Non‐paretic leg movements can facilitate cortical drive to the paretic leg in individuals post stroke with severe motor impairment: Implications for motor priming

摘要

Abstract Cross‐education, a phenomenon where unilateral strength (or skill) training enhances strength (or skill) in the contralateral untrained limb, has been well studied in able‐bodied individuals. Cross‐education effect accompanies bilateral changes of corticomotor activity in the motor cortex (M1). Recent reports demonstrated greater cross‐education effect in stroke survivors compared to healthy individuals, however, corticomotor responses to cross‐education in stroke remains unclear. This study aimed to determine the effects of non‐paretic leg movements on corticomotor excitability (CME) and reaction time of the paretic leg in severely impaired stroke survivors. Seventeen post stroke individuals with severe leg motor impairment (Fugl‐Meyer lower extremity score less than 21 and absence of motor evoked potential in the paretic leg) performed three 20‐min motor trainings using their non‐paretic ankle: skill (targeted dynamic movements), strength (isometric resistance) and sham (sub‐threshold electrical nerve stimulation). During training, verbal instructions were given to the participants to limit their movement to the non‐paretic leg and this was confirmed with visual observation of the paretic leg. Transcranial magnetic stimulation measured CME of the contralateral pathways from the non‐lesioned M1 to the non‐paretic tibialis anterior (TA) muscle, ipsilateral pathways to the paretic TA and transcallosal inhibition (TCI) from the non‐lesioned to lesioned M1. Paretic ankle reaction time was measured using a reaction time paradigm. All outcomes were measured before, immediately post, 30‐min post and 60‐min post priming. CME of the non‐paretic TA increased after skill (.08?±?.10?mV) and strength (.06?±?.05?mV) training (p?