Improvement of Cortical Morphology in Infantile Hydrocephalic Animals after Ventriculoperitoneal Shunt Placement

Abstract

As a sequel to our previous descriptions of the pathological changes induced by hydrocephalus in the infantile cerebral cortex, the study presented here has evaluated the effects of surgical decompression on cortical cytology and cytoarchitecture. Hydrocephalus was induced in 14 kittens by the intracisternal injection of kaolin at 4 to 11 days of age. Nine of these hydrocephalic animals received low-pressure ventriculoperitoneal shunts at 9 to 15 days after kaolin injection; these animals were monitored preoperatively and postoperatively by ultrasound and were killed at various postshunt intervals up to 30 days. Five normal or saline-injected animals served as age-matched controls. At the time of shunt placement, the ventricular index confirmed that all recipient animals had attained moderate or severe degrees of ventriculomegaly. Within 3 days after shunt placement, the size of the lateral ventricles had decreased to control levels and was accompanied by rapid and dramatic improvements in behavior and skull ossification. When the animals were killed, gross inspection revealed that about half of the animals exhibited mild to moderate ventriculomegaly, with cortical mantles 50 to 80% their normal thickness. Tissue from frontal (primary motor), parietal (association), and occipital (primary visual) cortical areas was processed for light microscopic analysis. Pyknotic or dark shrunken neurons, which are found typically in hydrocephalic brains, were observed only occasionally in the cortex of shunted animals. Gliosis and mild edema were prevalent, however, in the periventricular white matter. The laminae of the cerebral cortex could be identified in all shunted animals. In those animals with mild residual ventriculomegaly, the entire cortical mantle was somewhat compressed, as evidenced by an increased packing density of neurons. Furthermore, the somata of some neurons were disoriented. Overall, these results indicate that most of the morphological characteristics of the cerebral cortex are preserved after surgical decompression and suggest that ventriculoperitoneal shunts may prevent neuronal damage and/or promote neuronal repair.

Hydrocephalus and Syringomyelia in a Cat.

“…They reported that the diagnosis was made by ventriculography, but did not mention what occurred in the brain after surgery. Other reports have indicated that reconstitution of the cerebrum after shunting occurs only in the white matter [5,7,14,21,26,27]. In our case, the ventricles did not differ significantly in size at the first and forth MRI scans, but the syrinx was no longer recognizable at the fourth MRI.…”

“…Both hydranencephaly and hydrocephalus have been known to occur concurrently with parvovirus infection [13,15]. On the other hand, experimentally induced hydrocephalus becomes apparent within 1 to 2 weeks of a kaolin injection [5,7,9,10,14,21,26,27] and the central canal dilates within 2 to 6 weeks [9,10]. As regards parvovirus infection, serum IgM and IgG levels have indicated that the infection is established within 3 days to 3 weeks after contact (Unpublished information; Nikken Bio Medical Laboratory Inc., Japan).…”

Acute and Subacute Hydrocephalus in a Rat Neonatal Model: Correlation with Functional Injury of Neurotransmitter Systems

“…Early-onset hydrocephalus often result in permanent deficits in motor and/or mental function with the delay of adequate treatment [1, 2]. There have been many reports of animal models in which the pathological changes of brain were investigated to determine the mechanism of neuronal damages in hydrocephalus.…”

“…There have also been many studies about recovery in the physiological metabolism and morphological structure of neonatal hydrocephalus with shunt placement [2, 8, 9, 11, 12, 13]. The condition of the neonatal brain is very different from that of the adult brain in neuronal development, myelination and cranial vault mechanics with open sutures and fontanel.…”

“…Although neuronal injury in the cerebral cortex was often described [2, 14, 15, 16, 17], the basal ganglia has become a major site of functional research in hydrocephalus. The function of the basal ganglia, in particular the neostriatum, is considered to have a role in the initiation and control of movement [18, 19, 20].…”