Sural nerve conduction studies using ultrasound-guided needle positioning: Influence of age and recording location.

INTRODUCTION: The aim of this study was to compare results of orthodromic sural nerve conduction studies (NCS) using ultrasound-guided needle positioning (USNP) to those of surface electrode recordings. METHODS: Fifty-one healthy subjects, aged 24-80 years, divided into 5 age groups, were examined. Electrical stimuli were applied behind the lateral malleolus. Sensory nerve action potentials (SNAPs) were recorded 8 and 15 cm proximally with surface and needle electrodes. RESULTS: Mean SNAP amplitudes (surface / needle electrodes) averaged 12.7 (SD 7.6) µV / 40.6 (SD 20.8) µV (P < 0.001) for subjects aged 20-29 years, and 5.0 (SD 2.4) µV / 19.8 (SD 9.8) µV (P < 0.01) for subjects >60 years of age. SNAP amplitudes were smaller at the proximal recording location. CONCLUSIONS: NCS using USNP yield higher amplitude responses than surface electrodes in all age groups at all recording sites. SNAP amplitudes are smaller at proximal recording locations due to sural nerve branching. Muscle Nerve 54: 879-882, 2016.