Pulsed Radiofrequency in Treatment of Peripheral Neuralgias All rights r

PRINTER-FRIENDLY VERSION AVAILABLE AT PAINMEDICINENEWS.COM
Pulsed Radiofrequency in
Treatment of Peripheral Neuralgias
LISA DOAN, MD
ll
A
Assistant Professor
Department of Anesthesiology
New York University School of Medicine
New York, New York
s
ite
d.
ib
te
oh
no
pr
e
is
is
rw
on
si
he
is
ot
m
er
ss
le
tp
un ou
up
ith
ro
w
G
rt
ng
pa
hi
in
is
bl
or
Pu
le
ho
on
ah in w
cM
n
M
tio
13
uc
20
od
©
pr
ht
Re
rig ed.
py
rv
se
re
ht
Co
rig
DILIP SIDHU, MD
Anesthesiologist
Department of Anesthesiology New York
Langone Medical Center
New York, New York
CHRISTOPHER GHARIBO, MD
Medical Director of Pain Medicine
NYU Langone Hospital for Joint Disease
Associate Professor of Anesthesiology
& Orthopedics
Department of Anesthesiology
New York University
School of Medicine
New York, New York
Dr. Doan, Sidhu and Gharibo have nothing to disclose.
A
lthough peripheral
neuralgias are treated
with a rich range of
options, they can be difficult to treat
effectively. Conservative management
may include physical therapy, topical
agents, and neuropathic medications.
d.
Interventional techniques include local
anesthetic and steroid injections, while
radiofrequency (RF) procedures offer
another interventional option.
I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G
PA I N M E D I C I N E N E W S S P E C I A L E D I T I O N • D E C E M B E R 2 0 1 3
57
Table. Thermal Radiofrequency Versus Pulsed Radiofrequency
Pulsed
Radiofrequency
Mechanism
Neurodestructive lesion
Neuromodulatory lesion
Cannula placement in relation to nerve
Parallel
Perpendicular
80o-85oC
<42oC
ll
A
Thermal Radiofrequency
s
ite
d.
ib
te
oh
no
pr
e
is
is
rw
on
si
he
is
ot
m
er
ss
le
tp
un ou
up
ith
ro
w
G
rt
ng
pa
hi
in
is
bl
or
Pu
le
ho
on
ah in w
cM
n
M
tio
13
uc
20
od
©
pr
ht
Re
rig ed.
py
rv
se
re
ht
Co
rig
Temperature setting
Duration of lesioning
60-90 seconds
2-6 minutes
Possible adverse effects
Neuritis, motor dysfunction
Low risk for these side effects
Benefits of Thermal and Pulsed
Radiofrequency
All interventional procedures, including RF methods, may offer several benefits. Interventions lack the
systemic side effects seen with medications. For RF
procedures, therapeutic effects are usually longer lasting than local anesthetic and steroid injections. Recovery is brief. Compared with thermal conventional RF,
pulsed radiofrequency (PRF) avoids the possible complications of postprocedure neuritis, motor dysfunction, and deafferentation pain.
Thermal Radiofrequency Versus
Pulsed Radiofrequency
Differences between thermal RF and PRF are summarized in the Table.
TECHNIQUE
58
I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G
MECHANISM
OF
ACTION
Thermal RF causes neurodestructive lesions. RF
of the dorsal root ganglia (DRG) in dogs and goats
showed indiscriminate destruction of unmyelinated
and myelinated fibers.2,3 Electron microscopy of rabbit DRG treated with RF showed cytoplasmic vacuoles, enlarged endoplasmic reticulum, degenerated
mitochondria, and loss of nuclear membrane although
the neurolemma integrity was maintained.4 Electron
microscopy of rat sciatic nerve treated with RF showed
Wallerian degeneration.5
The mechanism of action of PRF is less clear than that
of thermal RF. Most animal studies have shown a lack of
neurodestruction after PRF. In rabbit DRG treated with
PRF, electron microscopy showed no structural pathology in cell membranes, and myelinated and unmyelinated
d.
Thermal or conventional RF creates a thermal neurodestructive lesion at the active tip of an insulated
cannula. A circuit is created with a ground plate, an
insulated cannula with an active tip, tissues, and a generator. The generator produces an alternating current
and electrical field at the active tip of the cannula. The
electrical field causes charged molecules to oscillate,
generating heat in the surrounding tissues. Temperatures of 80oC to 85oC at the active tip will heat tissues
within a few millimeters to 60oC to 65oC, the temperature at which soft tissues coagulate. The lesion that
is created is spheroid in shape with its long axis along
the active tip of the cannula; thus, the cannula must be
placed parallel to the target nerve. The lesion is created at 80oC to 85oC for 60 to 90 seconds.1
PRF is thought to create a neuromodulatory lesion
rather than a destructive thermal lesion. It uses the
same circuit as used in thermal RF. However, the current is applied in brief pulses and at temperatures
lower than 42oC to avoid heating the target nerve.
A current of 50,000 Hz in 20 millisecond pulses is
applied at a frequency of 2 per second. The electric
field is densest at the tip of the cannula, so the cannula is often placed perpendicular to the target nerve.
The lesion is created at a temperature below 42oC for
2 to 6 minutes, depending on the area being lesioned.1
ll
A
fibers were normal.4 In rat sciatic nerve treated with PRF,
electron microscopy did not reveal any severe degeneration in myelinated axons.5 A recent study examined rat
DRG 1.5 hours after PRF; electron microscopy showed
cytoplasmic vacuoles, enlarged endoplasmic reticulum, and degenerated mitochondria. Some myelinated
axons appeared damaged, whereas unmyelinated axons
were intact.6 This seems to contradict the above studies
showing no histologic damage; however, note that this
study examined histology acutely after PRF treatment,
whereas the previous studies examined histology 2 to 3
weeks after PRF treatment. Two studies investigated the
role of c-fos, an immediate early gene involved in upregulating transcription of a diverse set of genes. In one
study, rats were sacrificed 3 hours after PRF was applied
to the cervical DRG. Expression of c-fos was increased
in the dorsal root and superficial laminae I and II of the
dorsal horn. Rats treated with thermal RF did not have
increased c-fos expression.7 In another study, however,
in which rats were sacrificed 7 days after treatment, significant increases in c-fos expression in the dorsal horn
were observed in both PRF and RF groups compared
with sham treatment.8 In a study using rat hippocampal
slices, PRF produced a transient decrease in the amplitude of excitatory postsynaptic potentials, whereas the
reduction with thermal RF lasted for the duration of
the experiment.9 In an inflammatory model of pain in
rats, analgesic effects of PRF of the sciatic nerve were
inhibited by an α2-adrenergic and a serotonin antagonist, suggesting a possible mechanism of action of PRF
involving noradrenergic and serotonergic descending
inhibitory pathways.10 In a spared nerve injury rat model
of neuropathic pain, the levels of met-enkephalin, an
endogenous opioid, were significantly higher in the spinal cord of animals treated with PRF of the DRG than
in control and sham groups.11 Thus, the mechanism of
action of PRF has not been clearly elucidated although
it is less destructive than thermal RF and may have a
neuromodulatory effect.
s
ite
d.
ib
te
oh
no
pr
e
is
is
rw
on
si
he
is
ot
m
er
ss
le
tp
un ou
up
ith
ro
w
G
rt
ng
pa
hi
in
is
bl
or
Pu
le
ho
on
ah in w
cM
n
M
tio
13
uc
20
od
©
pr
ht
Re
rig ed.
py
rv
se
re
ht
Co
rig
of 44 patients (16%) from the RF group versus 9 of
36 (25%) from the control group reported success
from treatment at 3 months. There was no difference
between the groups with regard to adverse events or
side effects.12
In a randomized, prospective study by Simopoulos
et al, 76 patients with chronic lumbosacral radicular
pain were randomized to receive either PRF or PRF
followed by continuous thermal RF of the DRG or segmental nerve. Seventy percent of the PRF-only group
and 82% of the PRF followed by RF group reported a
successful reduction in VAS score at the first followup period at 2 months. The authors concluded that the
thermal aspects of RF do not add any significant benefit to PRF. A majority of the patients lost the beneficial
effect by 8 months. Again, no significant side effects
or neurologic deficits were detected.14
Considering the relatively short-term benefit that
was observed, the authors conducted a follow-up
study to investigate whether repeat application provides the same analgesic effect without a higher risk
for complications. They retrospectively reviewed 50
patients who reported at least 50% pain relief after
PRF followed by continuous thermal RF of the lumbar DRG or segmental nerve. Forty patients underwent
a repeat procedure and reported a mean duration of
pain relief of 4.7 months. Twenty-eight patients continued on to receive a third treatment after the effect had
worn off, and the average duration of relief was 4.5
months. Eighteen patients had 5 or more treatments;
the duration of relief and success frequency remained
constant after each subsequent RF treatment. There
was one report of transient thigh numbness following a second therapy that resolved within a week. It
appears that PRF followed by continuous thermal RF
may be a time-sensitive pain management modality
with minimal risk to patients.13
Tsou et al reported on a prospective observational
study of PRF for chronic low back pain. In a group of
78 patients with both low back pain and lower limb
pain, 47.4% reported greater than 50% pain improvement at 3-month follow-up. At 1-year follow-up, 46%
continued to report greater than 50% pain relief.16 No
complications were reported in this study.
Van Boxem et al retrospectively observed 60 consecutive patients who presented for lumbosacral radicular
pain and were treated with single-level DRG PRF therapy. Using a 50% reduction in pain relief sustained for at
least 2 months, investigators found that 29.5%, 22.9%,
and 13.1% at 6, 8, and 12 months, respectively, reported
successfully meeting the end point. Mean duration of
action was 9.89 months, and there were no differences
in success based on age, sex, level, or history of prior
back surgery. Secondary end point measures such as
daily pain medication intake also were evaluated using
Lumbosacral Radicular Pain
d.
One of the most common problems seen in the
pain medicine specialty setting is chronic lumbosacral
radicular pain with a prevalence ranging from 9.9% to
25%.12 The evidence is mixed concerning RF therapy
providing long-term relief to these patients.
Geurts et al conducted a randomized controlled
trial (RCT) comparing thermal RF lesioning with sham
therapy in 83 patients and did not show any advantage of lumbrosacral DRG RF over sham therapy. The
primary outcome of the study was success or failure of treatment. Success was defined with a multidimensional decision rule based on reduction in median
visual analog scale (VAS) leg pain score, changes in
physical activities score, and use of analgesics. Seven
PA I N M E D I C I N E N E W S S P E C I A L E D I T I O N • D E C E M B E R 2 0 1 3
59
the Medication Quantification Scale III. There was a significant reduction in the success group.15 The success
rate in the study was considerably lower than in other
studies; possible explanations included limiting the therapy to a single intervention or single level, as it has been
hypothesized that injury at one level could produce
changes in adjacent levels. Another explanation for the
low success rate could be a longer follow-up period.
Chronic Cervical Pain Syndromes
A
ll
Van Kleef et al conducted a prospective, double-blind,
randomized study on 20 patients with at least 1 year
of intractable chronic cervicobrachial pain. The study
divided the patients into 2 groups: the RF group, which
received a 67oC RF lesion adjacent to the DRG and the
sham group, which received sham therapy in which no
actual RF lesion was made. Follow-up was conducted
at 1 and 8 weeks after therapy, and patients were evaluated using the VAS and McGill Pain Questionnaire. The
study demonstrated treatment success in 8 of 9 patients
randomized to the RF group and only 1 of 11 in the sham
group. There was a 77% chance with conventional RF
therapy of burning pain in the associated dermatome,
but the symptoms resolved spontaneously by 3 weeks.22
Van Zundert et al performed a retrospective review
of PRF for cervicogenic headache and cervicobrachialgia. All the patients had therapy targeted at the
DRG. Of 18 patients, 13 (72%) showed greater than
50% improvement in pain relief at the 8-week followup. Patients who demonstrated positive outcomes at 8
weeks continued to be monitored for long-term effect.
The success rate declined to 50% at 3 months and 33%
at 12 months, with a mean duration of effect lasting for
9.2 months. No major adverse events were reported.20
The investigators followed up these findings with
an RCT evaluating PRF for chronic cervical radicular pain. Twenty-three patients with cervical radicular pain were randomized to PRF of the DRG or sham
intervention. The primary outcome was success or
failure of treatment; success was defined as at least
50% improvement on the global perceived effect
scale and 20-point reduction in pain intensity on a
0 to 100 VAS scale. Nine of 11 (82%) patients in the
PRF group reported greater than 50% improvement
on the global perceived effect scale after 3 months
of follow-up as opposed to 4 of 12 (33%) in the sham
group. A 20-point reduction in VAS score was also
seen in 9 of 11 patients in the PRF group and 3 of 12 in
the sham group. Both these findings were statistically
significant. Pain medication intake was less in the
PRF group; however, significance was not reached.
No side effects were reported.21 The study was limited by a small sample size and differences in baseline demographic characteristics of the 2 groups. The
PRF group was younger and had a shorter duration
of pain. However, the results support the notion that
PRF may provide pain relief for carefully selected
patients with chronic cervical radicular pain.
Occipital Neuralgia
s
ite
d.
ib
te
oh
no
pr
e
is
is
rw
on
si
he
is
ot
m
er
ss
le
tp
un ou
up
ith
ro
w
G
rt
ng
pa
hi
in
is
bl
or
Pu
le
ho
on
ah in w
cM
n
M
tio
13
uc
20
od
©
pr
ht
Re
rig ed.
py
rv
se
re
ht
Co
rig
Occipital neuralgia (ON) may be one of the more
challenging conditions to treat. Conservative management includes medications, reducing secondary muscle tension, and improving posture with the hope of
reducing stress on the nerve. Reported interventional
options include nerve blocks, peripheral nerve stimulation, neurolysis, and dorsal root entry zone lesioning. PRF therapy has shown promising results as well.
Vanelderen et al prospectively studied 19 patients
with ON who responded favorably to a diagnostic local
anesthetic block and subsequently underwent PRF.
VAS and Likert scale scores were analyzed in addition to quality-of-life (QoL) and medication intake
questionnaires. Substantial pain improvement was
reported in 68.4%, 57.9%, and 52.6% of patients 1, 2,
and 6 months after PRF, respectively. The authors also
noted a significant decrease in medication use and
QoL parameters.18
Choi et al prospectively studied 10 patients who
underwent PRF for ON for a mean follow-up period of
7.5 months. Mean VAS score, measured on a 10-point
scale, dropped from 6.9 to 1.2 and 0.8 at 1- and 6-month
follow-up, respectively. The Total Pain Index (TPI), a
pain scale that measures the intensity and duration
of headaches, also was assessed. The mean TPI score
decreased from 232.7 to 53.7 and 40.6 over the same
time period. Eight of the 10 patients stopped using
analgesics completely, and no complications were
observed.19
Huang et al retrospectively analyzed 102 individuals who were treated for ON with PRF in an effort to
identify any patient-specific factors that could be predictive of successful therapy. Successful therapy was
defined as greater than 50% pain relief on a 10-point
numeric scale lasting at least 3 months; 51% of patients
met these criteria. Having a history of a previous inciting event, greater ON involvement only (as opposed
to having lesser ON or both), requiring lower injectate
volumes of local anesthetic during diagnostic workup,
and undergoing multiple cycles of PRF were all characteristics associated with good outcomes. In contrast, extensive pain anterior to the scalp apex, pain
that contained both neuropathic and nociceptive characteristics, and the possibility of ongoing secondary
gain issues all were associated with a negative result.
Symptoms radiating above the scalp apex could have
been suggestive of confounding pathology such as
migraine headaches. Six episodes of complications
were noted, primarily temporary worsening of pain, all
of which resolved within 3 weeks of onset.17
I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G
d.
60
ll
A
s
ite
d.
ib
te
oh
no
pr
e
is
is
rw
on
si
he
is
ot
m
er
ss
le
tp
un ou
up
ith
ro
w
G
rt
ng
pa
hi
in
is
bl
or
Pu
le
ho
on
ah in w
cM
n
M
tio
13
uc
20
od
©
pr
ht
Re
rig ed.
py
rv
se
re
ht
Co
rig
than 50% pain relief, and 6 (14.6%) had no improvement in pain. The authors addressed possible reasons
for treatment failure such as a more localized action of
the RF lesion compared with the local anesthetic, heat
loss from nearby vessels, afferent fibers in the ventral
root, ectopic ganglion cells, intersegment nervous connections, placebo effect of the diagnostic block, or sympathetic maintenance of pain.23
Van Kleef et al reported on RF lesioning adjacent
to the DRG in 43 patients with chronic thoracic pain.
Inclusion and exclusion criteria were similar to those
of Stolker et al. Patients were divided into 2 groups.
Group 1 included 27 patients with symptoms limited
to no more than 2 segments, and group 2 comprised
16 patients with more than 2 segments involved. At
the first follow-up period of 8 weeks, 18 of 27 (67%)
patients in group 1 had positive outcomes: 6 (22%)
had complete relief, 8 (30%) had good relief, and 4
(15%) reported moderate relief. Of the patients in
group 1, 52% had long-term pain relief lasting more
than 36 weeks. Group 2 did not report such favorable outcomes: 2 (12%) reported complete pain relief,
1 (6%) had good relief, and 3 (18%) stated only moderate relief. Long-term pain relief was achieved in 30%
of patients. Fourteen patients experienced transient
burning, and 7 had slight hypoesthesia, all of which
resolved without therapy after 12 weeks. No other
major complications were reported.24
Cohen et al retrospectively analyzed data from 49
patients who received either PRF of the DRG, PRF of
intercostal nerves (ICN), or conservative medical management for chronic postsurgical thoracic pain. Key
inclusion criteria were duration of symptoms greater
than 3 months, VAS score greater than 5 on a 10-point
scale, and pain deemed to be neuropathic in origin based on history and physical exam. Patients in
the pharmacotherapy group received treatment with
either a secondary amine tricyclic antidepressant (nortriptyline or desipramine), or an anticonvulsant (gabapentin or oxcarbazepine) titrated to efficacy and side
effects. Successful treatment was defined as greater
than 50% pain reduction plus an affirmative answer to
2 questions centered on patient satisfaction and functional improvement. Fifteen patients received PRF of
ICN, 13 received DRG procedures, and 21 patients were
in the pharmacotherapy group. The average number
of levels treated was 2.6 in the DRG group and 2.5 in
the ICN group. At 6-week follow-up, patients in the
DRG, ICN, and medical management groups had 61.5%,
28.6%, and 27.3% success rates, respectively; however,
the difference between the DRG and ICN group did
not reach statistical significance. At the 3-month follow-up, success rates were 53.8% for the DRG group
and only 6.7% for the ICN group; this was a statistically significant difference. Mean duration of relief was
Figure. Pulsed radiofrequency for
trigeminal neuralgia.
In patients whose pain has been refractory to other
forms of therapy, such as occipital nerve stimulation, neurolysis, or dorsal root entry zone rhizotomy, PRF shows
efficacy with fewer complications. Further study is warranted to establish a more concrete consensus on its role.
Intercostal Neuralgia/Chronic Thoracic Pain
d.
Pain in the thoracic region, whether it is intercostal
or multifactorial, historically is difficult to treat.
Stolker et al reported on 45 patients with chronic thoracic segmental pain who had failed conservative treatment and underwent thermal RF of the DRG. Inclusion
criteria included a segmental distribution and temporary relief with an intercostal nerve block using lidocaine. Symptoms were unilateral in all but one of the
patients and the duration of symptoms ranged from 6
months to 51 years. The initial follow-up was at 2 months,
and 30 patients (66.7%) were pain-free, 11 (24.4%) had
greater than 50% improvement, and 4 (8.9%) showed no
improvement. Six patients experienced transient burning
pain lasting 3 weeks, and 2 patients had slight sensory
loss in the corresponding dermatome, which improved
after 3 months. No patient suffered any motor loss or a
pneumothorax. Long-term follow-up was conducted in
41 patients with a mean follow-up of 25 months. Twenty
patients (48.8%) were pain-free, 15 (36.6%) had greater
PA I N M E D I C I N E N E W S S P E C I A L E D I T I O N • D E C E M B E R 2 0 1 3
61
11.5 weeks in the ICN group and 4.74 months in the
DRG group. Of the 21 patients in the medical management group, 7 (33%) experienced adverse side effects
including sedation, urinary retention, or persistent
nightmares. The ICN and DRG groups each had one
episode of pneumothorax.25
Trigeminal Neuralgia
ll
A
Trigeminal neuralgia (TN) historically is a difficult
condition to treat. Primary treatment is pharmacologic, with carbamazepine being the medication of
choice. If patients remain refractory to medication,
they may become candidates for surgical microvascular decompression. Other alternatives include balloon
decompression, retrogasserian glycerol injection, RF,
and PRF. PRF for TN is shown in the Figure.
The largest study with the longest follow-up period
for RF therapy in patients with TN was carried out by
Kanpolat et al. It followed 1,600 patients for a period of
1 to 25 years. In all, 2,138 procedures were conducted:
1,216 patients (78%) received a single treatment and
384 (24%) received multiple treatments. Acute pain
relief was achieved by 97.6%. The recurrence rate was
25.1% over the average follow-up period of 68.1 months
(± 66.4 months). Seven hundred and nineteen patients
were followed for 5 years; of these, 57.7% had complete
pain relief after a single RF procedure, and this rate
increased to 92% with multiple procedures. Three hundred and sixty-five patients were followed for 10 years,
and 94.2% reported pain control after single or multiple procedures. Thirty-nine patients were followed for
20 years, with 41% reporting pain control after a single procedure. The most common side effects were
an absent corneal reflex and masseter dysfunction.
The author stressed the importance of clinician experience as well as proper patient cooperation as variables directly related to success rates.26
The role of PRF in facial neuralgia has only gained
momentum in the past 10 years. Van Zundert et al first
reported on 5 patients who received PRF for idiopathic
TN. Mean follow-up was 19.2 months at 2-month intervals; 3 of 5 patients reported excellent results. These
patients had failed conservative, pharmacologic
options. The author did not comment on the pain scoring system; however, the 3 patients who were considered a success all reported they were “pain-free.” The
fourth patient required a repeat procedure 15 months
into follow-up, which provided complete relief at
the last follow-up period, 18 months after the study
commenced. No side effects or complications were
mentioned.27
Erdine et al conducted a prospective, randomized
double-blind study comparing PRF with conventional
RF therapy in 40 patients. Evaluation criteria included
VAS score on a 10-point scale, patient satisfaction
s
ite
d.
ib
te
oh
no
pr
e
is
is
rw
on
si
he
is
ot
m
er
ss
le
tp
un ou
up
ith
ro
w
G
rt
ng
pa
hi
in
is
bl
or
Pu
le
ho
on
ah in w
cM
n
M
tio
13
uc
20
od
©
pr
ht
Re
rig ed.
py
rv
se
re
ht
Co
rig
using the Patient Satisfaction Scale, additional pharmacologic requirements, and side effects. The results
did not support the use of PRF over RF. The preprocedure median VAS score was 9 in both groups, and
although the median VAS score was 0.5 at both 3- and
6-month follow-ups in the RF group, it remained 8.5 in
the PRF group at 3 months. Only 2 of 20 patients in
the PRF group achieved a significant decrease in the
VAS score, and in both cases, the pain recurred within
3 months. It was then decided to perform RF therapy on the PRF group as all patients still had intractable pain. At 3-month follow-up, these patients had
a median pain score of 1. All patients who underwent
RF reported mild hypoesthesia and paresthesia after
the procedure. One patient in the RF group developed
anesthesia dolorosa that was successfully managed
with medication.28
Fang et al investigated the efficacy of use of computed tomography (CT)-guided PRF for TN. The
3-dimensional CT-guided PRF therapy allowed for
more precise needle positioning. Goals of therapy
were pain reduction of 50% for at least 2 weeks using
a 10-point numeric rating scale. Of the 20 patients
included in the study, only 7 reported a favorable outcome at 2-week follow-up. Of these patients, only 2
did not have a relapse at 1-year follow-up.29 There were
no complications mentioned in the study.
I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G
Werner et al conducted a systematic review of
the literature to support the use of PRF in the management of chronic pain after inguinal hernia repair.
Although only 1% to 3% of patients will develop this
complication, this corresponds to an estimate of 6,000
to 18,000 patients every year given the routine nature
of herniorrhaphy. Their literature search yielded 4 case
reports analyzing 8 patients for efficacy of treatment.
Seven of the 8 patients received diagnostic blocks, 3
of the ilioinguinal nerve and 4 of the DRG. Pain relief
varied from 63% to 100% with 5 patients reporting at
least 90% pain relief; the follow-up period ranged from
3 to 9 months.30 No adverse effects or complications
were noted in any of the studies.
Pudendal Neuralgia
Pudendal neuralgia can present postoperatively but
also from repetitive bicycling or without any known
provocation. Rhame et al presented a case report of
a patient with 1.5 years of sharp pain in the left gluteal
and perianal region, which interfered significantly with
her QoL. The pain had been refractory to treatment
with multiple medications, as well as interventions such
as sacroiliac joint, epidural steroid, and piriformis injections. After the patient had a good response to a diagnostic pudendal nerve block, she elected to undergo
d.
62
Post-Inguinal Herniorrhaphy Pain
PRF therapy. After the procedure, she was successfully weaned from her multianalgesic therapy and had
improved sitting tolerance. At 1.5 years postprocedure,
she continued to report good sitting tolerance and pain
relief.31 There were no side effects or complications of
the therapy.
Glossopharyngeal Neuralgia
ll
A
Glossopharyngeal neuralgia (GPN) is not as common as TN, with an incidence of 0.7 per 100,000.32
Pain typically is shooting from the oropharynx upward
to the Eustachian tube. Surgical treatment has historically has been the treatment of choice; however, it is
associated with a high chance of complications. Chua
et al described 2 case reports of GPN that had been
managed successfully with PRF. The patients did not
receive diagnostic blocks because of the close proximity of the nerves to major vascular structures. The first
patient had a 15-year history of unilateral facial neuralgia. She had been worked up extensively and had
been refractory to previous medical management. She
reported complete pain relief at the point of her last
follow-up at 5 months. The second patient reported
her symptoms had persisted for more than 40 years.
This patient reported a reduction in pain intensity 2
weeks after the procedure, and at 4-month follow-up
she reported lasting pain relief. Although these results
show promise, the author highlighted the risk for bradycardia, asystole, and hypotension from vagal stimulation that can occur during the PRF procedure.32
mechanical compression from tight-fitting belts, obesity, pregnancy, or pelvic tumors. The condition also
may be idiopathic. The incidence is low, with one study
citing 4.3 in 10,000.33,34 Symptoms may resolve spontaneously or with the implementation of physical therapy, weight loss, and anti-inflammatory or antiepileptic
therapies. Patients who respond to local anesthetic
injection typically only benefit from temporary relief
and may be candidates for PRF therapy.
s
ite
d.
ib
te
oh
no
pr
e
is
is
rw
on
si
he
is
ot
m
er
ss
le
tp
un ou
up
ith
ro
w
G
rt
ng
pa
hi
in
is
bl
or
Pu
le
ho
on
ah in w
cM
n
M
tio
13
uc
20
od
©
pr
ht
Re
rig ed.
py
rv
se
re
ht
Co
rig
Philip et al published the first case report of PRF
treatment for meralgia paresthetica in a 33-year-old
morbidly obese woman. The patient had achieved
temporary relief with multiple nerve blocks but had
been refractory to physical and medical therapy. The
patient had good pain relief at 6-month follow-up.35
Meralgia Paresthetica
Meralgia paresthetica is a sensory mononeuropathy of the lateral femoral cutaneous nerve (LFCN),
which produces discomfort in the anterolateral aspect
of the thigh. Symptoms often develop because of
compression or irritation of the LFCN. Risk factors
for the development of meralgia paresthetica include
Chua et al presented two cases. Both individuals were able to achieve complete pain relief at both
6-week and 3-month follow-up intervals.32 Fowler et al
suggested the added benefit of ultrasound guidance
because of the variation in location of the nerve with
regard to the anterior superior iliac spine.33
Conclusion
Given the safety and emerging evidence, there
seems to be a role for RF and especially PRF in the
treatment of peripheral neuralgias. Future research
should focus on producing well-designed RCTs that
compare the effectiveness of RF therapy with current standards of care, especially for some of the lessstudied disease processes such as pudendal neuralgia,
GPN, and meralgia paresthetica.
Acknowledgment
I acknowledge Dr. John Delfino for providing the
image of PRF for TN.
References
1.
Bogduk N. Pulsed radiofrequency. Pain Med. 2006;7(5):396-407.
2. Smith HP, McWhorter JM, Challa VR. Radiofrequency neurolysis
in a clinical model: neuropathological correlation. J Neurosurg.
1981;55(2):246-253.
6. Protasoni M, Reguzzoni M, Sangiorgi S, et al. Pulsed radiofrequency effects on the lumbar ganglion of the rat dorsal root: a
morphological light and transmission electron microscopy study
at acute stage. Eur Spine J. 2009;18(4):473-478.
7. Higuchi Y, Nashold BS Jr, Sluijter M, et al. Exposure of the dorsal root ganglion in rats to pulsed radiofrequency currents
activates dorsal horn lamina I and II neurons. Neurosurgery.
2002;50(4):850-855.
d.
3. de Louw AJ, Vles HS, Freling G, et al. The morphological effects
of a radio frequency lesion adjacent to the dorsal root ganglion (RF-DRG)—an experimental study in the goat. Eur J Pain.
2001;5(2):169-74.
4. Erdine S, Yucel A, Cimen A, et al. Effects of pulsed versus conventional radiofrequency current on rabbit dorsal root ganglion
morphology. Eur J Pain. 2005;9(3):251-256.
8. Van Zundert J, de Louw AJ, Joosten EA, et al. Pulsed and continuous radiofrequency current adjacent to the cervical dorsal root
ganglion of the rat induces late cellular activity in the dorsal horn.
Anesthesiology. 2005;102(1):125-131.
5. Tun K, Cemil B, Gurcay AG, et al. Ultrastructural evaluation of
pulsed radiofrequency and conventional radiofrequency lesions in
rat sciatic nerve. Surg Neurol. 2009;72(5):496-500.
9. Cahana A, Vutskits L, Muller D. Acute differential modulation of
synaptic transmission and cell survival during exposure to pulsed
and continuous radiofrequency energy. J Pain. 2003;4(4):197-202.
PA I N M E D I C I N E N E W S S P E C I A L E D I T I O N • D E C E M B E R 2 0 1 3
63
10. Hagiwara S, Iwasaka H, Takeshima N, et al. Mechanisms of analgesic action of pulsed radiofrequency on adjuvant-induced pain in
the rat: roles of descending adrenergic and serotonergic systems.
Eur J Pain. 2009;13(3):249-252.
11. Wu B, Ni J, Zhang C, Fu P, Yue J, Yang L. Changes in spinal cord
met-enkephalin levels and mechanical threshold values of pain
after pulsed radio frequency in a spared nerve injury rat model.
Neurol Res. 2012;34(4):408-414.
12. Geurts JW, Van Wijk RM, Wynne HJ, et al. Radiofrequency lesioning of dorsal root ganglia for chronic lumbosacral radicular
pain: a randomized, double-blind, controlled trial. Lancet. 2003;
361(8351):21-26.
A
ll
13. Nagda JV, Davis CW, Bajwa ZH, et al. Retrospective review of the
efficacy and safety of repeated pulsed and continuous radiofrequency lesioning of the dorsal root ganglion/segmental nerve for
lumbar radicular pain. Pain Physician. 2011;14(4):371-376.
a prospective double blind randomized study. Neurosurgery.
1996;38(6):1127-1132.
23. Stolker RJ, Arnoud CM, Vervest CM, et al. The treatment of
chronic thoracic segmental pain by radiofrequency percutaneous
partial rhizotomy. J Neurosurg. 1994;80(6):986-992.
24. Van Kleef M, Barendse GA, Dingemans WA, et al. Effects of producing a radiofrequency lesion adjacent to the dorsal root
ganglion in patients with thoracic segmental pain. Clin J Pain.
1995;11(4):325-332.
s
ite
d.
ib
te
oh
no
pr
e
is
is
rw
on
si
he
is
ot
m
er
ss
le
tp
un ou
up
ith
ro
w
G
rt
ng
pa
hi
in
is
bl
or
Pu
le
ho
on
ah in w
cM
n
M
tio
13
uc
20
od
©
pr
ht
Re
rig ed.
py
rv
se
re
ht
Co
rig
25. Cohen SP, Sireci A, Wu CL, et al. Pulsed radiofrequency of
the dorsal root ganglia is superior to pharmacotherapy or
pulsed radiofrequency of the intercostal nerves in the treatment of chronic postsurgical thoracic pain. Pain Physician.
2006(3);9:227-236.
14. Simopoulos TT, Kraemer J, Nagda JV, et al. Response to pulsed
and continuous radiofrequency lesioning of the dorsal root ganglion and segmental nerves in patients with chronic lumbar
radicular pain. Pain Physician. 2008;11(2):137-144.
15. Van Boxem K, van Bilsen J, de Meji N, et al. Pulsed radiofrequency
treatment adjacent to the lumbar dorsal root ganglion for management of lumbosacral radicular syndrome: a clinical audit. Pain
Med. 2011;12(9):1322-1330.
16. Tsou HK, Chao SC, Wang CJ, et al. Percutaneous pulsed radiofrequency applied to the L-2 dorsal root ganglion for treatment
of chronic low back pain: 3-year experience. J Neurosurg Spine.
2010;12(2):190-196.
17. Huang JHY, Galvagno Jr SM, et al. Occipital nerve pulsed radiofrequency treatment: A multi-center study evaluating predictors
of outcome. Pain Med. 2012;13(4):489-497.
18. Vanelderen P, Rouwette T, Vooght PD, et al. Pulsed radiofrequency for the treatment of occipital neuralgia. Reg Anesth Pain
Med. 2010;35(2):148-151.
19. Hyuk JC, Oh IH, Choi SK, et al. Clinical outcomes of pulsed
radiofrequency neuromodulation for the treatment of occipital
neuralgia. J Korean Neurosurg Soc. 2012; 51(5):281-285.
20. Van Zundert J, Lame IE, de Louw A, et al. Percutaneous pulsed
radiofrequency treatment of the cervical dorsal root ganglion in
the treatment of chronic cervical pain syndromes: a clinical audit.
Neuromodulation. 2003;6(1):6-14.
21. Van Zundert J, Patijn J, Kessels A, et al. Pulsed radiofrequency
adjacent to the cervical dorsal root ganglion in chronic cervical
radicular pain: a double blind sham controlled randomized clinical
trial. Pain. 2007;127(1-2):173-182.
22. Van Kleef M, Liem L, Lousberg R, et al. Radiofrequency lesion
adjacent to the dorsal root ganglion for cervicobrachial pain:
26. Kanpolat Y, Savas A, Bekar A, et al. Percutaneous controlled
radiofrequency trigeminal rhizotomy for the treatment of idiopathic trigeminal neuralgia: 25-year experience with 1600
patients. Neurosurgery. 2001;48(6):524-532.
27. Van Zundert J, Brabant S, Van de Kelft E, et al. Pulsed radiofrequency treatment of the Gasserian ganglion in patients with
idiopathic trigeminal neuralgia. Pain. 2003;104(3):449-452.
28. Erdin S, Ozyalcin NS, Cimen A, et al. Comparison of pulsed radiofrequency with conventional radiofrequency in the treatment of
idiopathic trigeminal neuralgia. Eur J Pain. 2007;11:309-313.
29. Fang L, Ying S, Tao W, et al. 3D CT-guided pulsed radiofrequency
treatment for trigeminal neuralgia. Pain Pract. 2013. [Epub ahead of print]
30. Werner MU, Bischoff JM, Rathmell JP, et al. Pulsed radiofrequency
in the treatment of persistent pain after inguinal herniotomy: a
systematic review. Reg Anesth Pain Med. 2012;3:340-343.
31. Rhame E, Levey K, Gharibo C. Successful treatment of refractory
pudendal neuralgia with pulsed radiofrequency. Pain Physician.
2009;12(3):633-638.
32. Chua NH, Beems T, Vidders KC. Two cases of glossopharyngeal
neuralgia successfully treated with pulsed radiofrequency treatment. Ann Acad Med. 2011;40(8):387-389.
33. Fowler I, Tucker A, Mendez RJ. Treatment of meralgia paresthetica with ultrasound-guided pulsed radiofrequency ablation of the
lateral femoral cutaneous nerve. Pain Pract. 2011;12(5):394-398.
34. Patijin J, Mekhail N, Hayek S, et al. Meralgia paresthetica. Pain
Pract. 2011;11(3):302-308.
35. Philip CN, Candido KD, Joseph NJ, et al. Successful treatment of
meralgia paresthetica with pulsed radiofrequency of the lateral
femoral cutaneous nerve. Pain Physician. 2009;12(5):881-885.
d.
64
I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G