Beyond traditional predictors: the impact of the pulsatility index and cortical subarachnoid space diameter on endoscopic third ventriculostomy success

OBJECTIVE Determining the long-term success of endoscopic third ventriculostomy (ETV) remains challenging. This study aimed to investigate the impact of clinical and radiological factors on ETV success in pediatric patients with hydrocephalus. METHODS The study included patients < 18 years old with hydrocephalus who underwent ETV between March 2014 and May 2021. Data including patient age, gender, history of previous shunt surgery, previous external ventricular drain placement, intraventricular hemorrhage history, and postoperative meningitis were extracted from medical records. Imaging features such as aqueductal stenosis, third ventricle floor bowing, displaced lamina terminalis, pulsatility index (PI), and maximum diameter of the cortical subarachnoid space (CSAS) were recorded for each patient using preoperative CT scans. Two independent neurosurgeons measured the CSAS maximum diameter and the PI. CSAS measurements were obtained on axial slices of the preoperative CT scans, whereas the PI was based on intraoperative third ventricle pulsatility. Patients were followed up for 1 year after surgery, with failure defined as the need for ventriculoperitoneal shunt (VPS) placement or death attributable to hydrocephalus. RESULTS Ninety-eight children with a mean age of 16.39 ± 19.07 months underwent ETV for hydrocephalus. No deaths were recorded, but over 6 months and 1 year of follow-up, 12.2% and 22.4% of patients, respectively, experienced documented ETV failure requiring VPS placement. At the 6-month follow-up, a smaller maximum diameter of the CSAS was significantly associated with ETV failure; multivariate analysis revealed that CSAS maximum diameter was a predictor of 6-month ETV failure. At the 1-year follow-up, a lower PI was significantly associated with ETV failure, and multivariate analysis confirmed the PI as a significant predictor of ETV failure within 1 year after surgery. CSAS and PI measurements were repeated to assess interrater reliability: the intraclass correlation coefficients were 0.897 and 0.669 for CSAS and PI, respectively. CONCLUSIONS This study found that the CSAS maximum diameter and the PI are predictors of ETV failure at 6 months and 1 year, respectively. These findings highlight the importance of considering specific factors such as the CSAS and PI when assessing the likelihood of ETV success in pediatric patients with hydrocephalus. Further research and consideration of these factors may help optimize patient selection and improve outcomes for those undergoing ETV as a treatment for hydrocephalus.