Diagnostic value of high-resolution sonography in common fibular neuropathy at the fibular head

Introduction: In 30% of patients with common fibular (CF) neuropathy at the fibular head, reliable localization of the site of the lesion by means of electrodiagnostic testing is challenging. Methods: We prospectively assessed proximal CF nerve cross-sectional area (CSA) measurements and at the fibular head in 87 patients with CF neuropathy and 16 with a different condition. Reference values were obtained in 64 healthy volunteers. Results: Patients with CF neuropathy had a significantly larger CF nerve CSA than controls and patient controls (P < 0.0001). Sonography localized the lesion at the fibular head in 55% and just above it in 71% of patients. Assessment of the most thickened part of the CF nerve resulted in a cut-off value of >8 mm(2) with a sensitivity of 90% (CI 81-95%) and a specificity of 69% (CI 58-78%). Conclusion: High-resolution sonography in addition to electrodiagnostic testing improves diagnostic reliability in CF neuropathy.