Threshold of cerebral perfusion pressure as a prognostic factor in hydrocephalus during infancy

An analysis of the intracranial pressure (ICP) was done on 30 hydrocephalic infants using a newly devised computerized analyzing system. As a cerebrovascularly compromised index of the ICP, the transmission ratio of systemic arterial pulse pressure (SABP) to ICP as defined by Ikeyama [eta HB (PP of ICP/PP of SABP)] was used. Cerebral perfusion pressure (CPP) versus eta HB showed significant bilinear relationship. From this correlation the threshold of CPP in relation to ICP level was calculated. A reduction of CPP below this level abruptly reduced the correlation with ICP. Thus, the CPP threshold showed an increase related to age (from 20 mm Hg in preterm babies at birth to 80 mm Hg at 12 months of age) and is correlated with the psychomotor development evaluated 6-36 months after shunting. The abnormal waves that appear when there is a high level of eta HB and that also appear below the threshold level of CPP can be defined as pressure waves, based on the physiological findings. It was shown that in hydrocephalus during infancy, a prolonged ICP below the threshold of CPP is one of the cerebrohemodynamic factors that can adversely affect the outcome of psychomotor development.