Therapeutic Application of the Alteration of Brain Volume

The brain and spinal cord lie within a space of fixed capacity formed by the closed cranium and the spinal canal. The pressure within the meninges is determined by two factors, the amount of cerebrospinal fluid present and the volume of the brain. The removal of spinal fluid by lumbar puncture is commonly employed in controlling intraspinal pressure in a large number of conditions. If there is a very marked increase in the bulk of the brain, however, the intraspinal pressure may still be high, even after the maximum amount of spinal fluid has been drained off. It is also true that the withdrawal, when the high pressure is due to the increased volume of the brain, may cause a herniation of the base of the brain through the foramen magnum, with resulting collapse and death. The one medical condition in which we are most interested in intracranial pressure is