Relationship Between Descending Neural Drives from the Non-Injured Hemisphere and Lower Limb Motor Function and Gait...

BackgroundThe relationship between the functional recovery of patients in the subacute phase of stroke and descending neural drives from the non-injured hemisphere to the paretic lower limb muscles during movement remains unclear. We investigated this relationship in patients with severe paralysis.MethodsTwenty-nine patients with stroke were recruited and categorized into three groups based on paralysis severity. Within 1 month of admission, each patient received 10 min of anodal tDCS applied to the cortical motor areas of the injured or non-injured hemispheres. Each stimulation condition was performed in a random order, one day at a time, with a 7-day washout period. Before and after each stimulation, patients performed multiple voluntary knee extensions on the paretic side 20% of their maximal strength, sustained for 6 s. Coherence analysis of EMG signals from proximal and distal segments of the vastus medialis muscle was conducted to quantify common neural drive from each cortical motor-related area based on coherence variations before and post stimulation in each condition. We investigated the relationship between the excitability of the descending neural pathway from the non-injured hemisphere in the initial phase and motor function recovery at 3 months.ResultsNo significant differences emerged across groups in the change in coherence values when the non-injured hemisphere stimulated. However, within the severe group, an increase in β-band coherence following non-injured hemisphere stimulation correlated with greater recovery of paretic-side muscle strength and trunk function at 3 months.ConclusionOur findings deepen understanding of paralysis pathophysiology based on severity level and may support the development of targeted neuromodulation strategies to enhance motor recovery.