Smith, Benn E.

ABSTRACT Introduction: There are not uniform standards for nerve conduction testing across the United States. The objective of this study is to present a set of methodologically sound criteria to evaluate the literature for the purpose of identifying high‐quality normative nerve conduction studies (NCS) suitable for widespread use. Methods: The Normative Data Task Force (NDTF) was formed to review published studies on methodological issues related to NCS. A set of criteria was then developed to evaluate the literature. These criteria and their rationale are described. Results: We identified 7 key issues that reflect high quality in NCS. For each issue, specific review criteria were developed. Conclusion: Rigorous criteria enable identification of high‐quality studies dealing with nerve conduction reference values. This represents the first step toward the overarching goal of recommending NCS techniques and reference values for electrodiagnostic medicine. Muscle Nerve 54 : 366–370, 2016

ABSTRACT 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 metrics. 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. Muscle Nerve 54 : 371–377, 2016

ABSTRACTIntroduction: Apart from a case series of 100 subjects in 1996 and several small cohorts, there have been no large retrospective series of cranial nerve XII (CN XII) palsy. Methods: From 1984 to 2014, 245 cases of CN XII palsy were identified via retrospective chart review using historical and exam findings that confirmed the diagnosis. In addition to clinical characteristics, univariate and multivariate models were investigated to predict neoplastic CN XII palsy. Results: Major etiologic categories included: postoperative (29.3%), idiopathic (15.1%), primary neoplastic (14.2%), metastatic malignancy (13.0%), inflammatory (7.3%), radiation (6.1%), and traumatic (4.1%). A multivariate model revealed male gender and a personal history of cancer as predictive of neoplastic CN XII palsy. Conclusions: The most frequent etiologies and disease categories of CN XII palsy were identified, and male gender and personal history of cancer were found to be predictive of a neoplastic cause of CN XII palsy. Muscle Nerve 54: 1050–1054, 2016

ABSTRACT Introduction: The aim of this study was to create reference values for jitter measured with concentric needle electrodes. Methods: Operators worldwide contributed recordings from orbicularis oculi (OO), frontalis (FR), and extensor digitorum (ED) muscles in healthy controls. Criteria for acceptable signal quality were agreed upon in advance. Fifteen or 20 recordings of acceptable quality from each muscle were required for voluntary and electrical stimulation recordings, respectively. Results: Recordings from 59 to 92 subjects were obtained for each muscle and activation type. Outlier limits for mean consecutive difference and individual jitter data for voluntary activation were: OO, 31 and 45 µs; FR, 28 and 38 µs; ED, 30 and 43 µs; and for electrical stimulation they were: OO, 27 and 36 µs; FR, 21 and 28 µs; ED, 24 and 35 µs. Conclusion: Reference jitter values from concentric needle electrode recordings were developed from signals of defined quality while seeking to avoid creating supernormal values. Muscle Nerve 53: 351–362, 2016

ABSTRACTIntroduction: Ten new features of motor unit potential (MUP) morphology and stability are proposed. These new features, along with 8 traditional features, are grouped into 5 aspects: size, shape, global complexity, local complexity, and stability. Methods: We used sequential forward and backward search strategies to select subsets of these 18 features to discriminate accurately between muscles whose MUPs are predominantly neurogenic, myopathic, or normal. Results and Conclusions: Results based on 8102 motor unit potential trains (MUPTs) extracted from 4 different limb muscles (n = 336 total muscles) demonstrate the usefulness of these newly introduced features and support an aspect‐based grouping of MUPT features. Muscle Nerve 49: 680–690, 2014