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Randomized Controlled Trial of
Preservation or Elective Division of Ilioinguinal Nerve on Open
Inguinal Hernia Repair With Polypropylene Mesh
Marcello
Picchio, MD; Domenico Palimento, MD; Ugo
Attanasio, MD; Pietro Filippo Matarazzo, MD;
Chiara Bambini, PhD; Angelo Caliendo, MD
Arch Surg. 2004;139:755-758.
ABSTRACT
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Hypothesis Our study aimed to evaluate the
effect of preservation or elective division of the
ilioinguinal nerve on pain and postoperative symptoms
after open inguinal hernia repair with mesh.
Design Double-blind, randomized trial.
Setting Four public, government-financed hospitals
in Italy.
Patients From January 1, 1997, to June 30, 2002, 813
patients with primary inguinal hernia were randomly
allocated to undergo inguinal hernia repair either with
ilioinguinal nerve preservation (408 patients, group A)
or elective transection (405 patients, group B).
Intervention Hernia repair with sutureless
apposition of a polypropylene mesh.
Main Outcome Measures The primary outcome was the
evaluation of chronic pain 1 year after operation.
Secondary outcomes were postoperative symptoms assessment
at 1 week and 1, 6, and 12 months after operation.
Telephone interview was performed 35.5 months (range,
12-59 months) after operation to assess the presence of
chronic pain.
Results Of the 302 group A and 291 group B patients
who made an office visit 1 year postoperatively, pain was
absent in 231 (76.5%) and 213 (73%) (difference, 3.30%;
95% confidence interval, 3.68% to 10.28%), mild in 55
(18%) and 60 (21%), moderate in 11 (4%) and 9 (3%), and
severe in 5 (2%) and 9 (3%), respectively (P =
.55; Pearson  755_file/chi.gif) 23 test). At 1-month and 6-month
follow-up visits, no difference was found between the 2
groups with respect to pain, but loss of pain or touch
sensation were significantly greater when the
ilioinguinal nerve was divided. One year after operation,
the 2 groups were also comparable with respect to loss of
pain sensation, but touch sensation remained decreased in
group B. At telephone interview, the presence of chronic
pain was similar in both groups.
Conclusions Pain after open hernia repair with
polypropylene mesh is not affected by elective division
of the ilioinguinal nerve; sensory disturbances in the
area of distribution of the transected nerve are
significantly increased.
INTRODUCTION
Pain after
inguinal hernia repair may be an incapacitating complication
that represents an important diagnostic and therapeutic
challenge. Normal postoperative pain affects patients
immediately after surgery and gradually subsides within a
few days. Some patients experience chronic debilitating
pain that is often unresponsive to medical treatment,
including nonsteroidal anti-inflammatory drugs and
opiates.
Neuropathy is a widely recognized cause of chronic
postherniorrhaphy pain. One of the mechanisms responsible
for this chronic pain may be the damage to the sensory
nerves (ilioinguinal, iliohypogastric, and genitofemoral)
passing through the inguinal region.1
However, elective division of all these sensory nerves
may reasonably lead to considerable sensory loss in the
inguinal region.
Ilioinguinal nerve is normally encountered during open
inguinal hernia repair. It may be traumatized during
dissection and interfere with placement of the mesh. Our
study aimed to assess the influence of preservation vs
division of the ilioinguinal nerve on pain and
postoperative symptoms after open inguinal hernia repair
with polypropylene mesh.
METHODS
From January
1, 1997, to June 30, 2002, 892 patients 18 years and
older with primary inguinal hernia who presented for operation
to their general surgeon at the 4 participating public,
government-financed hospitals in Italy were considered
eligible for the study. Patients with bilateral hernia or
a subsequent hernia repair in the observation period were
excluded, so the study group was reduced to 813 patients.
After approval by local bioethics committees, informed
consent was obtained preoperatively on hospital admission.
Before operation patients were randomly allocated to
undergo hernia mesh repair either with ilioinguinal nerve
preservation (group A) or transection (group B).
Randomization was computer generated, using numbered and
sealed envelops that were opened in the operating theater
before operation.
Operations were performed with the patients under local or
spinal anesthesia. A polypropylene mesh was positioned
without sutures in the floor of the inguinal canal and in
the lateral space under the aponeurosis of the external
oblique muscle, according to the technique described by
Trabucco.2
Division of the ilioinguinal nerve was performed lateral
to the deep ring to avoid any contact with the mesh.
Histologic analysis of a section of the removed nerve was
performed to confirm the division of the ilioinguinal
nerve.
Postoperative pain was assessed using a 4-point verbal scale
(none, mild, moderate, or severe), assigning numerical
values of 0 to 3 one week after operation. Mild pain was
defined as an occasional disturbance that did not limit
normal activities, moderate pain as pain that interfered
with normal-day life activities, and severe pain as pain
that rendered the patient unable to perform normal
activities. At 1-month, 6-month, and 1-year follow-up
visits, pain experienced during the last week before the
visit was assessed using the same scale. Follow-up
telephone calls were performed at the end of the study
with the aim of assessing the presence and intensity of
pain related to the operation, using the same 4-point
verbal scale. In addition, during follow-up visits,
patients were also tested for the presence of numbness
and sensory loss to light touch and pain sensation in the
area of distribution of the ilioinguinal nerve.
Follow-up was performed by assessors unaware of the
procedure and patients, so the study was conducted in a
double-blind fashion. Results were analyzed on an
intention-to-treat basis. In particular, patients were
analyzed on the basis of randomization, regardless of
whether the ilioinguinal nerve was identified. The primary
outcome was the evaluation of chronic pain 1 year after
operation. Secondary outcomes were symptoms assessment at
1 week and 1, 6, and 12 months after operation and at
telephone interview.
Sample size calculation was based on the aim of detecting a
difference of 10% in the proportion of patients with
absence of chronic pain 1 year after operation, assuming
from previous studies that 70% of patients were pain
free. With a type I error of 0.05 and a type II error of
0.20 for a 2-tailed test, 291 patients per group were
required.
Pearson 2 and Yates corrected 2 were used for categorical data.
Spearman rank correlation coefficient was used as
appropriate. All tests were 2-tailed, and the level of
significance was .05. The collection and analysis of data
were performed using SPSS statistical software version
10.0 (SPSS Inc, Chicago, Ill).
RESULTS
The profile
of the trial is shown in Figure
1. Both groups were comparable with respect to age,
sex, type of hernia, and presence of preoperative pain
(Table
1). The ilioinguinal nerve was not identified in 55
(13%) of the 408 patients in group A and in 41 (10%) of
the 405 patients in group B (P = .16, 21 with Yates correction
for continuity). Postoperative complications were similar
in both groups and included wound and/or scrotal hematoma
in 31 (8%) of the group A patients and 40 (10%) of the
group B patients (P = .26, 21 with Yates correction for
continuity), requiring surgical drainage in 4 and 3
cases, respectively.
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| Randomized control trial flowchart.
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| Table 1. Characteristics of Patients*
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One week after operation, in groups A and B, respectively,
pain assessed with the use of the 4-point verbal scale
was absent in 150 patients (37%) and 141 patients (35%)
(difference, 2.00%; 95% confidence interval [CI], 4.59%
to 8.59%), mild in 180 (44%) and 183 (45%), moderate in
65 (16%) and 73 (18%), and severe in 13 (3%) and 8 (2%)
(P = .58, Pearson 23 test). Postoperative
pain was not correlated with the presence of preoperative
pain ( 755_file/rho.gif) = 0.064, P = .07, Spearman rank
correlation), and no correlation was evidenced in the 2
subgroups (group A: = 0.031, P = .53; group B:
= 0.040, P = .43, Spearman rank
correlation).
One month after operation, follow-up visits were performed
in 391 group A patients (96%) and 380 group B patients
(94%). The numbers of patients with pain and loss of
sensation in the area of distribution of the ilioinguinal
nerve are given in Table
2. In particular, pain was absent in 195 (50%) of 391
patients in group A and 184 (48%) of 380 patients in
group B (difference, 2.50%; 95% CI, 4.56% to 9.56%). For
the entire cohort, when pain experienced after 1 week was
compared with that referred after 1 month, a
statistically significant positive relation was evidenced
(= 0.120, P = .001, Spearman rank
correlation); similar results were obtained when the 2
subgroups were analyzed (group A: = 0.125, P = .02; group B: = 0.113, P = .03, Spearman
rank correlation). No difference was found between the 2
groups with respect to the presence of numbness, but loss
of pain and touch sensation were significantly greater
when the ilioinguinal nerve was divided.
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| Table 2. Pain Scores and Loss of Sensation
at the Follow-up Visits*
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Results of the follow-up visit after 6 months are given in Table
2. The 6-month follow-up was performed in 354
patients (87%) in group A and in 358 patients (88%) in
group B. The pain scores are similar in both groups. In
particular, pain was absent in 222 group A patients (63%)
and 238 group B patients (66%) (difference, 3.80%; 95%
CI, 3.22% to 10.82%). For the entire study group and
each subgroup, when pain experienced after 6 months was
compared with that referred after 1 month, a statistically
significant positive relation was found (= 0.113, P = .002; group A:
= 0.134, P = .01; group B: = 0.108, P = .04; Spearman
rank correlation). The data showed a persisting decrease
in touch and pain sensation in group B.
A total of 302 patients (74%) in group A and in 291 patients
(72%) in group B attended an office visit 1 year
postoperatively. Of the group A and group B patients,
pain was absent in 231 (76%) and 213 (73%) (difference,
3.30%; 95% CI, 3.68% to 10.28%), mild in 55 (18%) and 60
(21%), moderate in 11 (4%) and 9 (3%), and severe in 5
(2%) and in 9 (3%), respectively (P = .55; Pearson
23 test). For the entire cohort, when
pain experienced after 1 year was compared with that
referred after 6 months, a statistically significant
positive relation was found (= 0.140, P = .001, Spearman rank
correlation); similar results were obtained in group A
and group B (group A: = 0.123, P = .04; group B:
= 0.136, P = .02; Spearman rank
correlation). Touch sensation remained significantly
decreased when the ilioinguinal nerve was removed (Table
2).
A median telephone follow-up of 33.5 months (range, 12-62
months) was performed in 344 patients (84%) in group A
and 334 patients (82%) in group B. Pain score was similar
in both groups (Table
3). In particular, pain was absent in 262 patients
(76%) in group A and 249 patients (75%) in group B
(difference, 1.70%; 95% CI, 4.79% to 8.19%).
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| Table 3. Pain Score at Telephone Follow-up*
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COMMENT
Postoperative pain is a significant problem after open
inguinal hernia repair. Moderate or severe pain was still
present in 11% of patients during mobilization and in 5%
at rest 4 weeks after operation in the study by Callesen
et al.3
In the same group of patients, 19% reported some degree
of pain at 1-year follow-up; the pain was moderate or
severe in 6% of cases.4
In a large-scale study,5
chronic pain was present in 28.7% of patients 1 year
after hernioplasty, leading to some degree of functional
impairment in 11% of patients. In another large-scale
study,6
chronic pain was present in 43% of patients, and it was
reported as severe or very severe in 3% of cases. Chronic
pain occurred in 30% of patients in the study by Poobalan
et al.7
Tension-free repair of inguinal hernia with mesh prosthesis
should lead to less postoperative pain. However, acute
postoperative pain was similar in patients who underwent
conventional or mesh hernia repair.3,
8
In a recent meta-analysis of randomized controlled
trials, comparing hernia repair with or without mesh, the
results showed a significant reduction in chronic pain
when mesh was applied; however, there is still a relevant
proportion of patients (10.7%) who complained of
persisting pain after hernia repair with mesh.9
In our group of study, globally considered, chronic pain
1 year after operation was present in 149 (25%) of 593
patients, and it was described as moderate or severe in 34
(6%) of these patients. The telephone interview showed
that the proportion of patients who still experienced
chronic pain was considerable at long-term follow-up. No
correlation was found between the presence of
preoperative pain and the occurrence of postoperative
pain. According to other studies,4,
10
chronic pain was significantly related to the presence
and intensity of postoperative pain.
Damage to 1 or more of the 3 nerves passing through the
surgical field is suspected to be one of the main causes
of chronic postherniorrhaphy pain. This theory is
supported by the association between chronic pain and
sensory disturbances.11
A nerve may be damaged during operation as a result of
perineural fibrosis, entrapment by staples, sutures, or
prosthetic materials, and direct lesions due to
stretching, contusion, electrical injury, and partial or
complete division of the nerve.12
Elective division of the ilioinguinal nerve was proposed
by hernia surgeons to reduce the risk of its inadvertent
damage and consequent chronic pain. Wantz13
showed that chronic pain was not present in 546 patients
who underwent hernia repair with elective division of the
ilioinguinal nerve, whereas it was seen in patients with
the nerve preserved. No relation between ilioinguinal
nerve preservation or elective division and chronic pain
was reported in a large study by Cunningham et al.10
The study by Ravichandran et al14
was the first to assess the effect of division of the
ilioinguinal nerve in a randomized setting. The authors
found no evidence to support the benefit of ilioinguinal
nerve division with respect to postoperative pain within
the limitation of a small sample size. Our data confirm
that ilioinguinal nerve division does not affect postoperative
pain after mesh repair of the inguinal hernia with the
support of a large number of patients and an appropriate
long-term follow-up. In particular, considering the
primary end point of our trial, after 1 year there was no
difference in the rates of patients free from pain in
both groups, and the 95% CI for the difference was so low
that is was without clinical importance.
After inguinal hernia repair, sensory changes are common.12
In the study by Ravichandran et al,14
loss of sensation in the territory supplied by the
ilioinguinal nerve occurred in 40% to 45% of patients
when the nerve was divided and in 5% to 25% of cases when
it was preserved after 6 months. Our data confirm that
elective transection of the ilioinguinal nerve leads to a
significant increase in the proportion of patients who complain
of a decrease in pain and touch sensation in the
postoperative period with respect to those with preserved
nerve. In particular, touch sensation was still impaired
at the 1-year follow-up visit.
In conclusion, our study showed that pain after open hernia
repair with polypropylene mesh is a relevant problem and
is unaffected by elective division of the ilioinguinal
nerve. Moreover, the transection of the ilioinguinal
nerve was significantly related to sensory disturbances
in the area of distribution of the nerve.
AUTHOR INFORMATION
Accepted for publication February 18,
2004.
Correspondence: Marcello Picchio, MD, Via Stefano
Boccapaduli, nr 51, 00151 Rome, Italy (marcellopicchio@libero.it).
From the Departments of Surgery, Civil Hospital Dono
Svizzero, Latina (Dr Picchio), Civil Hospital S. Paolo, Naples (Drs
Palimento and Caliendo), Civil Hospital S. Rocco, Caserta (Dr
Attanasio), and Civil Hospital G. De'Bosis, Frosinone (Dr
Matarazzo), Italy; and Institute of Statistics, University La
Sapienza, Rome, Italy (Dr Bambini).
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Gillion JF, Fagniez PL. Chronic pain and cutaneous sensory changes
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laparoscopic techniques. Hernia. 1999;3:75-80.
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Amid PK. A 1-stage surgical treatment of postherniorrhaphy
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Wantz GE. Testicular atrophy and chronic residual neuralgia as risks
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