Article
Cortical spreading depression dynamics in gyrencephalic cortex are complex
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Published: | June 4, 2012 |
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Objective: Movement patterns of cortical spreading depolarisations (CSDs) on the human cortex are unknown. The aim of this study was to characterize the dynamics of blood volume changes using intrinsic optical signal imaging (IOS) during the induction, propagation and termination of CSDs in a large gyrencephalic brain model.
Methods: Anaesthetized male swine (mean weigh of 30 kg) were craniotomized and monitored over 16–20 hours. A 10-contact electrode strip was placed on the cortex of one hemisphere for ECoG. A video recording was implemented using a camera with an optical bandpass filter (564 nm, FWHM: 15 nm) and a light source. Blood volume changes in relationship to a reference picture over the cortex surface were visualized over time. CSDs were induced by potassium stimulation with a 5 mm diameter blunt in both hemispheres.
Results: In a total of 4 swine, a mean of 4 stimulations per hour were performed for a mean of 20 hours. The success of the CSD induction and propagation distance increased progressively over the monitoring time. Mainly two types of CSDs were identified: a) Biphasic CSDs (hypoperfusion followed by hyperperfusion) that travelled over the gyrus in one direction and were mostly limited by the sulci (>90%), some of them could find a way to come back to the same starting point and create repetitive cycles, and b) CSDs that moved in spirals and produced repetitive hypoperfusions in short time in the area where they appeared.
Conclusions: The CSD movement over the gyrencephalic brain is complex and can be evaluated in-vivo using IOS.
Notes: E.Santos & M. Schoell contributed equally to this work.