Intracranial pressure in a case of isolated fourth ventricle.

Since the report by Lundberg (1960), the importance of analysis of pressure waves has been recognized with respect to the intracranial pressure, apart from the level of pressure. More recently, various instruments for measuring the intracranial pressure have been developed and measurements of the extradural and intraventricular pressure have become relatively easy. At the same time, efforts to analyse pressure waves are equally intensive. Since the skull of a newborn or infant is not closed and the intracranial environment is considerably different from those of an adult skull, the pressure waves themselves, rarely behave as classified by Lundberg (1960). Recently during the treatment of hydrocephalus due to intraventricular hemorrhage, in a premature infant, there was a complication causing the so-called isolated fourth ventricle, after ventriculoperitoneal shunt. When the intracranial pressure was measured in this case using our "Fontanometer" (NEC, Sanei Co.), B-waves, so named by Lundberg (1960), were clearly observed. From the results in this case, the mechanism of occurrence of the B-wave will be discussed based on our experience and previously published reports.