Sciatic nerve: sonographic evaluation and anatomic-pathologic considerations.

Sonographic analysis of the sciatic nerve was performed in vitro (anatomic specimen), in vivo (healthy volunteers), and in 16 patients with suspected peripheral sciatic nerve lesions. The ultrasound (US) examinations were performed with standard and high-resolution US equipment with linear-array configuration. The normal nerve displayed an echogenic fibrillar texture with round cross-sectional structure on both in vitro and in vivo sonograms. Satisfactory delineation of the nerve was obtainable in all cases. Nerve displacement was the main sonographic finding in cases of extrinsic compression. The lesion displayed variable echotexture, ranging from hypoechogenicity or mixed echogenicity in hematomata to hyperechogenicity in cases of fibrosis. Primary nerve tumors (neurofibroma) or infiltrating tumors (desmoid) caused clear disruption of the nerve structure. Use of sonography enabled assessment of the continuity of the nerve margins with the interposed graft in a case of reconstructive surgery. The potential to image sciatic nerve lesions noninvasively may have an important impact on diagnosis, treatment, and prognosis in symptomatic patients.