Case Report: An Atypical Innervation to the Gluteus Maximus by the Sciatic Nerve and its Clinical Implications

Abstract

Anatomical variations, concerning the gluteus maximus (GM), are uncommon and of clinical importance. Usually, the GM is innervated by Inferior Gluteal Nerve (IGN), a branch of the sacral plexus arising from the ventral rami of L5 to S2. An unusual innervation was identified in routine cadaveric dissection in an elderly Puerto Rican female. Here, both the left and right GM were innervated by their corresponding IGN, yet both had an additional innervation by the Sciatic Nerve (SN). The bilateral SN branch to the GM was located proximally, when compared to the IGN, and emerged by the inferior border of the Piriformis muscle. In literature, there have been previous studies reporting multiple forms of innervations to the GM by the SN. Nevertheless, in these cases, the IGN was absent, and this anomaly was usually unilateral.The implications of this variation encompass both clinical and surgical correlations with respect to patient care. Regarding clinical aspects, patients with this dual variation to the GM can present with unique clinical scenarios which might be easily misdiagnosed. For instance, pain caused by inflammation of the GM in these patients might be misinterpreted and associated to pain felt in other conditions related to the SN, such as sciatica and piriformis syndrome. Likewise, women considering surgical intervention in this area might be at a higher risk of an iatrogenic nerve injury due to the anomalous SN branch to the GM.Thus, goal of this case report is to highlight the clinical and surgical implications of this finding based on the variant anatomy of the gluteal region. Physicians need to be aware of the existence of this variation. This might clarify the puzzling clinical manifestations of patients with the latter as well as avoid iatrogenic nerve injuries during surgical interventions.