Spinal cerebrospinal fluid flow is increased in rats with elevated intracranial pressure 18 hours after cortical ischaemic stroke

Abstract

Background A dramatic oedema-independent intracranial pressure (ICP) rise occurs 24 hours post-stroke in rats and may explain infarct expansion. Underlying mechanisms of this rise are unknown but evidence suggests cerebrospinal fluid (CSF) dynamics are involved. Methods We investigated how CSF flow changes post-stroke and how this relates to ICP by infusing CSF tracer into the lateral ventricles of rats and assessing transport time and total tracer transport to the spinal subarachnoid space over a 90 minute period. Results Stroke animals with ICP rise had faster tracer transit when compared with stroke animals without ICP rise (27.6 ± 4, n = 6, vs 48.6 ± 4.5 mins, n = 6) or animals subjected to a sham procedure (47.9 ± 4 mins, n = 8), F(2,17) = 0.1, p≤0.01. There was a correlation between tracer transit time and ΔICP (R = -0.52, p=0.02) and infarct volume (R = -0.6, p=0.04). There was no difference in total tracer observed. Conclusions Faster tracer transit in stroke animals may be explained by impairment of other CSF outflow pathways, whereby, spinal drainage acts as a compensatory mechanism. Investigation into the disruption of other CSF drainage routes post-stroke may offer insight into the underlying mechanisms of infarct expansion post-stroke.