Spinal versus general anaesthesia in surgery for inguinodynia (SPINASIA trial): study protocol for a randomised controlled trial
Zwaans et al. Trials
Spinal versus general anaesthesia in surgery for inguinodynia (SPINASIA trial): study protocol for a randomised controlled trial
Willem A. R. Zwaans 0 1 3 4
Léon H. P. M. le Mair 2
Marc R. M. Scheltinga 0 1 3 4
Rudi M. H. Roumen 0 1 3 4
0 SolviMáx, Center of Excellence for Abdominal Wall and Groin Pain, Máxima Medical Centre , Eindhoven , The Netherlands
1 Department of General Surgery, Máxima Medical Centre , PO Box 77775500 MB Veldhoven/Eindhoven , The Netherlands
2 Department of Anaesthesiology, Máxima Medical Centre , Veldhoven , The Netherlands
3 SolviMáx, Center of Excellence for Abdominal Wall and Groin Pain, Máxima Medical Centre , Eindhoven , The Netherlands
4 Department of General Surgery, Máxima Medical Centre , PO Box 77775500 MB Veldhoven/Eindhoven , The Netherlands
Background: Chronic inguinodynia (groin pain) is a common complication following open inguinal hernia repair or a Pfannenstiel incision but may also be experienced after other types of (groin) surgery. If conservative treatments are to no avail, tailored remedial surgery, including a neurectomy and/or a (partial) meshectomy, may be considered. Retrospective studies in patients with chronic inguinodynia suggested that spinal anaesthesia is superior compared to general anaesthesia in terms of pain relief following remedial operations. This randomised controlled trial is designed to study the effect of type of anaesthesia (spinal or general) on pain relief following remedial surgery for inguinodynia. Methods: A total of 190 adult patients who suffer from unacceptable chronic (more than 3 months) inguinodynia, as subjectively judged by the patients themselves, are included. Only patients scheduled to undergo a neurectomy and/ or a meshectomy by an open approach are considered for inclusion and randomised to spinal or general anaesthesia. Patients are excluded if pain is attributable to abdominal causes or if any contraindications for either type of anaesthesia are present. Primary outcome is effect of type of anaesthesia on pain relief. Secondary outcomes include patient satisfaction, quality of life, use of analgesics and (in)direct medical costs. Patient follow-up period is one year. Discussion: The first patient was included in January 2016. The expected trial deadline is December 2019. Potential effects are deemed related to the entire setting of type of anaesthesia. Since any setting is multifactorial, all of these factors may influence the outcome measures. This is the first large randomised controlled trial comparing the two most frequently used anaesthetic techniques in remedial surgery for groin pain. There is a definite need for evidence-based strategies to optimise results of these types of surgery. Besides pain relief, other important patient-related outcome measures are assessed to include patient's perspectives on outcome.
Anesthesia; Pain; Postoperative; Randomised controlled trail [publication type]; Chronic pain; Pain management; Surgical procedures; Operative
Background and objectives
Chronic postoperative groin pain (inguinodynia) is defined
as pain beyond 3 months after inguinal surgery. In the
majority of patients, inguinodynia develops following open
inguinal hernia repair (66%; Zwaans WA, van Kuijk SM,
le Mair LH, van Kleef M, Scheltinga MR, Roumen RM –
unpublished observations). One third of patients with
chronic postherniorrhaphy pain experience impairment of
daily activities [1, 2]. This pain is either neuropathic (47–
70%), nociceptive (26%) or a combination .
Inguinodynia may also be found after other types of groin surgery
[4–7]. Concise history taking and an extensive physical
examination provide the cornerstones for diagnosing
inguinodynia. A diagnostic local nerve block may confirm
the diagnosis [8, 9]. Interestingly, one of three patients
benefits from these injections on the long term .
When these minimally invasive regimens fail, surgical
options may be considered. Removal of the inguinal nerves,
funiculolysis, and/or removal of the mesh may all be
effective [7, 11–14, 17]. Furthermore, the post-Pfannenstiel
pain syndrome, which often is neuropathic in origin, also
responds well to an inguinal neurectomy .
The SolviMáx Centre of Excellence is a third-line referral
centre for abdominal wall and groin pain. Experience with
a spectrum of surgical procedures for inguinodynia is
growing. One retrospective study in patients with inguinodynia
suggested that spinal anaesthesia is associated with a
superior outcome in terms of pain relief when compared to
general anaesthesia . A more robust trial is required to
confirm these preliminary findings. The objective of the
present paper is to present a randomised controlled trial
that is designed to investigate the effect of type of
anaesthesia on long-term pain relief in patients who are surgically
treated for chronic inguinodynia.
This monocenter, nonblinded, randomised controlled trial
is performed in the SolviMáx Centre of Excellence for
Abdominal Wall and Groin Pain. SolviMáx is a subdivision
of the Surgical Department of Máxima Medical Center
(MMC), a teaching hospital situated in the southern part of
The Netherlands serving a population of approximately
200,000 inhabitants. The study aims at investigating a
potential difference in pain relief following remedial surgery
that is performed in two different settings, spinal
anaesthesia versus general anaesthesia. The present trial is not
considered a drug study as other variables associated with
type of anaesthesia are not under control of the
investigators. The present trial follows guidelines of the declaration
of Helsinki (version 19 October 2013). The protocol
(protocol number NL54115.015.15) is approved by the Medical
Ethics Committee of Máxima Medical Centre, Veldhoven,
the Netherlands. The study protocol (version 1) is registered
at www.trialregister.nl (NTR registration number: 5586).
The present paper is written according to the Standard
Protocol Items: Recommendations for Interventional Trials
(SPIRIT) 2013 Statement for reporting a clinical trial
protocol . The SPIRIT Checklist is provided as
Additional file 1.
Patient enrolment started in January 2016. Chronic
inguinodynia that is unacceptable as subjectively judged
by patients themselves is a prerequisite for inclusion.
Only patients scheduled to undergo remedial surgery
including a neurectomy and/or a meshectomy (if
patients have mesh) by an open approach are considered
for inclusion (Fig. 1). Patients are excluded if pain is
due to intercostal neuralgia of the abdominal wall,
such as abdominal cutaneous nerve entrapment syndrome
(ACNES), or due to lateral femoral cutaneous nerve
entrapment. Other contraindications are listed in Table 1.
Cognitively impaired individuals, patients with ASA class
IV or undergoing secondary or bilateral remedial surgery
are also excluded.
The decision to perform a neurectomy and/or mesh
removal depends on the surgeon’s subjective interpretation
of patient history, physical examination and intraoperative
findings . All remedial surgeries are performed using
an open approach as previously published . Patients
are randomised to either spinal or general anaesthesia.
Hyperbaric articaine 5% is used for spinal anaesthesia,
considering the relatively short duration of action.
Articaine is a amide-type local anaesthetic agent that is
preferentially used for short (1 h or less) surgical procedures in
MMC. General anaesthesia is given to the patients
following standardised procedures.
The administration of other medications during the
perioperative phase (e.g. ephedrine, atropine and sedatives) is
left to the discretion of the attending anaesthesiologist.
Consequently, the setting of the two types of anaesthesia
rather than the actions of the anaesthetic drugs are
investigated. It is allowed for patients who are randomised to the
spinal anaesthesia group to receive midazolam during the
procedure. Midazolam has no effect on perception of pain
so no drug-related sequelae on the primary outcome
measure are expected. If requested, midazolam will be
administered in a dose of 1 mg (if aged over 65 years) or
2 mg (if ASA class below III).
If a patient receives spinal anaesthesia but intrathecal
articaine has insufficient effect, the patient will undergo
surgery under general anaesthesia. Subsequently, this
will be considered as a protocol violation and the
particular patient will be excluded from further analysis.
Fig. 1 Mesh removal (left) and a neurectomy (right) in patients with inguinodynia following open inguinal hernia repair
Primary outcome is the effect of type of anaesthesia on
pain relief after surgery. Patients are asked to score their
pain using the Numerical Rating Scale (NRS, 0, absent
pain – 10, worst pain imaginable). The first pain score is
obtained in the preoperative phase (t0), Fig. 2. Follow-up
pain levels are determined at five time points to
determine short-term (1 week, 6 weeks and 3 months
postoperatively, t1–t3) and long-term results (6 months and 12
months postoperatively, t4–t5).
Secondary outcome measures are the effect of type of
anaesthesia on quality of life and patient satisfaction.
Quality of life is measured using the Short Form Health
Survey-12 questionnaire (SF-12). To avoid confusion,
satisfaction is also measured by a NRS-like method,
using an 11-point rating scale.
Other secondary endpoints include differences in pain
medication and both direct and indirect medical costs.
Two different validated questionnaires, developed by the
Deformities of the spinea
Severe back pain or headache Inadequate coagulation
Pre-existent neurological deficiency
Infection near puncture site
Allergy to local anaesthetic
Inability to communication properly
Expected difficulty with airway Refusal by patient
Allergy for (components of) medications
aE.g. arthritis, osteoporosis, metastasis, spinal disc herniation, scoliosis
institute for Medical Technology Assessment (iMTA, Eras
mus University Rotterdam, www.imta.nl) are used .
Complications (both surgery- and anaesthesia-related) are
scored as based on the complication register of the Dutch
Society for Anaesthesiologists. They are classified using the
validated Clavien-Dindo classification . Differences
between various types of remedial surgery and specific
causes of inguinodynia (primary inguinal hernia repair,
primary Pfannenstiel incision, other index surgery, idiopathic
inguinodynia) in relation to efficacy are also determined.
SolviMáx was founded in 2011. An increasing
number of patients with potential abdominal wall or
groin pain syndromes are referred to the surgical
specialists (Fig. 3). Approximately 840 unique
patients were analysed in 2014, and 1045 patients in
2015. Approximately 40–45% of these undergo
Sample size was calculated by using a web-based
calculator (www.openepi.com). Results from previous
retrospective studies were used as criteria for
eligibility were similar (Zwaans WA, van Kuijk SM, le Mair
LH, van Kleef M, Scheltinga MR, Roumen RM –
unpublished observations). Additional literature
regarding anaesthesia on remedial surgery is not available.
Previously demonstrated success rates were 77% in
the spinal anaesthesia group and 58% in the general
anaesthesia group (Zwaans WA, van Kuijk SM, le
Mair LH, van Kleef M, Scheltinga MR, Roumen RM –
unpublished observations). Based on these data, a sample
size of 190 patients is calculated to demonstrate a
potential effect of either type of anaesthesia on pain relief.
This volume of patients is attained after three years
as based on the number of included patients in
previously performed studies (Fig. 4).
Fig. 2 Content for the schedule of enrolment, interventions and assessments according to the SPIRIT Statement 
Patients will be electronically randomised by the
web-based research software Research Manager (RM,
Cloud 9 Health Solutions©). No blocked randomisation
or prestratification is performed. The decision to execute
a neurectomy and/or mesh removal depends on patient
history, physical examination and intraoperative findings
. Therefore, a prestratified randomisation is not
possible for type of remedial surgery. Consequently,
stratification will be executed within the analysis.
Sequence generation, allocation concealment and
RM is used to establish an appropriate sequence
generation and allocation concealment. RM generates a
random allocation sequence, after which patients will be
enrolled by the coordinating investigator. By using RM
software, foreknowledge of (upcoming) anaesthesia
assignments by the investigators is secured. Consequently,
bias due to improper randomisation techniques is
Blinding of anaesthesiologists, surgeons and patients
is not possible. Since the study is designed to
investigate the setting of type of anaesthesia, where all
factors associated with anaesthesia are of interest,
blinding is not conditional for a robust conclusion
on efficacy of either anaesthetic technique setting.
Fig. 3 Number of unique patients analysed at SolviMáx Centre of Excellence for Chronic Abdominal Wall and Groin Pain over the years
Data analysis will be performed using SPSS version 22
(SPSS Inc. ©) for Windows. Digital data are easily
exported from RM to SPSS. The primary outcome
measure is pain relief using NRS as compared to the
preoperative pain levels (t0). Pain reduction is calculated by
using the following formula:
Data of the general and spinal anaesthesia group will be
compared using the Student’s t test or the Wilcoxon signed
rank test, as appropriate.
Secondary outcome measures will be compared between
groups at the various postoperative follow-up points. In
Fig. 4 Expected inclusion in the present trial, calculated by included patients in previously performed retrospective studies 
addition, outcomes at each evaluation time (t1–t5) will be
compared to preoperative data within groups. The Student’s
t test or the Wilcoxon signed rank test will be used as
appropriate. P values ≤ 0.05 are considered statistically
significant. Intention-to-treat analysis will be applied on the
primary outcome measure.
Patients will be recruited at SolviMáx once the shared
decision is taken to perform remedial surgery. During the
subsequent preoperative screening, eligibility of patients
for both general and spinal anaesthesia is assessed. Within
14 days of consideration, informed consent is obtained. If
the patient consents, the coordinating investigator will
randomise the patient as previously described. Patients are
allowed to withdraw at any time point during the study.
General anaesthesia is still applied in the majority (60–
70%) of hernia operations . Spinal anaesthesia, on the
other hand, is only performed in 10–20% patients
undergoing inguinal hernia surgery , although the beneficial
effects regarding postoperative pain were previously
demonstrated in primary hernia repair [21, 22]. In addition,
studies on primary inguinal herniorrhaphy showed that
spinal anaesthesia results in shorter hospital stay, less
postoperative analgesic requirements, prolonged time to
first analgesic requirement, equal operation room time
and equal time-to-home readiness [22–24]. Only recently,
a potential beneficial effect of spinal anaesthesia on
surgery for groin pain was demonstrated . This is the
first randomised trial comparing two routine anaesthetic
modalities for remedial surgery. Results of the present trial
may aid in optimising care in these patient populations.
Considering groin pain relief following remedial surgery
for groin pain, spinal anaesthesia is hypothesised to be
superior to general anaesthesia. The assumed beneficial
effect is possibly associated with the spinal block itself
diminishing transmission of nociceptive signals from the
operation site toward the nervous system [21, 25].
However, as potential confounding factors are not excluded, a
possible beneficial effect cannot be attributed to just one
particular factor. Any potential effect should be
considered as the end result of the total setting of type of
anaesthesia and associated factors. These confounding factors
include the intrathecal administration of anaesthetics,
articaine or other drugs, patient expectations, surgical
stress, patient’s state (sedated or awake) during surgery,
communication with patients and various other individual
psychological factors. The present study is designed to
generate clinically relevant conclusions that can be
directly implemented in clinical practice.
In 2004, Burney and coauthors performed a randomised
trial on the effects of anaesthesia in primary herniorrhaphy
. A disappointingly low recruitment rate was observed.
The authors stated that patients had conceptualised
concerns regarding the anaesthetic techniques, and
consequently did not accept a random assignment . It
is theoretically possible that patients who are more anxious
about the upcoming surgical procedure prefer general over
spinal anaesthesia as they do not wish to experience any
‘noise’ from within the operation room. Studies have
demonstrated that anxiety is a risk factor for postoperative pain
[27–29]. When these patients are prone to more intense
postoperative pain and thus prefer general anaesthesia,
these issues may have influenced previous outcomes.
In contrast, another study showed that preferred type
of anaesthesia did not contribute to success after
remedial surgery (Zwaans WA, van Kuijk SM, le Mair
LH, van Kleef M, Scheltinga MR, Roumen RM –
unpublished observations). In SolviMáx, a standard
set of intake questionnaires is obtained from all
preoperative patients including a Pain Catastrophising
Scale (PCS) and a Hospital Anxiety and Depression
Scale (HADS) [30–32]. By analysing these scores in
relation to outcome, it is possible to analyse the
influence of mental status in a later phase.
The majority of studies on chronic postoperative pain
lack sufficient data to draw any robust conclusions.
Previously, authors have claimed that extensive preoperative
data, detailed characteristics of surgical procedures and
measures of acute and chronic postoperative pain (up to
1 year) are essential for a proper evaluation of effects on
pain . The present trial design has included all of
these factors and, therefore, the results can be
considered of sufficient scientific evidence. Furthermore,
costeffectiveness of both anaesthetic techniques is assessed,
which is critical for clinical practice.
A potential limitation of the present study is its
nonblinded design. Blinding of patients is, in our opinion,
unethical and hardly practicable. Moreover, the main
outcomes of the present trial are subjective.
Consequently, these outcomes may be contaminated by recall
bias if patients enrolled in the trial are not blinded to
their treatment allocation .
This is the first large randomised controlled trial
comparing two routinely used anaesthetic techniques in
remedial surgery for groin pain. There is a definite need
for evidence-based strategies to optimise the results of
these types of surgery. Besides pain relief, other
patientrelated outcome measures are assessed to include
patient’s perspectives on outcome. The first study results
are expected in 2019 and will be communicated via
ACNES: Abdominal cutaneous nerve entrapment syndrome; ASA: American
Society Anesthesiologists; HADS: Hospital Anxiety and Depression Scale;
iMTA: Institute for Medical Technology Assessment; MMC: Máxima Medical
Center; NRS: Numerical Rating Scale; PCS: Pain Catastrophising Scale;
RM: Research Manager; SF-12: Short Form Health Survey-12 questionnaire
WZ: conception and design of study, acquisition of data, drafting of
manuscript, critical revision of manuscript. LL: conception and design of
study, drafting of manuscript, critical revision of manuscript. MS: conception
and design of study, acquisition of data, drafting of manuscript, critical
revision of manuscript. RR: conception and design of study, acquisition of
data, drafting of manuscript, critical revision of manuscript. All authors read
and approved the final manuscript.
Ethics approval and consent to participate
The protocol (protocol number NL54115.015.15) is approved by the Medical
Ethics Committee of Máxima Medical Centre, Veldhoven, the Netherlands.
After recruitment of patients, patients have 14 days of consideration before
informed consent is obtained.
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