NEUROIMAGING measures, specifically lower white matter hyperintensities and larger ipsilesional thalamus volume, are associated with greater improvements in arm function in stroke patients undergoing vagus nerve stimulation (VNS) therapy.
This study examined the relationship between neuroimaging and clinical measures and motor recovery outcomes in stroke patients participating in a phase III clinical trial of VNS paired with rehabilitation therapy. VNS has demonstrated efficacy in improving arm impairment compared to rehabilitation alone, yet patient responses vary. Researchers hypothesised that neuroimaging metrics might help predict treatment outcomes. Baseline MRI scans and clinical measures from 80 trial participants were analysed to identify associations with changes in the Fugl-Meyer Upper Extremity (FM-UE) score, a standard measure of motor function.
Methods included evaluating regional injury measures (such as corticospinal tract and thalamic injury), global brain health metrics (like white matter hyperintensities), and eight clinical parameters (e.g., age, time since stroke, baseline FM-UE score). Results showed that, across all participants, less white matter hyperintensities at baseline (r = -0.25, p = 0.028) correlated with greater FM-UE score improvements. In the VNS group specifically, greater ipsilesional thalamus volume (r = 0.33, p = 0.046) and fewer white matter hyperintensities (r = -0.37, p = 0.018) were associated with better outcomes. An ANCOVA analysis revealed a significant interaction between white matter hyperintensities and treatment group, with greater baseline white matter damage predicting less benefit from VNS therapy (2.3 FM-UE points decrease per Fazekas scale point, p < 0.05).
These findings underline the potential of neuroimaging to inform clinical practice by identifying patients most likely to benefit from VNS therapy. While regional brain injury measures showed some associations, global brain health metrics, such as white matter hyperintensities, proved more predictive of treatment outcomes. This aligns with the hypothesis that VNS acts through widespread brain mechanisms. Future research should explore additional neuroimaging markers and refine personalised approaches to stroke rehabilitation, potentially tailoring therapy based on individual brain health profiles.
Katrina Thornber, EMJ
Reference
Schwarz A et al. Association that Neuroimaging and Clinical Measures Have with Change in Arm Impairment in a Phase 3 Stroke Recovery Trial. Annals of neurology. 2024;DOI:10.1002/ana.27156.
