Establishing between-session reliability of TMS-conditioned soleus H-reflexes

• Type of Material: Article
• Authors: WA Gray, Emory University; Manning Sabatier, Emory University; Trisha M. Kesar, Emory University; Michael R. Borich, Emory University
• Language: English
• Date: 2017-02-15
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2017 Elsevier B.V. All rights reserved.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.neulet.2017.01.032
• Title of Journal or Parent Work: Neuroscience Letters
• ISSN: 0304-3940
• Volume: 640
• Start Page: 47
• End Page: 52
• Grant/Funding Information: MJS is supported by the National Institutes of Health [grant number HD083727-01A] and the National Multiple Sclerosis Society [PP2321].; MRB is supported by the National Institute of Child Health and Human Development [grant number K12HD055931] and was supported by the National Institutes of Health [grant number 5R24HD050821-11].; WAG was supported by a postdoctoral fellowship from the National Institute of Neurological Disorders and Stroke [grant number 1U10NS086607].; TMK is supported by the National Institute of Child Health and Human Development [grant number K01 HD079584].
• Keywords: Neurosciences & Neurology; BRAIN-STIMULATION; HUMANS; TMS; H-reflex; Neurosciences; Reliability; CONTRACTION; TMS-conditioning; Science & Technology; Facilitation; MOTONEURONS; MODULATION; Corticospinal excitability; TRANSCRANIAL MAGNETIC STIMULATION; HARNESSING NEUROPLASTICITY; INHIBITION; CLINICAL-APPLICATIONS; Life Sciences & Biomedicine; SPINAL EXCITABILITY
• Research Categories: Health Sciences, Rehabilitation and Therapy

Abstract

Transcranial magnetic stimulation (TMS) of the primary motor cortex (M1) can be used to evaluate descending corticomotor influences on spinal reflex excitability through modulation of the Hoffman reflex (H-reflex). The purpose of this study was to characterize between-session reliability of cortical, spinal, and cortical-conditioned spinal excitability measures collected from the soleus muscle. Thirteen able-bodied young adult participants were tested over four sessions. Intraclass correlation coefficients were calculated to quantify between-session reliability of active motor threshold (AMT), unconditioned H-reflexes (expressed as a percentage of Mmax), and conditioned H-reflexes using short-latency facilitation (SLF) and long-latency facilitation (LLF). Pearson correlation coefficients were calculated to assess associations between H-reflex facilitation and unconditioned H-reflex amplitude. Between-session reliability for SLF (ICC=0.71) was higher than for LLF (ICC=0.45), was excellent for AMT (ICC=0.95), and was moderate for unconditioned H-reflexes (ICC=0.63). Our results suggest moderate-to-good reliability of SLF and LLF to evaluate cortical influences on spinal reflex excitability across multiple testing sessions in able-bodied individuals.