The Effect of Electrocautery, Atmospheric Exposure, and Surgica Retraction on the Permeability of the Blood-Brain-Barrier

Alterations in the permeability to Evans-blue dye of the blood-brain-barrier were encountered in a group of squirrel monkeys that were being readied for surgical occlusion of the middle cerebral artery. Extravasation of the dye and grossly visible hemispheric cerebral swelling took place before the artery was clipped. These permeability modifications are felt to be directly related to any of the following factors: (1) use of unipolar electrocautery on the scalp and underlying muscles, (2) exertion of mechanical pressure (i.e., retraction) on the surface of the cerebrum, and (3) exposure of the arachnoid membrane and underlying cerebral cortex to atmospheric conditions for periods of up to five hours. Previously reported experiments involving alterations in the permeability of cerebral vessels should be reevaluated in the light of the findings herein reported. Methods are described to avoid the previously mentioned artefacts on the function of the blood-brain-barrier.