Abstract
In order to study epispinal circulation one has to release the cerebrospinal fluid pressure by dural opening. “Water-tight spinal window” which the auther had devised made possible the direct observation of epispinal circulation at the various stages of intrathecal pressure(ITP) less than 110 mmHg in adult dogs. The device requires vertebrectomy of the atlas and the axis for the exposure of the dura, attachment of a glass window having two plastic tubes for pressurization and pressure measurement on to the dura and water-tight sealing around the window with cotton pledget, Biobond® and Aron Alpha A®. The ITP is controlled by the hydrostatic infusion of Lactate-Ringer's solution through the plastic tube attached at the window. By this device “water-tight spinal window, ” we found ITP was equal to that of lateral ventricle.
Serial fluorescein angiography was performed at 0.5 seconds interval for 15-25 seconds, just the same time as retrograde injection of 0.5% fluorescein sodium solution into the brachial arteries on both side.
At the level of high cervical cord, unlike the cerebral cortex, microvasculature did not seem to be finely distributed and the fluorescein material only appeared in some of vasculature, not necessarily showing all the vessels in that region. In veins with the diameter of less than 200μ, a laminar flow was observed frequently. Regional circulation time (RCT) was determined by the time between the appearance of the fluorescein material into an artery with the diameter of 100 s and reappearance of the fluorescein in the vein in the same field.
As the results, the author found when ITP was 7-20 mmHg, RCT was 2.4±0.4 seconds and an elevation of ITP leads to a prolongation of RCT. There was no filling of fluorescein material when ITP was over 80 mmHg.
