Significance of Chronic Abdominal Wall Pain, Association With Fibromyalgia and Response to Treatment With Trigger Point Injections: A Retrospective Study

Abstract

Introduction: Chronic abdominal wall pain (CAWP) is seen in about 10-30% of chronic abdominal pain patients and is often underdiagnosed or misdiagnosed. CAWP can be diagnosed clinically using Carnett's sign. In this study, we have looked at the incidence of CAWP in chronic abdominal pain patients, association with fibromyalgia and response to trigger point injections. Methods: This is a retrospective study and we identified adult patients > 18 years of age who were referred to our Gastroenterology clinic for chronic abdominal pain (duration >3 months) evaluation. CWAP patients were further identified by positive Carnett’s sign (increased tenderness with the straight leg or head raise maneuvers) and negative gastrointestinal workup by endoscopy, colonoscopy, CT/MRI, ultrasound imaging and laboratory testing. Patients with CAWP were treated with trigger point injections with lidocaine and steroids and response to treatment was observed. Results: The total number of patients with chronic abdominal pain were 123 patients and out of these 30 had CAWP. The median duration of abdominal pain was 3 years (IQR 2 - 6.5). Females constituted 90% and the median age was 45 years (IQR 37 - 49 years). Fibromyalgia was present in 11 (36.6%) patients. Out of the 30 patients with CAWP, 25 (8 fibromyalgia) patients received treatment. Trigger point injections were administered to 25 patients. Simultaneous neuromodulator therapy with tricyclic agents was given to 20 (80%) of the patients and 3 of these patients had fibromyalgia. Complete response was observed in 5 (20%) and partial response was observed in 14 (56%) of the patients. In patients with fibromyalgia, 3 (37.5%) patients had a complete response to treatment and another 3 (37.5%) patients had a partial response to treatment. Repeat trigger point injections were administered in 9 (36%) of the patients and of these 3 patients had fibromyalgia. Conclusion: CAWP is an important etiology of chronic abdominal pain and the most common cause of CAWP is anterior cutaneous nerve entrapment syndrome (ACNES). In our study, 24% of chronic abdominal pain patients had CAWP and in that nearly one-third had fibromyalgia. Trigger point injections were associated with complete or partial response in 76% of all CAWP patients and 75% in fibromyalgia patients. CAWP is a clinical diagnosis and should be considered in patients with chronic abdominal pain and a thorough physical examination will help avoid unnecessary investigations, and initiate earlier treatment.