engleski

Development of transmantle pressure gradient in cats with acute aqueductal blockage

Introduction: It is not known whether pressure gradient of cerebrospinal fluid (CSF) between brain ventricles and cortical subarachnoid space (transmantle pressure gradient) is necessery for development of hydrocephalus. Some results in patients with noncommunicating hydrocephalus show that such a transmantle pressure gradient is not present. We have investigated in cats with acute occlusion of aqueduct whether transmantle pressure gradient can be developed. Material and Methods: In chloralose anaesthetized cats the aqueduct was totally occluded by implantation of plastic cannula with tip covered by cyanoacrylate glue through a small tunnel in vermis of cerebellum and the CSF pressure recorded in both isolated ventricles and cisterna magna after hermetic reconstruction of skull. The head of cat was fixed in stereotaxic holder and CSF pressures were recorded under control conditions and during infusion of arteficial CSF (aCSF) either in isolated ventricles or in cisterna magna. Results: In control condition without infusion of aCSF, the CSF pressure in isolated ventricles and cisterna magna were not different from control value (about 10 cm H2O) and cerebral transmantle pressure gradient did not develop over 120 min. Infusion of aCSF in cisterna magna at two rates (13 and 52 µ l/min ; n=4) during 5 min increased the CSF pressures in both cisterna magna and isolated ventricles without development of transmantle pressure gradient. However, when aCSF was infused (rates of 13 and 52 µ l/min ; n=4) for 5 min in isolated ventricles the transmantle pressure gradients were developed. Conclusions: Acute occlusion of aqueduct does not cause transmantle pressure gradient during 120 min, while a such gradient develops very soon during infusion of aCSF in isolated ventricles. During infusion of aCSF in cisterna magna the CSF pressure increase in cranial subarachnoid space is immediately transmitted across brain parenchyma to isolated ventricles preventing development of any pressure gradient. Thus, it would appear that transmantle pressure gradient in noncommunicating hydrocephalus can develop only in pathological conditions which cause an acute increase of intraventricular pressure

transmantle pressure gradient ; cats ; acute aqueductal blockage

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