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Deriving reference values in electrodiagnostic medicine
Author(s) -
Campbell William W.,
Robinson Lawrence R.
Publication year - 1993
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880160414
Subject(s) - normality , statistics , standard deviation , nerve conduction , reference values , normal distribution , nerve conduction velocity , mathematics , normal values , medicine
Abstract Traditional methods for determining nerve conduction reference values have usually involved studying a group of normal controls, and determining the mean ± 2 standard deviations (SD) for each parameter. Recent studies suggest other factors should be taken into account. Height has a greater effect on conduction velocity than age or temperature. The common assumption that conduction values follow a normal, bell‐shaped Gaussian distribution appears unwarranted. The curve for some conduction parameters is significantly skewed, making a mean ± 2 SD definition of normality inaccurate to a clinically important degree. In developing and using reference values one should consider height, age, and temperature, and calculate the mean ± 2 SD of the transformed data to remove the effects of skew. Reference values provide only a guide to the probability a given result came from a healthy or diseased individual; one should therefore seek multiple internally consistent abnormalities before diagnosing disease on the basis of electroneurography. © 1993 John Wiley & Sons, Inc.