In the following patient, a giant shenoid wing meningioma resulted in occlusion of both supraclinoid ICAs, similar to a Moya-Moya pattern. Therefore, the primary method of reconstitution is via leptomeningeal PCA-MCA (purple arrows) and PCA-ACA (light blue arrows) collaterals, the posterior to anterior pericalossal (yellow) anastomosis, and left more than right middle meningeal artery auto-synangioses with the MCA territory on the left (motor strip, purple oval) and right MMA to left ACA territory as well (white arrows). Notice meningioma tumor blush (orange oval)
Local anesthetics have been shown to produce permanent injury [Rigler et al. Anesth Analg 72: 275, 1991; Drasner et. al. Anesthesiology 75: 713, 1991]. Hypotension occurs in 1/3 of patients, initially due to decreased SVR but in severe cases due to decreased venous return and cardiac output (GREATLY enhanced by hypovolemia). Baby Miller recommends a modest head-down position (5-10 degrees) to increase venous return without altering the spread of anesthetic. Hydration is critical, although in excess can be detrimental. Ephedrine is the first line drug (phenylephrine may decrease cardiac output but is still commonly used by anesthesiologists, may have a role in an add-on drug when ephedrine causes increased HR). 10-15% of patients will experience bradycardia, the treatment of which is volume -> ephedrine -> atropine -> epinephrine as needed.
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