AUTHOR=Sathialingam Eashani , Cowdrick Kyle R. , Liew Amanda Y. , Fang Zhou , Lee Seung Yup , McCracken Courtney E. , Akbik Feras , Samuels Owen B. , Kandiah Prem , Sadan Ofer , Buckley Erin M. TITLE=Microvascular cerebral blood flow response to intrathecal nicardipine is associated with delayed cerebral ischemia JOURNAL=Frontiers in Neurology VOLUME=Volume 14 - 2023 YEAR=2023 URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1052232 DOI=10.3389/fneur.2023.1052232 ISSN=1664-2295 ABSTRACT=One common complication of non-traumatic subarachnoid hemorrhage is delayed cerebral ischemia. Intrathecal administration of nicardipine, a calcium channel blocker, upon detection of large-artery cerebral vasospasm holds promise as a treatment that reduces the incidence of delayed cerebral ischemia. In this observational study, we prospectively employed a non-invasive optical modality called diffuse correlation spectroscopy to quantify the acute microvascular cerebral blood flow response to intrathecal nicardipine (up to 90 min) in 20 medium-high grade non-traumatic subarachnoid hemorrhage patients. On average, cerebral blood flow increased significantly with time post-administration. However, the cerebral blood flow response was heterogeneous across subjects. A latent class mixture model was able to classify 19/20 patients into two distinct classes of cerebral blood flow response: patients in Class 1 (n=6) showed no significant change in cerebral blood flow, while patients in Class 2 (n=13) showed a pronounced increase in cerebral blood flow in response to nicardipine. The incidence of delayed cerebral ischemia was 5/6 in class 1 and 1/13 in class 2 (p<0.001). These results suggest that the acute (<90 min) DCS-measured CBF response to IT nicardipine is associated with intermediate term (up to 3 weeks) development of delayed cerebral ischemia.