Production and Distribution of Intracranial and Intraspinal Pressure Changes at Sudden Extradural Fluid Volume Input in Rabbits

Abstract A device is described for sudden application of a mechanical load to the brain in animals by displacing a column of fluid within a plunger system towards its connection with a hole in the skull. Velocity and displacement of the piston, moving the fluid into the skull cavity, were varied in a series of experiments in rabbits. Simultaneous recordings were made of the pressure pulses produced in the fluid near the parietal site of loading of the brain and at several places within the contents of the skull cavity and spinal canal. By adjusting the fluid input to the skull cavity it was possible to produce intracranial pressure pulses predictable with respect to peak amplitude and duration within a range between 0.1 and 4.0 atm. and one and several hundred msec, respectively. The pressure pulses produced extracranially and in the major part of the skull contents were similar. Simultaneous recordings of the pressure course in the vicinity of the cranio‐spinal junction and in the spinal canal revealed however, that peak amplitude and duration of the pressure pulse then decreased continuously at increasing distance from the site of application of the load. No pressvire changes were found to occur caudally to the level of the fifth cervical vertebra. This method seems suitable for studying the effects of controlled and varied sudden mechanical loading of the brain in animals and the relations between subsequent brief intracranial pressure changes and pathological alterations, similar to those occurring in skull trauma.