Reduced Fascicle Area Demonstrated in Ilioinguinal Nerves Resected from Primary Inguinal Herniorrhaphy Patients as Evidence of Compression Neuropathy.

Methods: 30 male patients with primary inguinal hernias undergoing primary inguinal herniorrhaphy were prospectively recruited for ilioinguinal nerve resection and evaluation. Three samples of the resected ilioinguinal nerve (proximal, canal, and distal) were evaluated using Masson's trichrome stain to measure fascicle and total nerve cross-sectional area and detect changes in collagen. Results: The fascicle cross-sectional area in the canal segment was significantly decreased compared to the proximal control with a large effect size observed (p = 0.016, η2 = 0.16). There was no significant difference in the nerve cross-sectional area between locations, but there was a moderate to large effect size observed between locations (p = 0.165, η2 = 0.105). There was no significant difference in collagen content nor effect size observed between locations (p = 0.99, η2 = 1.503 × 10-4). Interpretation. The decrease in the fascicle cross-sectional area within the inguinal canal further suggests that there is chronic pressure applied by hernia tissue consistent with axon degeneration. Collagen content is uniformly distributed along the length of the nerve. Further studies with larger samples are needed to confirm the observed effect of nerve location on the total nerve cross-sectional area and axon loss.

Groin anatomy, preoperative pain, and compression neuropathy in primary inguinal hernia: What really matters.

INTRODUCTION: Enlargement of the ilioinguinal nerve distal to the inguinal ring is common in primary open inguinal herniorrhaphy and is histologically consistent with compression neuropathy. However, the origin of this neuropathy has not been thoroughly studied in primary inguinal hernia. METHODS: In this prospective study, 143 primary inguinal herniorrhaphies were performed. Prior to surgery, all patients completed a preoperative pain questionnaire from the Carolina Comfort Scale and Visual Analog Scale-evaluating pain with various activities. Pain scores were statistically compared with several different anatomical surgical observations. RESULTS: When each variable is individually compared with pain scores, a significant positive correlation exists between nerve enlargement and increased pain compared to those without enlargement for preoperative "most of the time pain" (P < 0.0017). There is also a statistically significant positive correlation between nerve enlargement and external ring fibrosis (P < 0.001). 81% of patients with enlargement have histological abnormalities. CONCLUSION: Preoperative pain in primary inguinal hernia is correlated with ilioinguinal nerve enlargement, which is also correlated with fibrosis of the external oblique fascia at the external ring.