Ryuichi Tsugane

BULK FLOW IN THE CEREBROSPINAL FLUID SYSTEM OF THE DOG

Ventriculo‐cisternal, intracranial subarachnoid‐to‐subarachnoid space and spinal subarachnoid space perfusions were carried out on dogs. The perfusate contained inulin as a tracer and the design of these experiments was based upon the concept that inulin leaves cerebro‐spinal fluid (CSF) compartments only by means of bulk absorption, and that actual diffusion and active transport of inulin is negligibly small. Inulin was removed from different CSF spaces by bulk absorption at rates which varied linearly with hydrostatic pressure. The rate of formation of CSF is equal to inulin clearance plus the difference between outflow and inflow rates. The total CSF formation in dogs weighing 12 to 17 kg was measured as 0.065 ml/min, and 58.5 per cent of this amount was found to come from extraventricular CSF space. The rates are independent of hydrostatic pressure in the range studied.

Growing Skull Fractures of Childhood

Four cases of growing skull fracture are presented. Pneumoencephalography done on these cases showed a moderate to extensive degree of focal ventricular dilatation beneath the skull defect. An important factor, heretofore overlooked in explaining this focal ventricular enlargement, is our hypothesis that the force exerted on the particular area of the ventricular wall represents a pulsatile CSF movement damped in the region which is liable to yield to this compression wave in the absence of covering resistant dura mater. Because of the importance of early diagnosis in order to avoid possible delayed neurologic complications such as convulsive disorders, it is advisable to carry on repeated radiological examinations of the skull following fracture in this particular age group until the fracture heals by the progressive apposition of the bone on either side of the fractured line.