Objective: To evaluate the effect of fascia penetration and develop a new technique for lateral femoral cutaneous nerve (LFCN) conduction studies based on the fascia penetration point (PP) identified using ultrasound.
Methods: The fascia PP of the LFCN was localized in 20 healthy subjects, and sensory nerve action potentials (SNAPs) were obtained at four different stimulation points-2 cm proximal to the PP (2PPP), PP, 2 cm distal to the PP (2DPP), and 4 cm distal to the PP (4DPP). We compared the stimulation technique based on the fascia penetration point (STBFP) with the conventional technique.
Results: The SNAP amplitude of the LFCN was significantly higher when stimulation was performed at the PP and 2DPP than at other stimulation points. Using the STBFP, SNAP responses were elicited in 38 of 40 legs, whereas they were elicited in 32 of 40 legs using the conventional technique (p=0.041). STBFP had a comparable SNAP amplitude and slightly delayed negative peak latency compared to the conventional technique. In terms of the time required, the time spent on STBFP showed a more consistent distribution than the time spent on the conventional technique (two-sample Kolmogorov-Smirnov test, p<0.05).
Conclusion: SNAP of the LFCN significantly changed near the fascia PP, and stimulation at PP and at 2DPP provided high amplitudes. STBFP can help increase the response rate and ensure stable and consistent procedure time of the LFCN conduction study.
Keywords: Diagnostic imaging; Electromyography; Femoral nerve; Methods; Neural conduction; Physiology; Ultrasonography.