Rare, Overlooked, or Underappreciated Causes of Recurrent Abdominal Pain: A Primer for Gastroenterologists

Development and validation of a mouse model to investigate post surgical pain after laparotomy

Background

Postoperative pain following abdominal surgery is a significant obstacle to patient recovery, often necessitating high analgesic doses associated with adverse effects like cognitive impairment and cardiorespiratory depression. Reliable animal models are crucial for understanding the pathophysiology of post surgical pain and developing more effective pain-relieving strategies.

Methods

We developed a mouse model to replicate peritoneal trauma induced by abdominal surgery. 30 C57BL/6 mice underwent laparotomy, with half undergoing standardised peritoneal abrasion and the rest serving as controls. Mouse recovery was assessed using two validated scoring systems of surgical recovery: Post surgery Severity Assessment (PSSA) and Mouse Grimace Score (MGS). Blood samples were taken for cytokine analysis. Adhesions were evaluated on day 6, and peritoneal tissue was examined for healing markers.

Results

After laparotomy, all mice exhibited expected pain profiles. Mice with peritoneal abrasion had significantly higher PSSA (7.2 ± 1.2 vs 4.68 ± 0.82, p ≤ 0.001) and MGS scores (3.62 ± 0.74 vs 0.82 ± 0.40, p ≤ 0.05) with slower recovery. Serum inflammatory cytokine levels were significantly elevated in the abraded group, and adhesion formation was higher in this group. Immunohistochemical analysis showed significantly increased expression of α-SMA, CD31, CD68, and F4/80 in peritoneal tissue in the abraded group.

Discussion

A mouse model involving laparotomy and standardised peritoneal abrasion replicates the expected pathophysiological changes following abdominal surgery. It will be a useful model for better understanding the mechanisms of post surgical pain and developing improved pain-relief strategies. It also has utility for the study of intra-abdominal adhesion formation.

Key message

To understand the intricate relationship between peritoneal trauma-induced pain, cytokine response, and post-operative adhesion formation in mouse models for advancing therapeutic interventions and enhancing post-operative recovery outcomes.

Imatinib and Trigger Avoidance for Mast Cell Activation Syndrome Presenting With Attacks of Abdominal Pain, Nausea, Vomiting, and Diarrhea

The etiology for concurrent attacks of abdominal pain, nausea, vomiting, and diarrhea can be obscure. Mast cell activation syndrome is not usually considered in this differential diagnosis. A 53-year-old paint salesman suffered severe attacks of these symptoms for the 3 decades of his career. Nortriptyline, loperamide, hyoscyamine, and ondansetron failed to address his symptoms. Mast cell activation syndrome was ultimately diagnosed. Intravenous mast cell-targeted therapy reduced severity of attacks. Multiple oral mast cell-targeted treatments were ineffective, but addition of low-dose imatinib resulted in dramatic improvement. Recognition that paint-fume exposure-triggered attacks led to behavioral modifications which further reduced symptoms.

Detect Acute Porphyrias in Emergency Departments (DePorED) - a pilot study

BACKGROUND

Acute porphyrias (APs) are a group of rare metabolic diseases related to a disturbed heme biosynthesis. Symptoms may first occur as life threatening attacks, comprising abdominal pain and/or variable neuro-psychiatric symptoms, thus leading to presentation in emergency departments (ED) first. Due to the low prevalence, diagnosis of AP is often missed, even after readmission to the ED. Therefore, strategies are needed to consider APs in ED patients with unexplained abdominal pain, especially since early and adequate treatment will avoid an unfavorable clinical course. Aim of this prospective study was to investigate the prevalence of APs in ED patients and thus, addressing feasibility of screening for rare diseases, such as APs in the real life setting.

METHODS

From September 2019 to March 2021, patients presenting to the ED of three German tertiary care hospitals with moderate to severe prolonged abdominal pain (Visual Analog Scale, VAS > 4 out of 10 points) not otherwise explained were screened and prospectively enrolled. In addition to standard of care (SOC) diagnostics a blood and urine sample for plasma fluorescence scan and biochemical porphyrin analysis were sent to a certified German porphyria laboratory.

RESULTS

Overall, of 653 screened patients, 68 patients (36 females; mean age 36 years) were included for biochemical porphyrin analysis. No patient with AP was detected. The most frequent discharge diagnoses included "abdominal and digestive symptoms" (n = 22, 32%), "gastrooesophageal diseases" (n = 18, 27%), "infectious bowel disease" (n = 6, 9%) and "biliopancreatic diseases" (n = 6, 9%). Although not primarily addressed, we observed an increase in knowledge of the ED staffs at all study sites regarding our screening algorithm and thus, awareness for APs.

CONCLUSIONS

To the best of our knowledge, we performed the first prospective screening project for APs in the ED. Although we detected no patient with AP in this study, we demonstrated the feasibility of a multicenter screening process for APs by building up a well-working infrastructure comprising laboratory testing as well as data management. This enables the set-up of a larger scale revised follow-up study with a central focus on structured education, thus, possibly acting as blueprint for other rare diseases.