Anatomic Variations of the Lateral Femoral Cutaneous Nerve: Remnants of Atypical Nerve Growth Pathways Revisited by Intraneural Fascicular Dissection and a Proposed Classification

OBJECTIVE: To trace anatomic variations of the lateral femoral cutaneous nerve (LFCN) in its intrapelvic course. METHODS: Ferry cadavers (80 sides) fixed in 10% formalin solution were dissected. The following parameters were recorded: LFCN diameter and variations in its origin and number. The dissection comprised exposure and excision of the lumbar plexus, together with the roots of LFCN, followed by retrograde intraneural fascicular dissection using microsurgical instruments. RESULTS: Several types of LFCN origin from the lumbar plexus were observed. Typically, the LFCN appears as a single trunk arising from dorsal divisions of the ventral ram of the lumbar plexus. The most prevalent origin of the nerve was from the 12 and 13 roots (47 cases; 58.75%). The LFCN took an origin from the 11-1.2 level in 12 cases (15%) and from the L2 nerve in 9 cases (11,25%), The main observed variations were the presence of the accessory LFCN (2 cases; 2.5%) and branching of the LFCN from the femoral nerve (6 cases; 7.5%). Communications between the LFCN and the femoral or genitofemoral nerves also were observed occasionally. An atypical course of the LFCN with respect to the anterior psoas was observed in our material in 3 of the 80 sides (3.75% of the examined LFCN specimens). CONCLUSIONS: Considerable variability in the origin and the course of the LFCN was observed, which should be taken into account during clinical assessment of nerve lesions and during surgery via transpsoas approaches to the lumbar spine.