Objectives: In this study, we aim to show our eligible experience in the treatment of patients with chronic pelvic pain attributed to pudendal neuralgia and not responding to conventional drugs or rehabilitation by methods of serial injections and surgery.
Methods: This study was conducted in a private medical centre (Humanitas San Pio X) in Milan/Italy. Data collected from records of 169 patients treated for pudendal neuralgia from June 2006 till May 2018. Patients were diagnosed to have pudendal neuralgia by means of clinical diagnosis, pudendal nerve blocks, and neurophysiologic studies. Treatment by perineural pudendal injections (PNPI) was offered to all patients. Surgery was considered for patients who met the Nantes criteria with a positive pudendal block but persistent pain after injections. Type and approach of surgery were trans-gluteal or trans-ischiorectal pudendal neurolysis.
Results: The total number of patients is 169; 118 females and 51 males. The mean age of patients was 53.2 years. 66.3% of patients responded well to PNPI; 20.5% had a complete recovery, 79.5% had a positive temporary response. 33.7% of patients did not benefit from PNPI. A total number of 43 patients were considered for surgery. 72% of patients after surgery responded well; 13 had a complete recovery and 18 showed improvements> 80% in a VAS scale. Twelve patients did not improve after surgery.
Conclusion: Pudendal neuralgia is an infrequent cause of chronic pelvic pain affecting the quality of patient's life. PNPI and pudendal neurolysis can give hope to most of the patients with good results.
Keywords: Pudendal nerve, Neuralgia, Pudendal injections, Neurolysis.
JRMS April 2020; 27 (1): 10.12816/0055463
The pelvis is innervated to a large extent by the pudendal nerve (PN) which is a mixed sensory, motor, and autonomic nerve. The pudendal nerve arises from the sacral plexus and is formed by the second, third, and fourth sacral nerve roots
The nerve exits the pelvis through the greater sciatic foramen,
crossing the ischial spine, between the sacrospinous ligament (SS), and the
sacrotuberous ligament (ST).1 PN entrapment is a painful condition
causing Pudendal neuralgia (PNa) (also called Alcock’s syndrome) that is
frequently difficult to diagnose and is fundamentally a clinical finding. Most of
the patients who suffer from PNa are females with nearly one out of seven women
affected by chronic pelvic pain, and
it’s most likely due to etiological factors such as the long list of
gynecological causes.2,3 These patients have sought medical attention
by visiting multiple doctors regularly complaining of chronic pelvic pain, and
are frequently offered multiple diagnoses and treatments without resolution of
symptoms.4 The diagnosis is often obscure leading to several
modalities of treatment. The International Pudendal Neuropathy Association
evaluates the incidence of PNa to be 1:100,000, but, because it is often
overlooked as a diagnosis, the incidence may be much higher.5
There are multiple sites of
pudendal nerve entrapment (PNE), and the presentation may be different with
different entrapments. A group of clinicians (the Nantes group) set up in 2008
the diagnostic criteria for PNE in which the five essential criteria including
pain in the distribution of the PN, pain predominately with sitting, that does
not wake the patient at night, no objective sensory deficit on clinical exam,
and pain relieved by diagnostic pudendal nerve block.6 Initially PNa
was called "cycling syndrome" because the first identified etiology
for its occurrence was cycling attributed to mechanical compression of PN.7
Other causes of PNa are
direct injuries to the nerve during pelvic prolapse surgery using mesh and
gynecological surgeries like hysterectomy and anterior colporrhaphy which could
be explained theoretically by bleeding from the procedures into the Alcock's
canal leading to scarring.8 Traumatic falls on the buttock or back
or vaginal delivery with or without instrumentation also are considered as part
of etiology of PNa from a mechanical point of view. Non-mechanical or
biochemical causes of PNa are usually uncommon; including viral infection
(herpes zoster, HIV), diabetes, multiple sclerosis, and others.9,10 Regarding
entrapment of the PN, the nerve could be trapped or compressed at greater
sciatic foramen, between SS and ST ligaments, and in the Alcock's canal; with
the interligamentous space being the most common site of entrapment (>90%).11
Various tests are used to aid in the diagnosis of PNa including diagnostic
blocks of the pudendal nerve, pudendal nerve motor terminal latency (PNMTL),
sensory threshold testing, Doppler ultrasound, and functional MRI. The
diagnostic pudendal nerve block is part of the Nantes criteria and can be
performed both unguided or with the use of electrical or image-guided
techniques.12, 13 PNa can often be treated conservatively or by
medical treatment, or by injections, considering surgery in the case of failure
of previous managements. In this study the main concern will be the outcome of
PNPI and surgical decompression in the treatment of PNa.
This is a retrospective study of
prospectively collected data from records of 169 patients who received
treatment for pudendal neuralgia in the period from June 2006 till May 2018 in
a private medical centre (Humanitas San Pio X) in Milan/Italy.
Nantes criteria for PNa were applied on patients to aid in the diagnosis
including pudendal nerve blocks and also, neurophysiologic studies. Diagnostic
pudendal blocks were performed using electrical stimulation through
a needle with infiltration of Bupivacaine 0.25% 5
cc around the pudendal nerve. The diagnosis was confirmed when patients
documented disappearance of pain after nerve block (positive block). For
neurophysiologic investigation we used PN somatosensory evoked potential
(SSEP), sacral reflex and PN motor terminal latency (PNMTL) to objectively
assess integrity of pudendal nerve and degree of affection.
Abnormal values were considered for latencies more than 3.5 milliseconds in
PNMTL, P40, N50 and P40-N50 were evaluated with SSEP.
pudendal injections (PNPI) were offered to all patients with persistent pain
after conservative treatments. PNPIs were usually achieved in a similar way to
the diagnostic block injecting Bupivacaine 0.25% 5 cc and Methylprednisolone 40 ml around the pudendal
nerves with two blocks, between the SS and ST ligaments and one into Alcock's
canal between the obturator muscle and its fascia. When patient
documented an improvement of symptoms PNPI was continued for a series of three
PNPI at 4 weeks interval 0, 4, and 8. Surgery was considered for patients who
met the Nantes criteria with a positive pudendal block but persistent pain
after PNPI. Type and approach of surgery were selected by our surgeons
according to experience. Trans-gluteal and trans-ischiorectal pudendal
neurolysis were the two surgical approaches.
approach with a buttock incision at the level of ischial spine explores the ST,
SS ligaments and Alcock's canal through which relieving compression on PN.
Trans-ischiorectal approach was performed on a female patient through a small
incision which was made in the back of the vagina and the surgeon cut the SS
ligament to release the compression between the ST and SS ligaments. Also, the
surgeon explored the Alcock’s canal by finger dissection and released the nerve
from any tethering fascia. Visual Analogue Scale (VAS) was used to subjectively
measure the responses of patients to our diagnostic and therapeutic procedures.
Patients were instructed to point to the position on a line between two faces
to indicate how much pain they are currently feeling. The far left face
indicates "no pain" and the far right one indicates "worst pain
ever." The mean time for follow up of patients was for 32.3 months (2-101)
in the form of regular visits to out-patient clinic and/or contacting them by
phone call. Patients with anal fissure, abscess, inflammatory bowel disease,
solitary rectal ulcer, prostatitis, pelvic endometriosis, neurologic diseases,
and psychiatric disorders were excluded. Approval for the conduction of the
study was given by both the ethical committee of the hospital and patients.
Appropriate tests were applied for statistics.
The total number of patients was 169; 118 were females and 51 males. The
mean age of patients was 53.2 years (28-78). All patients were diagnosed to
have PNa according to Nantes criteria; 80% had also an abnormal value at
neurophysiologic investigation (SSEP and PNMTL). Fifty seven patients (33.7%)
had no improvement after a series of three PNPI. Eight patients (4.7%) showed
no response to the first injection of PNPI series and management had been
abandoned. Six percent of patients underwent repeated courses of the three PNPI
series but showed no improvement. Approximately 66.3% of patients (112)
responded well to PNPI series; 20.5% (23) had a complete recovery, while 79.5%
(89) had a positive temporary response. The total number of patients considered
for surgery was 43 (25.4%); 17.7% (30) who showed no improvement after PNPI
series but with positive block, and 7.7% (13) among the patients who showed a
PNPI positive temporary response.
Forty-two patients underwent trans-gluteal pudendalneurolysis, while one
patient underwent trans-ischiorectal pudendal nerve decompression surgery.
After surgery 72% of patients did respond well; 13 (30%) complete recovery and
18 (42%) showed improvements (> 80% in a VAS scale). Twelve (28%) patients did not improve after surgery.
therapy is considered as the core treatment for PNa. Prevention of certain
exercises like cycling and adduction at hip joint is important along with
modification of lifestyle behavior and work environment that lead to minimize
sitting and so decrease pressure on pudendal nerve.
pain of PNa produces spasm in pelvic floor muscles which in turn adds more
pressure on the pudendal nerve causing an increase in levels of pain. This
vicious circle seems difficult to break, leading to peripheral and central
sensitization of pain. Nevertheless 20%-30% of patients following lifestyle
modification are predicted to improve.14once patients did not
respond well to lifestyle modifications; medications can play a role in
treatment such as muscle relaxants, anticonvulsants, antidepressants, and
In this study
66.3% of patients who did not respond to conservative treatments showed
improvements after PNPI in accordance with the results of a study conducted by
Vancaillie in 2012.17
PNPI is an
imperative treatment for PNa through which local anesthetics (to block the
nerve) and steroids (to minimize inflammation) are injected around the nerve
and this is performed both image guided by fluoroscopy, ultrasound, or CT scan
or using electrical stimulation through a needle or unguided and transvaginal
in women. PNPI aims to relieve pain initially with
Bupivacaine which is of rapid onset; lasting hours to a few days. But for
longer term effect corticosteroids are used with onset after 1‐3 days; lasting
0‐5 weeks.Symptoms relief after PNPI may last hours, days, weeks and they may
completely resolve after one, two, or three PNPI. Failure of PNPI
to relieve pain may occur in case of severe nerve compression, presence of
concurrent Pain Generators like Maigne syndrome or posterior ramus syndrome,
and injections into ischio-anal fat rather than Alcock's canal.12, 18, 19
neurolysis surgery is usually considered after failure of conservative
therapies. The length, degree, and etiology of nerve injury usually affect the
outcomes from PN decompression surgery. The four approaches are the
trans-gluteal, the trans-ischiorectal fossa, the perineal, and the
laparoscopic. One of the most commonly used approaches is the trans-gluteal one
which was described by Roger Robert in which a good visualization of the nerve is
achieved. The sacrotuberous and sacrospinous ligaments are divided to relieve
compression on the nerve at the ischial spine. Alcock’s canal is also explored
to free the nerve from any tethered fascia.19
trans-ischiorectal fossa approach described by Bautrant, a small incision is
made in the back of the vagina and the surgeon divides the sacrospinous
ligament to release the compression between the ST and SS ligaments. Again
Alcock’s canal is explored by finger dissection and the nerve is released from
any fascia that might be tethering it. Bautrant showed the response to 104
decompression surgeries; with 62% (38 out of 62 patients) of totally
asymptomatic patients after 1 year.20
approach was described by Shafik. In this technique (Anterior approach); the
patient is in the lithotomic position, a vertical para-anal incision 2 cm from
anal orifice is made and the ischio-rectal fossa is entered across which the
inferior rectal nerve is identified and hooked by finger and traced to PN in
the pudendal canal where fasciotomy can be performed. This approach is totally
blind using surgeon's finger and Shafik reported disappearance of pain in 9
women out of 11.21, 22
laparoscopic surgery, the SS ligament is divided allowing visual access of the
nerve at the ischial spine and Alcock’s canal. The nerve is released from
scarring, fibrotic tissue, and swollen varicose veins. A solution of heparin
may be infused into the area to prevent scar tissue formation.5, 23
The outcome of
surgical decompression of PN through the previously mentioned approaches is
reviewed in literature and summarized in (Table I).
Table I: Comparison of the surgical outcome of PN decompression.
de Bisschop 24
Possover M 25
Popeney C 27
literature almost 40 % of patients who underwent decompression surgery have
significant improvement in pain and 30 % have some improvement while the
remaining 30 % have no change in pain. However it is considered a successful
surgery if there is at least a 50% reduction in pain and symptoms.2
showed 72% improvement in patients with PNa treated by surgical decompressions
which were comparable to what is evident in literature. According to our study, 30% had a complete
recovery and 42% showed an improvement> 80% in a VAS scale after nerve decompression.
Pudendal neuralgia is an infrequent cause of
chronic pelvic pain affecting the quality of patient's life. PNPI and surgical
decompression of pudendal nerve can give hope to most of the patients with good
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