Can We Predict Early Endoscopic Third Ventriculostomy Failure? The Role of Ultra-Early Postoperative Magnetic Resonance Imaging in Predicting Early Endoscopic Third Ventriculostomy Failure

The Predictive Role of Early Postoperative Magnetic Resonance Imaging After Endoscopic Third Ventriculostomy

OBJECTIVE

Endoscopic third ventriculostomy (ETV) is a treatment option for obstructive hydrocephalus; reported success rates vary. We investigated immediate postoperative magnetic resonance imaging to evaluate the role of imaging parameters associated with outcomes.

METHODS

Retrospective chart review was performed on patients undergoing initial ETV between 2005 and 2019. Patients with preoperative and postoperative magnetic resonance imaging with follow-up>one year were included. The following were noted: changes in subarachnoid cerebrospinal fluid, third ventricle diameter, bowing of the third ventricle floor, and postoperative flow void. Kaplan-Meier survival methods were used to assess ETV success and univariable and multivariable Cox proportional-hazards models were fitted to assess factors contributing to ETV success.

RESULTS

Fifty-eight subjects were included. Nineteen (32.8%) experienced failure within one year; individually, no single imaging parameter predicted success. However, all cases of failure had no identifiable flow void. Any postoperative radiological change was not consistently associated with decreased odds of failure. Obstructive hydrocephalus treated with ETV demonstrated significantly better ETV success than patients treated with nonobstructive hydrocephalus. Interobserver reliability was moderate for 2 of the radiological variables and substantial for 1 of the radiological variables.

CONCLUSIONS

Individually, none of the qualitative radiologic parameters measured in our study predicted ETV success. Absence of a flow void predicted ETV failure, but additional studies are needed to determine its true negative predictive value. Inability to clarify which specific parameter predicts success reflects the limited role of immediate postoperative imaging in influencing clinical management.

Interesting negative correlation between transorbital optic nerve sheath diameter and Evans' index values; can it be predictive for failure of endoscopic third ventriculostomy?

Background: Currently, Endoscopic third ventriculostomy (ETV) is one of the commonly used surgical options for the treatment of non-communicating hydrocephalus but reported success rates from ETV vary considerably, and a reliable noninvasive means to detect the efficacy of ETV is still lacking. In this study, the changes in Evans's Index and the transorbital optic nerve sheath (ONSD) diameter measurement after endoscopic third ventriculostomy were compared. Methods: Preoperative and early postoperative ultrasonographic ONSD measurement and preoperative and postoperative 3 months Evans' index of patients with hydrocephalus on whom ETVs were performed between 1 February 2018 and 23 May 2022 and analyzed. Results: The chart of 8 male and 2 female patients was analyzed. Their median age at presentation was 5.3 years (range 1 - 14 years). Mean ONSD values were 5.66 mms in the preoperative period, which was decreased to a mean of 4.17 mms in the early postoperative period. The Evans' index was 0.5320 in the preoperative period; however, it decreased to 0.4460 in the postoperative 3rd months. The preoperative and early postoperative mean ONSD values and Evans' Index of patients were significantly different. Interestingly, a negative correlation was also observed between ONSD values and Evans' index. Conclusions: ONSD measurement and Evans' index have been commonly used after ETV procedures İn pediatric patients with hydrocephalus. Still, there is an unexplained negative correlation between ONSD and Evans' index values. This study indicates that the two measures (Evans's index and ONSD) should be considered when performing follow-up examinations in patients after ETV.

Simple Identification of Cerebrospinal Fluid Turbulent Motion Using a Dynamic Improved Motion-sensitized Driven-equilibrium Steady-state Free Precession Method Applied to Various Types of Cerebrospinal Fluid Motion Disturbance

The motion of cerebrospinal fluid (CSF) within the subarachnoid space and ventricles is greatly modulated when propagating synchronously with the cardiac pulse and respiratory cycle and path through the nerves, blood vessels, and arachnoid trabeculae. Water molecule movement that propagates between two spaces via a stoma, foramen, or duct presents increased acceleration when passing through a narrow area and can exhibit “turbulence.” Recently, neurosurgeons have started to perform fenestration procedures using neuroendoscopy to treat hydrocephalus and cystic lesions. As part of the postoperative evaluation, a noninvasive diagnostic technique to visualize the water molecules at the fenestrated site is necessary. Because turbulence is observed at this fenestrated site, an imaging technique appropriate for observing this turbulence is essential. We therefore investigated the usefulness of a dynamic improved motion-sensitized driven-equilibrium steady-state free precession (Dynamic iMSDE SSFP) sequence of magnetic resonance imaging that is superior for ascertaining turbulent motions in healthy volunteers and patients. Images of Dynamic iMSDE SSFP from volunteers revealed that CSF motion at the ventral surface of the brainstem and the third ventricle is augmented and turbulent. Moreover, our findings confirmed that this technique is useful for evaluating treatments that utilize neuroendoscopy. As a result, Dynamic iMSDE SSFP, a simple sequence for visualizing CSF motion, entails a short imaging time, can extensively visualize CSF motion, does not require additional processes such as labeling or trigger setting, and is anticipated to have wide-ranging clinical applications in the future.