The rat in experimental obstructive hydrocephalus.

The effects of kaolin-induced hydrocephalus on CSF turnover was studied in rats by ventricular perfusion and the results compared to normals. The mean CSF formation rate measured in 20 normal rats was 2.83 microliter/min. Approximately three weeks after intracisternal kaolin, the mean CSF formation rate in 17 hydrocephalic rats was reduced by 40%. CSF absorption in hydrocephalic and normal rats varied linearly with perfusion pressures between -10 and 10 cm H2O. The response of CSF absorption rate to changes in intracranial pressure was decreased in hydrocephalic rats. Ventriculomegaly of hydrocephalic rats was associated with a dilated spinal cord central canal. This suggests that kaolin hydrocephalus alters CSF pathway in rats in a manner similar to that described previously in cats and dogs. Ventriculomegaly is limited by the supporting structures of the brain because the removal of the calvarium and dura after kaolin results in massive ventriculomegaly.