Inter and intra-examiner reliability of nerve conduction measurements in normal subjects (original) (raw)
Related papers
Nerve Conduction Studies as a Measure of Disease Progression: Objectivity or Illusion?
Journal of neuromuscular diseases, 2017
Background. Clinical nerve conduction studies (NCS) are often used as a secondary outcome measure in therapeutic trials, but show a high degree of inter-trial variability even when technical factors known to affect the recorded responses are minimised. This raises the intriguing possibility that some of the observed variability may reflect true changes in nerve activity. Objectives. Our aim was determine how much variability these factors might produce, and how this might affect the results of commonly used neuropathy rating scales. Methods. A standardised protocol was repeated over forty consecutive trials by the same operators in two healthy subjects. The protocol included recordings that shared either a stimulating or a recording electrode position, such that changes due to electrode position could be excluded, and hand temperature was closely controlled. Results. Despite controlling for inter-operator differences, electrode position, and hand temperature, the variability in sensory nerve action potential (SNAP) amplitude was extremely high (Range 23µV, CoV=10.7-18.8). This variability was greater than the change in amplitude needed to move a subject from point 0 to point 4 on the CMT neuropathy rating scale. Neither temperature or electrode position accounted for all of this variability, suggesting that additional as yet unidentified factors are responsible. Conclusion. Even under closely controlled conditions and sophisticated laboratory methods, test-totest variability can be significant. The factors responsible for this variability may be difficult to control, limiting the utility of single nerve recordings as a trial outcome measure.
Clinical Neurophysiology, 2005
Objective: To present criteria for pathophysiological interpretation of motor and sensory nerve conduction studies and for pathophysiological classification of polyneuropathies suggested by a group of European neurophysiologists. Methods: Since 1992 seven neurophysiologists from six European countries have collected random samples of their electrodiagnostic examinations for peer review medical audit in the ESTEEM (European Standardized Telematic tool to Evaluate Electrodiagnostic Methods) project. Based on existing criteria in the literature, the experience with a patient material of 572 peer reviewed electrodiagnostic examinations, and productive discussions between the physicians at workshops, the collaboration has produced a set of criteria now routinely used at the centres involved in the project. Results: The first part of the paper considers pathophysiology of individual nerve segments. For interpretation of motor and sensory nerve conduction studies, figures showing change in amplitude versus change in conduction velocity/distal latency and change in F-wave frequency versus change in F-wave latency are presented. The suggested boundaries delimit areas corresponding to normal, axonal, demyelinated, or neuropathic nerve segments. Criteria for motor conduction block in upper and lower extremities are schematically depicted using the parameters CMAP amplitude and CMAP duration. The second part of the paper suggests criteria for classification of polyneuropathies into axonal, demyelinating, or mixed using the above-mentioned criteria. Conclusions: The suggested criteria are developed during many years of collaboration of different centres and may be useful for standardization in clinical neurophysiology. Significance: Consistent interpretation of nerve conduction studies is an important step in optimising diagnosis and treatment of nerve disorders.
Muscle and Nerve , 2016
Introduction: To address the need for greater standardization within the field of electrodiagnostic medicine, the Normative Data Task Force (NDTF) was formed to identify nerve conduction studies (NCS) in the literature, evaluate them using consensus-based methodological criteria derived by the NDTF, and identify those suitable as a resource for NCS met-rics. Methods: A comprehensive literature search was conducted of published peer-reviewed scientific articles for 11 routinely performed sensory and motor NCS from 1990 to 2012. Results: Over 7,500 articles were found. After review using consensus-based methodological criteria, only 1 study each met all quality criteria for 10 nerves. Conclusion: The NDTF selected only those studies that met all quality criteria and were considered suitable as a clinical resource for NCS metrics. The literature is, however, limited and these findings should be confirmed by larger, multicenter collaborative efforts.
Repeatability of Nerve conduction Measurements using Automation
Journal of Clinical Monitoring and Computing, 2006
Objective. To quantify nerve conduction study (NCS) reproducibility utilizing an automated NCS system (NC-stat Ò , NeuroMetrix, Inc.). Method. Healthy volunteers without neuropathic symptoms participated in the study. Their median, ulnar, peroneal, and tibial nerves were tested twice (7 days apart) by the same technician with an NC-stat Ò instrument. Prefabricated electrode arrays specific to each nerve were used. Both motor responses (compound motor action potential [CMAP] and F-waves-all nerves) and sensory responses (sensory nerve action potentials [SNAP]-median and ulnar nerves only) were recorded following supramaximal stimuli. Automated algorithms determined all NCS parameters: distal motor latency (DML), mean F-wave latency (FWL), distal sensory latency (DSL), CMAP amplitude, and SNAP amplitude. Latency was adjusted for skin temperature deviation from reference. Pearson correlation coefficient (CC), intraclass correlation coefficient (ICC), coefficient of variance (CoV), and relative intertrial variation (RIV) were calculated. Results. Fifteen subjects participated in either upper or lower extremity studies with nine participating in both. With the exception of CMAP amplitude, all parameters had CoV less than 0.06. Upper extremity amplitude parameters had CCs greater than 0.85. CCs for latencies were greater than 0.80 except for the median nerve FWL (CC = 0.69). For lower extremity nerves, ICCs were highest for mean FWL (>0.90), followed by DML (>0.82) and then CMAP (peroneal 0.33, tibial 0.73). The 10th to 90th RIV percentiles were bounded by ±7% for F-wave latencies; ± 9% for all DSLs; and ± 11% for DML (except peroneal at 15%). Conclusions. The reproducibility of NCS parameters obtained with an automated NCS instrument compared favorably with traditional electromyography laboratories. F-wave latencies had the highest repeatability, followed by DML, DSL, SNAP and CMAP amplitude. Given their high reproducibility, automated NCS instrument may encourage wider utilization of NCS in clinical and research applications.
Comparison of expert and algorithm agreement in measurement of nerve conduction study parameters
Biomedical Signal Processing and Control, 2010
In this study, the nerve conduction study (NCS) waveform assignment performance of algorithms used in a commercial electrodiagnostic instrument was compared against three neurophysiology experts for motor, F-wave, and sensory parameters. Assignments were made on a common set of waveforms, thereby eliminating a source of variability present in earlier studies that relied on re-testing patients. The performance of the algorithms was comparable to the experts as quantified by the inter-class correlation coefficient and Bland-Altman analyses. The observed algorithm-expert agreement was higher than previously reported estimates, suggesting that the approach of scoring a common set of waveforms may provide a more accurate measure of algorithm performance.
Reliability of nerve conduction studies among active workers
Muscle & Nerve, 1999
Nerve conduction studies play an important role in clinical practice and research. Given their widespread use, reliability of tests merits careful attention. We assessed interexaminer and intraexaminer reliability of median and ulnar sensory nerve measures of amplitude, onset latency, and peak latency. In a two-phase cross-sectional study, two examiners tested 158 workers. Reliability was assessed with intraclass correlations (ICC) and kappa statistics. Median nerve measures were more reliable (ICC range, 0.76 to 0.92) than ulnar measures (ICC range, 0.22 to 0.85). Ulnar-onset latencies had the worst reliability. The median-ulnar peak latency difference was a particularly stable measure (ICC range, 0.79 to 0.92). The median-ulnar peak latency difference had high interexaminer reliability (κ range, 0.71 to 0.79) for normal tests defined by cut points of 0.8 ms and 0.5 ms. Intraexaminer reliability was higher with the 0.8-ms cut point (κ = 0.90 and κ = 0.85 for examiners 1 and 2, respectively). Rather than absolute cut points to describe normality, a more rational interpretation of results can be made with ordered categories or continuous measures. © 1999 John Wiley & Sons, Inc. Muscle Nerve 22: 1372–1379, 1999.
Clinical Neurophysiology, 2006
Objective: To evaluate the possible influence of peer review medical audit on experienced physicians' pathophysiological interpretation of nerve conduction studies in polyneuropathy patients. Methods: Since 1992, 7 European neurophysiologists have collected samples of their patient examinations for regular review where the physicians interpret each other's cases electronically and subsequently discuss them at regular workshop meetings (i.e. a form of medical audit). Two sets of 100 polyneuropathy examinations interpreted with an interval of 4-6 years were selected. The sets contained 1456 and 1719 nerve conduction studies, each given a pathophysiological test conclusion by each individual physician. Inter-physician agreement on interpretation of demyelination and axonal loss of the nerve, as well as neuropathic and unspecific findings, was estimated using kappa statistics. Results: Increased agreement from set 1 to set 2 was found on interpretation of demyelination of the nerve (set 1: kZ0.22; set 2: kZ0.45), and of neuropathic (set 1: kZ0.46; set 2: kZ0.64) and unspecific findings (set 1: kZ0.35; set 2: kZ0.54). No changes were found on interpretation of axonal loss (set 1: kZ0.26; set 2: kZ0.31) and normal findings (set 1 and set 2: kZ0.90). Conclusions: Participation in regular peer review medical audit resulted in increased agreement on interpretation of nerve conduction studies for 6 of the 7 participants. The study further highlights the need for better definition of criteria for identification of demyelinating, and in particular, axonal peripheral neuropathies. Significance: International collaboration involving peer review medical audit may contribute to development of practice guidelines and, in turn, to increased quality of electrodiagnostic medicine.
Reliability of clinical nerve function assessment in peripheral neuropathies
Leprosy review, 2014
Sensory and/or motor nerve function impairment as a consequence of neuropathy is often assessed using electroneurophysiological tests. However, in low-resource countries where the required equipment is rarely available, manual muscle strength testing (MMST) and monofilament testing (MFT) offer very reliable alternatives. In six leprosy programmes in four Asian countries, a multi-centre randomised clinical trial (RCT) was carried out to assess the effect of corticosteroids on neuropathy in leprosy-affected people. The sensory and motor nerve function was tested using MMST and MFT, including new test sites for the sural and radial cutaneous nerves (MFT) and the posterior tibial and common peroneal nerves (MMST). The reliability studies of the MMST and MFT tests of the TENLEP (Treatment of Early Neuropathy in LEProsy) trials are presented here. Two assessors in each centre independently used the MFT and MMST in 30 leprosy-affected people. Reliability is good to very good for MFT in nea...
Measurement of nerve conduction study in a sample of healthy Iraqi: Normative data
Electrophysiological study (nerve conduction study " NCS ") is useful adjunct test to the medical history and clinical examination in the diagnosis of such complication, early detection and differentiation of type of peripheral neuropathy. The aims of this study are designed to Decide the most necessary parameters of NCS of healthy subjects to establish the normal electrophysiological values of the common nerves in upper and lower limb .The present study was carried out at the neurophysiology unit in Al-yarmouk Teaching Hospital.The study group consists of eighty six (86) healthy volunteers (45 males and 41 females). The age of this group ranged between 20 to 75 years with a mean (52.48 ±10.63) years. All subjects were healthy and symptoms free, with no history of systemic and neurological diseases. No history of alcohol abuse or drug intake. They compromised normal relatives, medical staff, students and workers. All of 86 subjects that were included in this study were informed about the aim and technique of the study and their acceptance was taken. Each subject was submitted to medical history and electrophysiological tests (NCS) of the two limbs i.e. the upper and the lower. These tests include Sensory nerve conducting study (SNCS) for Median, Ulner and Sural nerves and Motor nerve conducting study (MNCS) for Median, Ulnar, Fibular (Common peroneal), and tibialnerves. The results showed data were processing separately between males and females with mean accompanying with standard deviation for sensory and motor of median, ulnar sural, common peroneal and tibialnerves. Conclusion: The study will be helpful normative parameters of the common tested nerves of the upper and lower limbs were established for the EMG laboratory in our region.