To begin, place the prepared and anesthetized animal on the operating table for the procedure. Using a cotton swab, apply Betadine to the prepared skin in a spiral motion, starting from the center of the surgical area. Then wipe the area with an alcohol pad.
Using small scissors, make a vertical cut between the corner of the eye and the fold of the ear to expose the superficial fascia and underlying muscle. Then employing sharp forceps and curved scissors, carefully cut through the muscle layer until reaching the skull. Employing forceps cautery tool, clot any emerging blood before widening the window as necessary to ensure a clear route to the skull.
After blotting with cotton swabs to remove excess blood, place the animal supine. Use forceps to retract any skin or tissue and place the Doppler probe into the periorbital window so that it abuts the skull without any skin or muscle obstructing the laser signal. Secure the probe with laboratory tape.
Monitor the relative blood flow readings using the appropriate software. A typical ischemia pattern during distal middle cerebral artery or MCA occlusion surgery was evident as there was a rapid cerebral blood flow drop when the carotid artery was tied in the filament advanced to the MCA osteo, followed by a quick CBF increase indicating reperfusion when the filament was withdrawn and the carotid artery was untied. The tracing during rat and mouse MCAO surgery showed failed ischemia due to a loosened carotid occlusion, indicated by a slow drop in CBF.
