In this issue of the Scandinavian Journal of Pain Robbert Maatman, and his co-workers in The Netherlands publish their retrospective observational study on 21 women and 9 men presenting with flank pain in whom they were able to make a diagnosis of lateral cutaneous entrapment syndrome (LACNES) [1]. These authors have long experience diagnosing and treating chronic abdominal pain due to entrapment in the abdominal wall of terminal endings of intercostal nerves (ACNES, anterior abdominal cutaneous nerve entrapment syndrome) [2,3].
These syndromes occur only occasionally, many physicians and even pain specialists are not familiar with these entrapment phenomena and the pain they generate. Therefore these patients may suffer prolonged periods from undiagnosed abdominal or flank pain, often with a diagnosis of “idiopathic” pain, “functional” pain, or even “psychogenic” pain. Such diagnoses are just expressions of failure to find any somatic cause of the pain. Patients may often have the impression that the health care providers consider them to have “imagined” pain. They have been exposed to several failed treatments. They risk being prescribed opioid analgesics in increasing doses. This adds to the patients’ problems, risking opioid use disorder.
Specific ACNES characteristics include a small area (several square centimetres) of maximum pain, altered skin sensation covering this tender point, a positive “pinch test” and a positive Carnett’s test (increased local tenderness by tensing the abdominal muscles) [1]. It is interesting that these authors described a novel variant of ACNES associated with severe localized (lower) back pain, and it was found that posterior branches of the intercostal nerve were entrapped in the region of the thoracolumbar muscle group [2].
Similar to the procedure to diagnose ACNES, when LACNES is suspected because of a constant area of flank tenderness, a small area of maximal pain, and locally altered skin sensation, a specific localized point of pressure-generated intense pain, increases the likelihood of LACNES: Injection of a small amount of a local anaesthetic will confirm the diagnosis if the pain intensity decreases at least 50% [1]. Injections of a local anaesthetic caused prolonged or permanent pain relief in about 50% of the patients, and minimally invasive surgery to relieve the entrapped nerve was necessary in about 1/3 of the LACNES patients [1].
It is important that the surgical relief of an entrapped nerve is done as “atraumatically” as possible. Rough handling of the already damaged entrapped nerve can aggravate the nerve damage and the patient’s pain problem.
We recommend our readers to study this article from the surgeons in Veldhoven and the specialized Center of Excellence for Chronic Abdominal Wall and Groin Pain in Eindhoven, The Netherlands [1], as well as their recent publications on the more frequently occurring ACNES [3,4].
1 Why does local injections in ACNES and LACNES cause prolonged pain relief?
There is one great mystery in these optimistic reports of long- lasting or even permanent relief of ACNES or LACNES pain by injection of a small amount of lidocaine, or even only saline [1,2].
Patrick Wall in 1990 in his Editorial in the December issue of PAIN recommended highly [5] the study by the “Karolinska Pain Troika”, Staffan Arner, Ulf Lindblom, and Bjorn Meyerson, in addition to Carl Molander who reported prolonged relief of neuralgia after regional anaesthetic blocks [6]. Patrick Wall clearly was fascinated by their observations, especially of the puzzling finding that some patients reported that the pain returned after the anaesthetic block, but then a second phase of prolonged pain relief followed [6]. Patrick Wall strongly recommended more clinical research on the prolonged effect of the frequently performed local/regional injections, for which evidence of mechanisms of prolonged relief was lacking [5].
Patrick Wall and Clifford Woolf discussed this conundrum in Nature already in 1980: why can a blank injection cause analgesia? [7]. At that time, with the endorphins recently discovered, the hope was that somehow endorphins were mobilized; creating analgesia that in some circumstances could be reduced by injecting a large dose of naloxone. It is more complex than that, but we have to admit that even today “What we don’t know about pain” [7] is a huge “black box”. Clinical pain researchers should be busy for a long time to come.
DOI of refers to article: http://dx.doi.org/10.1016/j.sjpain.2017.10.007.
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Conflict of interest None declared.
References
[1] Maatman RC, Papen-Botterhuis NE, Scheltinga MRM, Roumen RMH. Lateral Cutaneous Nerve Entrapment Syndrome (LACNES): a previously unrecognized cause ofintractable flank pain. Scand J Pain 2017;17:211–7.Search in Google Scholar
[2] Boelens OB, Maatman RC, Scheltinga MR, van Laarhoven K, Roumen RM. Chronic localized back pain due to posterior cutaneous nerve entrapment syndrome (POCNES): a new diagnosis. Pain Phys 2017;20:E455–8.Search in Google Scholar
[3] Boelens OB, Scheltinga MR, Houterman S, Roumen RM. Randomized clinicaltrial oftrigger point infiltrationwith lidocaine to diagnose anteriorcutaneous nerve entrapment syndrome. Br J Surg 2013;100:217–21.Search in Google Scholar
[4] Boelens OB, van Assen T, Houterman S, Scheltinga MR, Roumen RM. A doubleblind, randomized, controlled trial on surgery for chronic abdominal pain due to anterior cutaneous nerveentrapment syndrome. Ann Surg 2013;257: 845–9.Search in Google Scholar
[5] Wall PD. Neuropathic pain. Pain 1990;43:287–8.Search in Google Scholar
[6] Arner S, Lindblom U, Meyerson BA, Molander C. Prolonged relief of neuralgia after regional anesthetic blocks. A call for further experimental and systematic clinical studies. Pain 1990;43:287–97.Search in Google Scholar
[7] Wall PD, Woolf CJ. What we don’t know about pain. Nature 1980;287:185–6.Search in Google Scholar
© 2017 Scandinavian Association for the Study of Pain
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- Observational study
- Perceived sleep deficit is a strong predictor of RLS in multisite pain – A population based study in middle aged females
- Clinical pain research
- Prospective, double blind, randomized, controlled trial comparing vapocoolant spray versus placebo spray in adults undergoing intravenous cannulation
- Clinical pain research
- The Functional Barometer — An analysis of a self-assessment questionnaire with ICF-coding regarding functional/activity limitations and quality of life due to pain — Differences in age gender and origin of pain
- Clinical pain research
- Clinical outcome following anterior arthrodesis in patients with presumed sacroiliac joint pain
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- Chronic disruptive pain in emerging adults with and without chronic health conditions and the moderating role of psychiatric disorders: Evidence from a population-based cross-sectional survey in Canada
- Educational case report
- Management of patients with pain and severe side effects while on intrathecal morphine therapy: A case study
- Clinical pain research
- Behavioral inhibition, maladaptive pain cognitions, and function in patients with chronic pain
- Observational study
- Comparison of patients diagnosed with “complex pain” and “somatoform pain”
- Original experimental
- Patient perspectives on wait times and the impact on their life: A waiting room survey in a chronic pain clinic
- Topical review
- New evidence for a pain personality? A critical review of the last 120 years of pain and personality
- Clinical pain research
- A multi-facet pain survey of psychosocial complaints among patients with long-standing non-malignant pain
- Clinical pain research
- Pain patients’ experiences of validation and invalidation from physicians before and after multimodal pain rehabilitation: Associations with pain, negative affectivity, and treatment outcome
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- Long-term treatment in chronic noncancer pain: Results of an observational study comparing opioid and nonopioid therapy
- Clinical pain research
- COMBAT study – Computer based assessment and treatment – A clinical trial evaluating impact of a computerized clinical decision support tool on pain in cancer patients
- Original experimental
- Quantitative sensory tests fairly reflect immediate effects of oxycodone in chronic low-back pain
- Editorial comment
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- Original experimental
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- Clinical pain research
- A randomized study to evaluate the analgesic efficacy of a single dose of the TRPV1 antagonist mavatrep in patients with osteoarthritis
- Editorial comment
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- Educational case report
- Pregabalin as adjunct in a multimodal pain therapy after traumatic foot amputation — A case report of a 4-year-old girl
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- Editorial comment
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- Editorial comment
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- Observational study
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- Clinical pain research
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- Editorial comment
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- Editorial comment
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- Observational study
- Identifying characteristics of the most severely impaired chronic pain patients treated at a specialized inpatient pain clinic
- Editorial comment
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- Editorial comment
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- Topical review
- Individual variability in clinical effect and tolerability of opioid analgesics – Importance of drug interactions and pharmacogenetics
- Editorial comment
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- Clinical pain research
- PhKv a toxin isolated from the spider venom induces antinociception by inhibition of cholinesterase activating cholinergic system
- Clinical pain research
- Lateral Cutaneous Nerve Entrapment Syndrome (LACNES): A previously unrecognized cause of intractable flank pain
- Editorial comment
- Towards a structured examination of contextual flexibility in persistent pain
- Clinical pain research
- Context sensitive regulation of pain and emotion: Development and initial validation of a scale for context insensitive avoidance
- Editorial comment
- Is the search for a “pain personality” of added value to the Fear-Avoidance-Model (FAM) of chronic pain?
- Editorial comment
- Importance for patients of feeling accepted and understood by physicians before and after multimodal pain rehabilitation
- Editorial comment
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- Observational study
- Assessment and treatment at a pain clinic: A one-year follow-up of patients with chronic pain
- Clinical pain research
- Randomized, double-blind, placebo-controlled, dose-escalation study: Investigation of the safety, pharmacokinetics, and antihyperalgesic activity of L-4-chlorokynurenine in healthy volunteers
- Clinical pain research
- Prevalence and characteristics of chronic pain: Experience of Niger
- Observational study
- The use of rapid onset fentanyl in children and young people for breakthrough cancer pain
- Original experimental
- Acid-induced experimental muscle pain and hyperalgesia with single and repeated infusion in human forearm
- Original experimental
- Swearing as a response to pain: A cross-cultural comparison of British and Japanese participants
- Clinical pain research
- The cognitive impact of chronic low back pain: Positive effect of multidisciplinary pain therapy
- Clinical pain research
- Central sensitization associated with low fetal hemoglobin levels in adults with sickle cell anemia
- Topical review
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- Original experimental
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- Original experimental
- Coping with pain in intimate situations: Applying the avoidance-endurance model to women with vulvovaginal pain
- Clinical pain research
- Chronic low back pain and the transdiagnostic process: How do cognitive and emotional dysregulations contribute to the intensity of risk factors and pain?
- Original experimental
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- Educational case report
- Erector spinae plane (ESP) block in the management of post thoracotomy pain syndrome: A case series
- Original experimental
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- Observational study
- Predictors of chronic neuropathic pain after scoliosis surgery in children
- Clinical pain research
- Hospitalization due to acute exacerbation of chronic pain: An intervention study in a university hospital
- Clinical pain research
- A novel miniature, wireless neurostimulator in the management of chronic craniofacial pain: Preliminary results from a prospective pilot study
- Clinical pain research
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- Original experimental
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- Original experimental
- Initial validation of the exercise chronic pain acceptance questionnaire
- Clinical pain research
- Exploring patient experiences of a pain management centre: A qualitative study
- Clinical pain research
- Narratives of life with long-term low back pain: A follow up interview study
- Observational study
- Pain catastrophizing, perceived injustice, and pain intensity impair life satisfaction through differential patterns of physical and psychological disruption
- Clinical pain research
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- Original experimental
- Evaluation of external vibratory stimulation as a treatment for chronic scrotal pain in adult men: A single center open label pilot study
- Observational study
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- Clinical pain research
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- Original experimental
- Developing a model for measuring fear of pain in Norwegian samples: The Fear of Pain Questionnaire Norway
- Topical review
- Psychoneuroimmunological approach to gastrointestinal related pain
- Letter to the Editor
- Do we need an updated definition of pain?
- Narrative review
- Is acetaminophen safe in pregnancy?
- Book Review
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- Book Review
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- Book Review
- Atlas of Pain Management Injection Techniques
- Book Review
- Sedation: A Guide to Patient Management
- Book Review
- Basics of Anesthesia