ABSTRACT NUMBER: ESOC2026A182 DOMAIN-SPECIFIC TRAJECTORIES OF EARLY NEUROLOGICAL DETERIORATION AFTER HEAD-OF-BED POSITIONING IN LVO STROKE

Abstract Background and aims In the ZODIAC trial of patients with large vessel occlusion stroke awaiting thrombectomy, 0° head positioning markedly reduced early neurological deterioration (END) compared with 30°. We aimed to identify which NIHSS domains contributed most to END, and determine when deterioration or improvement occurred. Methods NIHSS domain scores from baseline through 80 minutes were extracted. For each patient and domain, we computed the maximal signed change from baseline and the minute at which it occurred. Domains were collapsed into eight functional groups. Cumulative-link mixed-effects models estimated each collapsed domain’s association with END, reported as odds ratios with 95% confidence intervals. Timing distributions were compared across groups. Results The strongest associations with END were seen in motor (5.80, 2.49–13.49), dysarthria (3.81, 1.05–13.78), visual fields (3.62, 0.97–13.43), gaze (3.31, 0.90–12.12), and sensory (2.79, 0.76–10.25) domains. Neurological deterioration occurred early and was more frequent in the 30° group, typically within 10–30 minutes of randomization, and most often involved motor, language, gaze, and sensory functions. In contrast, the 0° group predominantly showed improvement, especially in the motor and dysarthria domains, later in the observation window. Conclusions END is driven primarily by rapid worsening of the motor domain, usually emerging within 10–30 minutes. Head position strongly shapes these trajectories, with 0° promoting early recovery, while 30° demonstrates early decline across multiple functional systems. These findings offer mechanistic insight into the ZODIAC trial results and reinforce the physiological effect of flat positioning before thrombectomy. Conflict of interest All of authors: nothing to disclose