Sural sensory nerve action potential: A study in healthy Indian subjects

Abstract

Background:The sural sensory nerve action potential (SNAP) is an important electrodiagnostic study for suspected peripheral neuropathies. Incorrect technique and unavailability of reference data can lead to erroneous conclusions.Objectives:To establish reference data for sural SNAP in age-stratified healthy subjects at three sites of stimulation.Materials and Methods:A prospective study was conducted in 146 nerves from healthy subjects aged between 18 years and 90 years, stratified into six age groups (a = 18-30 years, b = 31–40 years, c = 41–50 years, d = 51–60 years, e = 61–70 years, and f >71 years). Sural SNAP was recorded antidromically, stimulating at three sites at distances of 14 cm, 12 cm, and 10 cm from the recording electrode. Mean – 2 standard deviation (SD) of the transformed data was used to generate reference values for amplitudes. Analysis of variance (ANOVA) test was used for inter-group and between three sites comparisons of amplitudes.Results:The lower limits of amplitude at 14 cm were 12.4 μV, 10.4 μV, 6.5 μV, 5.3 μV, 2.9 μV, and 1.9 μV; at 12 cm were 13.5 μV, 13.6 μV, 8.5 μV, 7.8 μV, 3.5 μV, and 2.8 μV; and at 10 cm were 16.3 μV, 16.3 μV, 11.1 μV, 10.0 μV, 4.8 μV, and 3.7 μV for groups a, b, c, d, e, and f, respectively. A statistically significant difference in amplitudes was noted from the three different sites of stimulation (P < 0.001). The amplitude differed significantly above the age of 60 years (P < 0.01) but not between groups e and f (P > 0.05).Conclusion:This study provides reference data for sural SNAP in Indian population at three different sites of stimulation along the calf in six age groups. It also shows significant variation in amplitude from the three different sites of stimulation.

Could Ultrasound-Guided Stimulation of Sural Nerve Affect Nerve Conduction Study?

“…However, the increment of SNAP amplitude in the adjusted method was greater than that reported in a previous study [ 13 ]. In the previous study that tried to find the reference value for sural SNAP parameters with antidromic NCS method, the ratio of the amplitude in different stimulation distances (14 cm and 12 cm) was 1.10 [ 13 ]. Compared to the previous study, the average difference in stimulating distances in the present study was smaller than that in the previous study.…”

“…This was predictable because the average distance from the stimulation site to recording site (EI) was shorter in ultrasound-guided method. However, the increment of SNAP amplitude in the adjusted method was greater than that reported in a previous study [13]. In the previous study that tried to find the reference value for sural SNAP parameters with antidromic NCS method, the ratio of the amplitude in different stimulation distances (14 cm and 12 cm) was 1.10 [13].…”

Neurografie des N. Suralis

“…Bei antidromer Stimulation 10, 12 und 14 cm proximal und einer Ableitung am Außenknöchel wurden mit zunehmen dem Abstand niedrigere Amplituden registriert [25]. In or thodromer Technik nahm die Amplitude des sNAP mit der Distanz von Stimulus-und Ableitort ab [26].…”

Comparison of Sural Nerve Amplitude and Sural/Radial Amplitude Ratio in Electrodiagnosis of patients with neuropathy in Type 2 diabetes

“…The sural/radial nerve amplitude ratio is more sensitive to degradation than any potential for pure sensory nerve function in diabetes or another axonal polyneuropathy [Papanas N et al, 2010;Barnett C et al, 2012]. Although sensory nerve function can be affected by various factors (i.e., BMI, age, and sex), some studies found that the SRAR was more impervious to these factors [Sreenivasan A et al, 2016;Lai Y et al, 2020]. Therefore, the present study has been performed on diabetic patients to compare two electrophysiological methods, including the SRAR and sensory nerve function potential.…”