Licence: In copyright
Credit: Arterial hypertonus, sclerosis and blood-pressure. Source: Wellcome Collection.
Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.
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![SCHOO! CLINICAL APPLIdATION . , „ ^ action upon the pituitary, the cerebral analogue of the adrenal; and the cerel)ral circulation is also, (jutside tlie systemic vasomotor system. The conditions wliicli regulate the activity of the pituitary are as little known as those which determine adrenal activity, but it will not be questioned that Haynes' findings are highly suggestive, and suggest subtleties the investigation of which by physiologists might place most valuable measures in the hands of the clinician. Garnier and Thaon have shown that wlien the vagus is cut the pituitary hypophysis has no effect on the blood-pressure. Clinical Application.—It appears from the foregoing that we are abundantly justified in requisitioning cerebral vessel contraction for clinical purposes, and also in holding that the state of the systemic is in some cases a guide to the state of the cerebral vessels, while in other cases it is not a guide. This being the position, it must be further assumed that the vessels in localised o,nd circumscribed areas of brain can be affected without a like and simultaneous involvement of the entire intracranial circulation. Such a proposition is, in view of the anatomical and physical conditions, incapable of ocular demonstration; buc even here we are not without cognate facts which warrant us in accepting it. It is well known that local vessel constriction is an accompfiniment of migraine, and that relief of suffering accompanies vessel relaxation. It has also been noted that spasm of retinal vessels may occur in Eaynaud's disease. Dr. Lundie recorded a case recently in which he contended that temporary blindness was due to spasm of retinal vessels, the blindness passing off when the constricted vessels relaxed. In the argument in support of his contention regarding tlie cause of the temporary blindness in his own patient, he refers to other observations of the same kind in which l)oth generalised and limited constriction of retinal vessels had been noted. When the constriction is limited, the area of blindness corresponds with the position of the constricted l)ranc]i. Lundie's interesting paper brings together sufficient facts to prove that temporary constriction may occur in all or some of the branches of the retinal artery, and my contention has been that corresponding processes occur in the l)rain. That](https://iiif.wellcomecollection.org/image/b21516674_0193.jp2/full/800%2C/0/default.jpg)
