks down. 
As a practical matter, it is not uncommon for the patient 
to experience some sensory block prior to noticing the 
warmth associated with block of the sympathetic fi bers, 
rendering the test results suspect;
5) Th
  e fact that even in the presence of a neuroaxial 
block dense enough to allow a major surgical procedure, 
aff erent nociceptive input can still be demonstrated in 
the brain;
6) Th
  e fact that the neurophysiological changes as-
sociated with pain may increase or decrease the nerves’ 
fi ring threshold, suggesting that even in the present of 
sub-blocking concentrations, there is the possibility that 
the sensitized aff erent nerves will stop fi ring;
7) Th
  e fact that modulation of pain transmission at 
the spinal cord, brainstem, and higher levels is known to 
exist and may alter the results of even the most carefully 
performed diff erential neural blockade; and
8) Th
 e fact that there are signifi cant  behavioral 
components to a patient’s pain, which may infl uence the 
subjective response the patient reports to the clinician 
performing diff erential neuroaxial blockade.
In spite of these shortcomings, neuroaxial dif-
ferential block remains a clinically useful tool to aid in 
Table 2
Common diagnostic nerve blocks
Neuroaxial blocks: epidural, subarachnoid
Peripheral nerve blocks: greater and lesser occipital,  trigeminal, 
brachial plexus, median, radial and ulnar,  intercostal, selective 
nerve root, sciatic
Intra-articular nerve blocks: facet
Sympathetic nerve blocks: stellate ganglion, celiac   plexus, lumbar, 
hypogastric plexus and ganglion impar

296
Steven D. Waldman
the diagnosis of unexplained pain. Furthermore, there 
are some things that the clinician can do to increase the 
sensitivity of this technique, which include:
1) Using the reverse diff erential spinal or epidural 
block, in which the patient is given a high concentration 
of local anesthetic, which results in a dense motor, sen-
sory, and sympathetic block, and the observation of the 
patient as the block regresses;
2) Using opioids instead of local anesthetics, which 
removes the sensory clues that may infl uence patient re-
sponses;
3) Repeating the block on more than one occasion 
using local anesthetics or opioids of varying durations, 
e.g., lidocaine versus bupivacaine or morphine versus 
fentanyl, and comparing the results for consistency.
Whether or not this technique stands the test of 
time, Winnie’s admonition to clinicians that sympatheti-
cally mediated pain is often underdiagnosed most cer-
tainly will.
Greater and lesser occipital nerve block
Th
  e greater occipital nerve arises from fi bers of the dor-
sal primary ramus of the second cervical nerve and to a 
lesser extent from fi bers of the third cervical nerve [4]. 
Th
  e greater occipital nerve pierces the fascia just below 
the superior nuchal ridge along with the occipital ar-
tery. It supplies the medial portion of the posterior scalp 
as far anterior as the vertex. Th
  e lesser occipital nerve 
arises from the ventral primary rami of the second and 
third cervical nerves. Th
  e lesser occipital nerve passes 
superiorly along the posterior border of the sterno-
cleidomastoid muscle, dividing into cutaneous branches 
that innervate the lateral portion of the posterior scalp 
and the cranial surface of the pinna of the ear.
Selective blockade of greater and lesser occipi-
tal nerves can provide the pain management special-
ist with useful information when trying to determine 
the cause of cervicogenic headache. By blocking the at-
lantoaxial, atlanto-occipital, cervical epidural, cervical 
facet, and greater and lesser occipital nerve blocks on 
successive visits, the pain management specialist may 
be able to diff erentiate the nerves subserving the pa-
tient’s headache.
Stellate ganglion block
Th
  e stellate ganglion is located on the anterior surface 
of the longus colli muscle. Th
  is muscle lies just anterior 
to the transverse processes of the seventh cervical and 
fi rst thoracic vertebrae
.
[5]. Th
  e stellate ganglion is made 
up of the fused portion of the seventh cervical and fi rst 
thoracic sympathetic ganglia. Th
  e stellate ganglion lies 
anteromedial to the vertebral artery and is medial to 
the common carotid artery and jugular vein. Th
 e stel-
late ganglion is lateral to the trachea and esophagus. Th
 e 
proximity of the exiting cervical nerve roots and brachi-
al plexus to the stellate ganglion makes it easy to inad-
vertently block these structures when performing stel-
late ganglion block, making interpretation of the results 
of the block diffi
  cult.
Selective blockade of stellate ganglion can pro-
vide the pain management specialist with useful in-
formation when trying to determine the cause of up-
per extremity or facial pain without clear diagnosis. By 
blocking the brachial plexus(preferably by the axillary 
approach) and stellate ganglion on successive visits, the 
pain management specialist may be able to diff erenti-
ate the nerves subserving the patient’s upper extremity 
pain. Selective diff erential blockade of the stellate gan-
glion, trigeminal nerve, and sphenopalatine ganglion on 
successive visits may elucidate the nerves subserving of-
ten diffi
  cult-to-diagnose facial pain.
Cervical facet block
Th
  e cervical facet joints are formed by the articulations 
of the superior and inferior articular facets of adjacent 
vertebrae [6]. Except for the atlanto-occipital and atlan-
toaxial joints, the remaining cervical facet joints are true 
joints in that they are lined with synovium and possess 
a true joint capsule. Th
  is capsule is richly innervated 
and supports the notion of the facet joint as a pain gen-
erator. Th
  e cervical facet joint is susceptible to arthritic 
changes and trauma caused by acceleration-deceleration 
injuries. Such damage to the joint results in pain sec-
ondary to synovial joint infl ammation and adhesions.
Each facet joint receives innervation from two 
spinal levels. Each joint receives fi bers from the dorsal 
ramus at the same level as the vertebra as well as fi bers 
from the dorsal ramus of the vertebra above. Th
 is fact 
has clinical importance in that it provides an explana-
tion for the ill-defi ned nature of facet-mediated pain 
and explains why the branch of the dorsal ramus aris-
ing above the off ending level must often also be blocked 
to provide complete pain relief. At each level, the dorsal 
ramus provides a medial branch that wraps around the 
convexity of the articular pillar of its respective verte-
bra and provides innervation to the facet joint. Selective 
blockade of cervical facet joints can provide the pain 
management specialist with useful information when 

Diagnostic and Prognostic Nerve Blocks 
297
trying to determine the cause of cervicogenic headache 
and/or neck pain. By blocking the atlantoaxial, atlanto-
occipital, cervical epidural, and greater and lesser occip-
ital nerve blocks on successive visits, the pain manage-
ment specialist may be able to diff erentiate the nerves 
subserving the patient’s headache and/or neck pain.
Intercostal nerve block
Th
  e intercostal nerves arise from the anterior division 
of the thoracic paravertebral nerve [7]. A typical inter-
costal nerve has four major branches. Th
 e fi rst branch 
is the unmyelinated postganglionic fi bers of the gray 
rami communicantes, which interface with the sympa-
thetic chain. Th
  e second branch is the posterior cutane-
ous branch, which innervates the muscles and skin of 
the paraspinal area. Th
  e third branch is the lateral cu-
taneous division, which arises in the anterior axillary 
line. Th
  e lateral cutaneous division provides the major-
ity of the cutaneous innervation of the chest and ab-
dominal wall. Th
  e fourth branch is the anterior cutane-
ous branch supplying innervation to the midline of the 
chest and abdominal wall. Occasionally, the terminal 
branches of a given intercostal nerve may actually cross 
the midline to provide sensory innervation to the con-
tralateral chest and abdominal wall. Th
  is fact has spe-
cifi c import when utilizing intercostal block as part of 
a diagnostic workup for the patient with chest wall and/
or abdominal pain. Th
  e 12th nerve is called the subcos-
tal nerve and is unique in that it gives off  a branch to 
the fi rst lumbar nerve, thus contributing to the lumbar 
plexus.
Selective blockade of intercostal and/or sub-
costal nerves thought to be subserving a patient’s pain 
can provide the pain management specialist with use-
ful information when trying to determine the cause of 
chest wall and/or abdominal pain. By blocking the inter-
costal nerves and celiac plexus on successive visits, the 
pain management specialist may be able to diff erenti-
ate which nerves are subserving the patient’s chest wall 
and/or abdominal pain.
Celiac plexus block
Th
  e sympathetic innervation of the abdominal viscera 
originates in the anterolateral horn of the spinal cord 
[8]. Preganglionic fi bers from T5–T12 exit the spinal 
cord in conjunction with the ventral roots to join the 
white communicating rami on their way to the sym-
pathetic chain. Rather than synapsing with the sympa-
thetic chain, these preganglionic fi bers pass through it 
to ultimately synapse on the celiac ganglia. Th
 e greater, 
lesser, and least splanchnic nerves provide the major 
preganglionic contribution to the celiac plexus. Th
 e 
greater splanchnic nerve has its origin from the T5–T10 
spinal roots. Th
  e nerve travels along the thoracic para-
vertebral border through the crus of the diaphragm into 
the abdominal cavity, ending on the celiac ganglion of 
its respective side. Th
 e lesser splanchnic nerve arises 
from the T10–T11 roots and passes with the greater 
nerve to end at the celiac ganglion. Th
  e least splanchnic 
nerve arises from the T11–T12 spinal roots and passes 
through the diaphragm to the celiac ganglion.
Interpatient anatomical variability of the celiac 
ganglia is signifi cant, but the following generalizations 
can be drawn from anatomical studies of the celiac gan-
glia. Th
  e ganglia vary in number from one to fi ve  and 
range in diameter from 0.5 to 4.5 cm. Th
  e ganglia lie an-
terior and anterolateral to the aorta. Th
  e ganglia located 
on the left are uniformly more inferior than their right-
sided counterparts by as much as a vertebral level, but 
both groups of ganglia lie below the level of the celiac 
artery. Th
  e ganglia usually lie approximately at the level 
of the fi rst lumbar vertebra.
Postganglionic fi bers radiate from the celiac 
ganglia to follow the course of the blood vessels to in-
nervate the abdominal viscera. Th
 ese organs include 
much of the distal esophagus, stomach, duodenum, 
small intestine, ascending and proximal transverse co-
lon, adrenal glands, pancreas, spleen, liver, and biliary 
system. It is these postganglionic fi bers, the fi bers aris-
ing from the preganglionic splanchnic nerves, and the 
celiac ganglion that make up the celiac plexus. Th
 e dia-
phragm separates the thorax from the abdominal cav-
ity while still permitting the passage of the thoracoab-
dominal structures, including the aorta, vena cava, and 
splanchnic nerves. Th
  e diaphragmatic crura are bilateral 
structures that arise from the anterolateral surfaces of 
the upper two or three lumbar vertebrae and disks. Th
 e 
crura of the diaphragm serve as a barrier to eff ectively 
separate the splanchnic nerves from the celiac ganglia 
and plexus below.
Th
  e celiac plexus is anterior to the crus of the 
diaphragm. Th
  e plexus extends in front of and around 
the aorta, with the greatest concentration of fi bers ante-
rior to the aorta. With the single-needle transaortic ap-
proach to celiac plexus block, the needle is placed close 
to this concentration of plexus fi bers.  Th
 e relationship 
of the celiac plexus to the surrounding structures is as 

298
Steven D. Waldman
follows: Th
  e aorta lies anterior and slightly to the left of 
the anterior margin of the vertebral body. Th
 e inferior 
vena cava lies to the right, with the kidneys posterolat-
eral to the great vessels. Th
  e pancreas lies anterior to 
the celiac plexus. All of these structures lie within the 
retroperitoneal space. Selective blockade of the celiac 
plexus can provide the pain management specialist with 
useful information when trying to determine the cause 
of chest wall, fl ank, and/or abdominal pain. By block-
ing the intercostal nerves and celiac plexus on succes-
sive visits, the pain management specialist may be able 
to diff erentiate which nerves are subserving the patient’s 
pain.
Selective nerve root block
Improvements in fl uoroscopy and needle technology 
have led to increased interest in selective nerve root 
block in the diagnosis of cervical and lumbar radicular 
pain. Although selective nerve block is technically de-
manding and requires resources that may not be avail-
able in many settings, the technique may help identify 
the reason behind the patient’s pain complaint. Th
 e use 
of selective nerve root block as a diagnostic or prognos-
tic maneuver must be approached with caution because, 
due to the proximity of the epidural, subdural, and sub-
arachnoid spaces, it is very easy to inadvertently place 
local anesthetic into these spaces when intending to 
block a single cervical or lumbar nerve root. Th
 is error 
is not always readily apparent on fl uoroscopy, given the 
small amounts of local anesthetic and contrast medium 
used.
Pearls
• Th
  e use of nerve blocks as part of the evaluation 
of the patient in pain represents a reasonable next 
step if a careful targeted history and physical ex-
amination and available radiographic, neurophys-
iological, and laboratory testing fail to provide a 
clear diagnosis.
• Th
  e overreliance on a prognostic nerve block as 
the sole justifi cation to perform an invasive or 
neurodestructive procedure can lead to signifi -
cant patient morbidity and dissatisfaction.
•  Do analyze the information obtained from diag-
nostic nerve blocks in the context of the patient’s 
history, physical, laboratory, neurophysiological, 
and radiographic testing.
•  Don’t over-rely on information obtained from di-
agnostic nerve blocks.
•  Do view discordant or contradictory informa-
tion obtained from diagnostic nerve blocks with 
skepticism.
•  Don’t rely on information obtained from diagnos-
tic nerve block as the sole justifi cation to proceed 
with invasive treatments.
•  Do consider the possibility of technical limita-
tions that reduce the ability to perform an accu-
rate diagnostic nerve block.
•  Do consider the possibility of patient anatomical 
variations that may infl uence the results of diag-
notic nerve blocks.
•  Do consider the presence of incidence pain when 
analyzing the results of diagnostic nerve blocks.
•  Don’t perform diagnostic nerve blocks in patients 
who are not currently having the pain you are 
trying to diagnose.
•  Do consider behavioral factors that may infl uence 
the results of diagnostic nerve blocks.
•  Do consider that patients may premedicate them-
selves prior to diagnostic nerve blocks.
References
[1]  Dawson DM. Carpal tunnel syndrome. In: Entrapment neuropathies, 
3rd ed. Philadelphia. Lippincott-Raven; 1990. P. 53.
[2] Griffi
  th HR, Johnson E. Th
  e use of curare in general anesthesia. Anes-
thesiology 1942;3:418–20.
[3]  Pitkin G. Controllable spinal anesthesia. Am J Surgery 1928;5:537.
[4]  Waldman SD. Greater and lesser occipital nerve block. In: Atlas of in-
terventional pain management, 2nd ed. Philadelphia: Saunders; 2004. p. 
23.
[5]  Waldman SD. Stellate ganglion block. In: Atlas of interventional pain 
management, 2nd ed. Philadelphia: Saunders; 2004. p. 104.
[6]  Waldman SD. Cervical facet block. In: Atlas of interventional pain man-
agement, 2nd ed. Philadelphia: Saunders; 2004. p. 125.
[7]  Waldman SD Intercostal nerve block. In: Atlas of interventional pain 
management, 2nd ed. Philadelphia: Saunders; 2004. p. 241
[8]  Waldman SD. Celiac plexus block. In: In: Atlas of interventional pain 
management, 2nd ed. Philadelphia: Saunders; 2004. p. 265.
[9]  Winnie AP, Collins VJ. Th
 e pain clinic. I: Diff erential neural block-
ade in pain syndromes of questionable etiology. Med Clin North Am 
1968;52:123–9.

299
Guide to Pain Management in Low-Resource Settings, edited by Andreas Kopf and Nilesh B. Patel. IASP, Seattle, © 2010. All rights reserved. Th
  is material may be used for educational 
and training purposes with proper citation of the source. Not for sale or commercial use. No responsibility is assumed by IASP for any injury and/or damage to persons or property 
as a matter of product liability, negligence, or from any use of any methods, products, instruction, or ideas contained in the material herein. Because of the rapid advances in the 
medical sciences, the publisher recommends that there should be independent verifi cation of diagnoses and drug dosages. Th
  e mention of specifi c pharmaceutical products and any 
medical procedure does not imply endorsement or recommendation by the editors, authors, or IASP in favor of other medical products or procedures that are not covered in the text.
Guide to Pain Management in Low-Resource Settings
Winfried Meissner
Chapter 39
Post-Dural Puncture Headache
Case report
Mr. Lehmann, an expatriate, works for Bilfinger & 
Berger, a large construction company in Nigeria. For 
a knee arthroscopy, he received an uneventful spinal 
anesthesia in the company’s hospital. He recovered 
quickly, so he decided to travel to a business meet-
ing the next afternoon, although a light headache oc-
curred at noon. On the way to Kano the headache in-
creased in intensity, and only a reclining position gave 
Mr. Lehmann any relief.
When Mr. Lehmann arrived in Kano, the 
headache was so intense that he felt very unwell. He 
vomited once and was unable to walk. His driver 
could not contact the doctor at Bilfinger & Berger, so 
they decided to go to the nearest local hospital. Lehm-
ann was seen by the on-call physician, Dr. Adewale; 
however, as Lehmann did not know about the possible 
association between spinal anesthesia and headache, 
he did not mention it. On the other hand, Dr. Adewale 
only examined Lehman’s head and neck—so he missed 
the wound dressing (and because Lehmann could not 
walk due to his headache, Dr. Adewale could not no-
tice his limping).
Th
  e following features were documented: Slightly 
increased body temperature, increase of headache when 
bending the neck (imitating meningism), otherwise nor-
mal neurological status.
Dr. Adewale’s diff erential diagnoses were intra-
cranial hematoma, meningitis, or cerebral malaria.
However, there was no CT available in this hos-
pital. Mr. Lehmann asked for referral back to Abuja, 
where he was based, but Dr. Adewale recommended 
referral to the nearest teaching hospital for a CT scan. 
However, there was no ambulance immediately avail-
able, so the patient was kept under observation and 
clinically monitored. Finally, while admitting the pa-
tient to the ward, the head nurse Betty Hazika noticed 
the dressing on his knee and realized the complete med-
ical history. When she informed Dr. Adewale about her 
fi nding, he successfully contacted the anesthesiologist in 
Abuja, who confi rmed that he “might have nicked the 
dura a touch.” Th
  ey diagnosed a post-dural puncture 
headache (PDPH) and decided to monitor the patient 
for 2 days. As per guidelines in the hospital, Mr. Lehm-
ann was given paracetamol, lots of fl uid (which was 
very annoying to the patient because the headache se-
verely restricted walking to the toilet), and Betty added 
some herbal medicines of her own (the latter not in the 
hospital guidelines).
By evening next day, the headache decreased, 
and Mr. Lehmann recovered well. As he was very 
pleased by the care of the nurse, he associated her 
herbal treatment with his recovery, and he recom-
mended it to all his colleagues as a treatment for 
hangover!

300
Winfried Meissner