High-resolution ultrasound of the posterior femoral cutaneous nerve: visualization and initial experience with patients.

Abstract

The posterior femoral cutaneous nerve (PFCN) is a sensory nerve originating from the sacral plexus. PFCN neuropathy leads to pain within the inferior gluteal region and the posterior aspect of the thigh. As electrophysiological assessment is challenging, diagnosis of PFCN neuropathy has been, thus far, primarily based on clinical findings, which can result in misdiagnosis. Therefore, alternative confirmatory assessments such as an imaging modality that could aid in the diagnosis of PFCN neuropathy would be desirable. The purpose of this study was to determine the feasibility of visualization of the PFCN with high-resolution ultrasound (HRUS) and to test this technique in our clinical routine. The study consisted of two parts. In the first part, HRUS-guided perineural ink injections along the course of the PFCN were performed at the posterior aspect of the thigh in 26 lower limbs of 14 fresh non-embalmed cadavers. Subsequent dissection confirmed correct identification of the nerve. In the second part, patients with a suspected PFCN neuropathy were examined and a selective HRUS-guided nerve block was performed to verify the suspected diagnosis. The PFCN was correctly identified with HRUS in 96.2% (25/26) of cadavers. Further, six patients with a suspected lesion of the PFCN were examined, and the diagnosis was proven by successful HRUS-guided block in all cases. We confirmed the reliable visualization of the PFCN using HRUS. This offers a new technique for the assessment of the PFCN, which could also be demonstrated with the case series presented.