Cerebrospinal fluid dynamics and hydrocephalus after experimental subarachnoid hemorrhage.

The effects of three sequential injections of cisternal blood on ventricular size, cerebrospinal fluid (CSF) pressure, CSF formation rate, and CSF absorption rate were evaluated in adult rabbits. Autologous blood was injected into the cisterna magna on Days 1, 4, and 8 and ventriculocisternal perfusion was done on Day 15. Control animals received artificial CSF injection at these intervals. For each rabbit, the mean CSF pressure was higher after three injections of blood than before: 13 animals after blood injection had a mean CSF pressure of 15.59 +/- 1.15 cm H2O (mean +/- SE); before blood injection, their pressure had been 11.14 +/- 1.43 cm H2O (all figures are means +/- SE). This is a significant increase in pressure (P less than 0.01, paired t-test). Further, the 13 rabbits with cisternal blood injection had a significantly higher CSF pressure than 5 control animals: 15.59 +/- 1.15 vs. 10.50 +/- 1.06 cm H2O. The animals with cisternal blood injection all developed some degree of hydrocephalus; the ventricle to brain percentage ratio was 9.84 +/- 0.56 in blood-injected animals and 2.38 +/- 0.21 in control animals (P less than 0.01, two-tailed t-test). CSF formation and absorption rates were not significantly different after subarachnoid hemorrhage. The CSF formation rates were 9.85 +/- 1.8 microliter/minute in the experimental group and 9.53 +/- 1.9 microliter/minute in the control group; CSF absorption at the animal's opening pressure was 13.30 +/- 2.06 microliter/minute in the animals with cisternal blood injection and 9.97 +/- 2.4 microliter/minute in the control animals.(ABSTRACT TRUNCATED AT 250 WORDS)