[Changes in head circumference and ventricular system size after neuro-endoscopic third ventriculostomy in children]

The aim of the study was to compare changes in the head circumference ventricular system size after neuroendoscopic third ventriculostomy with those following shunt implantation in children suffering from chronic hydrocephalus. The data were analysed to establish criteria of success of neuroendoscopic procedures. In the years 1999-2001 neuroendoscopic third ventriculostomy was performed in 59 children at the Neurosurgery Department of the Research Institute of Polish Mothers' Memorial Hospital. However, the sample analysed in the paper consists of 29 children (16 boys, 13 girls aged from 18 days to 18 years, mean age 7.03, SD = 7.11 years) with chronic hydrocephalus successfully treated with neuroendoscopic procedures. The control group consists of 59 children (31 boys, 28 girls) selected out of 80 patients who underwent primary shunt implantation at the same Neurosurgical Department in the years 1992-1994. The control children (aged from 2 weeks to 9 months, mean age 2 months, SD = 1.92 months) did not need shunt revision during the clinical observation period. The ventricular system size was assessed in terms of the Frontal Index, while postoperative changes in the system size were expressed by the ratio of the Final Frontal Index to the Baseline Frontal Index. If the ventricular system size remained the same, the ratio was 1; if its size decreased after surgery, the ratio was less than 1, while any increases in the system size were reflected by a ratio over 1. Moreover, the head circumference (HC) was measured before and after surgery only in infants and neonates with non-communicating hydrocephalus. HC was expressed in centiles using the centile chart developed by Kurniewicz-Witczakowa for various age and sex groups of Polish children. The analysis included also post-surgery changes in HC over the observation period, in terms of the difference between the baseline HC value and HC measurements in relation to the observation period duration. A positive sign of this index evidenced a decrease in the rate of HC enlargement, while a negative sign--an increased rate of HC growth. The mean HC at the end of the observation period was 72.96 centile in the neuroendoscopy group and 52.36 centile in children after shunt implantation. The reduction of head circumference following neuroendoscopic procedures was significantly smaller than that after shunt implantation, as the average decrease in HC after neuroendoscopy was only 0.4 centile as compared to about 18 centiles after shunt implantation. In the neuroendoscopy group a relationship was found between HC and age: in newborns HC was significantly smaller than that in infants (20.25 and 82.55 centiles, respectively). An analysis of HC changes (in centiles) in relation to the time since the surgery in all the children aged under 1 year, successfully treated with neuroendoscopic procedures, indicated no tendency to a steady increase in the rate of HC enlargement, even though in many cases the HC after surgery was larger than that prior to the surgery. As regards changes in the ventricular system size, the average ratio of Final to Baseline Frontal Index was 0.9 in the neuroendoscopy group and 0.5 in the group after shunt implantation. The ventricular system turned out to be significantly larger in infants after neuroendoscopy than in other age groups (the mean Frontal Index values were 0.65 vs. 0.53, respectively). No tendency to constant enlargement of the ventricular system size after neuroendoscopy was found. In children with non-communicating hydrocephalus due to Chiarii II malformation a mild enlargement of the ventricular system was seen after successful neuroscopy (the ratio of the Final to Baseline Frontal Index amounted to 1.3).

The rate of head circumference (HC) enlargement in infants after succeeded neuroendoscopic procedures did not continually increase during the postoperative period, although their HC expressed in centiles could be higher than that before surgery. The average reduction of the ventricular system size was much smaller after neuroendoscopic ventriculostomy than than after shunt implantations. In children with Chiarii II malformation and in infants the ventricle system size may be somewhat increased in comparison to pre-operative levels. However, no tendency to a steady enlargement with time was found either in the HC or in the ventricle system size.