Utility of ultrasound-guided near-nerve needle recording for lateral femoral cutaneous sensory nerve conduction study: Does it increase reliability compared with surface recording?

Introduction: The aim of this study was to assess the reliability of a near-nerve needle recording technique in lateral femoral cutaneous nerve (LFCN) sensory nerve conduction studies (NCS). Methods: Bilateral LFCN sensory nerve action potentials (SNAPs) were recorded from 10 healthy volunteers using surface and near-nerve needle recording electrodes. Absolute amplitudes were compared side-to-side in each subject and between the 2 techniques. Results: Near-nerve needle electrode recording amplitude was significantly higher when compared with surface electrode recording (surface 9 μV, needle 58 μV; P < 0.0001), whereas side-to-side variability did not differ (surface 37%, needle 37%; P = 0.94). Conclusions: We propose that near-nerve needle recording is a simple technique to employ for clinicians with experience in ultrasound-guided needle placement, especially when evaluation is critical and responses are difficult to obtain. However, given the degree of side-to-side variability in healthy subjects, we recommend caution when interpreting side-to-side differences.