Prevalence of Anterior Cutaneous Nerve Entrapment Syndrome in a Pediatric Population With Chronic Abdominal Pain

Lidocaine patch as noninvasive alternative treatment option in children with anterior cutaneous nerve entrapment syndrome: A retrospective case series

BACKGROUND

Chronic abdominal pain in children is occasionally caused by anterior cutaneous nerve entrapment syndrome (ACNES). Diagnosing and treating this typical peripheral abdominal wall neuropathy is challenging. Management usually starts with minimally invasive tender point injections. Nevertheless, these injections can be burdensome and might even be refused by children or their parents. However, a surgical neurectomy is far more invasive. Treatment with a Lidocaine 5% medicated patch is successfully used in a variety of peripheral neuropathies.

AIMS

This single center retrospective case series aimed to evaluate the effectiveness and tolerability of lidocaine patches in children with ACNES.

METHODS

Children aged under 18 diagnosed with ACNES who were treated with a 10 day lidocaine patch treatment between December 2021 and December 2022 were studied. Patient record files were used to collect treatment outcomes including pain reduction based on NRS and complications.

RESULTS

Twelve of sixteen children (mean age 13 years; F:M ratio 3:1) diagnosed with ACNES started the lidocaine patch treatment. Two patients achieved a pain free status and remained pain free during a 4 and 7 months follow-up. A third child reported a lasting pain reduction, but discontinued treatment due to a temporary local skin rash. Five additional patients reported pain reduction only during application of the patch. The remaining four children experienced no pain relief. No adverse effects were reported.

CONCLUSION

Lidocaine patches provides pain relief in a substantial portion of children with ACNES.

Age and Sex Differences in Pediatric Neuropathic Pain and Complex Regional Pain Syndrome: A Scoping Review

BACKGROUND

Age and sex differences may exist in the frequency (incidence, prevalence) or symptoms of neuropathic pain (NP) and complex regional pain syndrome (CRPS) due to biopsychosocial factors (eg, neurodevelopment, physiological and hormonal changes, psychosocial differences) that evolve through childhood and adolescence. Age and sex differences may have implications for evaluating screening and diagnostic tools and treatment interventions.

OBJECTIVE

To map the existing literature on pediatric NP and CRPS with respect to age and sex distributions, and age and sex differences in symptomology and frequency.

METHODS

A scoping literature review was conducted. Databases were searched from inception to January 2023. Data were collected on study design, setting, demographics, and age and sex differences in frequency and symptoms.

RESULTS

Eighty-seven studies were included. Distribution of participants with CRPS (n=37 studies) was predominantly early adolescence (10 to 14 y) and female sex, while NP (n=42 studies) was most commonly reported throughout adolescence (10 to 19 y) in both sexes. Forty-one studies examined age and sex differences in frequency; 6 studies reported higher frequency in adolescence. Very few studies (n=11) examined differences in symptomology.

DISCUSSION

Large epidemiological studies are required to further understand age and sex differences in frequency of pediatric NP and CRPS. Age and sex differences must be considered when evaluating screening and diagnostic tools and treatment interventions to ensure relevance and validity to both sexes and across ages. Validated tools will improve understanding of age-dependent and sex-dependent differences in symptoms, pathophysiology, and psychosocial impact of pediatric NP and CRPS.

How Do We Treat Children with Anterior Cutaneous Nerve Entrapment Syndrome and Is the Biopsychosocial Model Also Being Applied? A Scoping Review

Background

Evidence-based guidelines for managing anterior cutaneous nerve entrapment syndrome (ACNES) in children are absent. The primary aim of this review was to scrutinize the evidence supporting currently used treatment interventions. In accordance with the World Health Organization (WHO) guidelines for managing chronic pain in children, these patients and their families and caregivers should be treated within the context of the biopsychosocial model; pain should not be treated purely as a biomedical problem. Therefore, our second aim was to evaluate whether these interventions are applied within the context of the biopsychosocial model, utilizing an inter- or multidisciplinary approach.

Materials and Methods

A scoping review of the literature was conducted to explore treatment strategies for ACNES in children. To ensure a comprehensive overview of published literature on this topic, the search was not restricted based on study type. Two reviewers independently assessed titles and abstracts. After excluding records unrelated to children, full texts were screened for inclusion. Any discrepancies in judgement were resolved through discussion with a third reviewer.

Results

Out of 35 relevant titles, 22 were included in this review. Only 4 articles provided information on long-term outcomes. The overall quality of the review was deemed low. The majority of reports did not address treatment or education within the psychological and social domains. A structural qualitative analysis was not feasible due to the substantial heterogeneity of the data.

Conclusion

The evidence supporting current treatment strategies in children with ACNES is of low quality. More research is needed to establish an evidence-based treatment algorithm for patients with this challenging pain problem. In line with the WHO recommendation, greater emphasis should be placed on a biopsychosocial approach. The ultimate goal should be the development of a generic treatment algorithm outlining an approach to ACNES applicable to all professionals involved.

Three Subtypes of Cutaneous Nerve Entrapment Syndrome: A Narrative Review

Anterior, lateral, and posterior cutaneous nerve entrapment syndromes have been proposed as etiologies of trunk pain. However, while these syndromes are analogous, comprehensive reports contrasting the three subtypes are lacking. We therefore reviewed the literature on anterior, lateral, and posterior cutaneous nerve entrapment syndrome. We searched the PubMed and Cochrane Library databases twice for relevant articles published between March and September 2022. In addition to 16 letters, technical reports, and review articles, a further 62, 6, and 3 articles concerning anterior, lateral, and posterior cutaneous nerve entrapment syndromes, respectively, were included. These syndromes are usually diagnosed based solely on unique history and examination findings; however, the diagnostic process may be prolonged, and multiple re-evaluations are required. The most common first-line treatment is trigger point injection; however, the management of refractory cases remains unclear. Awareness of this disease should be expanded to medical departments other than general medicine.

Pulsed radiofrequency in a paediatric patient with disabling ACNES

Chronic abdominal pain is a highly prevalent entity in the paediatric population and represents a diagnostic challenge for professionals. It is frequently underdiagnosed, and must be treated by a multidisciplinary team after a detailed clinical evaluation has been performed to rule out other pathologies. Anterior cutaneous nerve entrapment syndrome (ACNES) occurs when the anterior cutaneous abdominal nerves become pinched or trapped, causing intense, unilateral, circumscribed abdominal pain. Patients often present a positive Pinch test or Carnett's sign. A stepwise therapeutic approach should be used, reserving the most invasive techniques for patients with refractory ACNES. Among the many different treatments available, local anaesthesia infiltration has shown a high success rate, and surgery should only be performed in the most refractory cases. We report the case of an 11-year old girl with a 6-month history of ACNES that severely affected her quality of life, who responded well to pulsed radiofrequency ablation.

The role of a simple questionnaire predicting treatment success in children with ACNES

BACKGROUND

Some children with chronic abdominal wall pain or groin pain do not have an inguinal hernia but suffer from anterior cutaneous nerve entrapment syndrome (ACNES). Diagnosing ACNES is challenging, especially in children as a diagnostic gold standard is lacking. A paediatric questionnaire containing 17 simple items was earlier found to discriminate between abdominal pain due or ACNES or IBS. Scores range from 0 points (ACNES very unlikely) to 17 points (ACNES very likely). The present study investigates whether this 17-item questionnaire predicted treatment success in children receiving therapy for ACNES.

METHODS

Children < 18 years who presented in a single institute between February 2016 and October 2021 with symptoms and signs suggestive of ACNES completed the questionnaire before intake and treatment. Treatment success after 6-8 weeks was defined as self-reported 'pain-free' (group 1), ' > 50% less pain' (group 2) and ' < 50% less pain' (group 3). Group differences regarding sex, age, BMI, symptoms duration and questionnaire scores were analysed.

RESULTS

Data of 145 children (female 78%, mean age 14.7 ± 2.3 years, mean BMI 21.1 ± 3.9) were analysed. All children received a diagnostic trigger point injection using an anaesthetic agent, and 75.5% underwent subsequent surgery for untractable pain. The three groups were comparable regarding sex distribution, age, BMI and symptoms duration. In addition, questionnaire scores were not different (group 1: n = 89, mean score 13.4 ± 2.7, group 2: n = 24, 13.4 ± 2.3 and group 3: n = 32, 13.0 ± 2.7, p > 0.05).

CONCLUSIONS

Treatment success was attained in 78% of children undergoing surgery for ACNES. A simple questionnaire scoring items associated with abdominal pain did not predict treatment success.

Nerve Identification Procedures Are Necessary for Complete Recovery From Recurrent Cases of Anterior Cutaneous Nerve Entrapment Syndrome: A Case Report

Anterior cutaneous nerve entrapment syndrome (ACNES) involves pain in the abdominal wall due to nerve compression or ischemia. The diagnosis of ACNES is challenging with the pain often inclined to be diagnosed as psychological in origin. A 20-year-old woman presenting with abdominal pain was initially diagnosed with mesenteric lymphadenitis and prescribed pain relievers. However, following worsened pain, she was hospitalized. Blood examinations, abdominal and gynecological ultrasonography, and gastrocolonoscopy yielded no abnormal findings, leading to suspicions of psychological factors. As the patient experienced sharp abdominal pain on movement, but not at rest, which was temporarily relieved by lidocaine injections, she was diagnosed with ACNES. Rectus abdominal resection was performed but the pain relapsed. Laparoscopic surgery was performed to cut the nerve that caused the pain. After three surgeries, the patient was completely symptom-free. ACNES should be considered as a differential diagnosis for intractable abdominal pain. For recurrent relapses, the triggering nerves must be carefully identified for the successful treatment of ACNES.

Persistent pain relief following a single injection of a local anesthetic for neuropathic abdominal wall and groin pain

OBJECTIVES

It is our experience that a small portion of patients with neuropathic abdominal wall pain syndromes such as the anterior cutaneous nerve entrapment syndrome (ACNES) have a long term beneficial response following just one single tender point injection (TPI) with a local anesthetic agent. This report focuses on the phenomenon of ongoing pain relief following a single local anesthetic injection in neuropathic abdominal wall and groin pain syndromes.

METHODS

This report is an overview based on earlier studies from a center of expertise for neuropathic abdominal wall and groin pain syndromes. All studies on neuropathic abdominal wall and groin pain syndromes reporting on efficacy of a diagnostic TPI using a local anesthetic agent were included.

RESULTS

A total of 10 studies including 834 patients fulfilled study criteria. Each of these 10 studies found that approximately 10% (range, 4-25%) of the cases experienced persistent pain relief after a single TPI with lidocaine 1%.

CONCLUSIONS

Persistent pain relief after a single TPI using a local anesthetic agent may be observed in approximately one of 10 patients suffering from neuropathic abdominal wall or groin pain syndromes. When a patient is suspected of having a neuropathic abdominal wall or groin pain syndrome, a single TPI using a local anesthetic agent should be administered as long term pain relief may occasionally occur.

Surgical Treatment of Abdominal Wall Neuromas

Neuromas are an under-recognized contributor to chronic abdominal pain. Other than after mesh inguinal hernia repair, surgical management of painful abdominal wall neuromas has not been well established in the literature.

Treatment strategies for anterior cutaneous nerve entrapment syndrome in children: A systematic review

BACKGROUND

Anterior cutaneous nerve entrapment syndrome (ACNES) is a frequently overlooked cause of chronic abdominal pain in children. Currently, both nonsurgical and surgical treatment options are available to treat this disease. The objective was to give insight into the success rate of different treatment strategies for children with ACNES, and provide treatment recommendations for physicians based on the published evidence.

METHOD

A literature search of PubMed, Embase.com and the Wiley/Cochrane Library was conducted for studies published up to 25 February 2020. Randomized controlled trials, prospective or retrospective cohort studies, meta-analyses and literature reviews describing the outcome of different treatment strategies for children (<18 years old) with ACNES with a follow-up duration of at least four weeks were included.

RESULTS

Six studies, involving 224 patients, were included with an overall quality reported to be between fair and poor. Treatment success of local injections with an anesthetic agent into the trigger point ranged from 38% to 87% with a follow-up ranging from 4 weeks to 39 months. In addition, treatment success of anterior neurectomy ranged from 86% to 100%, with a follow-up duration ranging from 4 weeks to 36 months.

CONCLUSION

A step-up treatment strategy should be applied when treating pediatric patients with ACNES. This strategy starts with an injection with a local anesthetic agent, reserving surgery (anterior neurectomy) as a viable option in case of persistent pain.

LEVEL OF EVIDENCE

II.

Histopathologic examination of resected nerves from children with anterior cutaneous nerve entrapment syndrome: Clues for pathogenesis?

BACKGROUND

Anterior cutaneous nerve entrapment syndrome (ACNES) has been described as a possible cause for chronic pain in the pediatric population. However, the exact pathophysiology of ACNES is unknown. It may be caused by compression or traction of cutaneous nerve branches of intercostal nerves, or it may be the result of an infection. Therefore, we present histopathological evidence to determine the pathophysiology of ACNES.

METHODS

A total of seven pediatric patients underwent a neurectomy for ACNES. All specimens were sent for histopathological evaluation, including immunohistochemical staining, to evaluate if there were any signs of infection, inflammation or compression.

RESULTS

Seven out of seven (100%) histopathological specimens showed non-specific nerve degeneration. Immunohistochemical evaluation showed there were several CD68-positive macrophages present in the specimens. Four out of seven (57%) specimens showed the presence of a few CD3-positive T-cells, however, this was not suggestive for inflammation or infection.

CONCLUSION

Our study supports the hypothesis that ACNES is caused by compression of the nerves rather than inflammation.

LEVEL OF EVIDENCE

III.

The technique of cutaneous neurectomy for anterior cutaneous nerve entrapment syndrome

Anterior cutaneous nerve entrapment syndrome (ACNES) is increasingly diagnosed in children. Pediatric surgeons may be approached to perform a cutaneous neurectomy, the preferred operative approach, and may have no experience with the procedure. This report provides a detailed description of the operative technique used by a pediatric surgeon who has performed over 70 neurectomies for ACNES. Dissemination of this simple procedure will hopefully allow children with ACNES to undergo the procedure locally.

Abdominal Wall Pain or Irritable Bowel Syndrome: Validation of a Pediatric Questionnaire

OBJECTIVES

A questionnaire study demonstrated that some adult patients who were diagnosed with irritable bowel syndrome (IBS) were in fact having an abdominal wall pain syndrome, such as anterior cutaneous nerve entrapment syndrome (ACNES). The aim of the present study was to investigate whether a pediatric version of this questionnaire was useful in diagnosing abdominal wall pain syndromes in children with chronic abdominal pain (CAP).

METHODS

An 18-item questionnaire was tested in 3 groups of children with CAP: group 1, children who underwent surgery for ACNES (n = 42); group 2, children who were found to have ACNES after an outpatient analysis (n = 57); and group 3, children diagnosed with IBS (n = 53). Qualities including internal consistency (Cronbach α), cut-off points and a ROC-curve were calculated using standard statistical analysis.

RESULTS

Questionnaire response rates in the three populations of CAP children ranged from 69% to 92%. When comparing ACNES and IBS groups, 17 of 18 questions were discriminative (P < 0.01, Cronbach α 0.74). Total questionnaire scores ranged from 0 (IBS likely) to 17 points (ACNES likely). A median 13-point score (range 8-17) was found in both ACNES groups. In contrast, a median 8-point score was calculated in children with IBS (range 3-13, P < 0.01). Using an 11-point cut-off score, a child with CAP was diagnosed with ACNES with 86% sensitivity and 89% specificity. A ROC curve with an AUC of 0.94 was obtained.

CONCLUSIONS

A 17-item questionnaire showed good diagnostic test properties and may aid in distinguishing ACNES from IBS in pediatric populations with chronic abdominal pain.

Anterior Cutaneous Nerve Entrapment Syndrome in a Pediatric Patient Previously Diagnosed With Functional Abdominal Pain: A Case Report

Chronic abdominal pain is common in children and adolescents but challenging to diagnose, because practitioners may be concerned about missing serious occult disease. Abdominal wall pain is an often ignored etiology for chronic abdominal pain. Anterior cutaneous nerve entrapment syndrome causes abdominal wall pain but is frequently overlooked. Correctly diagnosing patients with anterior cutaneous nerve entrapment syndrome is important because nerve block interventions are highly successful in the remittance of pain. Here, we present the case of a pediatric patient who received a diagnosis of functional abdominal pain but experienced pain remittance after receiving a trigger-point injection and transverse abdominis plane block.

Peripheral neuropathic mimics of visceral abdominal pain: Can physical examination limit diagnostic testing?

BACKGROUND

The emergency department evaluation of patients with abdominal pain is most appropriately directed at identifying acute inflammation, infection, obstruction, or surgical disease. Doing so commonly involves "routine" (and often extensive) diagnostic imaging and laboratory testing. Benign mimics of serious visceral abdominal pain that can be diagnosed by physical exam and confirmed with local anesthetic injections have been identified over the last century. These syndromes derive from painful irritation of the intercostal nerves by a mobile rib below, or from impingement of the cutaneous branches of those same intercostal nerves as they penetrate the abdominal wall. These peripheral neuropathic mimics of visceral abdominal pain continue to go unrecognized and underdiagnosed.

METHODS

Our purpose is to review the affirmative diagnosis of non-visceral abdominal pain by physical examination.

RESULTS

The consequences of failure to identify these conditions are considerable. In the search for a diagnosis that is literally at the provider's fingertips, patients frequently undergo months to years of fruitless and often invasive diagnostic tests, not uncommonly including unsuccessful surgeries.

CONCLUSIONS

With proper consideration of and appropriate testing for visceral etiologies, a carefully directed physical examination may yield an affirmative diagnosis in a percentage of these common emergency department patients.

Neurectomy for anterior cutaneous nerve entrapment syndrome in children

INTRODUCTION

Anterior cutaneous nerve entrapment syndrome (ACNES) is an underrecognized etiology of chronic abdominal pain that causes great morbidity to those affected. We sought to determine the outcome of neurectomy for ACNES in children.

METHODS

Demographic and clinical data on children who underwent neurectomy for ACNES by a single surgeon from 10/2011 to 01/2017 were reviewed.

RESULTS

Twenty-six patients underwent neurectomy for ACNES. Five were male and average age was 15years (10-21). Median (IQR) preoperative pain duration was 15 (8-29) months and 19 reported their pain was 10/10 (6-10). Thirteen patients were taking antidepressants, 12 Gabapentin, and 4 narcotics. Most had been hospitalized at least once secondary to the pain. All 26 had undergone diagnostic studies including: nuclear medicine scan, fluoroscopy, computed tomography, magnetic resonance imaging, sonography, endoscopy and surgery. Once the diagnosis was suspected, all underwent at least one ultrasound-directed nerve block, which provided relief lasting from 6h to 14days. Patients then underwent outpatient surgery with division of the involved nerve(s). There were no perioperative complications. Most patients reported incisional discomfort for 3-14days afterward, and immediate resolution of the nerve pain without cutaneous numbness. Postoperatively, 15 patients (58%) were pain free long-term; pain recurred to a lesser severity in 8 (31%) and recurred to the same extent in 3 (11%), with average time to recurrence of 6.7months. Of those whose pain recurred to a lesser extent, all achieved long term relief, 4 improved with time, 1 through repeat neurectomy, 2 through medical treatment for underlying psychiatric disorders and 1 through treatment for newly diagnosed inflammatory bowel disease. Of those children with pain recurring to the same extent, all underwent repeat neurectomy, none of whom achieved pain relief.

CONCLUSION

ACNES should be considered in children with chronic abdominal pain. Neurectomy is safe and relieves pain in around 88% of selected children. Further investigation is necessary to optimize patient selection.

LEVEL OF EVIDENCE

IV.

Diagnostic characteristics of anterior cutaneous nerve entrapment syndrome in childhood

Some children suffering from chronic abdominal pain may have an abdominal wall entity such as anterior cutaneous nerve entrapment syndrome. This syndrome is largely suspected on a combination of findings at history and physical examination. The aim is to obtain clues in history and physical examinations in a selected population of children with anterior cutaneous nerve entrapment syndrome. We analyzed all children with abdominal pain visiting our hospital between January 2013 and January 2015. A total of 71 cases were identified (median age 15 years, range 8-17, 77% female). Pain was severe (median 8, range 6-9), stabbing/burning (84%), superficial (88%), aggravated by physical activity (91%), and always in one abdominal area (97%). Hypo-/hyperesthesia (87%) or a positive pinch test (89%) was often found at the skin overlying the painful spot. Increased pain was reported by 97% when the abdominal muscles were tensed (Carnett test). A single anterior rectus sheath block is successful in almost all patients (97%).

CONCLUSION

A combination of typical findings in history and physical examination allows for diagnosing childhood ACNES. What is Known: • Anterior cutaneous nerve entrapment syndrome (ACNES) is often overlooked in chronic abdominal pain. • Pediatric literature on diagnostic work up for ACNES is poor. What is New: • Two third reported treatment delay due to misdiagnosis as functional abdominal pain. • Medical history and physical examination revealed neuropathic pain characteristic in up to 90% of the cases.

Anterior rectus sheath blocks in children with abdominal wall pain due to anterior cutaneous nerve entrapment syndrome: a prospective case series of 85 children

BACKGROUND

Chronic abdominal pain in children may be caused by the anterior cutaneous nerve entrapment syndrome. Local nerve blocks are recommended as an initial treatment in adults. Evidence on effectiveness and safety of such a treatment in children is lacking.

AIM

Our aim was to study outcome and adverse events of anterior rectus sheath blocks in childhood anterior cutaneous nerve entrapment syndrome.

METHODS

Patients <18 years of age receiving anterior rectus sheath blocks were prospectively followed. Injections were administered using a free-hand technique in the outpatient department.

RESULTS

A total of 85 children were included (median age 15 years, range 8-17, 76% female). Eighty-three children reported immediate pain relief following a single lidocaine block and 13 achieved long-term success. Another 19 children was successfully treated with additional blocks combined with steroids. A total 38% success ratio was attained after a median 17-month follow-up (range, 4-39). Pain intensity and diagnostic delay were not associated with a beneficial outcome. However, young age predicted success. An infrequently occurring adverse event was temporarily increased pain some 6 h post injection.

CONCLUSION

Anterior rectus sheath blocks using local anesthetics and steroids are safe and long-term successful in more than one-third of children suffering from abdominal pain due to anterior cutaneous nerve entrapment syndrome.

Anterior neurectomy in children with a recalcitrant anterior cutaneous nerve entrapment syndrome is safe and successful

INTRODUCTION

Anterior cutaneous nerve entrapment syndrome (ACNES) is a relatively unknown cause of severe neuralgic abdominal pain. Treatment includes medication, local nerve blocks or, if unresponsive, a neurectomy of nerve endings. In children, the outcome of neurectomy for ACNES is scantly described in retrospective studies. The objective of this first prospective study was to investigate the safety and short term success rate of anterior neurectomy in a large pediatric population with ACNES.

METHODS

All children <18years with failed non-surgical treatments for ACNES who underwent an anterior neurectomy in a pediatric surgical referral center between March 2012 and June 2015 were prospectively followed. Patients with previous ACNES surgery were excluded. Primary outcome measures were pain relief and adverse events.

RESULTS

60 children were included (80% female, mean age 15years±2 SD). 75% had right lower abdominal pain. At first follow-up, 47 children were free of pain (78% success rate). Complications other than an occasional local hematoma were not reported. Outcome was not related to demographics, preoperative pain intensity, pain duration or localization.

CONCLUSION

Anterior neurectomy is safe and successful in most children with abdominal pain failing a conservative treatment for ACNES.

TYPE OF STUDY

Treatment study.

LEVEL OF EVIDENCE

IV.

Anterior cutaneous nerve entrapment syndrome: management challenges

Anterior cutaneous nerve entrapment syndrome (ACNES) is a commonly underdiagnosed and undertreated chronic state of pain. This syndrome is characterized by the entrapment of the cutaneous branches of the lower thoracoabdominal intercostal nerves at the lateral border of the rectus abdominis muscle, which causes severe, often refractory, chronic pain. This narrative review aims to identify the possible therapeutic strategies for the management of the syndrome. Seventeen studies about ACNES therapy were reviewed; of them, 15 were case-control studies, case series, or case reports, and two were randomized controlled trials. The presently available management strategies for ACNES include trigger point injections (diagnostic and therapeutic), ultrasound-guided blocks, chemical neurolysis, and surgical neurectomy, in combination with systemic medication, as well as some emerging techniques, such as radiofrequency ablation and neuromodulation. An increased awareness of the syndrome and the use of specific diagnostic criteria for its recognition are required to facilitate an early and successful management. This review compiles the proposed management strategies for ACNES.