Shunt treatment at two postnatal ages in hydrocephalic H-Tx rats quantified using MR imaging.

The H-Tx rat has inherited hydrocephalus with an onset in late gestation. Ventriculosubcutaneous shunts were placed in a group of hydrocephalic pups at 3-6 days after birth and in another group at 8-12 days after birth. Multislice proton magnetic resonance (MR) images were taken of shunt-treated pups at 7, 14, or 21 days and of age-matched control and untreated hydrocephalic rats and were subjected to quantitative analysis. Some rats were also imaged before surgery. The volume of the ventricles of untreated hydrocephalic pups increased linearly with age at a rate of 52 microliters/day. The ventricles of shunted pups were reduced from the preshunt condition and were around 20% of age-matched hydrocephalic rats. There was no significant difference in the post-shunt volume between early and late shunt groups. The cortical mantle thickness in both groups of shunt-treated rats was significantly thicker than in untreated pups and close to that of control rats. It is concluded that shunt treatment at both ages reversed the hydrocephalus as measured from MR images, although other evidence from fixed brains suggests that normal morphology may not be achieved at the cellular level even for early shunts.