Pre- and Postshunting Magnetization Transfer Ratios Are in Accordance with Neurological and Behavioral Changes in Hydrocephalic Immature Rats

Abstract

Hydrocephalus is a common neurological condition in children characterized by an imbalance between the production and absorption of cerebrospinal fluid (CSF), causing abnormal fluid accumulation in the brain cavities. Shunt systems have been used to drain excess CSF and to prevent progressive ventricular enlargement. However, despite improvements in these systems, neurological and structural changes cannot always be reversed. Our aim was to evaluate the magnetization transfer ratio as a biomarker for the effectiveness of a CSF shunt system to treat neurological and behavioral disorders observed in experimental hydrocephalus. Seven-day-old Wistar rats were used in this study. The pups were subjected to hydrocephalus induction via 20% kaolin intracisternal injection. After confirmation of ventriculomegaly by magnetic resonance imaging (MRI), a group of animals underwent placement of a ventriculosubcutaneous shunt (VSS). The reduction in ventricular size in hydrocephalic rats operated with functional VSS was observed as a decrease in ventricular ratio values and preservation of the corpus callosum thickness. Magnetization transfer values were significantly increased and matched to the recovery process of axonal myelination observed based on more-intense blue staining by solochrome cyanin. The histopathological analysis revealed a reduction in reactive astrocytes by means of GFAP immunostaining. The hydrocephalic rats operated with functional VSS also showed significant progress in motor and exploratory activities, similar to the control animals, at the end of the experiment. In conclusion, the VSS system employed 7 days after hydrocephalus induction was able to prevent structural damage and restore the axonal myelination process in periventricular structures by stabilizing and reducing the ventricular enlargement, and the results are in accordance with the magnetization transfer ratio in MRI.