title: Establishing between-session reliability of TMS-conditioned soleus H-reflexes.
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.
authors.affiliation: Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University,1441 Clifton Road NE, Atlanta, GA 30322 USA.
authors.forename: W A
authors.initials: WA
authors.lastname: Gray
authors.affiliation: Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University,1441 Clifton Road NE, Atlanta, GA 30322 USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Sabatier
authors.affiliation: Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University,1441 Clifton Road NE, Atlanta, GA 30322 USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Kesar
authors.affiliation: Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University,1441 Clifton Road NE, Atlanta, GA 30322 USA. Electronic address: michael.borich@emory.edu.
authors.forename: M R
authors.initials: MR
authors.lastname: Borich
mesh_terms: D000328:Adult; D004576:Electromyography; D006181:H-Reflex; D006801:Humans; D007866:Leg / Q000294:innervation; D009044:Motor Cortex / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation*; D011594:Psychometrics; D015203:Reproducibility of Results; D013116:Spinal Cord / Q000502:physiology*; D013979:Tibial Nerve / Q000502:physiology; D050781:Transcranial Magnetic Stimulation
keywords: Corticospinal excitability; Facilitation; H-reflex; Reliability; TMS; TMS-conditioning