Mechanical properties of brain tissue related to oedema development in rabbits

We studied the mechanical properties of the brain in anaesthetized rabbits by application of a standard external load to the exposed cerebral surface. The experimental model used allows one to eliminate potential circulatory factors. Brain oedema was produced by repeated episodes of ischaemia secondary to a decrease of the arterial blood pressure to zero. The development of brain oedema was assessed by an increase of the cerebral water content. In the course brain oedema development brain fluidity was found to steadily rise, while the brain compliance and the index of hysteresis decreased from the control value found at the onset of the experiment. Most important both, brain compliance and the index of hysteresis were already markedly elevated prior to the manifestation of brain oedema.