Unusual Anatomic Split with Reunification of the Mid-Thigh Sciatic Nerve Utilizing Sonography

Abstract

Variant sciatic nerve anatomy in the thigh occurs in about 4% of cadaveric specimens. Its significance is relevant in both clinical and surgical settings. This case describes a rare asymptomatic split with reunification of the sciatic nerve in the thigh utilizing sonography. A 27-year old male presented as a participant in a sonography research study (in preparation for publication). He was a healthy control subject without low back pain or radicular symptoms. A bilateral sonographic examination was performed to assess the sciatic nerve in the long (sagittal) and short (axial) planes. Incidentally demonstrated was a split of the sciatic nerve occurring approximately 8 cm distal to the ischial tuberosity. The finding was symmetric and bilateral. The split was maintained for 12 cm with a perpendicular epineural bridge connecting the two branches, reuniting proximal to the sciatic nerve bifurcation. Sciatic nerve variants are often described at the level of the piriformis. In contrast, there are few studies that describe variant anatomy of the sciatic nerve in the mid-thigh. Sonography provides a safe, easy, and available resource for depicting anatomic morphology of the sciatic nerve.