Progress in Neurology — 1929

Abstract

PROGRESS in neurology in the year 1928 consisted largely in advances all along the line; that is to say, in the accumulation of data regarding the nervous diseases and in an increase of precision in the methods used for study. No entirely new diagnostic or therapeutic innovation has been made in this year. THE CEREBROSPINAL FLUID: Hubert S. Howe19, dealing with the mechanism for the maintenance of intracranial pressure takes the following position: The cerebrospinal fluid is secreted mainly through the choroid plexus and from the perivaseular channels of the brain which communicate with the sub-arachnoid space. The absorption of cerebral spinal fluid occurs through the difference between the osmotic pressure of the venous blood channels and the cerebrospinal fluid. The normal pressure of the spinal fluid, which is sufficient to distend the spinal dura moderately, is roughly equal to the venous pressure, while the normal cerebral arterial pressure is about six times the venous pressure. An increase in the intracranial pressure, caused by augmentation of the amount of fluid in the subarachnoid space causes a compensating rise in the venous pressure and this in turn creates a rise in the general arterial pressure. That is to say, when there is intracranial pressure, the general arterial pressure rises, probably as a late factor and not as an early diagnostic factor.H. G. Wolff and H. S. Forbes54 studied the pial circulation during changes in intracranial pressure. They find that the rate of blood flow through the cerebral vessels depends on the relationship of the intracranial venous pressure to the intracranial arterial pressure. When the intracranial pressure is raised to a great height, the blood flow in the pial circulation becomes slow, with dilatation of the veins and arteries.Under extreme pressure the cerebral circulation stops and the arteries become narrow and empty.Moderately increased intracranial pressure does not cause any rise in the systemic arterial pressure.(Thus they agree with the author previously cited.) The rise in pressure of cerebrospinal fluid raises the pressure in the capillaries, in the arterioles, and in the smaller arteries of the pial, at the same time causing dilatation of all these vessels. When the intracranial pressure becomes so great that cerebral circulation begins to fall, then the systemic arterial pressure begins to rise and the circulation in the brain is re-ëstablished. (That is, the rise in *Myerson \p=m-\