Rectus nerve entrapment causing abdominal pain

Diagnostic Effect of Consultation Referral from Gastroenterologists to Generalists in Patients with Undiagnosed Chronic Abdominal Pain: A Retrospective Study

This study aimed to investigate consultation outcomes from gastroenterologists to generalist physicians for the diagnostic workup of undiagnosed chronic abdominal pain. This was a single-center, retrospective, descriptive study. Patients were included who were ≥15 years old and consulted from the Department of Gastroenterology to the Department of Diagnostic Medicine, to establish a diagnosis for chronic abdominal pain, at the Dokkyo University Hospital from 1 April 2016 to 31 August 2020. We retrospectively reviewed the patients' medical charts and extracted data. A total of 12 cases were included. Eight patients (66.7%) were diagnosed with and treated for functional gastrointestinal disorders (FGID) at the Department of Gastroenterology; their lack of improvement under treatment for FGID was the reason for their referral to the Department of Diagnostic Medicine for further examination. After this consultation, new possible diagnoses were generated for eight patients (66.7%). Six of the eight patients (75.0%) were diagnosed with abdominal wall pain (anterior cutaneous nerve entrapment syndrome, n = 3; myofascial pain, n = 1; falciform pain, n = 1; and herpes zoster non-herpeticus; n = 1). Consultation referral from gastroenterologists to generalists could generate new possible diagnoses in approximately 70% of patients with undiagnosed chronic abdominal pain.

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.

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.

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.

Successful treatment of abdominal cutaneous entrapment syndrome using ultrasound guided injection

There are various origins for chronic abdominal pain. About 10-30% of patients with chronic abdominal pain have abdominal wall pain. Unfortunately, abdominal wall pain is not thought to be the first origin of chronic abdominal pain; therefore, patients usually undergo extensive examinations, including diagnostic laparoscopic surgery. Entrapment of abdominal cutaneous nerves at the muscular foramen of the rectus abdominis is a rare cause of abdominal wall pain. If abdominal wall pain is considered in earlier stage of chronic abdominal pain, unnecessary invasive procedures are not required and patients will reach symptom free condition as soon as the diagnosis is made. Here, we report a case of successful treatment of a patient with abdominal cutaneous nerve entrapment syndrome by ultrasound guided injection therapy.

A double-blind, randomized, controlled trial on surgery for chronic abdominal pain due to anterior cutaneous nerve entrapment syndrome

OBJECTIVE

To clarify the role of a surgical neurectomy on pain in refractory patients after conservatively treated anterior cutaneous nerve entrapment syndrome (ACNES).

BACKGROUND

ACNES is hardly ever considered in the differential diagnosis of chronic abdominal pain. Treatment is usually conservative. However, symptoms are often recalcitrant.

METHODS

Patients older than 18 years with a diagnosis of ACNES were randomized to undergo a neurectomy or a sham procedure via an open surgical procedure in day care. Both the patient and the principal investigator were blinded to the nature of surgery. Pain was recorded using a visual analog scale (1-100 mm) and a verbal rating scale (score 0-5; 0 = no pain, 5 = severe pain) before surgery and 6 weeks postoperatively. A reduction of at least 50% in the visual analog scale score and/or 2 points on the verbal rating scale was considered a "successful response."

RESULTS

Forty-four patients were randomized between August 2008 and December 2010 (39 women, median age = 42 years; both groups, n = 22). In the neurectomy group, 16 patients reported a successful pain response. In contrast, significant pain reduction was obtained in 4 patients in the sham group (P = 0.001). Complications associated with surgery were hematoma (n = 5, conservative treatment), infection (antibiotic and drainage, n = 1), and worsened pain (n = 1).

CONCLUSIONS

Neurectomy of the intercostal nerve endings at the level of the abdominal wall is an effective surgical procedure for pain reduction in ACNES patients who failed to respond to a conservative regimen.

Randomized clinical trial of trigger point infiltration with lidocaine to diagnose anterior cutaneous nerve entrapment syndrome

Background

Anterior cutaneous nerve entrapment syndrome (ACNES) is hardly considered in the differential diagnosis of chronic abdominal pain. Some even doubt the existence of such a syndrome and attribute reported successful treatment results to a placebo effect. The objective was to clarify the role of local anaesthetic injection in diagnosing ACNES. The hypothesis was that pain attenuation following lidocaine injection would be greater than that after saline injection.

Methods

Patients aged over 18 years with suspected ACNES were randomized to receive an injection of 10 ml 1 per cent lidocaine or saline into the point of maximal abdominal wall pain just beneath the anterior fascia of the rectus abdominis muscle. Pain was recorded using a visual analogue scale (VAS; 1–100 mm) and a verbal rating scale (VRS; 0, no pain; 4, severe pain) during physical examination just before and 15–20 min after injection. A reduction of at least 50 per cent on the VAS and/or 2 points on the VRS was considered a successful response.

Results

Between August 2008 and December 2010, 48 patients were randomized equally (7 men and 41 women, median age 47 years). Four patients in the saline group reported a successful response compared with 13 in the lidocaine group (P = 0·007).

Conclusion

Entrapped branches of intercostal nerves may contribute to the clinical picture in some patients with chronic abdominal pain. Pain reduction following local infiltration in these patients was based on an anaesthetic mechanism and not on a placebo or a mechanical (volume) effect. Registration number: NTR2016 (Nederlands Trial Register; http://www.trialregister.nl).

Chronic postoperative breast pain: danger zones for nerve injuries

BACKGROUND

Postoperative breast pain is a frequent complaint, reported by 50 percent of women following a breast procedure. Breast pain interferes with sexual activity, as reported by 48 percent of patients, exercise (36 percent), social activity (13 percent), and employment (6 percent).

METHODS

To define neurogenic causes of chronic postoperative breast pain, the authors performed a retrospective review of consecutive patients from a single surgeon and performed 10 anatomical bilateral dissections. The authors evaluated the most commonly injured nerves, based on zone of injury, injury type, and precedent breast procedure. Dissections referenced the zone of injury with the specific procedure and designated the individual nerves at risk.

RESULTS

The authors identified 57 patients with chronic breast pain from breast reconstruction (n = 38), reduction (n = 2), mastopexy (n = 2), augmentation (n = 4) and irradiation (n = 11). On the basis of anatomic innervation, the authors designated five zones of nerve injury: superior, medial, inferior, lateral, and central/nipple-areola complex. The lateral zone was most commonly injured (79 percent), followed by inferior (10.5 percent), medial (5 percent), central (3.5 percent), and superior (2 percent) zones. Forty-two patients suffered intercostal nerve neuromas from mechanical nerve trauma/entrapment, with pain at the surgical scar or nearby tissue dissection. Four patients with traction-stretch neuropathy had pain from blunt augmentation pocket dissection. Eleven patients with irradiation-induced neuropathy had diffuse, nonlocalized nerve pain.

CONCLUSIONS

By shifting the approach to chronic breast pain from "global chronic breast pain" to defined danger zones of nerve injury, the practitioner can identify the type of nerve injury and associate the most common nerve injury to a given breast procedure. This approach should assist in diagnosis and treatment, and ultimately improve patient morbidity.

Diagnostic usefulness of Carnett's test in psychogenic abdominal pain

OBJECTIVE

Carnett's test is a simple clinical test in which abdominal tenderness is evaluated while the patient tenses the abdominal muscles. It is useful for differentiating abdominal wall pain from intra-abdominal pain. However, no study has reported its association with psychogenic abdominal pain. We evaluated its diagnostic usefulness in psychogenic abdominal pain.

METHODS

Two physicians performed Carnett's test on each patient, but only one received the medical history. The other physician only conducted the test. Based on the final diagnosis, patients were categorized into 3 groups: psychogenic pain, abdominal wall pain, or intra-abdominal pain. Each group was analyzed in association with the results of Carnett's test conducted by the blinded physician.

PATIENTS

A total of 130 outpatients with the chief complaint of abdominal pain who had abdominal tenderness.

RESULTS

There were 22 patients with psychogenic abdominal pain, 19 with abdominal wall pain and 62 with intra-abdominal pain. In patients with psychogenic pain or abdominal wall pain, Carnett's test was usually positive, whereas the test was usually negative in patients with intra-abdominal pain (p<0.001, respectively). The positive likelihood ratio of Carnett's test for psychogenic abdominal pain was 2.91 (95% confidence interval [CI], 2.71-3.13), while the negative likelihood ratio was 0.19 (95% CI, 0.11-0.34). The corresponding values for abdominal wall pain were 2.62 (95% CI, 2.45-2.81) and 0.23 (95% CI, 0.13-0.41), respectively.

CONCLUSION

Carnett's test may be useful for ruling in and ruling out psychogenic abdominal pain in addition to distinguishing between abdominal wall pain and intra-abdominal pain.

Chronic abdominal wall pain--a diagnostic challenge for the surgeon

BACKGROUND

Chronic abdominal wall pain (CAWP) occurs in about 30% of all patients presenting with chronic abdominal pain.

METHODS

The authors review the literature identified in a PubMed search regarding the abdominal wall as the origin of chronic abdominal pain.

RESULTS

CAWP is frequently misinterpreted as visceral or functional abdominal pain. Misdiagnosis often leads to a variety of investigational procedures and even abdominal operations with negative results. With a simple clinical test (Carnett's test), >90% of patients with CAWP can be recognized, without risk for missing intra-abdominal pathology.

CONCLUSION

The condition can be confirmed when the injection of local anesthetics in the trigger point(s) relieves the pain. A fasciotomy in the anterior abdominal rectus muscle sheath through the nerve foramina of the affected branch of one of the anterior intercostal nerves heals the pain.

Rectus sheath block: successful use in the chronic pain management of pediatric abdominal wall pain

Seven pediatric patients (aged 11-16 years) with chronic abdominal wall pain are presented who gained significant relief from a rectus sheath block (RSB). We describe the case histories and review the relevant literature for this technique. The etiology of the abdominal wall pain was considered to be abdominal cutaneous nerve entrapment, iatrogenic peripheral nerve injury, myofascial pain syndrome or was unknown. All patients showed significant initial improvement in pain and quality of life. Three patients required only the RSB to enable them to be pain-free and return to normal schooling and physical activities. Two children received complete relief for more than 1 year. In the majority of cases, the procedure was carried out under general anesthesia as a daycase procedure. Local anesthetic and steroids were used. This is the first report of the successful use of this technique in the chronic pain management setting in children.

Derivation and identification of questions that act as predictors of abdominal pain of musculoskeletal origin

OBJECTIVE

Although most causes of abdominal pain have a visceral origin, the musculoskeletal system must be considered when the cause is not obvious. This prospective study aimed to identify questions that would aid the diagnosis of patients with abdominal pain of musculoskeletal origin.

DESIGN

Assessment of consecutive patients with abdominal pain recruited from gastroenterological outpatient clinics to develop diagnostic pointers to identify abdominal pain arising from musculoskeletal disorders.

PARTICIPANTS

Subjects with benign abdominal pain, with or without a change in bowel habit, were recruited from gastroenterological clinics. Patients with inflammatory or neoplastic disease were excluded.

SETTING

The study was conducted in the Physiotherapy Department, Addenbrooke's NHS Trust Hospital, Cambridge.

MAIN OUTCOME MEASURES

A set of questions developed to indicate a musculoskeletal cause of a patient's abdominal symptoms. RESULTS The questions 'Does taking a deep breath aggravate your symptoms?' and 'Does twisting your back aggravate your symptoms?' had a significant positive indication of abdominal symptoms of musculoskeletal origin. The questions 'Has there been any change in bowel habit since onset of your symptoms?', 'Does eating foods aggravate your symptoms?' and 'Has there been any weight change since onset of symptoms?' had a significant negative indication for abdominal symptoms not of musculoskeletal origin. A combination of these questions gave 96% specificity and 67% sensitivity.

CONCLUSION

These questions may help with the early identification of patients with abdominal pain of musculoskeletal origin and will be tested in further studies.

Chronic abdominal wall pain: a frequently overlooked problem. Practical approach to diagnosis and management

Chronic abdominal wall pain is frequently misdiagnosed as arising from a visceral source, often resulting in inappropriate diagnostic testing, unsatisfactory treatment, and considerable cost. Its prevalence in general medical practice is unknown, although it may account for about 10% of patients with chronic idiopathic abdominal pain seen in gastroenterological practices. The most common cause appears to be entrapment of an anterior cutaneous branch of one or more thoracic intercostal nerves; myofascial pain and radiculopathy are less frequent. Sharply localized pain and superficial tenderness are suggestive of abdominal wall origin. Carnett's test (accentuated localized tenderness with abdominal wall tensing) is a helpful diagnostic sign, especially when incorporated with other findings. Early exclusion of a parietal source should increase diagnostic accuracy when evaluating patients with chronic abdominal pain. Reassurance of patients by the correct diagnosis and avoidance of precipitating causes is often sufficient treatment. However, accurately placed anesthetic/corticosteroid injections give substantial pain relief to more than 75% of patients, often for prolonged periods, and may be confirmatory for the source of the complaint. The probability of missing visceral disease is small (probably less than 7%) with strict adherence to diagnostic criteria and diligent observation of patients.

Outcome of patients with chronic abdominal pain referred to chronic pain clinic

OBJECTIVE

We determined the outcome of patients with chronic abdominal pain of unknown etiology referred by gastroenterologists to a chronic pain clinic.

METHODS

A retrospective chart review of 43 consecutive patients seen by a university-based gastroenterology group was referred to our Chronic Pain Clinic for evaluation and treatment. Pain character and location, the referring diagnosis, and initial Chronic Pain Clinic diagnosis was compared between responders and nonresponders. Early and long-term pain relief was scored by standard questionnaire.

RESULTS

Of the 43 patients with chronic abdominal pain of undetermined etiology, 70% reported complete or substantial pain relief by the end of chronic pain management. Pain character and location and the referring diagnosis were not predictors of pain relief. Long-term pain relief was reported by 35% of patients.

CONCLUSION

A substantial group of patients with chronic abdominal pain of unknown etiology benefited from Chronic Pain Clinic services.

Abdominal wall pain caused by cutaneous nerve entrapment in an adolescent girl taking oral contraceptive pills

The etiology of chronic abdominal pain can be elusive. The diagnostic workup, therefore, often includes superfluous and expensive tests, as well as invasive procedures which do not contribute to the final diagnosis. Studies have shown that some patients suffer from prolonged pain in the abdominal wall and often are misdiagnosed and treated as having a visceral source for their complaints. The abdominal wall might be considered to be an unlikely source of prolonged abdominal pain, but one study reported that in 15% of patients with prolonged, nonspecific abdominal pain, the abdominal wall was the source of the complaint. Abdominal pain resulting from cutaneous nerve entrapment has not been reported previously in children and adolescents, nor has nerve entrapment been reported as a complication of oral contraceptives. The case of a 15-year-old girl who came to the hospital emergency room with abdominal pain of 3 months duration is reported. A comprehensive workup had not established a specific cause for the pain. On the basis of the clinical findings, the possibility of a cutaneous nerve entrapment was suggested. After the involved cutaneous nerve was selectively blocked by subcutaneous infiltration, the pain disappeared immediately and completely. Recognition of this apparently unusual condition can lead to gratifying results. It is proposed that oral contraceptive therapy may have caused changes in the abdominal wall which led to nerve entrapment and the ensuing severe, prolonged pain.

Chronic abdominal wall pain. Diagnostic validity and costs

Chronic abdominal wall pain (CAWP) is common and frequently mistaken for visceral pain. We determined the stability of this diagnosis with Main Outcome Measures of: (a) change of pain intensity after local anesthetic-corticosteroid injection, (b) pain relief after three or more months follow-up, and (c) costs of diagnostic procedures for visceral causes of abdominal pain in patients with confirmed CAWP. Seventy-nine patients fulfilled tentative criteria for CAWP; 72 (91%) experienced > or = 50% pain relief with anesthetic injection and were followed for at least three months (mean = 13.8 months). Abdominal pain in four patients was later diagnosed as caused by visceral disease. CAWP was confirmed in 56 of remaining 68 patients; 12 of 19 patients with recurrent pain were unavailable for re-injection of anesthetic. Thirty patients with confirmed CAWP had had diagnostic procedures to exclude visceral disease costing almost $700 per patient. CAWP is usually easily identified and treated; greater awareness should minimize misdiagnosis.

Abdominal wall tenderness: a useful sign in chronic abdominal pain

The outcome in 72 patients with obscure abdominal pain and a positive Carnett's (abdominal wall tenderness) test, seen in one firm's surgical outpatient clinic between 1975 and 1983, was sought by a combination of hospital note retrieval and general practitioner questionnaire. Full follow-up data to date or death were available for 58 (81 per cent) patients and partial follow-up for 14 patients. The study showed that the patients generated a good deal of investigation and a number of surgical procedures but that seldom were their symptoms attributable to serious pathology. Familiarity with the test, taken in the context of a proper history and examination, has been found helpful in assessing such patients and saves the inconvenience, expense and occasional hazard of investigation, and even surgery.