REGIONAL BRAIN-TISSUE PRESSURE-GRADIENTS CREATED BY EXPANDING EXTRADURAL TEMPORAL MASS LESION

A porcine model of regional intracranial pressure was used to compare regional brain tissue pressure (RBTP) changes during expansion of an e xtradural temporal mass lesion. Measurements of RBTP were obtained by placing fiberoptic intraparenchymal pressure monitors in the right and left frontal lobes (RF and LF), right and left temporal lobes (RT and LT), midbrain (MB), and cerebellum (CB). During expansion of the righ t temporal mass, significant RBTP gradients developed in a reproducibl e pattern: RT > LF = LT > RF > MB > CB. These gradients appeared early , widened as the volume of the mass increased, and persisted for the e ntire duration of the experiment. The study indicates that RBTP gradie nts develop in the presence of an extradural temporal mass lesion. The highest RBTP was recorded in the ipsilateral temporal lobe, whereas t he next highest was recorded in the contralateral frontal lobe. The RB TP that was measured in either frontal lobe underestimated the tempora l RBTP. These results indicated that if a frontal intraparenchymal pre ssure monitor is used in a patient with temporal lobe pathology, the m onitor should be placed on the contralateral side and a lower threshol d for therapy of increased intracranial pressure should be adopted. Fu rthermore, this study provides further evidence that reliance on a sin gle frontal intraparenchymal pressure monitor may not detect all areas of elevated RBTP.