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Sural/radial nerve amplitude ratio: Reference values in healthy subjects

Authors

  • Berno U. H. Overbeek BSc,

    1. Department of Clinical Neurophysiology, Radboud University Nijmegen Medical Center, P.O. Box 9101, 314, 6500 HB Nijmegen, The Netherlands
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  • Nens van Alfen MD,

    Corresponding author
    1. Department of Clinical Neurophysiology, Radboud University Nijmegen Medical Center, P.O. Box 9101, 314, 6500 HB Nijmegen, The Netherlands
    • Department of Clinical Neurophysiology, Radboud University Nijmegen Medical Center, P.O. Box 9101, 314, 6500 HB Nijmegen, The Netherlands
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  • Jose A. Bor BSc,

    1. Department of Clinical Neurophysiology, Radboud University Nijmegen Medical Center, P.O. Box 9101, 314, 6500 HB Nijmegen, The Netherlands
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  • Machiel J. Zwarts MD, PhD

    1. Department of Clinical Neurophysiology, Radboud University Nijmegen Medical Center, P.O. Box 9101, 314, 6500 HB Nijmegen, The Netherlands
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Abstract

The sural/radial nerve amplitude ratio (SRAR) has been proposed as a sensitive indicator of early-stage axonal polyneuropathy. However, previous studies did not take into account the effect of sex differences or different calculating methods. To obtain reference values and information on the variability of the SRAR in daily practice, we measured amplitudes of sural and superficial radial sensory nerve action potentials in 106 healthy adults, correlated them with epidemiological variables, and calculated the SRAR in several ways. Our results show that the SRAR is a robust measure, independent of age, weight, sex, or method of calculation. The use of bilateral measurements is recommended. The cut-off value (5th percentile) of 0.2 in these healthy subjects is much lower than found previously, especially compared to defining cut-off values by comparing patients with matched controls. Further study is needed to establish the clinical value of this SRAR in the early detection of axonal polyneuropathies. Muscle Nerve, 2005

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