TMS-guided physiotherapy reduces pain and induces plasticity in the motor cortex in chronic knee osteoarthritis = Fisioterapia guiada por EMT reduz a dor e induz a plasticidade no cortex motor na osteoartrose cronica do joelho

Background: Knee osteoarthritis (OA) is associated with chronic pain, impaired function and loss of quality of life. Maladaptive plasticity of the motor cortex may be involved limiting the beneficial effects of exercises and other interventions. Neuromodulation with peripheral electrical stimulation guided by TMS mapping may specifically influence those maladaptive plasticity. Objective: To compare the cortical organization and excitability of three muscles (rectus femoris, vastus lateralis and vastus medialis) in a subject with knee OA. Methods: This single case (ABA) study involved a 66 years old woman with knee OA that was considering an arthroplasty. She was assessed for pain (VAS), function (WOMAC, ICOAP), and quadriceps strength once a week, for 10 weeks (A – four weeks assessment; B – two weeks assessment and intervention; A – four weeks assessment). TMS mapping was performed at baseline, after the two-week intervention period and at the end of the study. The baseline examination revealed less volume of the vastus medialis portion of the quadriceps muscle over the primary motor cortex (M1), which determined a peripheral electrical stimulation protocol specifically designed to increase this muscle’s excitability. During the intervention period the participant also performed other specific exercises daily. Results: WOMAC scores, and quadriceps strength were not changed during the study period. However, improvements were seen in the three subscales of the ICOAP following the intervention. This clinical change was associated with an increase in vastus medialis and also vastus lateralis, and a decrease in rectus femoris TMS map volumes, which were maintained until the last evaluation. Conclusion: TMS mapping may guide specific interventions to counteract motor cortex maladaptive plasticity and positively influence pain and function in knee OA.