This document reviews the evidence for various sympathetic blocks based on a literature search. It finds: 1) For sphenopalatine ganglion blocks, there were 14 relevant articles including case reports, case series, and 3 double-blinded placebo-controlled studies, providing low to moderate evidence of efficacy for headaches and facial pain. 2) For stellate ganglion blocks, 11 relevant articles including case reports and a prospective controlled study were found, providing low evidence for treating upper extremity pain and vascular disorders. 3) Few articles were found on thoracic sympathetic blocks despite their use for upper extremity pain, with only 2 relevant percutaneous technique articles identified. 4) Across block types, evidence from

1. EVIDENCE-BASED MEDICINE
Section Editor: Jan Van Zundert, MD, PhD, FIPP
Sympathetic Blocks: The Evidence
Miles Day, MD, FIPP, DABIPP
Department of Anesthesiology and Pain Management, Texas Tech University Health
Sciences Center, Lubbock, Texas, U.S.A.
᭿ Abstract: The sympathetic nervous system has been impli-
cated in numerous pain syndromes ranging from neuropathic
pain to vascular pain to visceral pain. In light of this, sympa-
thetic ganglia have been the target of local anesthetic block-
ade to determine the sympathetic role in the transmission of
pain. If analgesia is afforded with local anesthetic blockade,
chemical or thermal neurolysis have been utilized to attempt
to provide long-term relief. Despite frequent use of minimally
invasive sympathetic blocks and neurolysis by pain practitio-
ners, their efficacy for providing analgesia has been sparsely
reported in the literature. Many case reports and case series
have been published, but few placebo-controlled, blinded
studies exist. This manuscript will review the literature on
sympathetic blocks and summarize existing studies for each of
the sympathetic blocks. The goal is to provide past, current,
and future pain physicians with evidence that they can use to
provide appropriate care for their patients. ᭿
Key Words: sympathetic block, neurolysis, evidence
INTRODUCTION
The sympathetic nervous system has been implicated in
numerous pain syndromes ranging from neuropathic
pain to vascular pain to visceral pain. In some instances,
its role in other painful conditions such as headaches
and musculoskeletal pain has been explored. Local anes-
thetic blockade of sympathetic ganglia has become
common practice among pain practitioners to diagnose
and treat sympathetically mediated pain. When pain
relief has been afforded with the initial block, chemical
and thermal neurolysis has been performed in the
attempt to provide prolonged analgesia.
The most recent “Current Procedural Terminology
(CPT)” code book has codes for the following sympa-
thetic blocks:1
• 64505 Sphenopalatine ganglion.
• 64510 Stellate ganglion (cervical sympathetic).
• 64520 Thoracic or lumbar (paravertebral
sympathetic).
• 64530 Celiac plexus/splanchnic nerves.
• 64517 Superior hypogastric plexus.
• 64999 Ganglion impar.
While the sphenopalatine ganglion, celiac plexus/
splanchnic nerves, and the hypogastric plexus are not
purely sympathetic ganglia or nerves, they all contain
sympathetic fibers that many pain practitioners believe
are involved in the transmission of pain. With regard to
the ganglion impar, CPT code 64999 is an “unspecified,
other” code which is used for all blocks without a
specific code.
While the CPT code book has codes for the afore-
mentioned sympathetic blocks, it only contains 2 codes
specific for neurolysis of sympathetic nerves:
• 64680 Destruction by neurolytic agent; celiac
plexus.
• 64681 Destruction by neurolytic agent; supe-
rior hypogastric plexus.
Address correspondence and reprint requests to: Miles Day, MD, FIPP,
DABIPP, Department of Anesthesiology and Pain Management, Texas Tech
University Health Sciences Center, Lubbock, TX, U.S.A. E-mail: miles.day@
ttuhsc.edu.
This work was presented at the World Institute of Pain U.K. Section,
Symposium on “Evidence in Interventional Pain Procedures” in London on
June 21, 2007 and has subsequently undergone peer-review.
Submitted: October 24, 2007; Revision accepted: November 14, 2007
© 2008 World Institute of Pain, 1530-7085/08/$15.00
Pain Practice, Volume 8, Issue 2, 2008 98–109

2. It makes one wonder why the other sympathetic
blocks do not have specific neurolysis codes even though
they are routinely performed.
This manuscript will review the existing literature on
sympathetic blocks and summarize existing studies for
each block. It will attempt to answer the following
questions with regard to each sympathetic block:
1. Is the treatment supported by evidence (in terms
of randomized, controlled trials [RCTs], system-
atic reviews or guidelines)?
If the evidence is of lower quality according to
“evidence-based medicine guidelines” (Table 1), an
attempt will be made to answer the following 5
questions:2
1. Does the available information suggest an advan-
tage for the studied treatment compared with the
currently used treatment in terms of efficacy and
safety?
2. Can the treatment be used safely until further
evidence becomes available?
3. Should the treatment be reserved for specific con-
ditions or patient populations?
4. Are cost effectiveness analyses available?
5. Which research is necessary before the treatment
could be more recommended?
LITERATURE SEARCH
An online literature search on Entrez Pubmed, Cochrane
EBM, and Ovid Medline was performed with the fol-
lowing limits:
• English language.
• Humans.
• 1967 to 2007.
• Articles with abstracts.
The following terms or combination of terms were
entered into the search engine:
• Sympathetic block.
• Sympathectomy.
• Chemical sympathectomy.
• Neurolysis.
• Radiofrequency.
• Sphenopalatine ganglion/block.
• Stellate ganglion/block.
• Thoracic sympathetic nerves/block.
• Celiac plexus/splanchnic nerves/block.
• Lumbar sympathetic nerves/block.
• Hypogastric plexus/block.
• Ganglion impar/block.
• Phenol.
• Cryoneurolysis.
Table 1. Grade of Recommendation
Grade of Recommendation/
Description Benefit vs. Risk and Burdens
Methodological Quality of
Supporting Evidence Implications
1A/strong recommendation,
high-quality evidence
Benefits clearly outweigh risk
and burdens, or vice versa
RCTs without important limitations
or overwhelming evidence from
observational studies
Strong recommendation, can apply to
most patients in most circumstances
without reservation
1B/strong recommendation,
moderate-quality evidence
Benefits clearly outweigh risk
and burdens, or vice versa
RCTs with important limitations
(inconsistent results, methodological
flaws, indirect, or imprecise) or
exceptionally strong evidence from
observational studies
Strong recommendation, can apply to
most patients in most circumstances
without reservation
1C/strong recommendation,
low-quality or very
low-quality evidence
Benefits clearly outweigh risk
and burdens, or vice versa
Observational studies or case series Strong recommendation but may
change when higher-quality evidence
becomes available
2A/weak recommendation,
moderate-quality evidence
Benefits closely balanced with
risks and burden
RCTs without important limitations
or overwhelming evidence from
observational studies
Weak recommendation, best action
may differ depending on circumstances
or patients’ or societal values
2B/weak recommendations,
moderate-quality evidence
Benefits closely balanced with
risks and burden
RCTs with important limitations
(inconsistent results, methodological
flaws, indirect, or imprecise) or
exceptionally strong evidence from
observational studies
Weak recommendation, best action may
differ depending on circumstances or
patients’ or societal values
2C/weak recommendation,
low-quality or very
low-quality evidence
Uncertainty in the estimates or
benefits, risks, and burden:
benefits, risk, and burden
may be closely balanced
Observational studies or case series Very weak recommendations: other
alternatives may be equally reasonable
Redrawn from Guyatt et al.2
RCTs, randomized, controlled trials.
Sympathetic Blocks: The Evidence • 99

3. Articles discussing the treatment of patients’ pain
with percutaneous sympathetic blocks or neurolysis
were included, whereas articles published solely on tech-
nique and complications without specific mention of
specific patients were excluded.
THE BLOCKS
Sphenopalatine Ganglion Block
The sphenopalatine ganglion resides in the pterygopa-
latine fossa which is bordered medially by the palatine
bone, anteriorly by the posterior wall of the maxillary
sinus, posteriorly by the medial pterygoid plate, and
superiorly by the sphenoid sinus. It contains sympa-
thetic and parasympathetic fibers as well as sensory and
secretomotor fibers. Its involvement in pain transmis-
sion was first described by Greenfield Sluder in 1908.3
Secondary to its location just lateral to the nasal
mucosal wall at the posterior aspect of the middle tur-
binate, blockade of the sphenopalatine ganglion can be
performed via the nares using an atomizer filled with
local anesthetic, cotton-tipped applicators soaked in
local anesthetic, or with needles inserted through the
lateral nasal mucosal wall through which the local anes-
thetic is injected. It can also be blocked via an infrazy-
gomatic approach through the mandibular notch.
Neurolysis can be achieved with chemical and thermal
methods. Pulsed radiofrequency (PRF) has also been
described.
The literature search produced 17 articles on block-
ade and/or neurolysis of the sphenopalatine ganglion.
Three of the articles were not included in the review.
One was an endoscopic technique article, another was a
computerized tomography-enhanced technique article,
and the 3rd was published about complications of
thermal neurolysis of the ganglion.4–6
The remaining
14 are summarized in Table 2.7–20
There were 7 case
reports, 3 case series, 1 retrospective review, and 3
double-blinded, placebo-controlled studies. Treatment
indications included trigeminal neuralgia, posttraumatic
headache, cluster headache, migraine headache, spheno-
palatine neuralgia, atypical facial pain, complex
regional pain syndrome (CRPS) of the lower extremity,
fibromyalgia, and myofascial pain. Complications such
as bleeding, infection, intravascular injection, and
damage to nerves and blood vessels are minimal.
With respect to levels of evidence as described in
Table 1, 10 were graded as 1C and 4 received a 2B
grading. The reason for the 1C grade was that the articles
were of low quality of evidence, ie, case reports, case
series, and a retrospective review, but strongly recom-
mended secondary to the diagnoses for which the block
was performed. The remaining 4 were given the 2B grade
for moderate-quality evidence (3 were double-blinded,
placebo-controlled studies), but weak recommendations
based on the indication for the block (lower extremity
CRPS, fibromyalgia, and myofascial pain).
Stellate Ganglion Block
The stellate ganglion is a star-shaped ganglion formed
by the fusion of the 1st thoracic and inferior cervical
sympathetic ganglia. It resides anterolateral to the body
of C7 at the neck of the 1st rib and is bordered medially
by the longus coli muscle, laterally by the anterior
scalene muscle, anteriorly by the subclavian artery, pos-
teriorly by the prevertebral fascia, and inferiorly by the
dome of the lung. Blockade of the ganglion with local
Table 2. Summary of Sphenopalatine Block/Neurolysis Articles
Authors Study Type Diagnosis No. of Patients Grade of Recommendation
Gregoire et al.7
CR Trigeminal neuralgia 1 1C
Shah, Racz8
CR Posttraumatic HA 1 1C
Yang, Oraee9
CR Cluster HA 1 1C
Saade, Paige10
CR CA 1 1C
Manahan et al.11
CR Trigeminal neuralgia 1 1C
Peterson et al.12
CR Trigeminal neuralgia, Tooth pain 2 1C
Quevedo et al.13
CR CRPS lower extremity 2 2C
Salar et al.14
CS Sphenopalatine neuralgia 7 1C
Sanders et al.15
CS Cluster HA 66 1C
Puig et al.16
CS Sphenopalatine neuralgia 8 1C
Bayer et al.17
RR Atypical facial pain, sphenopalatine neuralgia,
atypical trigeminal neuralgia, migraine HA
30 1C
Berger et al.18
DB,PC Low back pain 21 2B
Janzen et al.19
DB,PC Myofascial pain, fibromylagia 21 2B
Ferrante et al.20
DB,PC Myofascial pain head, neck, shoulders 23 2B
CR, case report; CS, case series; RR, retrospective review; DB,PC, double-blinded, placebo-controlled; CRPS, complex regional pain syndrome; HA, headache; CA, cancer.
100 • day

4. anesthetic, opioids, and/or steroid can be performed
blindly at the anterior tubercle of the 6th cervical ver-
tebra, or under fluoroscopic guidance at the aforemen-
tioned location or at its anatomical location at C7.
Neurolysis has been performed either chemically with
phenol or thermally with conventional radiofrequency.
PRF has also been performed.
A search of the literature produced 13 articles of
which 11 were reviewable. These are summarized in
Table 3.21–31
Of the 2 articles not used, one was in
French without an English translation and the other was
a case report and discussion of the diagnostic criteria for
reflex sympathetic dystrophy (RSD). Among the usable
articles, there were 4 case reports, 5 case series, 1 ret-
rospective study, and 1 prospective, double-blinded,
placebo-controlled study. Listed indications for the stel-
late ganglion block (SGB)/neurolysis were RSD of the
face and upper extremity, facial causalgia, phantom
tongue pain and causalgia, cluster headaches, posther-
petic neuralgia of a trigeminal, cervical or thoracic der-
matome, and vasospastic disorders. Complications
include bleeding, infection, neuraxial and intravascular
injection, pneumothorax, and nerve damage.
All studies received a 1C grade. Ten of the 11 were
case reports, case series, and a retrospective study, but
were performed for the aforementioned diagnosis.21–30
The study by Price et al. was prospective, double-
blinded, and placebo-controlled, but included only 4
patients and, therefore, received a 1C grade.31
Patients
with CRPS, who previously underwent a successful
SGB, received 2 SGBs 7 to 10 days apart, 1 with local
anesthetic and the other with saline (patients served as
their own control). An analysis of the peak magnitude
and duration of analgesia produced by the local anes-
thetic was performed. The mean difference between
initial peak reduction in pain intensity produced by
saline and local anesthetic was not statistically signifi-
cant, but the duration of analgesia between the 2 blocks
was significant.
Thoracic Sympathetic Blocks
In some situations, an SGB may be ineffective in diag-
nosing or treating sympathetically maintained pain in
the upper extremity. The observation by Kuntz in 1927
that in 20% of people, nerves from the 2nd and 3rd
thoracic sympathetic ganglia bypass the stellate gan-
glion and directly join the brachial plexus may explain
the aforementioned situation.32
The nerves are appro-
priately called “Kuntz fibers.” The sympathetic ganglion
cell bodies that supply the upper limbs originate in the
intermediolateral horn of the spinal cord from the
T2 through T8 levels.32
The preganglionic sympathetic
fibers pass through the white rami communicantes and
synapse with their postganglionic components primarily
in the T2 ganglion. They also synapse in the T3, stellate,
and middle cervical ganglia. Although many techniques
existed for open, surgical sympathectomies, it was
Wilkinson in 1979 who devised a percutaneous tech-
nique.33
Indications include CRPS I and II, peripheral
neuropathy, brachial plexalgia, sympathetically main-
tained pain, and vascular disorders. Complications
include neuraxial injection, intravascular injection,
nerve injury, and pneumothorax.
The online literature search was disappointing. Only
2 articles on percutaneous techniques for thoracic sym-
pathectomy were found. These are summarized in
Table 4. One was a case report by Wilkinson who per-
formed radiofrequency of the T2 and T3 sympathetics on
Table 3. Summary of Stellate Ganglion Block/Neurolysis Articles
Authors Study Type Diagnosis No. of Patients Grade of Recommendation
Hanowell, Kennedy21
CR Phantom tongue pain, causalgia 1 1C
Khoury, Kennedy22
CR Facial causalgia 1 1C
Jaeger et al.23
CR RSD face 2 1C
Arden et al.24
CR RSD face 2 1C
Albertyn et al.25
CS Cluster 11 1C
Ackerman, Zhang26
CS CRPS I 25 1C
Milligan, Nash27
CS Postherpetic neuralgia 77 1C
Kastler et al.28
CS RSD 7 1C
Racz, Holubec29
CS RSD, vasospastic disorders, CA, phantom limb 24 1C
Forouzanfar et al.30
RR CRPS I & II, posttraumatic HA, central pain,
ischemic pain, deafferentation pain, atypical
facialpain, postherpetic neuralgia
86 1C
Price et al.31
DB,PC CRPS 4 1B
CR, case report; CS, case series; RR, retrospective review; DB,PC, double-blinded, placebo-controlled; CRPS, complex regional pain syndrome; HA, headache; CA, cancer; RSD,
reflex sympathetic dystrophy.
Sympathetic Blocks: The Evidence • 101

5. 2 patients with causalgia of the upper extremity.33
Only
1 had satisfactory pain relief. The other article by Ska-
belund and Racz was a retrospective review of 42
patients who had a total of 110 percutaneous thoracic
sympathetic blocks (local and steroid) or radiofrequen-
cies for various upper extremity diagnoses.32
No results
on effectiveness were discussed. Both received a grade of
1C. When SGBs are ineffective, thoracic sympathetic
blocks are recommended. Large studies and long-term
data are lacking.
Celiac Plexus Block/Splanchnic
Nerve Block
Sympathetic innervation of the abdominal viscera origi-
nates in the anterolateral horn of the spinal cord.
Preganglionic axons from T5-12 exit the spinal cord with
the ventral roots to join the white rami communicantes
en route to the sympathetic chain. These axons pass
through the sympathetic ganglia without synapsing and
continue to the celiac, superior mesenteric, and aortic-
orenal ganglia where they eventually synapse. The
postganglionic fibers accompany blood vessels to their
respective visceral structures. Preganglionic fibers from
T5-9 travel caudally from the sympathetic chain along
the lateral and anterolateral aspects of the vertebral
bodies. These axons coalesce to form the greater
splanchnic nerve at the level of T9 and T10, course
through the diaphragm and end in the celiac plexus. The
preganglionic axons from the T10 and T11 levels form the
lesser splanchnic and the least splanchnic nerve arises
from T12, both of which end in the celiac plexus. The
celiac plexus lies anterior to the aorta at the level of L1.
The plexus extends for several centimeters in front
of the aorta and laterally around the aorta. Fibers within
the plexus arise from preganglionic splanchnic nerves,
parasympathetic preganglionic nerves from the vagus
and phrenic nerves and sympathetic postganglionic
fibers. Afferent fibers concerned with nociception pass
diffusely through the plexus.34
Indications for blockade
of the celiac plexus or splanchnic nerves include cancer
of the abdominal viscera to the splenic flexure, and
chronic benign abdominal pain refractory to pharmaco-
logical treatment. Side effects include hypotension and
diarrhea. Complications include but are not limited to
nerve injury, paralysis, pneumothorax, bowel injury,
and bleeding.
This literature search was more productive.
Seventeen articles were reviewed with only 1 being dis-
carded, as it involved intraoperative chemical splanch-
nicectomy under direct vision.35
The remaining 16
articles are summarized in Table 5.36–51
References 36
to 44 were given a grade of 1C as they were case
Table 4. Summary of Thoracic Sympathetic Block/Neurolysis Articles
Authors Study Type Diagnosis No. of Patients Grade of Recommendation
Wilkinson33
CR Causalgia 2 1C
Skabelund, Racz32
RR CRPS I, brachial plexalgia, phantom limb pain,
brachialplexitis, deafferentation pain
42 2C
CR, case report; RR, retrospective review; CRPS, complex regional pain syndrome.
Table 5. Summary of Celiac Plexus/Splanchnic Nerve Block/Neurolysis Articles
Authors Study Type Diagnosis No. of Patients Grade of Recommendation
Matamala et al.36
CR CA-related pain 5 1C
Ina et al.37
CS CA-related pain 58 1C
Hol et al.38
CS CA-related pain 8 1C
Vranken et al.39
CS CA-related pain 12 1C
Fujita40
CS CA-related pain 27 1C
Fields41
CS CA-related pain, chronic pancreatitis 10 1C
Garcea42
CS Chronic panceatitis 10 1C
Brown et al.43
RR CA-related pain 136 1C
Brown44
RR CA-related pain 66 1C
Mercadante45
P,R,C CA-related pain 20 1B
Kawamata et al.46
P,R,C CA-related pain 21 1B
Wong et al.47
P,R,DB,C CA-related pain 100 1B
Özyalçin et al.48
P,R,SB,C CA-related pain 39 1B
Yan, Myers49
MA CA-related pain 302 1B
Eisenberg et al.50
MA CA-related pain 1117 1B
CR, case report; CS, Case series; RR, retrospective review; P,R,C, prospective, randomized, comparative; P,R,DB,C, prospective, randomized, double-blinded, comparative;
P,R,SB,C, prospective, randomized, single-blinded, comparative; MA, meta-analysis; CA, cancer.
102 • day

6. reports/series and 2 retrospective reviews (low-quality
evidence), but the blocks are strongly recommended,
and commonly performed for the treatment of intrac-
table, cancer-related, abdominal pain. References 45 to
51 received a grade of 1B, strongly recommended with
moderate-quality evidence.
Mercadante studied 20 pancreatic cancer patients to
evaluate the effectiveness and duration of neurolytic
celiac plexus block (NCPB) compared with treatment
with analgesics by considering the previous and subse-
quent consumption of opioids until death.45
Celiac
plexus block (CPB) made pain control possible with a
statistically significant reduction in opioids consump-
tion until death. Administration of analgesics only
resulted in an equivalent reduction in visual analog scale
(VAS) pain score, but required escalating doses resulting
in more unpleasant side effects.
Kawamata et al. evaluated the effectiveness of NCPB
vs. nonsteroidal anti-inflammatory drug (NSAID)-
morphine treatment on quality of life (QOL) and pain
relief in 21 pancreatic cancer patients.46
The VAS scores
of patients (n = 10) receiving NCPB were statistically
lower for the first 4 weeks after the block than those of
the patients receiving the standard analgesic treatment
(n = 11) during the same time period. Morphine con-
sumption was significantly lower in weeks 4 to 7 fol-
lowing the procedure in the NCPB group and continued
to be lower thereafter, although not significantly so.
Although QOL deteriorated in both groups, it was
greater in the analgesic only group.
Polati et al. performed a randomized, double-blinded
study comparing the efficacy of NCPB with pharmaco-
logical therapy in the treatment of pain from pancreatic
cancer.47
Twenty-four patients were divided into 2
groups: 12 patients underwent NCPB (group 1) and 12
were treated with pharmacological therapy (group 2).
Immediate and long-term efficacy, mean analgesic con-
sumption, mortality, and morbidity were evaluated at
follow-up. Immediately after the block, patients in group
1 reported statistically significantly pain relief compared
with those in group 2, but long-term results did not differ
between the groups. Mean analgesic consumption was
lower in group 1. No deaths were reported. Drug-related
adverse effects were reduced in the NCPB group.
In a prospective, randomized, double-blinded com-
parative study, Wong et al. studied the effect of NCPB
on pain relief, QOL, and survival in patients (n = 100)
with unresectable pancreatic cancer.48
Patients were
randomly assigned to receive either NCPB or systemic
analgesic therapy alone with a sham injection. They
concluded that although NCPB improves pain relief in
patients with pancreatic cancer vs. optimized systemic
analgesic therapy alone, it does not affect QOL or
survival.
Özyalçin et al. evaluated the pain relieving efficacy,
side effects and effects on QOL of NCPB and splanchnic
nerve neurolytic blockade (SNB) in body and tail located
cancer.49
Nineteen patients received NCPB and 20
patients had a bilateral SNB. Baseline data were collected
prior to the procedure and further data at 2 week inter-
vals after the procedure until death. The VAS values in the
SNB group decreased more than the VAS values in the
NCPB group. The SNB patients were found to decrease
opioids consumption significantly more than the NCPB
group till the 6th control. The mean survival rate was
found to be significantly lower in the NCPB group.
Yan and Myers performed a meta-analysis on the
efficacy and safety of NCPB compared with standard
treatment in RCTs involving patients with unresectable
pancreatic cancer.50
They found 5 RCTs involving 302
patients which met their inclusion criteria. Four of the
RCTs were references 45 to 48 mentioned in the previ-
ous paragraph of this article and the 5th was reference
35, the intraoperative block not included in this review.
They concluded that in patients with unresectable pan-
creatic cancer, NCPB was associated with improved
pain control, and reduced narcotic usage and constipa-
tion compared with standard analgesic therapy, but
with minimal clinical significance. Eisenberg et al.
performed a meta-analysis of the efficacy of NCPB for
cancer pain.51
Twenty-four articles met their inclusion
criteria and consisted of 21 retrospective studies, 1 pro-
spective study, and 2 RCTs. One of the included RCTs
was the Mercadante article previously mentioned. Their
analysis suggested that: NCPB had long-lasting benefit
(>3 months) for 70 to 90% of patients with pancreatic
and other intra-abdominal cancers; adverse effects were
common, but transient and mild; and severe adverse
effects were uncommon.
Lumbar Sympathetic Block
The lumbar sympathetic chain lies at the anterolateral
border of the vertebral bodies. There is considerable
variation in the size, number, and position on the verte-
bral bodies of the ganglia.34
The aorta is positioned
anteriorly and slightly medial to the left sympathetic
chain. The inferior vena cava is more closely approxi-
mated to the chain on the right in an anterior plane.
Many other small lumbar arteries and veins are posi-
tioned near the sympathetic chain. Blockade of the
Sympathetic Blocks: The Evidence • 103

7. lumbar sympathetic chain is indicated for CRPS I and II,
peripheral neuropathy pain, and sometimes performed
for ischemia-related pain. Hypotension secondary to
vasodilatation is a common side effect. Complications
from blockade and/or neurolysis are bleeding, nerve
root injury, genitofemoral neuritis/neuralgia, paralysis,
neuraxial injection, and renal puncture or trauma.
The literature search produced 12 articles of which 1
was eliminated secondary to it discussing surgical sym-
pathectomy. The remaining 11 are listed in Table 6.52–62
A grade of 1C was given to references 51 to 59 as these
were low-quality evidence, but the procedure was
strongly recommended for situations where analgesics
were ineffective for controlling pain. Two articles
received a 1B grade.
Haynsworth and Noe published a prospective, ran-
domized study comparing radiofrequency denervation
vs. phenol neurolysis for percutaneous lumbar sympa-
thectomy.61
The purpose of the study was to compare
duration of blockade, incidence of postsympathectomy
neuralgia, and other complications between the 2 tech-
niques. After temporary relief of RSD symptoms by
local anesthetic sympathetic block, 17 patients were
randomized to 2 groups for percutaneous denervation
with phenol (n = 9) or radiofrequency thermocoagula-
tion (n = 8). Duration of sympathetic block was fol-
lowed by a sweat test and temperature measurements.
The results of the study showed that 89% of patients in
the phenol group had evidence of sympathetic block
after 8 weeks as compared with 12% in the radiofre-
quency group. This was a statistically significant finding.
The incidence of postsympathectomy neuralgia was
22% with phenol and 0% with radiofrequency dener-
vation. There were no other adverse effects or compli-
cations associated with either technique.
Cross and Cotton did a randomized, prospective,
double-blinded, controlled trial on chemical lumbar
sympathectomy for ischemic rest pain.62
Thirty-seven
consecutive patients involving 41 limbs (some patients
had bilateral disease) were entered into the trial. After
randomization with computer-designated cards, 24
limbs were assigned to the treatment (phenol) group and
17 to the control (bupivacaine) group. Baseline param-
eters on analgesic use (as a measure of resting pain), skin
potential response (as an objective measure of the
success of sympathetic ablation), ankle-brachial index,
and blood flow across the dorsum of the foot were
recorded prior to the injection. The same parameters
were measured 24 hours, 7 days and 4 to 6 months after
the injection. There was a statistically significant reduc-
tion in rest pain (83.5% of the treatment group vs.
23.5% of the control group) at 1 week. This remained
significant at 6 months (66.7% of the treatment group
vs. 23.5% of the control group). The skin potential
response was significantly diminished at 1 week. After
the paravertebral block, there was a significant change
in the in the ankle-brachial systolic pressure index
within the phenol group at 24 hours and at 1 week, but
there was no significant difference when compared with
the control values at the same intervals. With regard to
blood flow across the dorsum of the foot, paravertebral
block did not produce a significant increase in resting
blood flow or increase in hyperemic peak blood flow in
the foot. In light of the above results, they concluded
that paravertebral block can be offered as an initial pain
relieving procedure while other diagnostic studies are
being performed and may also serve a purpose if recon-
structive procedures are not feasible.
Hypogastric Plexus Block
The superior hypogastric plexus is a retroperitoneal
structure located slightly left of midline at the level of
the lower 3rd of the 5th lumbar vertebral body and
upper 3rd of the sacral vertebral body at the sacral
Table 6. Summary of Lumbar Sympathetic Block/Neurolysis Articles
Authors Study Type Diagnosis No. of Patients Grade of Recommendation
Wettrell et al.51
CR RSD 2 1C
Plancarte, Calvillo52
CR Causalgia 1 1C
Tomlinson53
CR Ischemia/pain 1 1C
Furlan et al.54
CR Neuropathic pain 1 1C
Hughs-Davies, Redman55
CS Ischemia/pain 97 1C
Bristow, Foster56
CS Rectal tenesmoid pain 1 1C
Alexander57
CS Ischemia/pain 489 1C
Rocco58
CS Sympathetically maintained pain 20 1C
Ohno, Oshita59
CS Lower extremity pain 12 1C
Haynsworth, Noe60
P,R RSD 17 1B
Cross, Cotton61
P,RCT Ischemic rest pain 37 1B
CR, case report; CS, Case series; P,R, prospective, randomized; P,RCT, prospective, randomized, controlled trial; RSD, reflex sympathetic dystrophy.
104 • day

8. promontory and in the vicinity of the bifurcation of the
common iliac vessels.63
The plexus branches right and
left and descends into the pelvis as the inferior hypogas-
tric plexus which gives rise to the pelvic, middle rectal,
vesicle, prostatic, and uterovaginal plexus. It contains
postganglionic sympathetic fibers and afferent visceral
pain fibers. Many preganglionic parasympathetic fibers
run independently and to the left of the superior hypo-
gastric plexus. The inferior hypogastric plexus receives
more parasympathetic fibers from the 2nd, 3rd, and 4th
sacral levels. The block is indicated for benign and
malignant pain affecting the pelvic visceral structures.
The classic posterior approach for blockade was intro-
duced by Plancarte et al. in 1990. Complications include
intravascular injection, neuraxial injection, discitis,
urinary injury, and bladder/bowel incontinence.
The online literature search yielded 10 articles: 4 case
reports, 5 case series, and 1 prospective, randomized
trial. These are summarized in Table 7.64–72
The case
reports and case series received a grade of 1C. The
prospective, randomized trial by Gamal et al. was
graded a 1B.73
They compared the classic posterior
approach to blockade of the superior hypogastric plexus
with the transdiscal technique. Thirty patients were pro-
spectively, randomly allocated to 2 groups: the transdis-
cal group and the classic group. The VAS pain scores,
daily morphine consumption, duration of the proce-
dure, and side effects were recorded. Time points were
prior to the block and 24 hours, 1 week, 1 month,
2 months, and 3 months after the block. The VAS pain
scores were significantly decreased at all time points
except at 3 months where there was no significant
difference from baseline. There was no statistically
significant difference between the 2 groups at any mea-
surement time regarding VAS pain scores. The daily
morphine consumption followed the same trend and
statistical significance as the VAS scores. The duration of
the procedure was significantly decreased in the trans-
discal group compared with the classic group. Two
patients in the classic group did not get pain relief.
Complications were experienced in the classic group,
but none occurred in the transdiscal group. Based on the
aforementioned data, they concluded that the transdis-
cal technique was easier, safer, and more effective with
fewer side effects than the classic approach.
Ganglion Impar
The ganglion impar is the terminal ganglion of the sym-
pathetic chain. It is a single ganglion and although the
anatomy is variable, it is usually found just caudal of
the sacrococcygeal junction. It is also referred to as
“Walther’s Ganglion.” Plancarte et al. first described the
technique of ganglion impar block in 1990.74
A literature search produced 5 articles. One article
was purely a technique article75
and was not included.
The remaining articles consisted of 3 case reports and
1 prospective case series and are summarized in
Table 8.76–79
All received a grade of 1C, ie, strong rec-
ommendation, low-quality evidence. The strong recom-
mendation is secondary to the indications for the block:
vulvar cancer pain, chronic perineal pain, and sacral
postherpetic neuralgia. Low quality of evidence was
assigned as all were case reports or case series.
DISCUSSION
For any pain diagnosis, a treatment algorithm must be
developed. Commonly, conservative treatment with oral
medication, physical therapy, and/or psychological
therapy is attempted first. If these are successful, then
the patient continues with this treatment plan. When
conservative therapy is partially effective or altogether
ineffective, then interventional procedures should be
considered. The big question is: are the interventional
procedures effective and is this effectiveness backed by
Table 7. Summary of Hypogastric Plexus Block/Neurolysis Articles
Authors Study Type Diagnosis No. of Patients Grade of Recommendation
Rosenberg et al.63
CR Penile pain 1 1C
Kanazi et al.64
CR Endometriosis 3 1C
Wilsey, Ashford, Dolin65
CR Pelvic CA pain 2 1C
Mickalek, Dutka66
CR Non-CA pelvic pain 2 1C
Wechsler et al.67
CS Endometriosis 5 1C
Plancarte et al.68
CS Pelvic CA pain 227 1C
de Leon-Casasola et al.69
CS Pelvic CA pain 26 1C
Plancarte et al.70
CS Pelvic CA pain 28 1C
Erdine et al.71
CS Pelvic CA pain 20 1C
Gamal et al.72
P,R Pelvic CA pain 30 1B
CR, case report; CS, case series; P,R, prospective, randomized; CA, cancer.
Sympathetic Blocks: The Evidence • 105

9. the literature? We pain practitioners would most likely
say “Yes” as all of us have anecdotal evidence in our
own pain practices that support the use of interventional
procedures when conservative therapy partially or
completely fails. Unfortunately, anecdotal evidence is
not good, hard evidence. We (as do insurance com-
panies) would like prospective, randomized, placebo-
controlled, blinded studies. Are these available? The
answer is “Yes” but in small numbers. With that
said, what can be said about sympathetic blocks and
neurolysis?
From this review, the only block that has multiple
grade 1B evidence is the CPB/SNB and neurolysis. There
were 5 prospective, randomized, comparative studies (2
blinded), and 2 meta-analysis.46–51
The main thing that
prevented them from receiving a 1A grade was the
number of patients in the treatment groups. One meta-
analysis included a large number of patients, but the
majority of the articles included were retrospective
analyses.51
It is commonly accepted to perform this
block in situations where oral therapy is not effective.
The analgesia provided by the block/neurolysis is
significant.
One stellate ganglion article was a prospective,
double-blinded, placebo-controlled study, but was
graded as 1C because there were only 4 patients in the
treatment group.31
Two lumbar sympathetic block (LSB)
articles received a 1B grade. The studies did not receive
a 1A grade as the Haynsworth and Noe compared 2
types of lumbar sympathetic neurolysis and did not have
a control group, while the Cross and Cotton article used
a bupivacaine LSB as the control group.60,61
The hypo-
gastric article by Gamal et al. could not receive a 1A
grade as it was a comparative study as well with no
control group.72
As for the rest of the articles, almost all received a 1C
grade, ie, strong recommendation, low- to very-low-
quality evidence, as they were case reports and series.
With very limited evidence regarding the percutaneous
thoracic sympathetic block and neurolysis, its efficacy
remains to be seen. This block definitely needs to be
further studied.
Does this mean that based on the evidence, we should
not perform these procedures on our patients? The
answer is “No” and this is why:
1. These procedures are offered to patients whose
pain has proven refractory to conservative
therapy. They deserve to be offered a treatment
that may be effective albeit 1A studies may be
few or lacking. These blocks can help reduce the
requirement for oral analgesics while decreasing
tolerance and side effects which develops with
increasing doses and prolonged use. There is evi-
dence in a 20-patient case series of reduction in
mechanical allodynia and improved function in
the extremity after sympathetic blocks.80
2. The benefits of these procedures outweigh the
risks when performed by properly trained pain
practitioners. Physicians need to know their
limits. If they cannot safely perform the proce-
dure, the patient needs to be referred to some-
body who can.
3. The treatments should be performed for diag-
noses that are supported by the literature and
when conservative therapy is ineffective. In the
case of pancreatic cancer pain, a CPB and neu-
rolysis should be performed early in the treat-
ment algorithm as the analgesia provided can be
profound and decrease the requirement of tradi-
tional NSAID/opioid medications. I would not
recommend doing any of these procedures for
diagnoses outside those commonly reported in
the literature.
4. The reimbursement for these procedures, at least
by United States Medicare fee schedules, is rea-
sonable as most can be performed in a clinic
setting without sedation. Non-facility Medicare
reimbursement ranges from $90.19 for a sphe-
nopalatine ganglion block to $408.87 for a neu-
Table 8. Summary of Ganglion Impar Block/Neurolysis Articles
Authors Study Type Diagnosis No. of Patients Grade of Recommendation
Love et al.75
CR CA pain 1 1C
McAllister et al.76
CR Postherpetic neuralgia 1 1C
Ho et al.77
CR CA 1 1C
Reig et al.78
P,CS Non-CA perineal pain 13 1C
CR, case report; P,CS, prospective case series; CA, cancer.
106 • day

10. rolytic hypogastric plexus block. A cost-analysis
for each block was not identified in the literature.
CONCLUSION
Grade 1A studies need to be performed, but this task
can be difficult. I would surmise that most patients in
pain would not want to have a sham procedure per-
formed on them which in the end makes it difficult to
have a good control group. Treatment groups need to be
large which can take years at an individual institution,
so multicenter studies need to be organized. This in itself
is also a daunting task.
When conservative therapy fails, the pain practitio-
ner needs to move forward in the treatment algorithm.
Sympathetic blocks and neurolysis can benefit patients
and need to be considered.
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