Magnetic resonance imaging of water intoxication. An experimental study in dogs.

Sequential magnetic resonance imaging (MRI) was performed to correlate signs of herniation and increase in local brain tissue water content with continuous changes in vital physiologic parameters during progressive water intoxication in anaesthetized dogs. The intracranial pressure increase ultimately resulted in respiratory and cardiac arrest. MRI concomitantly showed an increase in local brain water content starting and dominating in the cerebral cortex but progressing to all parts of the central nervous system. The late appearance of transtentorial pressure gradients and of brain herniation suggests that development of cerebral edema occurs in at least two stages, an intracellular osmotic edema appearing first, being followed by an ischemic edema related to a progressive decrease in local perfusion pressure.