title: Electrical Intramuscular Stimulation in Osteoarthritis Enhances the Inhibitory Systems in Pain Processing at Cortical and Cortical Spinal System.
abstract: To determine if in knee osteoarthritis (KOA), one session of active electrical intramuscular stimulation (a-EIMS) compared with sham causes an effect on the motor cortex excitability parameters [motor evoked potential (MEP; the primary outcome), short intracortical inhibition (SICI), intracortical facilitation (ICF) and cortical silent period (CSP)] and pain measurements [pain pressure threshold (PPT); visual analog scale (VAS) and change in numerical pain scale (NPS0-10) during the conditioned pain modulation (CPM)-task]. This study also set out to determine if serum brain-derived neurotrophic factor (BDNF) mediates the effect of treatment on the cortical spinal system as assessed by MEP and PPT.
  
  
  
  Randomized clinical trial.
  
  
  
  Women with KOA, 50-75-years old received a 30-min session of either sham (n = 13) or a-EIMS (n = 13) with 2 Hz. The pain measures and excitability parameters were measured before and immediately after a-EIMS or sham.
  
  
  
  The a-EIMS group compared with sham decreased the MEP by 31,67% [confidence interval (CI) 95%, 2.34-60.98]. For the secondary outcomes, the a-EIMS reduced the ICF and increased the CSP but not changed the SICI. The a-EIMS improved the pain reported on VAS, the PPT, and the score of the NPS (0-10) during the CPM-task The BDNF was negatively correlated with the PPT (r = -0.56).
  
  
  
  The serum BDNF revealed an inverse relationship with PPT independent of the treatment group. These results suggest that a-EIMS enhanced the corticospinal inhibitory systems in cortical and infracortical pain processing sites most likely by bottom-up regulation mechanisms.
authors.affiliation: Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal Do Rio Grande Do Sul (UFRGS), Porto Alegre, Brazil.|Laboratory of Pain and Neuromodulation at HCPA, Porto Alegre, Brazil.
authors.forename: Maria
authors.initials: M
authors.lastname: da Graca-Tarragó
authors.affiliation: Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal Do Rio Grande Do Sul (UFRGS), Porto Alegre, Brazil.|Laboratory of Pain and Neuromodulation at HCPA, Porto Alegre, Brazil.
authors.forename: Alícia
authors.initials: A
authors.lastname: Deitos
authors.affiliation: Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal Do Rio Grande Do Sul (UFRGS), Porto Alegre, Brazil.|Laboratory of Pain and Neuromodulation at HCPA, Porto Alegre, Brazil.
authors.forename: Aline
authors.initials: A
authors.lastname: Patrícia Brietzke
authors.affiliation: Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal Do Rio Grande Do Sul (UFRGS), Porto Alegre, Brazil.|Pharmacology Department, Instituto De Ciências Básicas Da Saúde, UFRGS, Porto Alegre, Brazil.
authors.forename: Iraci L S
authors.initials: IL
authors.lastname: Torres
authors.affiliation: Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal Do Rio Grande Do Sul (UFRGS), Porto Alegre, Brazil.|Laboratory of Pain and Neuromodulation at HCPA, Porto Alegre, Brazil.|Surgery Department, School of Medicine at UFRGS, Porto Alegre, Brazil.|Anesthesia and Perioperative Pain Medicine at Hospital De Clínicas De Porto Alegre (HCPA), Porto Alegre, Brazil.
authors.forename: Luciana
authors.initials: L
authors.lastname: Cadore Stefani
authors.affiliation: Department of Physical Medicine and Rehabilitation Boston, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
authors.affiliation: Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal Do Rio Grande Do Sul (UFRGS), Porto Alegre, Brazil.|Laboratory of Pain and Neuromodulation at HCPA, Porto Alegre, Brazil.|Surgery Department, School of Medicine at UFRGS, Porto Alegre, Brazil.|Pain and Palliative Care Service at Hospital De Clínicas De Porto Alegre (HCPA), Porto Alegre, Brazil.
authors.forename: Wolnei
authors.initials: W
authors.lastname: Caumo
keywords: Brain-Derived Neurotrophic Factor; Conditioned Pain Modulation; Intramuscular Stimulation; Osteoarthritis; Pain Pressure Threshold; Transcranial Magnetic Stimulation