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Original Article

Int J Pain 2023; 14(1): 12-17

Published online June 30, 2023 https://doi.org/10.56718/ijp.23-005

Copyright © The Korean Association for the Study of Pain.

Percutaneously Inserted Continuous Peripheral Nerve Block Catheter as a Novel Minimal Invasive Treatment of Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES): A Pilot Study to Assess Efficacy of This Novel Treatment

Joshua Field, Jeroen Heemskerk

Department of Surgery, Laurentius Hospital Roermond, Roermond, The Netherlands

Correspondence to:Jeroen Heemskerk, Department of Surgery, Laurentius Hospital Roermond, Mgr Driessenstraat 6, CV Roermond 6043, The Netherlands. Tel: +31-475475240, Fax: +31-0627045976, E-mail: j.heemskerk@lzr.nl

Received: April 24, 2023; Accepted: April 28, 2023

Background: Anterior cutaneous nerve entrapment syndrome (ACNES) is an often overlooked and under diagnosed medical condition characterized by abdominal wall pain. The cause is supposedly an entrapment of one of the cutaneous branches of the intercostal nerves in the abdominal fascia. Treatment options are restricted to pain killers, infiltration with local anaesthetics and operative neurectomy. The use of a percutaneously inserted peripheral block catheter could be a useful minimal invasive treatment strategy for patients suffering from ACNES if medication and infiltration are unsuccessful.
Methods: We report our first series of ten patients suffering from ACNES, who were treated with an ultrasound guided, percutaneously inserted peripheral block in the retro-rectus space at the level where the corresponding intercostal nerve was anticipated The procedure was performed in an outpatient setting.
Results: Following the insertion of a percutaneous retrorectus catheter and three days of local anaesthetic infiltration, a significant proportion of these patients reported a reduction in pain. Six out of ten patients derived sufficient benefit from this treatment 14 days and six months after catheter placement, thus eliminating the need for operative treatment.
Conclusions: Percutaneous inserted, ultrasound guided catheter placement seems to result in adequate short-term and long-term pain reduction in a significant proportion of patients suffering from ACNES. Up until now, surgery seemed the only viable treatment for patients suffering from ACNES who did not respond to conservative treatment. Using this minimal invasive percutaneous technique, over 50% of patients might be offered a definitive treatment, thus preventing surgical treatment.

Keywordsabdominal cutaneous nerve entrapment syndrome, acnes, minimal invasive treatment, pain, peripheral nerve block catheter.

Anterior cutaneous nerve entrapment syndrome (ACNES) is a condition characterized by the entrapment of one of the cutaneous branches of the intercostal nerves in the abdominal fascia [1]. This entrapment leads to ischaemia of this nerve, which results in severe pain symptoms [2]. It is a commonly overlooked cause of abdominal pain, which means the cause of abdominal pain is often wrongly attributed to intra-abdominal disorders [3,4], resulting in unnecessary, costly consultation and potentially harmful testing and even surgery [5,6]. There is often a considerable delay before an ACNES diagnosis is made [7-10]. ACNES can be established in patients following a thorough patient history and physical examination [11].

The classic presentation of an ACNES patient is a young female who complains of severe, constant pain localized to an area of approximately one fingertip [12]. A positive Carnett’s and Pinch test increases the likelihood of the ACNES diagnosis [13,14]. A good response to trigger point infiltration using local lidocaine injection has both a diagnostic and therapeutic purpose [15] and can be performed freehand or ultrasound guided [16]. If this therapy provides inadequate pain relief, an ultrasound guided transverse abdominis block [17,18], pulsed radio frequency [19,20] or a surgical neurectomy should be discussed with the patient [21,22], offering an effective but potentially harmful treatment.

A new treatment modality, offering higher effectiveness than trigger point infiltration but with fewer complications than surgical neurectomy, is highly desirable. In this retrospective study we investigate the analgesic effect of a peripheral nerve block catheter in patients suffering from ACNES. The rationale behind this therapy is that it effectively serves as a continuous rectus sheath block. In this novel therapy, a nerve block catheter is placed percutaneously in the region corresponding to the expected course of the nerve thought to be responsible for the pain.

1. Study design

This single centre retrospective study selected patients treated in the period February 1 2022 to May 31 2022 at Laurentius Hospital in Roermond, the Netherlands. Inclusion criteria consisted of being > 18 years old and having a confirmed diagnosis of ACNES. All patients had consistent clinical signs of ACNES and had all previously been treated at least twice using ultrasound guided local infiltration with local anaesthetics (20 cc Bupivacaïne 5 mg/ml), resulting in short-term pain relief of less than one week. Exclusion criteria consisted of having an alternative or concomitant abdominal nerve pathology, allergy to local anaesthetics and patients who were not deemed suitable for an invasive procedure under local anaesthesia. The pain severity at each timepoint was documented using the Visual Analogue Scale (VAS) pain score from 0 (no pain) to 10 (most excruciating imaginable pain). We defined patients as being pain free if they gave a pain score of less than three. The requirement for informed consent was waived by the Institutional Review Board.

2. Intervention

Under ultrasound guidance and local anaesthesia using 20 cc Xylocaïne, a TuohySono 19 G cannula (Pajunk Holding GmbH, Geisingen, Germany) was placed percutaneously in the region corresponding to the expected course of the intercostal nerve thought to be responsible for the pathology. The tip of the cannula was placed between the posterior border of the rectus muscle and the posterior rectus sheath after hydrodissection of this plane using 5 cc Xylocaïne. Through this hollow needle, a peripheral nerve block catheter (Pajunk Infiltralong catheter with 15 holes over the last 4 cm) was advanced until it was located between the posterior rectus sheath and the abdominal rectus muscle. An image of the cannula and catheter set can be seen in Fig. 1, an image of the ultrasound guided procedure can be seen in Fig. 2. An initial bolus of 20 cc Ropivacaïne 7.5 mg/ml (Naropin, Aspen Pharma Trading Limited, Dublin) was injected through the catheter. Then, an elastomeric pump (FuserPump, Pajunk Holding GmbH, Geisingen, Germany) was filled with 350 ml of a Ropivacaïne 2 mg/ml solution and continuous infiltration was initiated at a 5 ml/hour rate. After three hours, evaluation of the current pain was performed. If the pain score was higher than three on a Numeric Rating Scale from 0 to 10, the anaesthetic effect of the peripheral nerve block catheter was considered insufficient. In that case, the flow rate was increased to 8 ml/hour leading to adequate anaesthetic effect in all patients. Patients were discharged the same day. All had a pain score that was considered acceptable. When the elastomeric pump was empty (normally after three days), patients removed the catheter themselves and discarded the catheter and pump. Evaluation of effectiveness was performed after 14 days and after six months. The primary outcome of this study was the level of pain reduction seen three hours after the introduction of the nerve block catheter. The secondary outcome was the level of pain reduction at 14 days and at six months.

Figure 1.Intraoperative picture of ultrasound guided percutaneous placement of the pain catheter. The needle can well be visualised, positioning the catheter between the dorsal rectus sheath and the dorsal border of the rectus muscle at the area where the affected and entrapped intercostal nerve is expected.
Figure 2.Ultrasound image of the catheter placement. The hollow needle is placed a few cm cranio-lateral from the intended point of maximum pain. Under ultrasound guidence, the needle advances till it is placed between the rectus muscle and the posterior rectus sheath. There, local anesthetic will be infiltrated, resulting in hydrodissection between muscle and posterior rectus sheath. The catheter can than easily be placed in the optimal position.

In the specified four month period, a total of 10 patients underwent this therapy. The mean age of the patients was 30 years and nine out of the ten patients were female. The median pre-operative pain score (measured on a Numerical Rating Score or NRS) was 7. The median post-operative score was 0, the median score on day 14 was 2.

The primary outcome parameter was the pain three hours after insertion of the catheter. All patients demonstrated a significant reduction in pain post-procedure. Nine patients reported being (almost) pain free, having a pain score of less than three.

The secondary outcome was the pain score 14 days after the procedure. Six patients reported being still free of significant pain, negating the need for surgical neurectomy. The other four patients derived insufficient benefit from the therapy and thus underwent a neurectomy shortly after the nerve block catheter therapy.

After six months, we performed a telephone interview. Of the six patients that had not been operated upon, five were still totally free of pain. The sixth patient experienced mild discomfort VAS 3, considered too mild to use pain medication or warrant surgery.

Results are shown in Table 1.

Table 1 Patient characteristics

PatientAgePre-op*Post-op*14d*Result6 months*
177615Neurectomy required0
264600No further treatment0
344725Neurectomy required0
421400No further treatment0
520505Neurectomy required0
619808Neurectomy required7
727700No further treatment0
832700No further treatment3
9326.52.52No further treatment0
1019851No further treatment0
Median30702

*Pain score, measured as a numeric rating scale ranging from 0 (no pain) to 10 (the most excruciating pain imaginable).

The goal of our study was to assess the short-term analgesic effect of a peripheral nerve block catheter in patients suffering from ACNES. These data demonstrate that nine out of ten patients who underwent this novel therapy were pain free immediately post-procedure, and that six out of ten patients remained sufficiently pain free after 14 days. We find these results to be quite satisfactory, given the fact that all these patients had been convincingly diagnosed with ACNES. They had all been treated using regular pain medication and at least twice with infiltration therapy with local anaesthetics.

This therapy seems preferable to surgery for a number of reasons. The therapy is less invasive and thus the post-operative pain is less and the recovery time is far shorter. Aesthetically unpleasant scars can be avoided in these (often young) patients. The risk of rare but disturbing complications such as seroma and wound infection is absent. Catheter placement was well tolerated in all patients under local anaesthesia, where the majority of surgical neurectomies is performed under general anaesthesia. Therapy can therefore take place in an outpatient setting.

Unfortunately, it is not clear why some patients responded well to therapy while others did not. All patients were assessed by a surgeon with extensive experience in ACNES treatment in a referral hospital for ACNES surgery. All patients had a good but short-term result on infiltration with local anaesthetics at least twice, suggesting the diagnosis of ACNES was made correctly. Despite this strict patient selection, ACNES remains a clinical diagnosis and it is impossible to prove that no other underlying disorder might have caused the symptoms in some of these patients.

Long-term results are not yet known for this novel therapy. More research and preferably a well-designed and adequately powered Randomized Controlled Trial are needed to enable us to assess mid-term and long-term efficacy, enabling better selection of patients for their most effective and least invasive treatment.

No potential conflict of interest relevant to this article was reported.

  1. Kopell HP, Thompson WA: Peripheral entrapment neuropathies. Malabar (FL): Robert E. Kreiger Publishing; 1976. pp. 1-7. pp. 85-8.
  2. Applegate WV, Buckwalter NR: Microanatomy of the structures contributing to abdominal cutaneous nerve entrapment syndrome. J Am Board Fam Pract 1997; 10: 329-32.
  3. Hershfield NB: The abdominal wall. A frequently overlooked source of abdominal pain. J Clin Gastroenterol 1992; 14: 199-202.
    CrossRef
  4. van Assen T, de Jager-Kievit JW, Scheltinga MR, Roumen RM: Chronic abdominal wall pain misdiagnosed as functional abdominal pain. J Am Board Fam Med 2013; 26: 738-44.
    Pubmed CrossRef
  5. Thompson C, Goodman R, Rowe WA: Abdominal wall syndrome: a costly diagnosis of exclusion. Gastroenterology 2001; 120: A637.
    CrossRef
  6. Carnett JB: Intercostal neuralgia as a cause of abdominal pain and tenderness. Surg Gynecol Obstet 1926; 42: 625-32.
  7. Applegate WV: Abdominal cutaneous nerve entrapment syndrome (ACNES): a commonly overlooked cause of abdominal pain. Perm J 2002; 6: 20-7.
  8. Srinivasan R, Greenbaum DS: Chronic abdominal wall pain: a frequently overlooked problem. Practical approach to diagnosis and management. Am J Gastroenterol 2002; 97: 824-30.
    Pubmed CrossRef
  9. van Assen T, Brouns JA, Scheltinga MR, Roumen RM: Incidence of abdominal pain due to the anterior cutaneous nerve entrapment syndrome in an emergency department. Scand J Trauma Resusc Emerg Med 2015; 23: 19.
    Pubmed KoreaMed CrossRef
  10. Siawash M, de Jager-Kievit JW, Ten WT, Roumen RM, Scheltinga MR: Prevalence of anterior cutaneous nerve entrapment syndrome in a pediatric population with chronic abdominal pain. J Pediatr Gastroenterol Nutr 2016; 62: 399-402.
    Pubmed CrossRef
  11. Chrona E, Kostopanagiotou G, Damigos D, Batistaki C: Anterior cutaneous nerve entrapment syndrome: management challenges. J Pain Res 2017; 10: 145-56.
    Pubmed KoreaMed CrossRef
  12. Mol FMU, Maatman RC, De Joode LEGH, Van Eerten P, et al: Characteristics of 1116 consecutive patients diagnosed with anterior cutaneous nerve entrapment syndrome (ACNES). Ann Surg 2021; 273: 373-8.
    Pubmed CrossRef
  13. Roumen RM, Scheltinga MR: Abdominale intercostale neuralgie: een vergeten oorzaak van buikpijn [Abdominal intercostal neuralgia: a forgotten cause of abdominal pain]. Ned Tijdschr Geneeskd 2006; 150: 1909-15.
  14. Cartwright SL, Knudson MP: Evaluation of acute abdominal pain in adults. Am Fam Physician 2008; 77: 971-8.
  15. Boelens OB, Scheltinga MR, Houterman S, et al: Randomized clinical trial of trigger point infiltration with lidocaine to diagnose anterior cutaneous nerve entrapment syndrome. Br J Surg 2013; 100: 217-21.
    Pubmed CrossRef
  16. Jacobs MLYE, van den Dungen-Roelofsen R, Heemskerk J, et al: Ultrasound-guided abdominal wall infiltration versus freehand technique in anterior cutaneous nerve entrapment syndrome (ACNES): randomized clinical trial. BJS Open 2021; 5: zrab124.
    Pubmed KoreaMed CrossRef
  17. Imajo Y, Komasawa N, Fujiwara S, Minami T: Transversus abdominal plane and rectus sheath block combination for intractable anterior cutaneous nerve entrapment syndrome after severe cholecystitis. J Clin Anesth 2016; 31: 119.
    Pubmed CrossRef
  18. Sahoo RK, Nair A: Ultrasound guided transversus abdominis plane block for anterior cutaneous nerve entrapment syndrome. Korean J Pain 2015; 28: 284-6.
    Pubmed KoreaMed CrossRef
  19. Maatman RC, van Kuijk SMJ, Steegers MAH, et al: 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. Pain Pract 2019; 19: 751-61.
    Pubmed CrossRef
  20. Maatman RC, Steegers MAH, Kallewaard JW, et al: Pulsed radiofrequency as a minimally invasive treatment option in anterior cutaneous nerve entrapment syndrome: a retrospective analysis of 26 patients. J Clin Med Res 2018; 10: 508-15.
    Pubmed KoreaMed CrossRef
  21. Boelens OB, van Assen T, Houterman S, et al: A double-blind, randomized, controlled trial on surgery for chronic abdominal pain due to anterior cutaneous nerve entrapment syndrome. Ann Surg 2013; 257: 845-9.
    Pubmed CrossRef
  22. Boelens OB, Scheltinga MR, Houterman S, et al: Management of anterior cutaneous nerve entrapment syndrome in a cohort of 139 patients. Ann Surg 2011; 254: 1054-8.
    Pubmed CrossRef

Article

Original Article

Int J Pain 2023; 14(1): 12-17

Published online June 30, 2023 https://doi.org/10.56718/ijp.23-005

Copyright © The Korean Association for the Study of Pain.

Percutaneously Inserted Continuous Peripheral Nerve Block Catheter as a Novel Minimal Invasive Treatment of Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES): A Pilot Study to Assess Efficacy of This Novel Treatment

Joshua Field, Jeroen Heemskerk

Department of Surgery, Laurentius Hospital Roermond, Roermond, The Netherlands

Correspondence to:Jeroen Heemskerk, Department of Surgery, Laurentius Hospital Roermond, Mgr Driessenstraat 6, CV Roermond 6043, The Netherlands. Tel: +31-475475240, Fax: +31-0627045976, E-mail: j.heemskerk@lzr.nl

Received: April 24, 2023; Accepted: April 28, 2023

Abstract

Background: Anterior cutaneous nerve entrapment syndrome (ACNES) is an often overlooked and under diagnosed medical condition characterized by abdominal wall pain. The cause is supposedly an entrapment of one of the cutaneous branches of the intercostal nerves in the abdominal fascia. Treatment options are restricted to pain killers, infiltration with local anaesthetics and operative neurectomy. The use of a percutaneously inserted peripheral block catheter could be a useful minimal invasive treatment strategy for patients suffering from ACNES if medication and infiltration are unsuccessful.
Methods: We report our first series of ten patients suffering from ACNES, who were treated with an ultrasound guided, percutaneously inserted peripheral block in the retro-rectus space at the level where the corresponding intercostal nerve was anticipated The procedure was performed in an outpatient setting.
Results: Following the insertion of a percutaneous retrorectus catheter and three days of local anaesthetic infiltration, a significant proportion of these patients reported a reduction in pain. Six out of ten patients derived sufficient benefit from this treatment 14 days and six months after catheter placement, thus eliminating the need for operative treatment.
Conclusions: Percutaneous inserted, ultrasound guided catheter placement seems to result in adequate short-term and long-term pain reduction in a significant proportion of patients suffering from ACNES. Up until now, surgery seemed the only viable treatment for patients suffering from ACNES who did not respond to conservative treatment. Using this minimal invasive percutaneous technique, over 50% of patients might be offered a definitive treatment, thus preventing surgical treatment.

Keywords: abdominal cutaneous nerve entrapment syndrome, acnes, minimal invasive treatment, pain, peripheral nerve block catheter.

INTRODUCTION

Anterior cutaneous nerve entrapment syndrome (ACNES) is a condition characterized by the entrapment of one of the cutaneous branches of the intercostal nerves in the abdominal fascia [1]. This entrapment leads to ischaemia of this nerve, which results in severe pain symptoms [2]. It is a commonly overlooked cause of abdominal pain, which means the cause of abdominal pain is often wrongly attributed to intra-abdominal disorders [3,4], resulting in unnecessary, costly consultation and potentially harmful testing and even surgery [5,6]. There is often a considerable delay before an ACNES diagnosis is made [7-10]. ACNES can be established in patients following a thorough patient history and physical examination [11].

The classic presentation of an ACNES patient is a young female who complains of severe, constant pain localized to an area of approximately one fingertip [12]. A positive Carnett’s and Pinch test increases the likelihood of the ACNES diagnosis [13,14]. A good response to trigger point infiltration using local lidocaine injection has both a diagnostic and therapeutic purpose [15] and can be performed freehand or ultrasound guided [16]. If this therapy provides inadequate pain relief, an ultrasound guided transverse abdominis block [17,18], pulsed radio frequency [19,20] or a surgical neurectomy should be discussed with the patient [21,22], offering an effective but potentially harmful treatment.

A new treatment modality, offering higher effectiveness than trigger point infiltration but with fewer complications than surgical neurectomy, is highly desirable. In this retrospective study we investigate the analgesic effect of a peripheral nerve block catheter in patients suffering from ACNES. The rationale behind this therapy is that it effectively serves as a continuous rectus sheath block. In this novel therapy, a nerve block catheter is placed percutaneously in the region corresponding to the expected course of the nerve thought to be responsible for the pain.

MATERIALS AND METHODS

1. Study design

This single centre retrospective study selected patients treated in the period February 1 2022 to May 31 2022 at Laurentius Hospital in Roermond, the Netherlands. Inclusion criteria consisted of being > 18 years old and having a confirmed diagnosis of ACNES. All patients had consistent clinical signs of ACNES and had all previously been treated at least twice using ultrasound guided local infiltration with local anaesthetics (20 cc Bupivacaïne 5 mg/ml), resulting in short-term pain relief of less than one week. Exclusion criteria consisted of having an alternative or concomitant abdominal nerve pathology, allergy to local anaesthetics and patients who were not deemed suitable for an invasive procedure under local anaesthesia. The pain severity at each timepoint was documented using the Visual Analogue Scale (VAS) pain score from 0 (no pain) to 10 (most excruciating imaginable pain). We defined patients as being pain free if they gave a pain score of less than three. The requirement for informed consent was waived by the Institutional Review Board.

2. Intervention

Under ultrasound guidance and local anaesthesia using 20 cc Xylocaïne, a TuohySono 19 G cannula (Pajunk Holding GmbH, Geisingen, Germany) was placed percutaneously in the region corresponding to the expected course of the intercostal nerve thought to be responsible for the pathology. The tip of the cannula was placed between the posterior border of the rectus muscle and the posterior rectus sheath after hydrodissection of this plane using 5 cc Xylocaïne. Through this hollow needle, a peripheral nerve block catheter (Pajunk Infiltralong catheter with 15 holes over the last 4 cm) was advanced until it was located between the posterior rectus sheath and the abdominal rectus muscle. An image of the cannula and catheter set can be seen in Fig. 1, an image of the ultrasound guided procedure can be seen in Fig. 2. An initial bolus of 20 cc Ropivacaïne 7.5 mg/ml (Naropin, Aspen Pharma Trading Limited, Dublin) was injected through the catheter. Then, an elastomeric pump (FuserPump, Pajunk Holding GmbH, Geisingen, Germany) was filled with 350 ml of a Ropivacaïne 2 mg/ml solution and continuous infiltration was initiated at a 5 ml/hour rate. After three hours, evaluation of the current pain was performed. If the pain score was higher than three on a Numeric Rating Scale from 0 to 10, the anaesthetic effect of the peripheral nerve block catheter was considered insufficient. In that case, the flow rate was increased to 8 ml/hour leading to adequate anaesthetic effect in all patients. Patients were discharged the same day. All had a pain score that was considered acceptable. When the elastomeric pump was empty (normally after three days), patients removed the catheter themselves and discarded the catheter and pump. Evaluation of effectiveness was performed after 14 days and after six months. The primary outcome of this study was the level of pain reduction seen three hours after the introduction of the nerve block catheter. The secondary outcome was the level of pain reduction at 14 days and at six months.

Figure 1. Intraoperative picture of ultrasound guided percutaneous placement of the pain catheter. The needle can well be visualised, positioning the catheter between the dorsal rectus sheath and the dorsal border of the rectus muscle at the area where the affected and entrapped intercostal nerve is expected.
Figure 2. Ultrasound image of the catheter placement. The hollow needle is placed a few cm cranio-lateral from the intended point of maximum pain. Under ultrasound guidence, the needle advances till it is placed between the rectus muscle and the posterior rectus sheath. There, local anesthetic will be infiltrated, resulting in hydrodissection between muscle and posterior rectus sheath. The catheter can than easily be placed in the optimal position.

RESULTS

In the specified four month period, a total of 10 patients underwent this therapy. The mean age of the patients was 30 years and nine out of the ten patients were female. The median pre-operative pain score (measured on a Numerical Rating Score or NRS) was 7. The median post-operative score was 0, the median score on day 14 was 2.

The primary outcome parameter was the pain three hours after insertion of the catheter. All patients demonstrated a significant reduction in pain post-procedure. Nine patients reported being (almost) pain free, having a pain score of less than three.

The secondary outcome was the pain score 14 days after the procedure. Six patients reported being still free of significant pain, negating the need for surgical neurectomy. The other four patients derived insufficient benefit from the therapy and thus underwent a neurectomy shortly after the nerve block catheter therapy.

After six months, we performed a telephone interview. Of the six patients that had not been operated upon, five were still totally free of pain. The sixth patient experienced mild discomfort VAS 3, considered too mild to use pain medication or warrant surgery.

Results are shown in Table 1.

Table 1 . Patient characteristics.

PatientAgePre-op*Post-op*14d*Result6 months*
177615Neurectomy required0
264600No further treatment0
344725Neurectomy required0
421400No further treatment0
520505Neurectomy required0
619808Neurectomy required7
727700No further treatment0
832700No further treatment3
9326.52.52No further treatment0
1019851No further treatment0
Median30702

*Pain score, measured as a numeric rating scale ranging from 0 (no pain) to 10 (the most excruciating pain imaginable)..


DISCUSSION

The goal of our study was to assess the short-term analgesic effect of a peripheral nerve block catheter in patients suffering from ACNES. These data demonstrate that nine out of ten patients who underwent this novel therapy were pain free immediately post-procedure, and that six out of ten patients remained sufficiently pain free after 14 days. We find these results to be quite satisfactory, given the fact that all these patients had been convincingly diagnosed with ACNES. They had all been treated using regular pain medication and at least twice with infiltration therapy with local anaesthetics.

This therapy seems preferable to surgery for a number of reasons. The therapy is less invasive and thus the post-operative pain is less and the recovery time is far shorter. Aesthetically unpleasant scars can be avoided in these (often young) patients. The risk of rare but disturbing complications such as seroma and wound infection is absent. Catheter placement was well tolerated in all patients under local anaesthesia, where the majority of surgical neurectomies is performed under general anaesthesia. Therapy can therefore take place in an outpatient setting.

Unfortunately, it is not clear why some patients responded well to therapy while others did not. All patients were assessed by a surgeon with extensive experience in ACNES treatment in a referral hospital for ACNES surgery. All patients had a good but short-term result on infiltration with local anaesthetics at least twice, suggesting the diagnosis of ACNES was made correctly. Despite this strict patient selection, ACNES remains a clinical diagnosis and it is impossible to prove that no other underlying disorder might have caused the symptoms in some of these patients.

Long-term results are not yet known for this novel therapy. More research and preferably a well-designed and adequately powered Randomized Controlled Trial are needed to enable us to assess mid-term and long-term efficacy, enabling better selection of patients for their most effective and least invasive treatment.

CONFLICT OF INTEREST

No potential conflict of interest relevant to this article was reported.

Fig 1.

Figure 1.Intraoperative picture of ultrasound guided percutaneous placement of the pain catheter. The needle can well be visualised, positioning the catheter between the dorsal rectus sheath and the dorsal border of the rectus muscle at the area where the affected and entrapped intercostal nerve is expected.
International Journal of Pain 2023; 14: 12-17https://doi.org/10.56718/ijp.23-005

Fig 2.

Figure 2.Ultrasound image of the catheter placement. The hollow needle is placed a few cm cranio-lateral from the intended point of maximum pain. Under ultrasound guidence, the needle advances till it is placed between the rectus muscle and the posterior rectus sheath. There, local anesthetic will be infiltrated, resulting in hydrodissection between muscle and posterior rectus sheath. The catheter can than easily be placed in the optimal position.
International Journal of Pain 2023; 14: 12-17https://doi.org/10.56718/ijp.23-005

Table 1 Patient characteristics

PatientAgePre-op*Post-op*14d*Result6 months*
177615Neurectomy required0
264600No further treatment0
344725Neurectomy required0
421400No further treatment0
520505Neurectomy required0
619808Neurectomy required7
727700No further treatment0
832700No further treatment3
9326.52.52No further treatment0
1019851No further treatment0
Median30702

*Pain score, measured as a numeric rating scale ranging from 0 (no pain) to 10 (the most excruciating pain imaginable).


References

  1. Kopell HP, Thompson WA: Peripheral entrapment neuropathies. Malabar (FL): Robert E. Kreiger Publishing; 1976. pp. 1-7. pp. 85-8.
  2. Applegate WV, Buckwalter NR: Microanatomy of the structures contributing to abdominal cutaneous nerve entrapment syndrome. J Am Board Fam Pract 1997; 10: 329-32.
  3. Hershfield NB: The abdominal wall. A frequently overlooked source of abdominal pain. J Clin Gastroenterol 1992; 14: 199-202.
    CrossRef
  4. van Assen T, de Jager-Kievit JW, Scheltinga MR, Roumen RM: Chronic abdominal wall pain misdiagnosed as functional abdominal pain. J Am Board Fam Med 2013; 26: 738-44.
    Pubmed CrossRef
  5. Thompson C, Goodman R, Rowe WA: Abdominal wall syndrome: a costly diagnosis of exclusion. Gastroenterology 2001; 120: A637.
    CrossRef
  6. Carnett JB: Intercostal neuralgia as a cause of abdominal pain and tenderness. Surg Gynecol Obstet 1926; 42: 625-32.
  7. Applegate WV: Abdominal cutaneous nerve entrapment syndrome (ACNES): a commonly overlooked cause of abdominal pain. Perm J 2002; 6: 20-7.
  8. Srinivasan R, Greenbaum DS: Chronic abdominal wall pain: a frequently overlooked problem. Practical approach to diagnosis and management. Am J Gastroenterol 2002; 97: 824-30.
    Pubmed CrossRef
  9. van Assen T, Brouns JA, Scheltinga MR, Roumen RM: Incidence of abdominal pain due to the anterior cutaneous nerve entrapment syndrome in an emergency department. Scand J Trauma Resusc Emerg Med 2015; 23: 19.
    Pubmed KoreaMed CrossRef
  10. Siawash M, de Jager-Kievit JW, Ten WT, Roumen RM, Scheltinga MR: Prevalence of anterior cutaneous nerve entrapment syndrome in a pediatric population with chronic abdominal pain. J Pediatr Gastroenterol Nutr 2016; 62: 399-402.
    Pubmed CrossRef
  11. Chrona E, Kostopanagiotou G, Damigos D, Batistaki C: Anterior cutaneous nerve entrapment syndrome: management challenges. J Pain Res 2017; 10: 145-56.
    Pubmed KoreaMed CrossRef
  12. Mol FMU, Maatman RC, De Joode LEGH, Van Eerten P, et al: Characteristics of 1116 consecutive patients diagnosed with anterior cutaneous nerve entrapment syndrome (ACNES). Ann Surg 2021; 273: 373-8.
    Pubmed CrossRef
  13. Roumen RM, Scheltinga MR: Abdominale intercostale neuralgie: een vergeten oorzaak van buikpijn [Abdominal intercostal neuralgia: a forgotten cause of abdominal pain]. Ned Tijdschr Geneeskd 2006; 150: 1909-15.
  14. Cartwright SL, Knudson MP: Evaluation of acute abdominal pain in adults. Am Fam Physician 2008; 77: 971-8.
  15. Boelens OB, Scheltinga MR, Houterman S, et al: Randomized clinical trial of trigger point infiltration with lidocaine to diagnose anterior cutaneous nerve entrapment syndrome. Br J Surg 2013; 100: 217-21.
    Pubmed CrossRef
  16. Jacobs MLYE, van den Dungen-Roelofsen R, Heemskerk J, et al: Ultrasound-guided abdominal wall infiltration versus freehand technique in anterior cutaneous nerve entrapment syndrome (ACNES): randomized clinical trial. BJS Open 2021; 5: zrab124.
    Pubmed KoreaMed CrossRef
  17. Imajo Y, Komasawa N, Fujiwara S, Minami T: Transversus abdominal plane and rectus sheath block combination for intractable anterior cutaneous nerve entrapment syndrome after severe cholecystitis. J Clin Anesth 2016; 31: 119.
    Pubmed CrossRef
  18. Sahoo RK, Nair A: Ultrasound guided transversus abdominis plane block for anterior cutaneous nerve entrapment syndrome. Korean J Pain 2015; 28: 284-6.
    Pubmed KoreaMed CrossRef
  19. Maatman RC, van Kuijk SMJ, Steegers MAH, et al: 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. Pain Pract 2019; 19: 751-61.
    Pubmed CrossRef
  20. Maatman RC, Steegers MAH, Kallewaard JW, et al: Pulsed radiofrequency as a minimally invasive treatment option in anterior cutaneous nerve entrapment syndrome: a retrospective analysis of 26 patients. J Clin Med Res 2018; 10: 508-15.
    Pubmed KoreaMed CrossRef
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