Introduction/Aims: Our electrodiagnostic laboratory uses reference limits (RL) that have been handed down for four decades. With changes in instrumentation and technique, we wish to know if our RL should be modified. It is also useful to have RL based on patient demographics.Methods: Latency and velocity data from motor nerve conduction studies of 740 adult patients studied over an 8 mo period were tabulated. RL were derived using both extrapolated reference value (ERef) and multi-variable extrapolated reference value (MeRef) methods.Results: Distal latency values showed a significant but weak correlation with age and/or height. ERef limits for the median and ulnar nerve latency (3.96 and 3.45 ms, respectively) were very similar to current laboratory limits (3.9 and 3.3 ms, respectively). ERef limits for the tibial and fibular nerve latency (5.1 and 4.95 ms,

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.

Background:Dorsal sural sensory nerve action potential (SNAP) could help diagnose early or subclinical peripheral neuropathy.Objectives:To establish reference data for dorsal sural SNAP amplitude, latency, and velocity in healthy participants.Materials and Methods:A prospective study was conducted in 45 nerves from healthy participants between 18 and 90 years and stratified into three age groups (a = 18–40 years, b = 41–60 years, and c>60 years). StataCorp 12.2 statistical program was used for all statistical analyses. Mean-2 standard deviation was used to generate reference values for the lower limit of amplitude and velocity in each age group. ANOVA with Bonferroni correction was used for intergroup comparisons of amplitude and velocity. Regression analysis was used to compute an equation for the predicted amplitude with age, height, and weight as the covariates.Results:The lower limit for amplitude (uv) in Groups a, b, and c was 2.57, 1.97, and 1.01, respectively. The lower limit for velocity (m/s) was 33.6, 32, and 22.8, respectively. Statistical significance was noted between the amplitudes of participants in Groups b and c (P = 0.039) and a and c (P = 0.001). Similarly, velocity was significantly different between Groups b and c (P = 0.04) and a and c (P = 0.008). Age was the covariate with maximum effect on the dorsal sural amplitude. Gender and side-to-side comparison did not show statistical significance for amplitude and velocity measurements. Linear regression analysis of the transformed amplitude gave the predictive equation as (y) =3.338 + age (−0.0167) + height in meters (−0.209) + weight (0.001).Conclusion:This study provides reference data for dorsal sural SNAP in Indian population stratified by age.

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Context: The medial plantar nerve (MP) sensory nerve action potential (SNAP) has been shown to be a sensitive indicator for detecting a length-dependent axonal peripheral neuropathy. However, literature survey shows paucity of age stratified data. This study was undertaken to obtain age stratified reference data for MP SNAP amplitude and latency. Aim: To establish age-stratified reference data in Indian subjects for the MP SNAP. Study Setting and Design: The study was conducted in the electrodiagnostic laboratory of a tertiary city hospital and is retrospective study. Materials and Methods: A retrospective study was conducted using the nerve conduction study reports of 173 patients with only upper limb symptoms and findings. Patients were between the ages of 18 and 86 years, stratified into six groups, a = 18-30 years, b = 31- 40 years, c = 41-50 years, d = 51- 60 years, e = 61-70 years, f ≥70 years. Statistical Methods: Stata 12.1 statistical program was used. Lower limit of the SNAP amplitude was obtained using mean-2SD of transformed data. Analysis of variance defined the intergroup variability, linear regression and Pearson's correlation assessed the statistical significance. Results: The lower limit of normal MP SNAP amplitude for each age group is as follows: a: 8.7uv b: 7.5uv c: 3.7 uv d: 2.9uv e: 2.0 uv f: 1.4uv. The amplitude difference between the groups b & c, c & d and e and f using analysis of variance with Bonferroni correction and Tukey post-hoc test was not significant, but the other groups showed statistically significant variance. The equation of regression for the predicted amplitude value with age was defined as Y^ = {3.5 + age (-.0233) – 2 (0.389)} 3 . Conclusion: This study provides age stratified reference data for MP SNAP. There is evidence to suggest that MP SNAP amplitude varies with age hence age stratified data should be used to define abnormality.