Title: Intracranial pressure spikes trigger spreading depolarizations
Journal: Brain, 2021; awab256.
Link: https://academic.oup.com/brain/advance-article/doi/10.1093/brain/awab256/6318773
Comments: Spreading depolarizations (SD) are recurrent waves of neuronal and glial depolarizations that are linked to poor neurologic outcomes after brain injury. Although characteristics and consequences of SDs are well known, the trigger factors of SDs are not very well understood. This paper investigated the role of intracranial pressure (ICP) spikes to trigger SDs using mouse model of filament middle cerebral artery occlusion. Animal study findings were also corroborated with clinical findings of aneurysmal subarachnoid hemorrhage patients.
Laser speckle imaging was used for SD detection coupled with either multispectral reflectance imaging of microvascular oxygen saturation or intravascular partial pressure of oxygen using phosphorescence lifetime microscopy to study the effect of ICP elevation on cerebral blood flow and oxygenation. Using these imaging tools and extracellular potassium concentration measurements, the data revealed that a mild and brief ICP spikes could trigger SDs in mice during focal cerebral ischemia and that the mechanism likely involves worsening supply-demand mismatch and elevations of potassium ion concentration in penumbra. Moreover, irrespective of the magnitude or duration of ICP spikes, SDs appeared to be more likely to originate from the watershed region between the middle, anterior and posterior cerebral arteries. The authors also found higher frequency of ICP spikes (≥30 mmHg) were associated with SD clusters in patients with aneurysmal subarachnoid hemorrhage.
Based on the findings in the paper, the authors suggest minimizing ICP spikes or aggressive prevention and treatment of cerebral edema as measures to improve brain injury outcomes
