Variant femoral nerve: the path beneath the iliacus muscle and into neuropathic symptoms

Abstract

Background Previous discussions regarding variant femoral nerves often report an aberrant slip of a small portion of the iliacus muscle as a common cause of the femoral nerve splitting. Within these reported cases, the variant path involves a small amount of the nerve and treatment often involves surgical intervention to relieve nerve entrapment. Only a few cases have been reported that were not secondary to an aberrant muscle slippage, none of which include the variant discussed below. Case presentation A Caucasian male cadaver in his 70 s was discovered to have a variant femoral nerve upon dissection and evaluation of the pelvic region, without evidence of muscle slippage or surgical intervention. The bulk of the nerve pierced and traveled deep within the iliacus muscle before emerging distal to the pubic eminence and merging with the smaller portion that continued with the native course anteriorly. This variation would result in a predisposition to nerve compression during hip flexion and knee extension, with subsequent patient concerns of muscle weakness and sensory loss of unknown origins. Conclusion Awareness of this atypical variation could provide clinicians with another potential diagnosis to consider when managing femoral neuropathy, as well as the rationale for a noninvasive treatment option.