Fluid-percussion model of mechanical XXXX in the cat.

@entity1545 @entity548 @entity510 @entity75 @entity73 @entity468
Mechanical @entity1545 was produced in 36 @entity468 with a fluid-percussion model in which @entity75 is produced by a single, brief, hydraulically-induced pressure transient that is conducted through the brain. Fluid-percussion injury induce elastic deformation of the brain resembling the @entity75 known to occur following head impact. Physiological responses and pahtological changes following injury were expressed as a function of peak pressure. Macroscopic central nervous system lesions concentrated at the pontomesencephalic junction, cervicomedullary junction, and in the cerebellar tonsils were consistently observed at and above 2.6 atmospheres (atm). At higher levels of injury (greater than or equal to 3.2 atm) there was extensive basal @entity510 . At very high levels of injury (greater than 4.0 atm) hemorrhagic contusions were noted at the cerebral hemisphere impact site. A spectrum of neuronal alterations was identified in the damaged areas. Computer analysis showed correlation of electroencephalographic (EEG) changes with the neuropathological changes, since EEG recovery became severely @entity73 .6 atm. No EEG changes were noted below 1.5 atm. From 1.5 to 2.2 atm there was a physiological response to injury but no significant changes were seen on neuropathological examination. This range of injury should permit further studies of the more subtle changes following mechanical @entity1545 without intraparenchymal @entity548 or @entity510 . The fluid-percussion model relates @entity75 following mechanical loading to a single pressure transient that is easily measured and controlled. Further quantitative investigation into the pathobiology of mechanical @entity1545 following graded @entity75 is thus made possible.
