BLOOD PRESSURE AND CEREBRAL BLOOD FLOW.

Systemic blood pressure has assumed an identity of its own with a rigid norm, deviation from which causes dismay to the patient and his advisers. The opportunity for hypotensive treatment has enhanced the emotional response of the profession to a raised blood pressure. There are, however, wide variations in blood pressure in any subject, and a wider justifiable range within the community. Emphasis is now more properly placed upon blood flow, and blood pressure which depends upon many factors is itself one of the factors maintaining flow. This underlies the present dynamic attitude to the understanding of the cerebrovascular disturbances, and has offered an explanation of many of the minor and transient forms which these disturbances present.