Deciphering Crossed Cerebellar Diaschisis in Patients with Large-Vessel Occlusion Acute Ischemic Stroke using BOLD Cerebrovascular Reactivity.

Crossed cerebellar diaschisis (CCD) is characterized by reduced perfusion and metabolism in the cerebellar hemisphere contralateral to a supratentorial lesion. In large-vessel occlusion acute ischemic stroke (LVO-AIS), CCD may result from hemodynamic impairment, structural injury, or both. From a blood-oxygenation-level-dependent cerebrovascular reactivity (BOLD-CVR) imaging database, we identified patients with anterior-circulation LVO-AIS who underwent BOLD-CVR MRI within 7 days of symptom onset. Patients were stratified into those with persistent occlusion (non-endovascular thrombectomy, non-EVT) and those imaged after successful reperfusion (EVT). CCD was defined by a cerebellar asymmetry index > 12%. Associations between CCD and imaging markers of structural injury (infarct lesion volume) and hemodynamic impairment (steal phenomenon volume) as well as associations with 90-day functional outcome were assessed using logistic regression models. Sensitivity analyses included multiple imputation and best-/worst-case scenarios for missing outcomes. Seventy-nine patients were included (23 EVT, 56 non-EVT). CCD was present in 35% of EVT and 41% of non-EVT patients. In non-EVT patients, CCD was independently associated with larger steal phenomenon volumes (adjusted OR 1.99; 95% CI 1.12-3.73), but not infarct size. In EVT patients, CCD was associated with larger infarct lesions (adjusted OR 5.75; 95% CI 1.41-68.92) but not steal phenomenon volume. CCD predicted poorer 90-day outcome only in non-EVT patients in complete-case analysis, but this association was not robust in sensitivity analyses. CCD in acute LVO-AIS reflects different mechanisms depending on occlusion status: hemodynamic impairment under persistent occlusion and structural injury after reperfusion. BOLD-CVR imaging provides insight into CCD, though larger studies are needed to clarify its prognostic value.