Brain oscillatory activity as a biomarker of motor recovery in chronic stroke

Abstract

In the present work, we investigated the relationship of oscillatory sensorimotor brain activity to motor recovery. The neurophysiological data of 30 chronic stroke patients with severe upper‐limb paralysis are the basis of the observational study presented here. These patients underwent an intervention including movement training based on combined brain–machine interfaces and physiotherapy of several weeks recorded in a double‐blinded randomized clinical trial. We analyzed the alpha oscillations over the motor cortex of 22 of these patients employing multilevel linear predictive modeling. We identified a significant correlation between the evolution of the alpha desynchronization during rehabilitative intervention and clinical improvement. Moreover, we observed that the initial alpha desynchronization conditions its modulation during intervention: Patients showing a strong alpha desynchronization at the beginning of the training improved if they increased their alpha desynchronization. Patients showing a small alpha desynchronization at initial training stages improved if they decreased it further on both hemispheres. In all patients, a progressive shift of desynchronization toward the ipsilesional hemisphere correlates significantly with clinical improvement regardless of lesion location. The results indicate that initial alpha desynchronization might be key for stratification of patients undergoing BMI interventions and that its interhemispheric balance plays an important role in motor recovery.

Intensity and Dose of Neuromuscular Electrical Stimulation Influence Sensorimotor Cortical Excitability

“…Understanding how NMES parameters, such as intensity and dose, can modulate the excitability of cortical oscillations measured by EEG could be clinically relevant. For instance, NMES could be used for regulating rolandic alpha, since motor recovery has been related to an enhancement of this activity ( Tangwiriyasakul et al, 2014 ; Ray et al, 2020 ), or could be integrated in rehabilitative neural interfaces that are controlled by sensorimotor oscillations.…”

“…The sensorimotor oscillations that mainly comprise the rolandic alpha [(7–13) Hz] and beta [(14–30) Hz] rhythms have been thoroughly used to study cortical involvement during sensorimotor tasks ( Ramos-Murguialday and Birbaumer, 2015 ; López-Larraz et al, 2018 ), being quantified as the event-related (de)synchronization (ERD/ERS) ( Pfurtscheller and Lopes da Silva, 1999 ). Furthermore, it has also been used as a feature for neuromodulation of sensorimotor neural network via proprioception and haptics ( Ray et al, 2020 ; Sebastián-Romagosa et al, 2020 ). To date, only a few studies have reported how oscillatory activity measured with EEG is modulated by NMES ( Vidaurre et al, 2016 , 2019 ; Tu-Chan et al, 2017 ; Corbet et al, 2018 ).…”

Driving Oscillatory Dynamics: Neuromodulation for Recovery After Stroke

“…After stroke, alpha oscillations in human patients are lower in frequency and more synchronised (Petrovic et al, 2017), while desynchronisation of this activity during recovery is associated with improved motor outcome (Westlake et al, 2012;Ray et al, 2020). Alpha oscillatory power has also been shown to be increased in both the unaffected and affected hemispheres in mice 9 days after stroke when compared to controls (Vallone et al, 2016).…”

"Investigating Reliable Recovery Biomarkers of Ischemic Stroke: An Evidence-Based Study"

“…A Stroke Recovery Biomarker (SRB) can be defined as an indicator of disease state that can be used as a measure of underlying molecular or cellular processes that may be difficult to measure directly in humans, and could be used to understand the outcome, or predict the recovery or treatment response [5]. Thus, when dealing with a condition as heterogeneous as stroke, validated biomarkers of recovery could help plan treatments and support efficient allocation of resource while maximizing outcome for the patients [7]. Identification of recovery biomarkers shall assist to advance the practice, rehabilitation and recovery after stroke.…”