On the regulation of the blood-supply of the brain / by C. S. Roy and C. S. Sherrington.

  • Roy, C. S.
Date:
[1890]
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Credit: On the regulation of the blood-supply of the brain / by C. S. Roy and C. S. Sherrington. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    Measurement of the outflow from one of the cerebral veins' is, in many respects, a considerable improvement on the mode by simple inspection. It is not, however, an easy thing to obtain graphic records of the venous ont-flow from the brain which can be compared with graphic records of the arterial pressure. Owing to this and other inherenb difficulties, the method has, as yet, been but scantily em- ployed. The method used by Francois-Franck^ and Hurthle^ of measur- ing simultaneously the pressures in one of the systemic arteries and in the cerebral end of the cut internal carotid is, we think, by no means free from serious sources of error. The freedom of anastomosis between the vessels forming the circle of Willis cannot, we are of opinion, be assumed to bear any constant relation to the degree of expansion of the vessels supplying the brain-substance. We may also add that we do not gather from the papers in question that adequate precautions were taken to control mistakes arising from changes in the general venous pressure. A fourth method, with which valuable work has been done by Mosso* and others, can be employed in man in cases where there is a defect of some part of the cranial vault. Such apertures being usually closed by a more or less elastic fibrous membrane, it is possible to see, feel, and, if desired, to record graphically the changes in volume of the cranial contents which result from variations in the amount of blood present within the intracranial vessels. Much of our knowledge regarding some of the characteristics of the cerebral circulation has been obtained by this method, which is well fitted to give information with regard to certain points. By it can be learned some of the conditions which cause cerebral congestion, and certain of those which produce cerebral ansemia. We can also study the form of the pulse- curve which results from changes in the pressure of the cerebro-spinal fluid after each heart-beat. We cannot, however, in man measure the pressure either in the systemic arteries or in the veins, so that we cannot tell whether any of the changes in the volume of the brain are or are not due to active changes in the calibre of the cerebral blood- vessels. Nor can we in man make such experiments as involve the section or stimulation of nerves, or observe the effects on the cerebral 1 Gaertner u. Wagner, Wien. Med. Wochensch. 1887. No. 19 and 20. 2 giij. Fonctions Matrices du Cerveau, p. 199. Paris, 1887.* 3 Beitrage zur Haemodynamik. Pjluger's Arch. Bd. xliv, S. 561. * Ueher den Kreislavf d. Blutcs im Menschlichen Geliirn. Leipzig, 1881.
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