Davide Giannuzzi

Background: Alterations in corticospinal and intracortical excitability are frequently observed following a stroke. Cortical plasticity and reorganization after stroke can be assessed using transcranial magnetic stimulation (TMS) measures. These include Motor Threshold (MT) and Motor Evoked Potential (MEP) obtained from single-pulse TMS and Short-Interval Intracortical inhibition (SICI) and Intracortical Facilitation (ICF) obtained from Paired-Pulse Paradigms (ppTMS). Objective: This narrative review aims to provide an update on the most relevant studies and clinically interpret alterations in excitability measures from ppTMS studies following a stroke, focusing on the effects of stroke on MT, MEP, SICI, and ICF in both hemispheres. Additionally, we analyze intracortical disinhibition across different stages of recovery and the implications for inter-hemispheric competition during recovery. Literature search strategy: Studies investigating corticospinal excitability and intracortical inhibition/facilitation after stroke using ppTMS paradigms were reviewed. The main neurophysiological outcomes included MT, MEP amplitude, SICI, and ICF, comparing the affected and unaffected hemispheres and healthy controls. Results: The reviewed literature consistently demonstrates reduced corticospinal excitability in the affected hemisphere, characterized by an increased MT and decreased MEP amplitude. Conversely, intracortical inhibitory and facilitatory circuits appear to be altered after stroke. Reduced SICI and modified ICF patterns suggest cortical disinhibition. Conclusions: Assessments based on ppTMS can be considered significant indicators of post-stroke cortical reorganization. Cortical motor inhibition may have an adaptable or stage-specific role, potentially beneficial in the acute and subacute stages, but harmful if it continues beyond the chronic phase.

Background: Spasticity significantly impairs functional recovery after severe acquired brain injury. Current management methods predominantly rely on pharmacological interventions, which can cause substantial side effects or require invasive medical procedures in refractory cases. Focal muscle vibration, a noninvasive technique that applies mechanical vibrations to muscle–tendon units and alters spinal and cortical excitability via proprioceptive pathways, has been effective in reducing spasticity in subjects with stroke. However, there is limited data to support focal muscle vibration as a viable option for improving functional recovery in patients with severe acquired brain injury. Objectives: To evaluate the clinical effects of adding focal muscle vibration to standard physiotherapy compared with standard physiotherapy alone in patients with severe acquired brain injury and spastic hypertonia. Methods: Twenty-four patients were randomly assigned to receive focal muscle vibration in addition to standard care (n = 12) or standard care alone (n = 12) for 3 weeks. Assessments were conducted at baseline, immediately after physiotherapy, and 3 weeks after physiotherapy. The outcomes assessed included the Modified Ashworth Scale, Disability Rating Scale, Modified Barthel Index, and three pain measures. Results: A significant reduction in spasticity was observed in the focal muscle vibration group, as indicated by the Modified Ashworth Scale scores (p = 0.014). Disability Rating Scale scores demonstrated a statistically significant decrease in disability ratings at the end of treatment (p = 0.002) and during the follow-up phase (p = 0.002). Between-group comparisons of change scores revealed a statistically significant improvement in disability ratings in the focal muscle vibration group during the treatment phase (p = 0.011). Significant functional gains were noted on the Disability Rating Scale, which persisted at the follow-up evaluation. Conclusions: Focal muscle vibration reduces muscle spasticity and improves functional status in patients with severe acquired brain injury during inpatient rehabilitation. Future studies with larger sample sizes, blinded assessments, and stratified randomization are needed to verify these findings and develop standardized treatment protocols for this underserved population.