ABSTRACT
BACKGROUND: Neuroplastic changes in nociceptive pathways contribute to severity of symptoms in knee osteoarthritis (KOA). A new look at neuroplastic changes management includes modulation of the primary motor cortex by transcranial direct current stimulation (tDCS). OBJECTIVES: We investigated whether tDCS combined with intramuscular electrical stimulation (EIMS) would be more efficacious than a sham (s) intervention (s-tDCS/s-EIMS) or a single active(a)-tDCS/s-EIMS intervention and/or s-tDCS/a-EIMS in the following domains: pain measures (visual analog scale [VAS] score and descending pain modulatory system [DPMS], and outcomes, and analgesic use, disability, and pain pressure threshold (PPT) for secondary outcomes. REGISTRATION: The trial is registered in Clinicaltrials.gov: NCT01747070. METHODS: Sixty women with KOA, aged 50-75 years old, randomly received five sessions of one of the four interventions (a-tDCS/a-EIMS, s-tDCS/s-EIMS, a-tDCS/s-EIMS, and s-tDCS/a-EIMS). tDCS was applied over the primary motor cortex (M1), for 30 minutes at 2 mA and the EIMS paraspinal of L1-S2. RESULTS: A generalized estimating equation model revealed the main effect of the a-tDCS/a-EIMS in the VAS pain scores at end treatment compared with the other three groups (P<0.0001). There existed a significant effect of time and a significant interaction between group and time (P<0.01 for both). The delta-(Δ) pain score on VAS in the a-tDCS/a-EIMS group was -3.59, 95% CI: -4.10 to -2.63. The (Δ) pain scores on VAS in the other three groups were: a-tDCS/s-EIMS=-2.13, 95% CI: -2.48 to -1.64; s-tDCS/a-EIMS=-2.25, 95% CI: -2.59 to -1.68; s-tDCS/s-EIMS MR =-1.77, 95% CI: -2.08 to -1.38. The a-tDCS/a-EIMS led to better effect in DPMS, PPT, analgesic use, and disability related to pain. CONCLUSION: This study provides additional evidence regarding additive clinical effects to improve pain measures and descending pain inhibitory controls when the neuromodulation of the primary motor cortex with tDCS is combined with a bottom-up modulation with EIMS in KOA. Also, it improved the ability to walk due to reduced pain and reduced analgesic use.
ABSTRACT
OBJECTIVE: 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. DESIGN: Randomized clinical trial. SUBJECTS AND METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.
