Authors:
Christopher T. Plastaras, MD
Christina M. Marciniak, MD
Daniel P. Sipple, DO
Kirsten Gross D’Amore, MD
Cynthia Garvan, PhD
Shehzaad M. Zaman, BS
Affiliations:
From The Rehabilitation Institute of
Chicago and Northwestern Feinberg
School of Medicine, Chicago, Illinois
(CTP, CMM, DPS); Rehab Med Assoc
of the Carolinas, Gaston Health
Resources, Gaston, North Carolina
(KGD); Division of Biostatistics,
University of Florida, College of
Medicine, Gainesville, Florida (CG);
and University of New England
College of Osteopathic Medicine,
Portland, Maine (SMZ).
Correspondence:
All correspondence and requests for
reprints should be addressed to
Christopher Plastaras, MD, Spine and
Sports Rehabilitation Center,
Rehabilitation Institute of Chicago,
1030 N. Clark St, Ste 500, Chicago,
Illinois 60610.
Disclosures:
Presented as a poster at the 2000
Annual Meeting of the Association of
Academic Physiatrists, San Antonio,
TX. No conflicts of interest exist for
any of the authors. This study was
unfunded. There are no disclaimers
or disclosures to be made.
0894-9115/08/8703-0183/0
American Journal of Physical
Medicine & Rehabilitation
Copyright © 2008 by Lippincott
Williams & Wilkins
DOI: 10.1097/PHM.0b013e318164aa04
Effect of Interelectrode Distance on
Sural Nerve Action Potential
Parameters
ABSTRACT
Plastaras CT, Marciniak CM, Sipple DP, D’Amore KG, Garvan C, Zaman SM:
Effect of interelectrode distance on sural nerve action potential parameters. Am J
Phys Med Rehabil 2008;87:183–188.
Objective: To assess differences in amplitude, latency, and duration,
using a 3-cm vs. 4-cm distance between the active and reference elec-
trodes when performing sural nerve conduction studies (NCS). Current
normative data in lower-limb studies are generally based on 3-cm inter-
electrode differences, although 4-cm differences have been reported to
be optimal in the upper limb.
Design: Prospective study comparing the onset latency, peak latency,
duration, and amplitude for the sural sensory nerve action potential
(SNAP) recording at two interelectrode distances in adult volunteers.
Results: Forty-three sural nerves were studied in 22 normal subjects.
Peak latencies recorded with a 4-cm interelectrode distance were signifi-
cantly longer than those recorded with a 3-cm distance (mean difference =
0.06 msecs [SD = 0.09, P = 0.0073]). Duration was significantly longer
(mean difference = 0.03 msecs [SD = 0.07, P = 0.0270]), conduction
velocities were significantly slower (mean difference =-0.7 msecs [SD 1.0,
P = 0.0012]), and onset latency and amplitude were not found to differ
significantly. Average differences in peak latencies, duration, velocity, onset
latency, and amplitude were not correlated with gender, age, or BMI.
Conclusions: In contrast to studies of upper-limb sensory NCS, sural
SNAP parameters obtained with 3- and 4-cm interelectrode distances did
not differ for onset latencies and amplitude. Peak latencies, duration, and
conduction velocity differences, though statistically significant, were of
insufficient magnitude to be clinically meaningful. By using a 4-cm instead
of a 3-cm interelectrode difference for sural nerve studies, the small
prolongation of 0.06 msecs in peak latency and tiny increment of 0.27
V observed in our investigation is unlikely to influence the electrodiag-
nostician’s interpretation of the study.
Key Words: Neural Conduction, Action Potentials, Sural Nerve, Electromyography
March 2008 Effect of Interelectrode Distance on SNAP 183
ORIGINAL RESEARCH ARTICLE
Electromyography