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

Abstract

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). 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. 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). 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.