Cerebrospinal fluid pressure in 10-day-old rats with congenital hydrocephalus.

Rats from the H-Tx strain develop hydrocephalus through a developmental obstruction of the cerebral aqueduct. The progressive ventriculomegally is accompanied by thinning of the cerebral cortex which is already present 10 days after birth. However, a previous study found that the CSF pressure was not significantly raised until 21 days after birth. New experiments have now been performed over a 90 min. period using control and hydrocephalic 10-day-old rats under light pentobarbitone anaesthesia, in order to study the level, time-course and morphology of the resting intraventricular pressure. The mean pressure and its fluctuations were calculated for each minute. Control rats had a mean pressure of 19.3 +/- 1.23 (SEM) mm H2O (n = 9, range: 13.6-24.7) and in hydrocephalic rats, pressure was significantly higher at 23.5 +/- 1.13 mm H2O (n = 9, range: 18.1-28.3). There was no consistent trend with time and no significant difference between groups in pressure fluctuations, but at least two of the hydrocephalic rats showed episodic waves similar to "B"-waves in humans.