Objective: The aim of this study was to discuss patient history and subjective findings at physical examination in a large case series to validate a proposed comprehensive set of major and minor diagnostic criteria. Summary Background Data: Chronic abdominal pain in some patients is caused by the anterior cutaneous nerve entrapment syndrome (ACNES). ACNES is a clinical diagnosis as no functional testing or imaging modalities are available up to date. Methods: This study retrospectively analyzed prospectively obtained data from consecutive patients who received the diagnosis ACNES during evaluation at the SolviMáx Center of Excellence for Abdominal Wall and Groin Pain, Eindhoven, The Netherlands, between June 1, 2011 and September 1, 2016. Questionnaires, standard case forms, and digital case files containing characteristics of individuals were used for analysis. Results: Data of 1116 patients suspected and treated for ACNES consistently showed the presence of the following 4 characteristics: sensory disturbances at the painful abdominal area (78%), a positive pinch sign (78%), a positive Carnett's sign (87%), and a positive response to a modified rectus sheath block (>50% pain reduction, 81%). The majority of patients are female of young or middle age with a normal BMI reporting complaints that occurred spontaneously in either a sudden or gradual timeframe, developing a severe (NRS 6-8) chronic abdominal pain that was only diagnosed after a substantial doctor's delay. Conclusion: A combination of typical findings in history and physical examination, combined with a positive modified rectus sheath block, may allow for diagnosing ACNES in patients with chronic abdominal pain.

Altered mesolimbic dopamine signaling has been widely implicated in addictive behavior. For the most part, this work has focused on dopamine within the striatum, but there is emerging evidence for a role of the auto-inhibitory, somatodendritic dopamine D2 receptor (D2R) in the ventral tegmental area (VTA) in addiction. Thus, decreased midbrain D2R expression has been implicated in addiction in humans. Moreover, knockout of the gene encoding the D2R receptor (Drd2) in dopamine neurons has been shown to enhance the locomotor response to cocaine in mice. Therefore, we here tested the hypothesis that decreasing D2R expression in the VTA of adult rats, using shRNA knockdown, promotes addiction-like behavior in rats responding for cocaine or palatable food. Rats with decreased VTA D2R expression showed markedly increased motivation for both sucrose and cocaine under a progressive ratio schedule of reinforcement, but the acquisition or maintenance of cocaine self-administration were not affected. They also displayed enhanced cocaine-induced locomotor activity, but no change in basal locomotion. This robust increase in incentive motivation was behaviorally specific, as we did not observe any differences in fixed ratio responding, extinction responding, reinstatement or conditioned suppression of cocaine, and sucrose seeking. We conclude that VTA D2R knockdown results in increased incentive motivation, but does not directly promote other aspects of addiction-like behavior.

Abstract 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.

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Anterior rectus sheath blocks using local anesthetics and steroids are safe and long-term successful in more than one-third of children suffering from abdominal pain due to anterior cutaneous nerve entrapment syndrome.