ABSTRACT NUMBER: ESOC2026A1083 EARLY MOTOR PATHWAY INTEGRITY ASSESSMENT USING TMS-EVOKED MEP IN ACUTE ISCHEMIC STROKE: A PILOT CLINICAL STUDY

Abstract Background and aims Understanding the extent of motor pathway disruption in the acute phase of stroke is vital, yet remains underutilized in bedside assessment.TMS offers a means to probe corticospinal tract integrity, with MEP responses serving as a potential functional biomarker.In this pilot setting, we sought to examine MEP-patterns in stroke patients shortly after onset, and how these compared to healthy individuals. Methods Forty-two volunteers were enrolled, including 18 individuals diagnosed with acute ischemic stroke and 24 controls. Single-pulse-TMS was administered over the primary motor cortex using a figure-8-coil. EMG was recorded from limb muscles contralateral to stimulation. MEPs were considered positive if post-stimulus amplitude exceeded resting baseline by at least 10%. Stimulus intensity was tailored to individual resting motor thresholds. Results MEP responses were identified in 6 of 18 patients with acute ischemic stroke (33.3%), while all 24 healthy-controls exhibited consistent responses. No adverse effects occurred during or after stimulation. Among MEP-positive patients, amplitudes were reduced, latencies were prolonged, and resting EMG values were lower compared to controls. The observed variability highlights impaired corticospinal excitability in the stroke-group. Full quantitative data on MEP amplitude, latency, resting-values, and percentage-increase are provided in the table for both groups. Conclusions These findings suggest that early TMS-based neurophysiological testing is not only safe but may reveal functional preservation in stroke-affected motor systems. With further validation, such methods could inform early rehabilitation strategies and prognostic insight. Conflict of interest Nothing to disclose Table 1 - belongs to Results

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