Stimulating circle of Willis nerve fibers preserves the diffusion-perfusion mismatch in experimental stroke
Department of Neurology
Animals; Blood Pressure; Cerebrovascular Circulation; Circle of Willis; Disease Models, Animal; Ganglia, Parasympathetic; Infarction, Middle Cerebral Artery; Magnetic Resonance Imaging; Male; Nerve Fibers; Rats; Rats, Sprague-Dawley
Nervous System Diseases | Neurology
BACKGROUND AND PURPOSE: Stimulation of the nerves traversing the ethmoidal foramen (including postsynaptic, parasympathetic projections from the sphenopalatine ganglion [SPG], henceforth referred to as "SPG-stimulation") has been shown to elevate cerebral blood flow (CBF) and to be neuroprotective after permanent, middle cerebral artery occlusion (pMCAO).
METHODS: Employing diffusion (DWI)- and perfusion (PWI) weighted MRI, the effect of SPG-stimulation (started at 60 minutes post-MCAO) on the spatiotemporal evolution of ischemia during and after pMCAO was investigated. In an additional experiment, regional CBF changes were investigated in the nonischemic brain.
RESULTS: In the nonischemic brain, SPG stimulation significantly elevated CBF predominantly within areas supplied by the anterior cerebral artery (by 0.64 mL/g/min relative to baseline). In the ischemic brain, CBF only marginally increased within the penumbra and core (by up to 0.08 and 0.15 mL/g/min relative to prestimulation, respectively). However, the threshold-derived CBF lesion volume did not change significantly. Penumbral apparent diffusion coefficient (ADC)-values improved to almost baseline values and the threshold derived ADC/CBF-mismatch was preserved up to 180 minutes after MCAO. TTC-derived lesion volumes were significantly smaller in stimulated versus nonstimulated animals (120.4+/-74.1 mm(3) versus 239.3+/-68.5 mm(3), respectively).
CONCLUSIONS: This study demonstrates that unilateral SPG-stimulation increases CBF bilaterally within the normal brain, acutely preserves the CBF/ADC mismatch largely independent of altering cerebral blood flow, and reduces infarct size in the rat permanent suture model.
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Citation: Stroke. 2007 Oct;38(10):2779-86. Epub 2007 Aug 30. Link to article on publisher's site