[CSF dynamics following shunt operation, with special reference to the diurnal changes of CSF circulation]

The purpose of this study is to study the pathophysiology of the cerebrospinal fluid (CSF) formation and circulation after a ventriculoperitoneal shunt operation. With the CSF flowmeter we developed, the CSF flow rate in the shunt tube has been measured non-traumatically over a 24-hour period in six patients. These include both communicating and noncommunicating hydrocephalus patients with ages ranging from 20 to 70. There were three cases of ruptured intracranial aneurysm, one cerebral contusion, one hypertensive brain stem hemorrhage and one occlusion of the aqueduct sylvius. Intraventricular pressure was continuously recorded for 24 hours prior to the shunt operation in each case, and the pressure changes were compared with the measured CSF flow rates in the shunt tube. The flow rate fluctuated between 0.05 ml/min and 1.2 ml/min with the supine position and high flow rates were detected in the early morning. Each case showed its own rhythm of CSF flow fluctuation during a 24-hour period, and the changes were compatible with the intraventricular pressure. It is suggested that there may be a relationship between these changes and an increased cerebral blood volume during the REM sleep stage.