The Faith of Ilioinguinal Nerve After Preserving, Cutting, or Ligating It: An Experimental Study of Mesh Placement on Inguinal Floor

Abstract

Postherniorrhaphy chronic pain may be related to the trauma to the regional nerves or prosthetic mesh. This study was aimed to search the objective findings of prosthetic mesh placement on the ilioinguinal nerve in three different nerve treatment patterns with two different mesh types. Thirty New Zealand rabbits were used. Bilateral ilioinguinal nerves were identified. A 2×1 cm standard polypropylene mesh was laid on the nerve on right side, whereas a same sized lightweight polypropylene was applied on the left after three different nerve treatments were carried out. The nerve was completely preserved in the first group [G1], cut by scissors without a further process in the second [G2], and proximal cut end was ligated with 5/0 polyglactin. Three months after the surgery, bilateral nerve samples were taken from the contiguous nerve segment for light microscopy and electron microscopy. Nerve protection could not prevent microscopic changes entirely. Prosthetic mesh itself seemed to cause histopathologic changes. Overall incidence of histopathologic changes in light microscopy, without taking the nerve treatment pattern into account, was somewhat lower at standard mesh side than that of lightweight mesh side. However this difference did not reach the level of significance (P=0.39). When three groups were evaluated in respect to overall nerve damage without paying attention to mesh type, the highest damage rate was observed in G3 (cut and ligate). When each group was compared separately within itself for histopathologic changes, no differences were observed between heavy and light mesh sides in any group. When the microscopic changes were compared in respect to the different nerve treatment patterns on heavyweight mesh side, the rates were 12.5%, 12.5%, and 33.3%, respectively. On lightweight mesh side, all three groups exhibited similar microscopic finding rates, 37.5%, 25.0%, and 33.3%, respectively. Protection of the nerve resulted in virtually zero neuroma formation after two types of mesh use. Surgical trauma to the nerve was observed to have an obvious potential for neuroma formation. Mesh type did not affect the overall neuroma rate within the whole subject pool; both groups displayed same 40% overall neuroma development rate. The neuroma incidence was in 43.8% G2 and 72.2% in G3, however the difference did not attain level of significance (P=0.09). The highest rate was observed when a lightweight mesh was used after dividing and ligating the nerve. Light mesh could not provide a protection in subjects whose nerves were injured during surgery. Ligation of the cut end of the nerve also could not be helpful. Nerve protection still seems to be the best way for a nerve-related complaint-free postoperative period. The merit of nerve end implantation into the muscle should also be reconsidered.