Imaging correlates of successful endoscopic third ventriculostomy

Object. The goal of this study was to determine and compare imaging correla tes in pediatric patients who underwent successful or failed endoscopic thi rd ventriculostomies (ETVs). To this end, the authors measured ventricular size changes and the presence of cerebrospinal fluid (CSF) flow void in bot h groups of children following ETV. Methods. Images obtained in children with hydrocephalus immediately before and at least 30 days after having undergone ETV were reviewed by four indep endent observers (two blinded and two nonblinded). Each observer independen tly measured the frontal and occipital horn ratio ([FOR], a reliable and va lid measure of ventricular size) and provided a subjective assessment of th e presence of a flow void at the ETV site, the degree of periventricular ed ema, and the amount of CSF over the cerebral hemispheres. There were 29 children whose mean age was 6.6 years at the time of ETV and who had a mean postoperative follow-up period lasting 1.6 years. Postoperat ively, the mean reduction in ventricular size (as measured using the FOR) w as 7% (95% confidence interval [CI] 3-11%) in cases that were deemed failur es (eight patients) and 16% (95% CI 12-20%) in clinically successful cases (21 patients). This reduction was significantly greater in cases of clinica l suc cess compared with those that were deemed failures (p = 0.03, t-test) . There were no substantial differences between blinded and nonblinded asse ssments. Flow void was present in 94% of successes and absent in 75% of fai lures (p = 0.01, Fisher's exact test). The other subjective assessments wer e not significantly different between the groups of successes and failures. Conclusions. Ventricular size appears to be somewhat reduced in both groups of patients who underwent clinically successful and failed ETV; however, t he reduction is significantly greater among clinically successful cases. Th e presence of a flow void also appears to correlate with clinical success a nd its absence with clinical failure.