Abstract
The changes of intracranial pressure (ICP) following experimental cerebral compression, which was caused by the infusion of dental impression material into the extradural space, were studied in dogs.
Five of eight animals, in which the brain compression was continued for more than 27 minutes, showed a secondary rise of ICP after removal of the infused material. Such a secondary rise of ICP was not observed in the animals in which the compression was relieved in less than 27 minutes.
Postmortem examination of the brains revealed the following findings: focal lesion of the portion where the adaptor was attached, herniation of the pyriform gyri, narrowing of the ventricles, coalesced hemorrhages in the hypocampus and thalamus, and paling and swelling of the pons and mid-brain. The common microscopic findings were shrinkage of neurons, congestion of blood vessels and perivascular hemorrhages. These findings were obtained in all the cases. In the cases in which the duration of compression was longer and the animals survived a longer period, shrinkage of neurons and peripheral chromatolysis were seen in the medial and lateral reticular substances of the pons and mid-brain. These findings are interpreted as representing an early phase of necrosis.
It is concluded that the secondary rise of ICP is attributed to the brain swelling due to cerebral compression, which causes acidosis and increase of intra- and/or inter-cellular fluid in the brain tissue.
