Impact of dehydration on functional outcomes in large vessel occlusion stroke

Background Dehydration at stroke onset has been linked to worse outcomes, but its impact in large vessel occlusion (LVO) stroke treated with endovascular thrombectomy (EVT) remains unclear. We evaluated whether dehydration at presentation influences functional recovery in this population. Methods A prospectively maintained registry of adults with anterior circulation LVO (ICA, M1, M2) who achieved successful EVT (mTICI ≥ 2B) between 10/2019 and 12/2021 was analyzed. Dehydration was defined as serum osmolality ≥ 295 mOsm/kg and BUN/Cr ≥ 20. Primary outcomes were NIHSS at 24 h and good functional recovery at 90 days (mRS 0–2 or return to baseline). Multivariable logistic regression adjusted for age, sex, baseline NIHSS, ASPECTS, occlusion site, diuretic use, and pre-stroke mRS. Results Of 206 patients, 31 were dehydrated at presentation. They were older (median 77 vs. 69 years), more often female, and more likely to use diuretics (p ≤ 0.03). Dehydrated patients had higher NIHSS at 24 h (median 14 vs. 10, p = 0.02) and worse 90-day mRS (p = 0.003). Good functional recovery occurred in 30 % of dehydrated vs. 50 % of non-dehydrated patients (p = 0.04). Dehydration independently predicted lower odds of NIHSS improvement at 24 h (aOR 0.37, 95 % CI 0.14–0.98, p = 0.04), but not worse recovery at 90 days. Conclusion Dehydration at presentation is associated with worse early neurological improvement and potentially poorer functional outcomes after EVT for LVO stroke. These findings highlight the importance of recognizing hydration status in this patient population and the need for future studies to confirm these findings and assess potential interventions.