Early microvascular cerebral blood flow response to head-of-bed elevation is related to outcome in acute ischemic stroke

Background and aims: Previously, microvascular cerebral blood flow (CBF) response to a mild head-of-bed (HOB) elevation has been shown to be altered in acute ischemic stroke (AIS) by diffuse correlation spectroscopy (DCS). We have hypothesized that early CBF response is related to the functional outcome. Methods: Patients with a non-lacunar AIS in the anterior circulation were monitored by DCS to measure relative CBF (ΔrCBF) on the frontal lobes bilaterally during a 0°–30° HOB elevation at early (≤ 12) or late (> 12) hours from symptom onset. National Institutes of Health Stroke Scale (NIHSS) scores were recorded at baseline at 24 and at 48 h. Functional outcome was measured by the modified Rankin Scale (mRS) at 3 months. Results: Thirty-eight (n = 38) AIS patients [baseline NIHSS = 19 (interquartile range: 16, 21)] were studied. ΔrCBF decreased similarly in both hemispheres (p = 0.4) when HOB was elevated and was not associated with baseline and follow-up NIHSS scores or patient demographics. At the early phase (n = 17), a lower or paradoxical ΔrCBF response to HOB elevation was associated with an unfavorable functional outcome (mRS > 2) in the ipsilesional (but not in the contralesional) hemisphere (p = 0.010). ΔrCBF response in the late acute phase was not related to mRS. Conclusions: Early CBF response to mild HOB elevation in the ipsilesional hemisphere is related to functional outcome. Further studies may enable optical monitoring at the bedside to individualize management strategies in the early phase of AIS.