Anatomic Variability of the Ilioinguinal and Genitofemoral Nerve: Implications for the Treatment of Groin Pain

Abstract

The differential diagnosis of groin pain must consider problems of the ilioinguinal and/or genitofemoral nerve. These nerves may become injured during hernia surgery or lower quadrant surgical procedures. To treat injury to these nerves, it is critical to understand their anatomic variability. In the present study the pattern of cutaneous nerve branches in the inguinal region was investigated through dissection in 64 halves of 32 human embalmed anatomic specimens. In contrast to usual textual descriptions, four different types of cutaneous branching patterns are identified: type A, with a dominance of genitofemoral nerve in the scrotal/labial and the ventromedial thigh region. In type A, the ilioinguinal nerve gives no sensory contribution to these regions (43.7 percent). In type B, with a dominance of ilioinguinal nerve, the genitofemoral nerve shares a branch with the ilioinguinal and gives motor fibers to cremaster muscle in the inguinal canal, but has no sensory branch to the groin (28.1 percent). In type C, with a dominance of genitofemoral nerve, the ilioinguinal nerve has sensory branches to the mons pubis and inguinal crease together with an anteroproximal part of the root of the penis or labia majora. The nerve was found to share a branch with the iliohypogastric nerve (20.3 percent). In type D, cutaneous branches emerge from both the ilioinguinal and the genitofemoral nerves. Additionally, the ilioinguinal nerve innervates the mons pubis and inguinal crease together with a very anteroproximal part of the root of the penis or labia majora (7.8 percent). The described patterns of innervation were bilaterally symmetric in 40.6 percent of the cadavers. The anatomic variability of both nerves has implications for all surgeons operating in the groin region and for those caring for the patient with groin pain.

International guidelines for prevention and management of post-operative chronic pain following inguinal hernia surgery

“…Looking at the literature, only two anatomical studies have investigated the presence and course of the three inguinal nerves together [55,64], while others have investigated the presence and course of only one or two inguinal nerves [8,9,19,27,39,42,47,50,51,53,62].…”

“…However, this does not imply that they also are identifiable during open hernia repair. For example, in the study by Rab et al [55], the ilioinguinal nerve was incorporated in the genitofemoral nerve, lateral to the deep inguinal ring in 44% of cases. Moosman et al [45] report the same course in 35% of patients.…”

Neuroanatomy and neurophysiology related to sexual dysfunction in male neurogenic patients with lesions to the spinal cord or peripheral nerves

“…The classical pattern of distribution and the terminal course of the ilioinguinal and genitofemoral nerve consistent with modern text descriptions were defined in only 20% of cadaveric dissections. 9,10 The dorsal penile nerve (pudendal nerve) is responsible for reflex erections. 11 Damage to the pudendal nerves (that is, Alcock syndrome) leads to erectile dysfunction.…”

Anatomic variability of groin innervation

“…The inguinal nerves are often found to follow variable patterns of distribution [1,5,6]. In a recent study of patients undergoing hernia repair, Al-Dabbagh [1] found that the course of the ilioinguinal and iliohypogastric nerves was only consistent with anatomic texts in 41.8% of cases.…”

“…Variation in the anatomical course of the inguinal nerves further complicates this already demanding procedure as nerves may be inadvertently compressed or sectioned. Injury to the innervation of this area can lead to postoperative pain [6,7]. For instance, in 49 out of 110 hernia repairs reported by Al-Dabbagh [1], the atypical superficial placement of the ilioinguinal nerve left it particularly vulnerable to transection in the early stages of the operation.…”