Progressive histomorphometric analysis of the lateral ventricle and cerebral cortex of Wistar rats following kaolin-induced hydrocephalus

Context: Hydrocephalus results in ventriculomegaly following excess production and/or impaired drainage of cerebrospinal fluid. The lateral ventricle (LV) is surrounded by critical structures such as hippocampus and thalamus; its enlargement will adversely impact surrounding brain structures including the cerebral cortex. Aims: This study aims to evaluate the morphometry of cerebral cortex and LV in hydrocephalus over 4 weeks. Settings and Design: Fifty-one 3-week-old rats were divided into Groups A (experimental = 6; control = 5), B (experimental = 8; control = 6), C (experimental = 8; control = 6) and D (experimental = 6; control = 6), sacrificed at the end of 1, 2, 3 and 4 weeks, respectively. Materials and Methods: Experimental rats were induced by injection of 0.04 ml of 200 mg/ml kaolin suspension into the cisterna magnum under ketamine (90 mg/kbw) and diazepam (12.5 mg/kbw) anaesthesia. Rats were sacrificed by cervical dislocation and brain fixed in 10% formal saline. Brain slices at the level of the optic chiasma were processed and stained with haematoxylin and eosin. Statistical Analysis Used: One-way ANOVA and Student–Newman–Keuls test. Results: In experimental rats, lethargy, poor feeding, globular head and exophthalmos were noted. The LV width and the LV/cortical thickness (CT) ratio were significantly increased from the 1st to the 4th post-induction week (P < 0.0001 across the weeks). CT was significantly reduced from the 2nd to 4th week (P < 0.0001 across the weeks). The subcortical white matter (SWM)/CT ratio was significantly reduced from 1st to 3rd week (P < 0.0001 across the weeks), but increased in the 4th week (P = 0.0003). Thinning/detachment of the choroid plexus was noted from the 3rd to the 4th week. Conclusions: White matter/cortical thinning and ventriculomegaly are acute-phase features, although cortical thinning lags behind others. Detachment of the choroid plexus and reversal of SWM thinning are features of chronicity.