Preservation versus elective neurectomy of the ilioinguinal nerve for open mesh inguinal hernia surgery

Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To statistically combine the data comparing preservation of ileo inguinal nerve with selective neurectomy, to obtain a meaningful conclusion in terms of Chronic Groin Pain following mesh repair of primary inguinal hernias. We have also planned to look at the sensory effect of selective neurectomy compared to preservation (Picchio 2004) .

Background

Inguinal hernia repair is one of the most common operations performed worldwide. 'Inguinodynia' or Chronic Groin Pain is a potential complication following inguinal hernia repair and affects the patient’s quality of life significantly (van Hanswijck de Jonge 2008). The reasons for such inguinodynia have been shown to be either due to per‐operative nerve damage or post‐operative fibrosis, or mesh related fibrosis. The three nerves involved in the aetiology of chronic groin pain are ilioinguinal, iliohypogastric and genitofemoral nerve. Ilioinguinal nerve is considered in most studies as this is encountered in most hernia repairs, easiest of the three to recognise and bulkiest of them all (Smeds 2010). Traditional surgical teaching dictates that the nerves should be preserved at all times during inguinal hernia repair because of the supposed morbidity associated with cutaneous sensory loss and chronic groin pain following nerve injury. Various surgical etiquettes have been proposed to reduce the incidence of unintentional intra‐operative nerve injury (Amid 2004). Other post herniotomy syndromes like ejaculatory pain, genital pain and sexual dysfunction have been reported sporadically and have been attributed to either nerve damage or damage to vas deferens (Aasvang 2008; Ducic 2004).

 

Recent cohort studies have shown that routine ilioinguinal neurectomy is associated with lower incidence of chronic groin pain and subjective paraesthesia is usually temporary (Zieren 2007; Dittrick 2004; Tsakayannis 2004). In addition, ilioinguinal neurectomy is a well documented effective treatment of relieving chronic groin pain following open hernia repair, achieving more favourable outcomes than nerve block or mesh removal alone (Loos 2010; Aasvang 2009). Randomized clinical trials comparing the preservation versus elective neurectomy of the ilioinguinal nerve have shown conflicting results (Malekpour 2008; Mui 2006; Picchio 2004; Ravichandran 2000). The aim of this systematic review is to identify the acceptable way of handling the ilioinguinal nerve during the primary open mesh inguinal hernia repair, so as to minimize chronic pain.

Description of the condition

Chronic Groin Pain is a significant complication after Lichtenstein tension free repair. As per the International Association of the Study of Pain, it is defined as groin pain reported by the patient at or beyond 3 months following inguinal hernia repair (Merskey 1994). The incidence varies with different studies published, ranging from 19.0% to 62.9% (Bay‐Nielsen 2001; Cunningham 1996; Callesen 1999). This pain is difficult to explain and has a significant impact on the quality of life and restricts the day to day activity (Poobalan 2001; Courtney 2002). By conducting this review, we aim to identify the best possible way to avoid this potential complication in the commonly performed operation.

Description of the intervention

The preservation (control group) or selective division (Intervention group) of the ilioinguinal nerve while dissecting the hernial sac will be compared to identify the difference in the chronic pain.

How the intervention might work

Division of the ileo inguinal nerve has been shown to reduce the incidence of Chronic Groin Pain by preventing the nerve entrapment caused by postoperative or mesh related fibrosis (Mui 2006; Malekpour 2008).

Why it is important to do this review

Chronic Groin Pain is a significant complication following inguinal hernia repair and affects the patient’s quality of life considerably. There is no consensus on the ideal way of handling the ilioinguinal nerve, to reduce the incidence of Chronic Groin Pain in such a situation.

Objectives

To statistically combine the data comparing preservation of ileo inguinal nerve with selective neurectomy, to obtain a meaningful conclusion in terms of Chronic Groin Pain following mesh repair of primary inguinal hernias. We have also planned to look at the sensory effect of selective neurectomy compared to preservation (Picchio 2004) .

Methods

Criteria for considering studies for this review

Types of studies

1. All published randomised controlled trials comparing nerve preservation with selective neurectomy.

2. All well conducted controlled studies without randomizations.

3. Case series and retrospective studies will be excluded from the study.

4. We will try to contact the authors of unpublished but completed studies on this topic.

Types of participants

1. Adult patients who underwent primary open inguinal hernia repair with mesh, unilateral or bilateral, with out sex discretion.

2. Any studies in paediatric population (less than 18 years), recurrent hernias, emergency repairs and patients with pre‐operative neuropathy or hip problems will be excluded. There is only a single study done on chronic pain following childhood groin hernia repair and only herniotomy (no mesh used) was done in this age group, therefore the study will not be included for this review (Aasvang 2007).

Types of interventions

1. Ilioinguinal nerve preservation (Control group) during primary inguinal hernia repair in adult patients.

2. Selective neurectomy (Intervention group) in the same population group.

Types of outcome measures

Primary outcomes

Incidence of Chronic Groin Pain at different time points after 3 months following elective open inguinal hernia repair and up to the point mentioned in the studies.

Secondary outcomes

1. Incidence of postoperative groin numbness or sensory loss.

2. Incidence of sexual dysfunction.

3. Quality of Life measure, if reported.

Search methods for identification of studies

We will adopt the search strategy advocated by Cochrane Colorectal Cancer Goup (CCCG). A comprehensive search of different electronic databases using a combination of free text and MESH (Medical Subject Heading) terms will be undertaken to identify potential studies for inclusion in the review.

Electronic searches

The following electronic databases will be searched for any trials comparing the two interventions:

1. The Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library 2009

2. MEDLINE / PubMed

3. EMBASE

4. CINAHL

5. Current Controlled Trials (http://controlled‐trials.com/)

6. Ongoing Trials: National Research Register, Current Controlled Trials

7. Related articles and Bibliographies of identified papers will be scrutinised for relevant studies

Searching other resources

1. Experts in this area will be contacted for advice and peer review, and to identify additional published and unpublished references.

2. Web of Science Proceedings (the Institute for Science Information Proceedings allow access to abstracts from papers delivered at international conferences, symposia, seminars, colloquia, workshops, and conventions), Health Management Information Consortium (HMIC; this database focuses on community care and health systems management in the UK, Europe and developing countries including journals, books, reports, official publications).

Data collection and analysis

Data extraction will be performed by AH and SM using standard data extraction form. Included studies will be analysed for details regarding methodological quality, participants, interventions, comparisons and outcomes. All analyses will be performed using Review Manager 5 (© 2009, The Cochrane Collaboration). Continuous variables will be dealt with by Weighted Mean Difference (WMD) provided, the mean and standard deviation are published. Otherwise, descriptive analysis will be carried out. The binary variables will be reported as Odds ratio.

Selection of studies

The titles and abstracts identified by the searches will be screened independently by two authors (AH and SM). Studies that don't meet the inclusion criteria will not be considered further. The full text of all other articles will be retrieved and further assessed for eligibility by VS independently, or in consultation with MD, to resolve any conflict. Studies will be included if they are randomised controlled trials comparing the preservation versus excision of ilioinguinal nerve for open mesh inguinal hernia repair and measures any of the stated outcomes.

Data extraction and management

AH and SM will independently extract data from all the included studies on to a standardised data extraction form and resolve discrepancies with the other two authors (MD and VS). The included studies will provide the context for discussing the reliability, internal and external validity and generalisability of the results. Data entry will be performed by AH and cross checked by SM. MD and VS will provide expert opinion and review the final manuscript before submission.

Assessment of risk of bias in included studies

Factors considered included the quality of the random sequence generation and allocation concealment, incomplete outcome data, analysis by intention‐to‐treat, blinding (participants, personnel, and outcome assessors), and selective outcome reporting (Higgins 2008). We will eliminate the studies with any significant bias after full agreement with all the authors.

Measures of treatment effect

Continuous variables will be dealt with by Weighted Mean Difference (WMD) provided, the mean and standard deviation are published. Otherwise, descriptive analysis will be carried out. The binary variables will be reported as Odds ratio.

Unit of analysis issues

Each outcome category will be analysed individually as per the above criteria. When we are unable to combine the outcome measure into single data, descriptive summary of the results will be considered.

Dealing with missing data

We will try to contact the authors for any missing data (withdrawals, dropouts, etc.). If not possible, "Available case analysis" will be performed to obtain a meaningful conclusion.

Assessment of heterogeneity

Heterogenity will be evaluated by a x² test and the Cochrane I² statistics. Random‐effects model will be used if the heterogeneity is significant (I² > 50%), as described by Dersimonian 1986. The remaining statistics will be calculated by fixed‐effects model.

Assessment of reporting biases

Any publication bias will be explored using a 'funnel plot'.

Data synthesis

Heterogeneity of the combined results for each outcome variable will be assessed using MetaView statistical software. Heterogeneity amongst included studies will be explored qualitatively (by comparing the characteristics of included studies) and quantitatively (using the Chi² test of heterogeneity and the I² statistic). Where appropriate, the results from included studies will be combined for each outcome to give an overall estimate of treatment effect. A fixed‐effect model meta‐analysis will be used and if there is statistical heterogeneity then random‐effects model will be used.

Subgroup analysis and investigation of heterogeneity

The sub‐group analysis will be performed if data are available from the included studies for the following outcomes.

1. Difference between male and female patients (Studies have shown that chronic groin pain and functional impairment are higher in females compared to males (Aasvang 2005; Bay‐Nielsen 2001)).

2. Difference in outcome based on the Surgeons experience (Surgeons experience and familiarity with the identification of nerves will be correlated with the outcome).

3. Difference in the outcome based on the life style of the patients (Severity of the pain based on life style has been studied previously and will be correlated with our outcome (Staal 2008)).

These will be analysed if they are mentioned in the publication.

Sensitivity analysis

Sensitivity analysis will be performed excluding the methodologically poor quality papers based on randomizations technique, concealment of allocation and intention to treat analysis (Higgins 2008).

Contributions of authors

AH and VS developed search strategy. AH and SM will identify the eligible studies. The full text of all the eligible articles will be retrieved and further assessed for eligibility by VS independently or in consultation with MD. Methodological quality will be assessed by AH and VS. AH and SM will extract the data on to a previously designed data extraction sheet. Data entry will be cross checked by VS. Final manuscript will be checked by MD and VS.

Declarations of interest

None known

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