Anatomical and MR correlative study of the proximal sciatic nerve vasculature

Objective: The aim of our study is to demonstrate that increased T-2 signal on MRI could be due to intraneural vessels in asymptomatic individuals, and may therefore be a normal finding. Methods: An initial anatomic cadaveric study was undertaken to gain a better understanding of the vascular supply of the proximal sciatic nerve. Secondly, a retrospective study of MR imaging of patients without sciatic symptoms was performed to assess the prevalence of intraneural vessels, defined as hyperintensity on at least three consecutive slices on both T-2 and gadolinium enhanced T-1 weighted imaging, visible on routine MSK pelvic imaging. Results: The anatomical study demonstrated a relatively abundant blood supply in the peri-ischiatic region. In the MR study, 20/76 (26%) patients showed visible intraneural vessels. More than one intraneural vessel was depicted in two of the sciatic nerves. Direct branching between the extrinsic and intrinsic systems was seen in only five cases. Conclusion: Normal intraneural vessels can frequently be seen within the sciatic nerve on routine musculoskeletal pelvic imaging. Advances in knowledge: T-2 hyperintensity in the proximal sciatic nerve can be due to intraneural vessels and should not necessarily be reported as abnormal.