High-energy phosphate metabolism in a neonatal model of hydrocephalus before and after shunting

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Abstract
The authors studied the effects of hydrocephalus on the high-energy phosphate metabolism of the brain and the impact of ventriculoperitoneal (VP) shunting on these changes in an experimental model of hydrocephalus. High-energy phosphate metabolism was analyzed using in vivo magnetic resonance (MR) imaging and 31P MR spectroscopy. Hydrocephalus was produced in 34 1-week-old kittens by cisternal injection of 0.05 ml of a 25% kaolin solution. Sixteen litter mates were used as controls. A VP shunt with a distal slit valve was implanted in 17 of the 34 hydrocephalic animals 10 days after induction of hydrocephalus. Both MR imaging and 31P MR spectroscopy were obtained 1 and 3 weeks after either kaolin or distilled water injection. Untreated hydrocephalic animals had marked dilatation of the lateral ventricles and periventricular edema. Magnetic resonance spectroscopy showed a significant decrease in the energy index ratio of phosphocreatine (PCR): inorganic phosphate (PI) and an increase in the PI:adenosine triphosphate (ATP) ratio. There was a direct correlation between the decrease in the energy index and ventricular size. Compared with preoperative scans, shunted animals showed no periventricular edema, and the ventricles decreased in size. Also, PCR:PI and PI:ATP ratios were within the levels of controls. This study suggests that neonatal hydrocephalus results in a mild hypoxic/ischemic insult that is treatable by VP shunting.