Perforator-Guided Drug Injection in the Treatment of Abdominal Wall Pain

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.

Ultrasound-guided abdominal wall infiltration versus freehand technique in anterior cutaneous nerve entrapment syndrome (ACNES): randomized clinical trial

Background

The optimal technique of abdominal wall infiltration for chronic abdominal wall pain due to anterior cutaneous nerve entrapment syndrome (ACNES) is unknown. The aim of this study was to compare pain reduction after an abdominal wall anaesthetic injection by use of an ultrasound-guided technique (US) or given freehand (FH).

Methods

In this multicentre non-blinded randomized trial, adult patients with ACNES were randomized (1:1) to an US or a FH injection technique. Primary outcome was the proportion of injections achieving a minimum of 50 per cent pain reduction on the Numeric Rating Scale (range 0–10) 15–20 min after abdominal wall infiltration (‘successful response’). Secondary outcomes were treatment efficacy after 6 weeks and 3 months, and the influence of the subcutaneous tissue thickness on treatment outcome.

Results

Between January 2018 and April 2020, 391 injections (US = 192, FH = 199) were administered in 117 randomized patients (US = 55, FH = 62; 76.0 per cent female, mean age 45 years). The proportion of successful responses did not significantly differ immediately after the injection regimen (US 27.1 per cent versus FH 33.2 per cent; P = 0.19) or after 3 months (US 29.4 per cent versus FH 30.5 per cent; P = 0.90). Success was not determined by subcutaneous tissue thickness.

Conclusion

Pain relief following abdominal wall infiltration by a US or FH technique in ACNES is similar and not influenced by subcutaneous tissue thickness.

Registration number

Dutch Clinical Trial Register NL8465.

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.

Bilateral distribution of anterior cutaneous nerve entrapment syndrome (ACNES): are clinical features and outcomes comparable to unilateral ACNES?

BACKGROUND AND OBJECTIVES

Mirror-image pain may occur in the presence of a one-sided peripheral nerve lesion leading to a similar distribution of pain on the contralateral side of the body ("mirrored"). Anterior cutaneous nerve entrapment syndrome (ACNES) is a neuropathic pain syndrome due to entrapment of terminal branches of intercostal nerves T7-12 in the abdominal wall and sometimes presents bilaterally. This study aims to address specifics of bilateral ACNES and to determine potential differences in clinical presentation and treatment outcomes when compared with the unilateral form of ACNES.

METHODS

Electronic patient files and questionnaires of a case series of patients who were evaluated for chronic abdominal wall pain in a single center were analyzed using standard statistical methods.

RESULTS

Between June 1, 2011 and September 1, 2016, 1116 patients were diagnosed with ACNES, of which a total of 146 (13%) with bilateral ACNES were identified (female, n = 114, 78 %; median (range) age 36 (1181) years). Average NRS (Numeric Rating Scale; 0-10) scores were similar (median (range) NRS scores 6 (0-10) although peak NRS scores were significantly higher in the bilateral group (9 (5-10) vs 8 (2-10); p=0.02). After a median of 26 months (1-68), the proportion of patients with bilateral ACNES reporting treatment success was 61%.

CONCLUSIONS

One in eight patients with ACNES has bilateral abdominal wall pain. Characteristics are similar to unilateral ACNES cases. Further studies aimed at underlying mechanisms in mirror image pain pathogenesis could provide a more targeted approach in the management of this neuropathic pain.

Ultrasound-guided Sympathetic Block of the Radial Artery with Botulinum Toxin to Treat Vasospasm

Supplemental Digital Content is available in the text.

Vasospastic disorders in the hand have been treated with surgical sympathectomy and recently with botulinum toxin A (BTX) injections in the palm. The purpose of this study was to evaluate if it is possible to obtain precise administration of BTX around the radial artery using a single ultrasound-guided injection. We present a novel technique using 1 single ultrasound-guided BTX injection around the radial artery to treat vasospastic symptoms. Ten patients were included in a pilot study. All patients were referred by a rheumatologist after been diagnosed with primary or secondary Raynaud. Under ultrasound guidance, BTX was injected around the radial artery and its comitant veins 3–5 cm proximal to the wrist. Ultrasound-guided injection of BTX allowed for a precise distribution of BTX into the perivascular space of the radial artery and its comitant veins. Intravascular injection could easily be excluded. One patient reported temporary reduced grip strength, most likely due to leakage of BTX to the flexor pollicis longus muscle. No other complications were registered. All patients reported reduced number of vasospastic episodes, warmer hands, and reduced pain. Ultrasound-guided injection enables precise administration of BTX in the space surrounding the radial artery and its comitant veins. This novel approach could be a promising treatment for vasospastic disorders of the hands in patients with primary and secondary Raynaud.

Adding steroids to lidocaine in a therapeutic injection regimen for patients with abdominal pain due to anterior cutaneous nerve entrapment syndrome (ACNES): a single blinded randomized clinical trial

Background and aims

Anterior cutaneous nerve entrapment syndrome (ACNES) may result in chronic abdominal pain. Therapeutic options include local injection therapy. Data on the efficacy of adding corticosteroids to these injections is lacking.

Methods

Patients ≥18 years with ACNES were randomized to receive an injection of lidocaine with (LC-group) or without (LA-group) the addition of methylprednisolone into the point of maximal abdominal wall pain. Pain was recorded using a numeric rating scale (NRS: 0–10) and a verbal rating scale (VRS: 0=no pain, 5=unbearable pain) at baseline and 6 weeks after the start of a bi-weekly injection regimen consisting of a total of three injections. A minimal 50% reduction on NRS and/or two points on VRS were considered successful responses.

Results

Between February 2014 and August 2016, 136 patients (median age 46 year, range 18–79, 75% females) were randomized (68 vs. 68). The proportion of patients demonstrating a successful response after 6 weeks did not significantly differ between groups (LA 38%, LC 31%, p=0.61). At 12 weeks, the number of patients still experiencing a minimal 50% pain relief had decreased but no group difference was observed (LA 20%, LC 18%, p=0.80). Minor side effects included temporary increase of pain, tenderness at injection sites or transient malaise (LA23/68, LC 29/68, p=0.46).

Conclusions

Adding corticosteroids to a lidocaine does not increase the proportion of ACNES patients with a successful response to injection therapy. Lidocaine alone can provide long term pain relief after one or multiple injections, in approximately 1 of 5 patients.

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.