Anatomical variations of ilioinguinal nerve: A systematic review of the literature

Several anatomical variations of the ilioinguinal nerve branches have been recorded in older studies. Knowledge of these variations is useful for the improvement of peripheral nerve blocks and avoidance of iatrogenic nerve injuries during abdominal surgeries. The purpose of this study is to perform a systematic review of the literature about the anatomical topography and variations of the ilioinguinal nerve. An extensive search in PubMed, Scopus, and Web of Science electronic databases was conducted by the first author in November 2021, with the use of the PRISMA guidelines. Anatomical or cadaveric studies about the origin, the course, and the distribution of the ilioinguinal nerve were included in this review. Thirty-one cadaveric studies were included for qualitative analysis. Several anatomical variations of the ilioinguinal nerve were depicted including its general properties, its origin, its branching patterns, its course, its relation to anatomical landmarks, and its termination. Among them, the absence of ilioinguinal nerve ranged from 0% to 35%, its origin from L1 ranged from 65% to 100%, and its isolated emergence from psoas major ranged from 47% to 94.5%. Numerous anatomical variations of the ilioinguinal nerve exist, not commonly cited in classic anatomical textbooks. The branches of the ilioinguinal nerve may be damaged during spinal anesthesia and surgical procedures in the lower abdominal region. Therefore, a better understanding of the regional anatomy and its variations is of vital importance for the prevention of ilioinguinal nerve injuries.