Anterior cutaneous nerve entrapment syndrome (ACNES)

Anterior Cutaneous Nerve Entrapment Syndrome Presenting as Chronic Abdominal Pain

Abdominal pain is one of the most common chief complaints that patients present with to healthcare facilities across specialties. Unfortunately for clinicians, the differential diagnosis for abdominal pain is vast. Abdominal pain can be broken down into two broad categories: visceral and non-visceral causes. One of the most common causes of non-visceral abdominal pain is anterior cutaneous nerve entrapment syndrome (ACNES). This report describes the case of a formerly active male in his 20s, who has been suffering from chronic abdominal pain for half of his life. Because of the broad differential and the overall lack of familiarity with ACNES, many patients face prolonged suffering and the psychological anguish of uncertainty. This report seeks to illuminate the importance of considering ACNES in a patient with chronic abdominal pain.

Long-Term Efficacy of Posterior Neurectomy in Anterior Cutaneous Nerve Entrapment Syndrome

Objective

To analyze long-term treatment outcomes of a posterior neurectomy in a large cohort of patients with anterior cutaneous nerve entrapment syndrome (ACNES).

Summary Background Data

The current step-up treatment approach for ACNES involves abdominal wall tender point injections, pulsed radiofrequency, and neurectomy. If an anterior neurectomy fails or pain reoccurs, a posterior neurectomy is considered as a final surgical option. Data on posterior neurectomy treatment outcomes are scarce.

Methods

ACNES patients who underwent a unilateral posterior neurectomy between 2012 and 2022 in a single institution completed a questionnaire regarding their current pain status. Primary outcomes were short- and long-term treatment success, defined as ≥50% pain relief. Patients were stratified whether the operative indication was recurrent pain (>3 months) after an initially successful anterior neurectomy or ongoing pain after an anterior neurectomy.

Results

Data from 260 of 379 patients (77% female, mean age 42 years) were analyzed (68.6% response rate). Sensitivity analysis found that short-term outcomes were similar between responders and non-responders. The recurrent pain group demonstrated significantly better treatment outcomes compared to the ongoing pain group, both in the short-term (7 weeks; treatment success 79.2% vs. 53.2%, p < 0.001) and long-term (58 months; treatment success 61.1% vs. 42.0%, p = 0.001). Sixteen (minor) complications (6.2%) were reported, resulting in three surgical re-interventions (1.2%).

Conclusion

A posterior neurectomy is long-term beneficial in approximately half of patients although treatment success is better for recurrent pain than ongoing pain. These findings aid in optimizing preoperative patient counseling.

Ultrasound-guided peripheral nerve blocks for anterior cutaneous nerve entrapment syndrome after robot-assisted gastrectomy: A case report

BACKGROUND

Anterior cutaneous nerve entrapment syndrome (ACNES) is a condition manifesting with pain caused by strangulation of the anterior cutaneous branch of the lower intercostal nerves. This case report aims to provide new insight into the selection of peripheral nerve blocks for the ACNES treatment.

CASE SUMMARY

A 66-year-old woman manifested ACNES after a robot-assisted distal gastrectomy. An ultrasound-guided rectal sheath block was effective for pain triggered by the port scar. However, the sudden severe pain, which radiated laterally from the previous site, remained. A transversus abdominis plane block was performed for the remaining pain and effectively relieved it.

CONCLUSION

In this case, the trocar port was inserted between the rectus and transverse abdominis muscles. The intercostal nerves might have been entrapped on both sides of the rectus and transversus abdominis muscles. Hence, rectus sheath and transverse abdominis plane blocks were required to achieve complete pain relief. To the best of our knowledge, this is the first report on use of a combination of rectus sheath and transverse abdominis plane blocks for pain relief in ACNES.

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.

Anterior Cutaneous Nerve Entrapment Syndrome Caused by a Fixation Device: A Case Report

Anterior cutaneous nerve entrapment syndrome (ACNES) is characterized by abdominal wall neuralgia. We report an 85-year-old woman with ACNES caused by a fixation device during the bipolar hip arthroplasty. To prevent ACNES as a perioperative peripheral nerve injury, it is important to maintain patients in the appropriate position during the operation. A positive Carnett's sign means the abdominal pain originates from the abdominal wall and is useful in diagnosing ACNES. Thus, physicians should examine Carnett's sign to differentiate ACNES in patients with abdominal pain developing after an operation.

Parietal abdominal pain with lower leg discrepancy: a case report

BACKGROUND

This report involves the first publication describing a case of parietal abdominal pain due to lower limb length discrepancy.

CASE PRESENTATION

A Caucasian male patient in his 50s was referred to our rehabilitation department with chronic abdominal pain that began in childhood. This chronic pain was associated with episodes of acute pain that were partially relieved by grade 3 analgesics. The patient was unable to sit for long periods, had recently lost his job, and was unable to participate in recreational activities with his children. Investigations revealed contracture and hypertrophy of the external oblique muscle and an limb length discrepancy of 3.8 cm (1.5 inches) in the left lower limb. The patient was effectively treated with a heel raise, physiotherapy, intramuscular injection of botulinum toxin, and lidocaine. The patient achieved the therapeutic goals of returning to work, and reducing analgesic use.

CONCLUSIONS

Structural misbalances, as may be caused by lower leg discrepancy, may trigger muscular compensations and pain. Complete anamnesis and clinical examination must not be trivialized and may reveal previously ignored information leading to a proper diagnosis.

Groin Pain Syndrome Italian Consensus Conference update 2023

Groin pain syndrome (GPS) is a controversial topic in Sports Medicine. The GPS Italian Consensus Conference on terminology, clinical evaluation and imaging assessment of groin pain in athletes was organized by the Italian Society of Arthroscopy in Milan, on 5 February 2016. In this Consensus Conference (CC) GPS etiology was divided into 11 different categories for a total of 63 pathologies. The GPS Italian Consensus Conference update 2023 is an update of the 2016 CC. The CC was based on a sequential, two-round online Delphi survey, followed by a final CC in the presence of all panelists. The panel was composed of 55 experts from different scientific and clinical backgrounds. Each expert discussed 6 different documents, one of which regarded the clinical and imaging definition of sports hernias, and the other 5 dealt with 5 new clinical situations thought to result in GPS. The panelists came to an agreement on the definition of a sports hernia. Furthermore, an agreement was reached, recognizing 4 of the 5 possible proposed pathologies as causes to GPS. On the contrary, the sixth pathology discussed did not find consensus given the insufficient evidence in the available scientific literature. The final document includes a new clinical and imaging definition of sports hernia. Furthermore, the etiology of GPS was updated compared to the previous CC of 2016. The new taxonomic classification includes 12 categories (versus 11 in the previous CC) and 67 pathologies (versus 63 in the previous CC).

Visceral symptoms in patients with anterior cutaneous nerve entrapment syndrome (ACNES): expression of viscerosomatic reflexes?

PURPOSE

Anterior cutaneous nerve entrapment (ACNES) is characterized by neuropathic pain in a predictable, circumscript abdominal area. The diagnostic delay is long, with half of ACNES-affected individuals reporting nausea, bloating, or loss of appetite mimicking visceral disease. The aim of this study was to describe these phenomena and to determine whether treatment could successfully reverse the visceral symptoms.

METHODS

This prospective observational study was conducted between July 2017 and December 2020 at SolviMáx, Center of Excellence for Chronic Abdominal Wall and Groin Pain, Máxima Medical Center, Eindhoven. Adult patients who fulfilled published criteria for ACNES and reported at least one visceral symptom at intake were eligible for the study. A self-developed Visceral Complaints ACNES Score (VICAS) questionnaire that scores several visceral symptoms (minimum 1 point, maximum 9 points) was completed before and after therapy. The success of treatment was defined as at least 50% reduction in pain.

RESULTS

Data from 100 selected patients (86 females) aged 39 ± 5 years were available for analysis. Frequently reported symptoms were abdominal bloating (78%), nausea (66%) and altered defecation (50%). Successful treatment significantly reduced the number of visceral symptoms, with a VICAS before of 3 (range 1-8) and after of 1 (range 0-6) (p < 0.001). A low baseline VICAS was associated with successful treatment outcome (OR 0.738, 95% CI 0.546-0.999).

CONCLUSION

Patients with ACNES may report a variety of visceral symptoms. Successful treatment substantially reduces these visceral symptoms in selected patients.

A positive scratch collapse test in anterior cutaneous nerve entrapment syndrome indicates its neuropathic character

OBJECTIVES

Chronic abdominal pain is occasionally caused by an abdominal wall entity such as anterior cutaneous nerve entrapment syndrome (ACNES). This syndrome is thought to occur due to intercostal nerve branches (T7-12) that are entrapped in the rectus abdominis muscles. The diagnosis is largely based on subjective clues in patient history and physical examination. A test referred to as the scratch collapse test (SCT) is used as an additional diagnostic tool in peripheral nerve entrapment syndromes such as the carpal tunnel syndrome. The aim of the present study is to investigate whether an SCT was positive in patients with suspected ACNES. If so, this finding may support its hypothesized neuropathic character.

METHODS

A prospective, case-control study was performed among patients with ACNES (n = 20) and two control groups without ACNES (acute intra-abdominal pathology n = 20; healthy n = 20), all were consecutively included. ACNES was diagnosed based on previously published criteria. The SCT test was executed at the painful abdominal area in both patient groups and at a corresponding area in healthy controls. Predictive values, sensitivity, and specificity were calculated. Videos of tests were evaluated by blinded observers.

RESULTS

SCT was judged positive in 19 of 20 ACNES patients but not in any of the 40 controls. A 95% sensitivity (confidence interval [CI]: 75-99) and optimal specificity (100%; CI: 83-100) were calculated.

CONCLUSIONS

The positive SCT supports the hypothesis that ACNES is an entrapment neuropathy. A positive SCT should be considered a major diagnostic criterion for ACNES.

The Scratch Collapse Test in patients diagnosed with Anterior Cutaneous Nerve Entrapment Syndrome (ACNES): A report of three cases

INTRODUCTION AND IMPORTANCE

The Scratch Collapse Test (SCT) is currently used as a supportive tool diagnosing peripheral nerve neuropathies including carpal tunnel syndrome or peroneal nerve entrapment. Some patients with chronic abdominal pain suffer from entrapment of terminal branches of intercostal nerves (anterior cutaneous nerve entrapment syndrome, ACNES). ACNES is characterized by a severe disabling pain at a predictable area of the anterior abdomen. Clinical examination shows altered skin sensation and painful pinching at the area of pain. However, these findings may be subjective.

CASE PRESENTATION

In three female patients aged 71, 33, and 43 years with suspected ACNES, the SCT was positive when scratching over the skin of the affected nerve-ending at the abdominal wall. The diagnosis ACNES was confirmed with a local abdominal wall infiltration at the tenderpoint in all three patients. In case three, the SCT turned negative after lidocaine infiltration.

CLINICAL DISCUSSION

ACNES was hitherto a clinical diagnosis just based on clues in medical history and physical examination. Performing a SCT in patients possibly having ACNES may additionally contribute to the diagnosis.

CONCLUSION

The SCT may serve as an additional tool for diagnosing patients with possible ACNES. A positive SCT in patients with ACNES supports the hypothesis that ACNES is indeed a peripheral neuropathy of terminal branches of the lower thoracic intercostal nerves. Controlled research is necessary to confirm the role of a SCT in ACNES.

Successful Nerve Block Therapy for Lateral Cutaneous Nerve Entrapment Syndrome (LACNES) Triggered by Exercise

This report presents a case of a 59-year-old man who experienced pain in the left abdomen during abdominal exercises, which gradually improved. Pain recurred in the same area one year later and gradually worsened, rendering him unable to work. The strongest tender point, with a positive Carnett's sign, was noted on the flank. Ultrasonography revealed a 5 × 10 mm mass shadow in the internal oblique muscle. Trigger point injection at the same site was remarkably effective. Lateral cutaneous nerve entrapment syndrome caused by a crush injury due to abdominal exercises was diagnosed. Nerve block therapy provided effective pain relief.

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.

Abdominal Pain in a 15-Year-Old Adolescent Girl

A 15-year-old adolescent girl taking an oral contraceptive had 3 days of pain in a 1-cm area of the lower left abdominal quadrant. She had no nausea/vomiting, diarrhea, hematochezia, bloating, or anorexia; no precipitating factors for the pain; and no history of pregnancy, abdominal surgery, or abdominal trauma. Results from laboratory tests, endoscopy, and abdominal computed tomography were normal. What is the diagnosis and what would you do next?

A Case Report on Abdominal Pain Treated With a New Technique of Ultrasound-Guided Transversus Abdominis Plane Hydrodissection Using a Low Concentration of Local Anesthetics

Hydrodissection, a technique for performing morphological dissection between the target tissues via injection, has attracted attention in recent years. However, high-quality evidence is available only for a few entrapment neuropathies, such as carpal tunnel syndrome, and further case studies are needed for other diseases. This case report presents the first case of hydrodissection of the ventral ramus of the spinal nerve, which innervates the abdominal wall, to improve abdominal pain. A 59-year-old Japanese man with a history of cerebral infarction and dyslipidemia presented to the emergency department with the chief complaint of left upper abdominal pain that began two days earlier. The pain radiated to the left side of the back and left axilla. The abdomen was flat and soft with no tenderness on examination, and the pinch test was negative. However, Carnett's sign was observed in the left upper abdomen, and the location of the left upper abdominal pain and that of the radiating pain were consistent with the ninth thoracic vertebra (Th9) dermatome; thus, the cause of the left upper abdominal pain was determined to be the ventral ramus of the spinal nerve of Th9. Two weeks of physical therapy and lifestyle guidance were ineffective; therefore, hydrodissection of the transversus abdominis plane (TAP) between the myofascia of the internal oblique muscle and that of the transversus abdominis at the Th9 level using a 23G 60 mm needle under ultrasound guidance was planned. The abdominal pain immediately improved after hydrodissection, and the patient was able to work without pain. Thus, ultrasound-guided TAP hydrodissection with a low-concentration local anesthetic is effective in the treatment of abdominal pain caused by the entrapment of the ventral ramus of the spinal nerve due to adhesions between the myofascia of the internal oblique muscle and that of the transversus abdominis. This condition should be termed ventral ramus of spinal nerve entrapment syndrome (VERNES), and this concept and TAP hydrodissection must be made known to the public.

A Rare Presentation of a Compression Fracture or a Typical Presentation of Lateral Cutaneous Nerve Entrapment Syndrome: A Diagnostic Error?

A 78-year-old woman complained of severe pain in the left costal region. Her body mass index was 23.1 kg/m2. Lateral cutaneous nerve entrapment syndrome (LACNES) was the suspected diagnosis because the affected area was 2×2 cm and positive for pinch sign. Seventeen days later, the patient again presented with complaints of lower back pain accompanied by back pain upon extending the spine. Magnetic resonance imaging of the spine showed a fracture of the vertebral body of T11. We herein discuss our errors in the diagnostic process and critical tactics for avoiding such errors in the future.

Endoscopy-induced anterior cutaneous nerve entrapment syndrome: a case series

Background and study aims  Anterior cutaneous nerve entrapment syndrome (ACNES) is a common but frequently overlooked disorder. Here we report on a series of patients with ACNES following endoscopy. Patients and methods  This case series included consecutive patients with localized abdominal pain following an endoscopic procedure that was consistent with ACNES who presented to the author's Gastroenterology Outpatient Clinic from February 2019 to February 2021. Results  Six patients presented with complaints compatible with ACNES. All of them were successfully managed with local injection therapy (n = 5) or pulsed radiofrequency (PRF) (n = 1). Conclusions  It appears that ACNES can be induced by endoscopy. Early recognition is important to avoid unnecessary diagnostics and delayed pain relief in patients. Most patients can be managed with local injection therapy.

Ultrasound-guided rectus sheath block for anterior cutaneous nerve entrapment syndrome after laparoscopic surgery: A case report

BACKGROUND

Anterior cutaneous nerve entrapment syndrome is defined as abdominal pain due to entrapped intercostal nerves. This is the first report of a patient successfully treated for anterior cutaneous nerve entrapment syndrome after laparoscopic surgery with an ultrasound-guided rectus sheath block. The rectus sheath block physically lysed adhesions and relieved pain from anterior cutaneous nerve entrapment syndrome.

CASE SUMMARY

The patient is a 44-year-old man who presented with severe left upper abdominal pain at an operative scar one month after laparoscopic ulcer repair. Diagnosis and treatment were performed using an ultrasound-guided rectus sheath block with 0.1% lidocaine 20 mL. The pain was relieved after the block. The diagnosis was anterior cutaneous nerve entrapment syndrome. Rectus sheath block may be effective for patients with anterior cutaneous nerve entrapment syndrome.

CONCLUSION

Ultrasound-guided rectus sheath block is a promising treatment modality for patients with postoperative anterior cutaneous nerve entrapment syndrome due to adhesions.

Unique Concerns of the Woman Cyclist

Previously a male-dominated activity, female cyclists now make up nearly half of all cyclists in the United States. Although cycling provides a significant number of health benefits, it is an activity that carries risk of injury, both traumatic and nontraumatic. Sex differences are seen in chest trauma and breast injury, as well as pelvic, given the inherent differences in anatomy. Understanding the relationship of the bicycle to the anatomy of the rider can help mitigate risks for injury.

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.

Chronic Abdominal Pain After Previous Bariatric Surgery: Consider the Abdominal Wall

BACKGROUND

Up to 30% of patients who undergo bariatric surgery experience recurrent abdominal pain within 3 years after the operation. Although some causes for persisting discomfort are well known, a small portion of patients may suffer from an abdominal wall pain associated with Anterior Cutaneous Nerve Entrapment Syndrome (ACNES). Aim of the present study is to discuss incidence, clinical presentation, and treatment outcome in patients with ACNES after bariatric surgery.

METHODS

This retrospective observational cohort study analyzed electronically stored data of patients with ACNES having a history of bariatric surgery. All were treated for ACNES between 2011 and 2017 in a Dutch center of excellence for abdominal wall and groin pain. Success after treatment was defined as a minimal 50% drop in pain level using a Numeric Rating Scale.

RESULTS

A total of 49 patients (female n = 44, median age 45 (25-63) years) were identified. Four (8%) experienced long-term pain relief after just one abdominal wall infiltration with lidocaine. Ten additional patients reported success after 2-5 injections. A total of 35 unresponsive patients chose to undergo a neurectomy that was successful in 27. Therefore, this step-up approach conferred an 84% success rate. Occurrence of ACNES after bariatric surgery was estimated at 1 in 100 patients.

CONCLUSION

ACNES should be considered in the differential diagnosis of ongoing pain following previous bariatric surgery. A treatment regimen including abdominal wall infiltrations using an anesthetic agent or a neurectomy is successful in a vast majority of these patients.

Surgical Management of Abdominal Anterior Cutaneous Nerve Entrapment Syndrome: Case Report, Surgical Technique, and Literature Review

Background:

Abdominal anterior cutaneous nerve entrapment syndrome (ACNES) is an emerging diagnosis, with estimated incidence of 13%–30% of the adult population. It is a syndrome characterized by chronic abdominal pain caused by entrapment of cutaneous branches of thoracoabdominal nerves at the lateral border of the rectus abdominis muscle. If conservative treatment with pain medication, botulinum toxin, or lidocaine injections is inadequate, surgical management is indicated.

Methods:

We present a case of a 40-year-old woman presenting with a 1-year history of daily right anterior abdominal wall pain, consistent with a diagnosis of ACNES. We describe our approach for an anterior neurectomy of the intercostal nerve with closure of its fascial foramen.

Results:

Three months after surgery, she remained pain free and was back to work full time. At a 13-month follow-up, the patient reported that her pain had resolved completely following surgery.

Conclusions:

Results are encouraging following anterior neurectomy for ACNES. Surgical descriptions in the literature are brief, with limited pictorial account. Our detailed surgical approach is provided along with a review of the existing literature on the management of ACNES.

A Primary Care Approach to Abdominal Pain in Adults

Abdominal pain is a common presenting problem with multiple aetiologies that often pose diagnostic and therapeutic dilemmas for primary care practitioners. The vague symptomatology and difficult correlation to specific organ pathology obscures clinical findings leading to incorrect diagnoses. Although most presentations of abdominal pain are benign, a significant number of patients have life-threatening conditions that require a meticulous approach to management in order to prevent morbidity and mortality. The skill in assessing patients presenting with abdominal pain is fundamental for all primary care doctors. This review will discuss an approach to the assessment and diagnosis of abdominal pain in the primary care setting.

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.

A Comprehensive Review and Update of Post-surgical Cutaneous Nerve Entrapment

PURPOSE OF REVIEW

This is a comprehensive review of the literature regarding post-surgical cutaneous nerve entrapment, epidemiology, pathophysiology, and clinical presentation. It focuses mainly on nerve entrapment leading to chronic pain and the available therapies.

RECENT FINDINGS

Cutaneous nerve entrapment is not an uncommon result (up to 30% of patients) of surgery and could lead to significant, difficult to treat chronic pain. Untreated, entrapment can lead to neuropathy and damage to enervated structures and musculature, and significant morbidity and financial loss. Nerve entrapment is defined as pressure neuropathy from chronic compression. It causes changes to all layers of the nerve tissue. It is most significantly associated with hernia repair and other procedures employing a Pfannenstiel incision. The initial insult is usually incising of the nerve, followed by formation of a neuroma, incorporation of the nerve during closing, or constriction from adhesions. The three most commonly involved nerves are the iliohypogastric, ilioinguinal, and genitofemoral nerves. Cutaneous abdominal nerve entrapment could occur during thoracoabdominal surgery. The presentation of nerve entrapment usually involved post-surgical pain in the territory innervated by the trapped nerve, possibly with radiation that tracks the nerve course. Once a suspected neuropathy is identified, it can be diagnosed with relief in pain after a nerve block has been instilled. Treatment is usually started with pharmaceutical solutions, topical first and oral if those fail. Most patients require escalation to a second line of treatment and see good result with injection therapy. Those that require further escalation can choose between ablation and surgical therapies. Post-surgical nerve entrapment is not uncommon and causes serious morbidity and financial loss. It is underdiagnosed and thus undertreated. Preventing nerve entrapment is the best treatment; when it does occur, options include topical and oral analgesics, nerve blocks, ablation therapy, and repeat surgery.

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.

Anterior Cutaneous Nerve Entrapment Syndrome Occurring after Endoscopy

A 45-year-old lady presented for a follow-up endoscopy examination for mild abdominal pain due to gastric ulcers. She experienced a severe, markedly different type of pain with labor-like contractions 3 days later. Physical examination revealed tenderness confined to a 1 × 1-cm area and positive Carnett's sign. The pain completely resolved 10 min after a subcutaneous lidocaine injection. The patient was diagnosed with anterior cutaneous nerve entrapment syndrome. The pain returned within several hours and anterior neurectomy was performed several days later. The pain subsided immediately and no recurrence was seen during 3 years of follow-up.

Anterior Cutaneous Nerve Entrapment Syndrome: Two Case Reports of the Forgotten Diagnosis After Bariatric Surgery

Unexplained abdominal pain is an increasing phenomenon after laparoscopic bariatric surgery, with an occurrence of 7.4%. The pain could be explained by the anterior cutaneous nerve entrapment syndrome (ACNES). However, the incidence of ACNES after laparoscopic bariatric surgery is unclear. We report the cases of two patients with unexplained abdominal pain after laparoscopic bariatric surgery and a significant delay in the diagnosis of ACNES. In both cases, clinical signs of ACNES were demonstrated by a centralized trigger point in the abdominal wall and specific neuropathic aspects during examination. Both patients were temporary pain-free after a diagnostic local lidocaine injection. A neurectomy was performed in both cases, after which they remained pain-free. There was a significant delay (six months and three years, respectively) in the diagnosis of ACNES, and many additional imaging procedures including a diagnostic laparoscopy were performed. ACNES is difficult to diagnose due to its relatively unknown entity.

This case report confirms that the diagnosis of ACNES is still frequently overlooked as a cause of chronic abdominal pain. Earlier diagnosis recognition can probably prevent unnecessary investigations and may improve the quality of life in bariatric patients with unexplained abdominal pain.

A Randomized Controlled Trial to Evaluate the Effect of Pulsed Radiofrequency as a Treatment for Anterior Cutaneous Nerve Entrapment Syndrome in Comparison to Anterior Neurectomy

BACKGROUND

Chronic abdominal pain can be due to entrapped intercostal nerves (anterior cutaneous nerve entrapment syndrome [ACNES]). If abdominal wall infiltration using an anesthetic agent is unsuccessful, a neurectomy may be considered. Pulsed radiofrequency (PRF) applies an electric field around the tip of the cannula near the affected nerve to induce pain relief. Only limited retrospective evidence suggests that PRF is effective in ACNES.

METHODS

A multicenter, randomized, nonblinded, controlled proof-of-concept trial was performed in 66 patients. All patients were scheduled for a neurectomy procedure. Thirty-three patients were randomized to first receive a 6-minute cycle of PRF treatment, while the other 33 were allocated to an immediate neurectomy procedure. Pain was recorded using a numeric rating scale (NRS, 0 [no pain] to 10 [worst pain possible]). Successful treatment was defined as >50% pain reduction. Patients in the PRF group were allowed to cross over to a neurectomy after 8 weeks.

RESULTS

The neurectomy group showed greater pain reduction at 8-week follow-up (mean change from baseline -2.8 (95% confidence interval [CI] -3.9 to -1.7) vs. -1.5 (95% CI -2.3 to -0.6); P = 0.045) than the PRF group. Treatment success was reached in 12 of 32 (38%, 95% CI 23 to 55) of the PRF group and 17 of 28 (61%, 95% CI 42 to 72) of the neurectomy group (P = 0.073). Thirteen patients were withdrawn from their scheduled surgery. Adverse events were comparable between treatments.

CONCLUSIONS

PRF appears to be an effective and minimally invasive treatment option and may therefore be considered in patients who failed conservative treatment options before proceeding to a neurectomy procedure. Anterior neurectomy may possibly lead to a greater pain relief compared with PRF in patients with ACNES, but potential complications associated with surgery should be discussed.

Abdominal Wall Pain: A Common Clinical Problem

Abdominal wall pain (AWP) is a common and underrecognized cause of chronic abdominal pain. The etiology of AWP varies. History and physical examination are critical to an accurate diagnosis of AWP. Trigger point injection using either a corticosteroid, a local anesthetic, or a combination of both often gives relief of pain and is of diagnostic and therapeutic value. Increased awareness of AWP as a cause of chronic, nonvisceral abdominal pain can prevent fruitless searches for intra-abdominal pathology and reduce medical costs.

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.