TRANSCUTANEOUS VAGUS NERVE STIMULATION IN POST-STROKE COGNITIVE IMPAIRMENT: NEUROPLASTICITY, BDNF, EEG BIOMARKERS, AND A PRECISION REHABILITATION FRAMEWORK

Abstract

Post-stroke cognitive impairment (PSCI) is a major determinant of long-term disability after ischemic stroke and may compromise independence even when motor recovery is relatively favorable. Transcutaneous auricular vagus nerve stimulation (taVNS) is an emerging non-invasive neuromodulation technique that activates vagal afferents projecting to the nucleus tractus solitarius and, through downstream noradrenergic and cholinergic systems, may facilitate experience-dependent plasticity, modulate neuroinflammation, and influence neurotrophic signaling. This narrative review examines the rationale for taVNS in PSCI with a specific focus on the late recovery period, 6-12 months after ischemic stroke. The review integrates direct cognitive evidence with the broader stroke-rehabilitation literature and proposes a multimodal response model combining cognitive outcomes (Montreal Cognitive Assessment and Trail Making Test), neurological deficit, functional independence, electroencephalographic dynamics, and serum brain-derived neurotrophic factor (BDNF). A randomized protocol specifically targeting PSCI has established the feasibility of an 8-week taVNS paradigm, while a 2024 DTI case report described improvement in global cognition and executive performance together with white-matter remodeling. More recent stroke trials and meta-analyses strengthen the biological plausibility of taVNS by demonstrating functional benefit, neurophysiological effects, and treatment-related changes in plasticity biomarkers including BDNF. Nevertheless, direct high-quality evidence for cognitive recovery after stroke remains limited, and stimulation parameters, patient selection, timing, and response biomarkers are not yet standardized. A precision-rehabilitation strategy based on convergent clinical, neuropsychological, EEG, and neurotrophic markers may therefore be a rational next step for clinical research.