Neurectomy to Prevent Persistent Pain afterInguinal Herniorraphy: A Prospective StudyUsing Objective Criteria to Assess PainGiuseppe Pappalardo, MD,1 Fabrizio Maria Frattaroli, MD,1 Massimo Mongardini, MD,2

Pier Federico Salvi, MD,2 Augusto Lombardi, MD,2 Anna Maria Conte, MD,1

Maria Felice Arezzo3

1Department of General Surgery, P. Stefanini, University ‘‘La Sapienza’’, Rome, Italy2Department of Emergency Surgery and First Aid, University ‘‘La Sapienza’’, Rome, Italy3Department of Geoeconomics, Statistics, Linguistics and Historical Studies for Territorial Analysis, Rome, Italy

Abstract

Background: Although tension-free mesh repair has markedly improved the outcome of inguinal

hernia surgery, it has only minimally reduced the incidence of persistent postoperative pain. The

pathogenesis of this complication and treatment remain unclear.

Study design: In order to objectively assess whether iliohypogastric neurectomy reduces the

incidence and intensity of persistent postoperative pain, we prospectively studied 100 male pa-

tients with bilateral inguinal hernia who underwent tension-free surgical repair, combined with

iliohypogastric neurectomy on the right side alone. Pain was evaluated postoperatively on days 1

and 7 and at 1 and 2 years by means of a visual analog scale. Patients were given a questionnaire

including coded terms for describing pain. These terms were designed to compare pain on the

neurectomized and non-neurectomized sides and assess altered sensation (hypoesthesia and

paresthesia) on both sides.

Results: There were differences in the incidence and intensity of pain between the neurectomized

and non-neurectomized sides, though these differences were not significant. Individual patient

assessment showed that from postoperative day 7 onward patients had on average less pain on

the neurectomized side.Pain reduction was more prominent in patients who scored 4 or more on

the visual analog scale. No significant difference was found in the incidence of sensory alterations

between the two sides. Two years after inguinal hernia repair, only one of the 100 patients studied

still had persistent pain (>4 on the visual analog scale); this pain was on the non-neurectomized

side.

Conclusions: Our prospective data do not reach statistical significance to claim that iliohypogastric

neurectomy reduces the incidence and intensity of persistent postoperative pain after tension-free

inguinal hernioplasty. Studies on larger patient samples are warranted to provide definitive, sta-

tistically supported conclusions.

I nguinal herniorraphy is among the most common

general surgical procedures in Western countries. One

technique that has radically changed the therapeutic ap-

proach to inguinal hernia is tension-free mesh repair. The

use of this technique has spread at different rates in

various European countries. In 1997 tension-free repairs

exceeded all other inguinal herniorrhaphies by 75% inCorrespondence to: Giuseppe Pappalardo, via Sebastiano Conca 11,

00197, Rome, Italy, e-mail: contea75@libero.it

� 2007 by the Societe Internationale de Chirurgie World J Surg (2007) 31: 1081–1086

Published Online: 4 April 2007 DOI: 10.1007/s00268-006-7627-9

Italy, 69% in England, and 51% in Sweden, but only 1% in

Holland.1,2 In a large review including 170,000 patients,

tension-free repairs accounted for 92% of all inguinal

herniorrhaphies in Italy.3

The rapid spread of the tension-free technique is

somewhat surprising in a country where traditional tech-

niques (the Bassini technique and its modifications)4 had

for decades guaranteed results that were as good as, if

not better, than those obtained in other European coun-

tries and the United States. Tension-free hernioplasty

owes its success to its reproducibility, which makes it less

dependent on the surgeon’s skill; to the possibility it offers

of performing it in day surgery in most cases; to less

severe postoperative discomfort; to a more rapid return to

normal activities; and to lower incidence of recurrence.

Data regarding persistent postherniorrhaphy pain

and tension-free repair remain incomplete. In a meta-

analysis of groin hernia repair with synthetic mesh, the

overall incidence of persistent pain was 5% (120 of 2,368

patients).2 Persistent postoperative pain can be somatic,

visceral, or neuropathic in origin. Neuropathy may be

caused by nerve trauma during dissection, neuroma for-

mation after partial or complete transaction, and entrap-

ment by sutures or postoperative adhesions. Neuropathic

pain may also be exacerbated by implantation of mesh, a

procedure that induces scar formation through increased

inflammation.5

In a study that investigated the prevention of post-

herniorrhaphy neuralgia, Lichtenstein et al.6 proposed

transecting the ilioinguinal and genitofemoral nerves.

They also noted that the offending nerve is usually more

difficult to identify after mesh repair than after conven-

tional repair. Since patients who undergo tension-free

inguinal repair tend to have neuropathic rather than so-

matic or visceral pain,6,7 ideally the pain will be prevented

rather than treated.

Questions that have yet to be answered are which

nerve most often causes postoperative pain after tension-

free repair, whether its intentional transection induces

side effects, and what these side effects are. To answer

these questions Wantz8 intentionally transected the re-

gional inguinal nerves in all patients in whom these

nerves had been damaged during isolation. When they

did so, they found that none of the patients in their large

series had residual neuralgia.

In a previous prospective study that we performed to

investigate the effectiveness of iliohypogastric neurectomy

for the prevention of persistent pain after herniorraphy,9 we

observed that a standard-sized mesh invariably over-

lapped the nerve. This anatomical condition is therefore a

risk factor for nerve entrapment by fibrous adhesions be-

tween the mesh and the muscular layer. Unless patients

undergo suture-free procedures, stitches may lead to

nerve damage, thereby causing neuropathic pain.

The validity of data that assess a highly subjective

factor such as neuropathic pain is dependent on methods

for pain assessment. Data on the severity of pain based

on self-reports are particularly exposed to biases owing to

inter-patient variations in perceptions of pain. We de-

signed this prospective study to investigate whether ilio-

hypogastric neurectomy effectively reduces the incidence

and intensity of persistent postoperative pain, defined as

pain around the hernioplasty that persists for more than 3

months after the operation.5,7,10 We also assessed pos-

sible altered sensation related to neurectomy (anesthe-

sia, hypoesthesia, and paresthesia). To overcome any

subjectivity in the assessment of persistent postoperative

pain, we studied a group of consecutive patients who

underwent elective bilateral herniorraphy in a single

session. All the hernias were repaired using the same

surgical anterior tension-free technique, during which an

iliohypogastric neurectomy was added on the right side

and omitted on the left side. We assessed pain objec-

tively with a visual analog scale (VAS).

METHODS

In this prospective study, only male patients with bilateral

inguinal hernias were enrolled to undergo bilateral her-

nioplasty in a single session. Patients were excluded from

the study if they had recurrent hernias, required emergency

surgery, had coexisting neurological disease with altered

peripheral sensitivity, pre-existing back pain, or any other

pain in the inguinal region not related to the presence of

hernia. The patients were informed that a neurectomy was

to be performed on one side, but they were blinded as to

which side. Local bilateral anesthesia with endovenous

sedation or spinal anesthesia was used in this study. All the

patients were operated on by the same surgeon (G.P.).

The iliohypogastric and ilioinguinal nerves were identified

in all the patients selected. A plug and polypropylene mesh

(10 · 4.5 cm) and the interrupted stitch technique were

used in all the patients. On the right side, the iliohypogastric

nerve was resected from the point where it emerges on the

internal oblique muscle to the terminal division branches.

Unless the ilioinguinal nerve had suffered evident damage

during isolation of the hernial sac, it was detected and

preserved. None of the patients required ilioinguinal neur-

ectomy. On the left side, the iliohypogastric and ilioinguinal

nerves were identified and preserved, with care being ta-

ken not to damage them or include them in the sutures.

1082 G. Pappalardo et al: Neurectomy to Prevent Persistent Pain after Inguinal Herniorraphy

All patients were assessed at 1 and 7 days, at 6 months,

and 1 and 2 years after surgery. The follow-up assess-

ments elicited information on the patients’ return to pre-

operative activities and the incidence of complications and

recurrent lesions on each side. At each clinical visit, the

patients underwent a neurological examination performed

by physicians blinded to the neurectomized side to assess

pain and hypoesthesia (diminished sensitivity to stimula-

tion) on each side. Pain was subjectively quantified on a

VAS ranging from 0 (no pain) to 10 (worst pain imagin-

able). In accordance with Keele et al., we defined as

incapacitating pain scores of 4 points or above. The pa-

tients were asked to select one or more words used in the

neuropathic pain scale to describe their pain.11 Any al-

tered sensation on either side (including hypoesthesia,

numbness, or paresthesia) possibly related to neurectomy

was described by the patients. Persistent postoperative

neuropathic pain, the primary outcome measure, was

defined as pain in the inguinal area around the site of the

hernioplasty persisting longer than 3 months.4,6,9

The study was scheduled to end when 100 patients,

enrolled according to the aforementioned criteria, had

attended the 2-year postoperative follow-up assessment.

The study began in January 1993 and ended in May

2003. Of the 100 men enrolled (mean age 61 years;

range 32–78 years), 64 were operated on under local

anesthesia and 36 under spinal anesthesia. There was no

significant difference in the type (indirect, direct, ingui-

noscrotal), or size of the hernias involving the right or left

sides. All the patients gave their written informed consent

to the study, and the procedures were approved by the

hospital ethics committee.

Statistical analysis

Data were analyzed using the software programs

SPSS12 11.0 and Matlab 6.0; tests were conducted at a

significance level of 5% (i.e., a 5% probability of type I

error in the decisional process).13 Two-tailed t-tests were

used to assess differences in mean pain scores, as well

as to distinguish between incapacitating pain (VAS ‡ 4)

and non-incapacitating pain (VAS £ 3). For hypoesthesia,

the nonparametric sign test was used to assess the

homogeneity of the study population.

RESULTS

All 100 patients enrolled were discharged within 2 days

of surgery: 47 on the same day, 49 on day 1, and 4 on

day 2. All the patients were followed-up for 24 months.

Complications after herniorrhaphy included 9 wound se-

romas (5 involving the left side and 4 the right side). In

one patient, inflammation developed in the left spermatic

cord but responded to therapy within 4 weeks without

causing testicular atrophy. No patient had recurrent her-

nia during the 2-year follow-up. The mean time taken to

return to preoperative activities was 9.3 days (range: 4–

38 days). The wide variability in the time the patients took

to return to preoperative activities was closely related to

the type of job they had (brain-related work as opposed to

manual labor; self-employment or employee). Nonpara-

metric tests indicated that the patients studied came from

homogeneous populations (Table 1).

According to the VAS scores, the incidence of post-

operative neuropathic pain differed, though not signifi-

cantly, on the neurectomized and non-neurectomized

sides. On postoperative day 1, 49 patients had incapac-

itating pain (VAS ‡ 4) on at least one side. Paired t-test

showed that the difference in pain between the right and

left sides was not statistically significant (p = 0.345). On

postoperative day 7, there was a difference of –1.14,

which indicates that the pain was slightly less marked on

the neurectomized side; the p value shows that this dif-

ference is statistically significant. At 1 year after surgery,

only one patient still had incapacitating pain, and that, it is

worth noting, was on the left side (Table 2). At 2 years

after surgery, only 13 of the 100 patients still complained

of occasional, mild pain (5 on the right side and 8 on the

left).

Postoperative neuropathic pain mainly involved the

groin; it often radiated to the scrotal skin and upper

medial thigh, and it was, in most cases, aggravated by

walking.

None of the patients complained of anesthesia in the

cutaneous sensory distribution of the iliohypogastric, ili-

oinguinal, or genitofemoral nerves. At the assessment on

postoperative day 7, most patients had altered sensation

(hypoesthesia, reported as numbness, paresthesia, re-

ported as a burning sensation, or both; 82 patients on the

right side and 83 on the left). The symptoms on both

sides improved as the duration of follow-up increased, the

incidence decreasing from 19% and 16% at 1 year to 13%

and 8% at 2 years for the right and left sides, respectively.

None of the patients considered these symptoms inca-

pacitating. Nonparametric tests did not identify any dif-

ference in the incidence of hypoesthesia between the two

sides (at 1 day and 7 days: 5 right-sided/11 left-sided

patients; at 1 year, 8/19; and at 2 years, 2/9; al-

pha = 0.05).

G. Pappalardo et al Neurectomy to Prevent Persistent Pain after Inguinal Herniorraphy 1083

DISCUSSION

Our prospective study differs from other studies pre-

viously performed to assess persistent postoperative

pain after herniorraphy for three reasons: (1) we elimi-

nated subjectivity in the perception and definition of pain

between patients by having the same patient compare

pain on the neurectomized and non-neurectomized

sides; (2) we assessed pain, which is known to be a

highly variable element, more objectively by combining

a VAS and a neurological questionnaire; (3) we as-

sessed whether neurectomy caused adverse effects

such as anesthesia, hypoesthesia, and paresthesia by

asking patients to describe those sensations using

common descriptors.

The difference in our results between the neurectom-

ized and non-neurectomized sides does not reach sta-

tistical significance. However, the crude data do show

that on postoperative day 7 fewer patients had incapaci-

tating pain on the neurectomized side, and that 2 years

after surgery fewer patients had occasional, mild pain on

the neurectomized side (5 versus 8). Moreover, at the

follow-up assessment 1 and 2 years after inguinal her-

nioplasty, no patient complained of severe pain on the

neurectomized side, and only one had severe persisting

pain on the non-neurectomized side.

Neurectomy also seems to reduce the intensity of pain,

especially in patients who complained of severe pain

(VAS ‡ 4). From as early as postoperative day 1, patients

reported less intense pain on the neurectomized side

Table 1.Results of non-parametric tests

Kolmogorov-Smirnov test for two samples

Postoperative visual analog scale scores Z p ValueDay 1 0.283 1.000Day 7 0.707 0.6991 year 0.424 0.994

Wilcoxon testPostoperative visual analog scale scores n1 W Critical values

Day 1 65 )0.389 )1.96Day 7 35 )1.163 )1.961 year 7 0 2

Z = statistical test of Kolmogorov-Smirnov; W = statistical test of Wilcoxon;Ni = number of samples

Table 2.The incidence and intensity of postoperative pain on the neurectomized (right) and non- neurectomized sides

Results of t-test (two independent samples)

Postoperative VAS score All cases t-test p Value1 day: right side 100 3.56 1.986 –0.557* 0.5781 day: left side 100 3.72 2.0757 days: right side 100 2.31 1.187 –1.529* 0.1287 days: left side 100 2.61 1.5631 and 2 years: right side 100 0.14 0.472 –1.524* 0.1291 and 2 years: left side 100 0.31 0.974

Patients with VAS £ 3 N Mean SD t-test p Value1 day: right side 58 2.10 0.788 –0.053* 0.9581 day: left side 54 2.11 0.7447 days: right side 82 1.85 0.705 0.661* 0.5097 days: left side 72 1.78 0.716

Patients with VAS ‡ 41 day: right side 42 5.57 1.233 –0.130* 0.8971 day: left side 46 5.61 1.4377 days: right side 18 4.39 0.502 –1.412* 0.1657 days: left side 28 4.75 1.005

All data are expressed as means – SD.*Variance is equal at 5% significance level.The p values were calculated by t-test for two independent samples.

1084 G. Pappalardo et al: Neurectomy to Prevent Persistent Pain after Inguinal Herniorraphy

than on the non-neurectomized side , even though this

difference failed to reach statistical significance. It is

noteworthy that the pain in the only patient who did

complain of severe persistent pain (VAS > 4) was on the

non-neurectomized side.

None of our patients reported any altered sensation

related to the neurectomy: no patient had anesthesia on

either side, nor did we find any significant difference in the

incidence of hypoesthesia and paresthesia between the

two sides. None of the few patients who still complained

of hypoesthesia and paresthesia at 2 years considered

these symptoms to be incapacitating.

Our study substantiates previous findings that have

highlighted the advantages of the anterior tension-free

technique over traditional methods.14,15

Recent studies have reported a higher frequency of

postoperative pain than had previously been believed.

Overall, 120 patients of 2,368 (5%) complained of per-

sistent postoperative pain after mesh repair versus 215 of

1,998 (10.8%) after a traditional technique.2 In a study

conducted by Courtney et al.,10 30 months after surgery

26% of the patients reported severe or very severe pain,

only 29% reported no pain, and in the remaining 45% the

pain had become very mild or mild. In a series of 1,652

patients studied by Bay-Nielsen and colleagues,7 4% of

the patients reported persistent postoperative pain,

probably caused by nerve damage. These investigators

therefore recommended that nerve ends should be li-

gated16 or intentionally severed 8 to reduce the risk of

chronic pain, although neither author subsequently doc-

umented the outcome of these recommendations. The

anterior tension-free technique reduces the risk of ilioin-

guinal and genitofemoral nerve lesion, mainly by avoiding

excessive tightness of the suture around the internal ring;

however, it increases the risk of injury owing to the ana-

tomical distribution of the iliohypogastric nerve and its

position in relation to the standard-sized mesh.

In a previous prospective study, we reported our find-

ings on the effectiveness of iliohypogastric neurectomy in

preventing postoperative pain.9 In the consecutive series

of 180 anterior tension-free repairs, no patient com-

plained of severe postoperative pain. Two years after

surgery, 15 patients complained of hypoesthesia, al-

though no one ever considered it to be incapacitating.

The limitations of our earlier study were the small number

of herniorrhaphies and the subjectivity of the pain evalu-

ation.

Although the results we obtained in the present pro-

spective study using a more objective protocol for eval-

uating pain did not, owing to small study sample, reach

statistical significance either, our findings do provide

useful insight into how neurectomy-induced pain and al-

tered sensation arise.

The problem of persistent pain after tension-free her-

nioplasty, as other investigators have underlined,5–10,16,17

basically involves pain of neuropathic origin. The ilio-

hypogastric nerve is the regional nerve that is at highest

risk during tension-free repair, because it can be trapped

by the overlapping mesh in the scar tissue that forms

between the mesh and the muscle plane along which the

nerve runs. The nerve may also be trapped by the stit-

ches unless a sutureless technique is used.

In conclusion, the problem of persistent postoperative

pain after inguinal hernia repair remains unresolved. The

incidence of such pain is higher than generally hitherto

believed for tension-free surgical repair, a technique that

otherwise achieves the best results. In most patients who

undergo tension-free inguinal hernia repair, postoperative

pain is probably neuropathic in origin. Identifying the

culprit nerves is a laborious undertaking, especially after

the mesh has been applied. Postoperative pain is best

prevented by neurectomy of the nerve or nerves at risk of

damage during surgery or of entrapment in scar tissue.

Our results do not allow us to claim iliohypogastric

neurectomy as preventive of persistent postoperative

pain because they do not reach statistical significance.

Further studies on larger number of patients treated with

an identical surgical procedure and evaluated with the

same assessment techniques are now warranted to

provide statistically significant results. The ideal way to

achieve this objective in a relatively short time would be to

conduct a multicenter study.

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