Neuropathic inguinal pain: neurectomy associated with open prosthetic hernioplasty for the prevention of post-operative pain.

Introduction: Inguinal hernia is one of the most common surgical diseases in the world. Today, this disease is treated by surgical technique only. Among the late complications after surgery, the most frequent is the appearance of chronic post-operative pain after surgical treatment. The incidence of this complication is about 28% of patients undergoing hernioplasty suffering a varying degree of chronic pain, severe enough to interfere with normal daily activities.

Objectives: In this study we evaluated the onset of the neuropathic pain as a complication of inguinal prosthetic hernioplasty surgery.

Methods: This is a prospective observational study run between September 2019 and August 2020. All patients, during the first visit conducted in an outpatient clinic, were recruited in a specific database. Subsequently, surgery was planned in election on one day surgery, patients were administered a specific questionnaire aiming at the identification of any pain and its exact location. The Inguinal Pain Questionnarie (IPQ) was used. During the surgical procedure the selective neurectomy of the 3 nerves has been documented, the entire population of patients has undergone a standardized surgical treatment. At the end of surgery, a follow-up was carried out administering two questionnaires (IPQ Short Form Modified and the IPQ Short Form Paresthesia Modified) concerning the possible chronic post-operative pain and the eventual paresthesia. The questionnaires were administered at first, third and sixth month from the date of surgery.

Results: A total of 266 patients were screened from September 2019 to October 2020. Fiftyseven male patients were included in the study with a confirmed diagnosis of primary inguinal hernia. Clinical data, baseline characteristics and outcomes are described. Preoperatively, at the time of IPQ administration, 1.8% of patients had a pain score of 6, 10% of 5, 21% of 4, 31% of 3, 28% with a score of 2 and 7% of patients with a score of 1. In all cases the ileoinguinals and ileohypogastric nerves found were subjected to neurectomy, in 19% of cases also the genitofemoral nerve was subjected to surgical resection. At the end of the follow-up, the first questionnaire (IPQ Short Form Modified) results did show that, among the total of patients who had an open prosthetic hernioplasty with extensive nerves resection in the inguinal canal, 84% of them indicated a pain score equal to 0 (no pain) after 6 months of treatment and only 1.7% indicated a score equal to 4. Analyzing the second questionnaire on paresthesia (IPQ Short Form Paresthesia Modified), 79% of patients indicated a score equal to 0 by describing no paresthesia and no changes in sensitivity; 15.7% score 1; 3.5% score 2; 1.7% score 3.

Conclusions: Based on our experience and according to the modern literature, we would advise prophylactic total neurectomy of the inguinal canal nerves during prosthetic inguinal hernioplasty.

Key Words: Abdominal Surgery, Chronic pain, Inguinal hernioplasty, Neurectomy, Paresthesia.