Successful treatment of abdominal cutaneous entrapment syndrome using ultrasound guided injection

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.

Role of magnetic resonance neurography in intercostal neuralgia; diagnostic utility and efficacy

OBJECTIVE

To evaluate the utility and efficacy of MR neurography (MRN) in the diagnostic work-up for intercostal neuralgia and to assess the treatment course and outcomes in MRN-imaged clinically suspected intercostal neuropathy cases of chronic chest and abdominal wall pain syndromes.

METHODS

Following a retrospective cross-sectional study, a consecutive series of patients who underwent MRN of torso for suspected intercostal neuralgia were included. Patient demographics, pain location/level/duration, previous work-up for the same indication, MRN imaging results, and MRN cost per patient were recorded. An inter-reader reliability assessment was performed on the MRN findings using Cohen's weighted κ analysis. Post-MRN treatment choice, as well as success rates of MRN directed perineural injections and surgical management were also evaluated.

RESULTS

A total of 28 patients (mean ± SD age, 48.3 ± 18.0 years, female/male = 3.0) were included. Pain and/or numbness in the right upper quadrant were the most common complaints. The mean maximum pain level experienced was 7.4 ± 2.5 on a 1 (lowest pain level) - 10 (highest pain level) visual analog scale. The duration of pain before MRN work-up was 36.9 ± 37.9 months. The patients had seen an average of 5 ± 2.8 physicians for such syndromes. 20 (71%) patients had one or multiple other imaging studies for prior work-up. MRN identified positive intercostal nerve abnormality in 19 cases with clinical symptoms of intercostal neuralgia. From the inter-reader reliability assessment, a Cohen's weighted κ value of 0.78 was obtained. The costs of work-up was about one-third with MRN for diagnostic purposes with less financial and psychological harm. Among the MRN-positive cases, 9/19 patients received perineural injections, of which 6 reported improvement after their first round, lasting an average of 41.1 ± 83 days. Among the nine MRN-negative cases, two received perineural injections, of which none reported improvement. Surgical management was mostly successful with a positive outcome in six out of seven operated cases (85.7%).

CONCLUSION

MRN is useful in diagnostic algorithm of intercostal neuralgia and MRN-positive cases demonstrate favorable treatment response to perineural injections and subsequent surgical management.

ADVANCES IN KNOWLEDGE

The use of MRN in intercostal neuralgia is an application that has not been previously explored in the literature. This study demonstrates that MRN offers superior visualization of pathology in intercostal neuralgia and confirms that treatment directed at MRN identified neuropathy results in good outcomes while maintaining cost efficiency.

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.

Chronic Abdominal Wall Pain

BACKGROUND

Chronic abdominal wall pain is a poorly recognized clinical problem despite being an important element in the differential diagnosis of abdominal pain.

METHODS

This review is based on pertinent articles that were retrieved by a selective search in PubMed and EMBASE employing the terms "abdominal wall pain" and "cutaneous nerve entrapment syndrome," as well as on the authors' clinical experience.

RESULTS

In 2% to 3% of patients with chronic abdominal pain, the pain arises from the abdominal wall; in patients with previously diagnosed chronic abdominal pain who have no demonstrable pathological abnormality, this likelihood can rise as high as 30% . There have only been a small number of clinical trials of treatment for this condition. The diagnosis is made on clinical grounds, with the aid of Carnett's test. The characteristic clinical feature is strictly localized pain in the anterior abdominal wall, which is often mischaracterized as a "functional" complaint. In one study, injection of local anesthesia combined with steroids into the painful area was found to relieve pain for 4 weeks in 95% of patients. The injection of lidocaine alone brought about improvement in 83-91% of patients. Long-term pain relief ensued after a single lidocaine injection in 20-30% of patients, after repeated injections in 40-50% , and after combined lidocaine and steroid injections in up to 80% . Pain that persists despite these treatments can be treated with surgery (neurectomy).

CONCLUSION

Chronic abdominal wall pain is easily diagnosed on physical examination and can often be rapidly treated. Any physician treating patients with abdominal pain should be aware of this condition. Further comparative treatment trials will be needed before a validated treatment algorithm can be established.

Chronic Abdominal Wall Pain: An Under-Recognized Diagnosis Leading to Unnecessary Testing

Chronic abdominal wall pain (CAWP) refers to a condition wherein pain originates from the abdominal wall itself rather than the underlying viscera. According to various estimates, 10% to 30% of patients with chronic abdominal pain are eventually diagnosed with CAWP, usually after expensive testing has failed to uncover another etiology. The most common cause of CAWP is anterior cutaneous nerve entrapment syndrome. The diagnosis of CAWP is made using an oft-forgotten physical examination finding known as Carnett's sign, where focal abdominal tenderness is either the same or worsened during contraction of the abdominal musculature. CAWP can be confirmed by response to trigger point injection of local anesthetic. Once diagnosis is made, treatment ranges from conservative management to trigger point injection and in refractory cases, even surgery. This review provides an overview of CAWP, discusses the cost and implications of a missed diagnosis, compares somatic versus visceral innervation, describes the pathophysiology of nerve entrapment, and reviews the evidence behind available treatment modalities.

A systematic review of the treatment for abdominal cutaneous nerve entrapment syndrome

BACKGROUND

Abdominal cutaneous nerve entrapment syndrome (ACNES) is a frequently overlooked cause of chronic abdominal pain. We aim to outline the current available literature concerning the treatment of patients diagnosed with ACNES.

DATA SOURCES

A systematic search in PubMed, EMBASE, CINAHL, and Cochrane databases was performed. Seven studies were included; describing trigger point injection (TPI) or anterior neurectomy as stand-alone procedure, TPI followed by anterior neurectomy as stepwise regimen, and nerve stimulation and phenolization. After TPI, 86% of the patients showed successful response, 76% at long-term follow-up. Two other studies report successful treatment in 50% of patients. In the included trial using anterior neurectomy, 73% vs 18% of the patients demonstrate a successful pain response in the neurectomy and sham group, respectively. Two cohort studies showed that 69% and 61% of the neurectomy group reported to be satisfied at 18 months and 32 months follow-up, respectively.

CONCLUSIONS

There is significant pain relief after injections and anterior neurectomy. Awareness of the diagnosis is important. The validity of currently used diagnostic criteria needs to be evaluated in additional studies.

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

BACKGROUND

Pain from the abdominal wall can be caused by nerve entrapment, a condition called abdominal cutaneous nerve entrapment syndrome (ACNES). As an alternative to surgery, ACNES may be treated with injection of local anesthetics, corticosteroids, or botulinum toxin at the point of maximal pain.

METHOD

The point of maximal pain was marked on the abdominal skin. Using color Doppler ultrasound, the corresponding exit point of perforating blood vessels through the anterior fascia of the rectus abdominis muscle was identified. Ultrasound-guided injection of botulinum toxin in close proximity to the perforator's exit point was performed below and above the muscle fascia.

RESULTS

The technique was used from 2008 to 2014 on 15 patients in 46 sessions with a total of 128 injections without complications. The injection technique provided safe and accurate administration of the drug in proximity to the affected cutaneous nerves. The effect of botulinum toxin on ACNES is beyond the scope of this article.

CONCLUSION

Perforator-guided injection enables precise drug administration at the location of nerve entrapment in ACNES in contrast to blind injections.