Evaluation of the Endoscopic Third Ventriculostomy Success Score for Stereotactic Prepontine Stenting in Patients with Aqueductal Stenosis

Evaluation of the Endoscopic Third Ventriculostomy Success Score for Stereotactic Prepontine Stenting in Patients with Aqueductal Stenosis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluation of the Endoscopic Third Ventriculostomy Success Score for Stereotactic Prepontine Stenting in Patients with Aqueductal Stenosis Moritz Ueberschaer, Katja Wirtensohn, Sebastian Niedermeyer, Robert Forbrig, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8628583/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose: Stereotactic prepontine stenting (STS) has been shown to be a safe and effective alternative treatment to standard endoscopic third ventriculostomy (ETV) for the treatment of triventricular hydrocephalus. For ETV a success score (ETVSS) allows risk stratification for treatment failure. We sought to evaluate this score for patients undergoing STS. Methods: Patients with hydrocephalus due to obstruction of the aqueductal outflow tract undergoing either ETV or STS between January 2013 and July 2024 were retrospectively analyzed. Treatment failure was defined as absence of symptomatic and/or imaging improvement. ETVSS were calculated for each group and correlated with outcome. Predictive power of the score was compared. Various statistical approaches were applied in order to create an alternative score. Results: 50 STS patients had a mean ETVSS of 88.2 ± 3.9% versus a mean ETVSS of 81.8 ± 16.7% in 97 patients undergoing ETV (p = 0.009). Successful treatment of hydrocephalus was achieved in 87% of ETV and 96% of STS patients (p = 0.09). Mean ETVSS of patients with successful STS was 89.1 ± 2.9% compared to 81.7 ± 4.1% with STS failure and 84.1 ± 13.5% versus 71.7 ± 24.8% in the ETV group (p = 0.02 for successful treatment). ROC analysis showed poor performance of ETVSS in the STS (AUC = 0.553) and good performance in the ETV cohort (AUC 0.766). Univariate analysis and the importance plot showed significant influence of the clivus-basilar artery diameter on successfull ETV. The risk factors identified in our cohort did not allow for the establishment of a new scoring system. Conclusion: The ETVSS did not enable prediction of successful treatment of hydrocephalus by STS in our cohort, whereas prediction was good for ETV. Therefore, individual decision-making remains essential. Future studies must aim to identify additional risk factors to develop new scoring systems specifically for patients who are eligible for STS. ETVSS hydrocephalus aqueductal stenosis ETV stereotaxy endoscopy Figures Figure 1 Figure 2 Figure 3 Introduction Aqueductal stenosis (AS) is a common pathology leading to hydrocephalus 1 . The treatment of choice in symptomatic patients is endoscopic third ventriculostomy (ETV), which has been shown to be safe and effective 2 , 3 . In a recent publication, our group compared outcomes and complications in a cohort of patients who underwent either ETV or stereotactic prepontine stenting as an alternative treatment that may reduce the risk of stoma occlusion. We found that both treatment modalities had comparable clinical outcomes and complication rates with slightly lower rates of stoma occlusion after STS not reaching statistical significance 4 . The choice of treatment method therefore remains a challenge. A success score for ETV (ETVSS) has previously been developed to predict the risk of treatment failure 5 (Fig. 1 ). Age, etiology of the aqueductal stenosis and a previous shunt contribute to the probability of a successful ETV. While this scoring system has been validated several times in different cohorts 6 – 9 , we wondered whether it is also applicable to STS. Therefore, we sought to evaluate the score in our own cohort of patients with aqueductal stenosis who underwent STS and compare its performance with that of patients who underwent ETV. Methods We performed a retrospective single center study including all consecutive patients who underwent an ETV or STS procedure due to symptomatic AS between January 2013 and July 2024. Patients had either aqueductal stenosis caused by an arachnoid web or aqueductal stenosis caused by compression of a tumor or a cystic lesion. In order to be able to assess individual ETV success scores, patient age, reason for aqueductal stenosis and previous shunt were documented and scores were calculated as previously described 5 . The primary outcome (treatment success) was defined as no revision surgery being performed within 6 months due to inadequate treatment of the hydrocephalus. Inadequate treatment was considered as persisting or worsened symptoms and/or absence of flow void signal on MRI after ETV. The local ethics committee approved the study (reference number 22–0511). Surgical treatment decision was made according to the preferences of the surgeon and the patient. As already published by our group either ETV or STS was performed 4 . “For ETV either the Lotta or the little Lotta endoscopes (Karl Storz SE & Co. KG) were used. The Minop ® endoscope (B.Braun SE) was used for the last patients in the series (2023–2024), as the little Lotta was no longer available. After puncturing the ventricle, the endoscope was advanced into the lateral ventricle and further through the foramen of Monro into the third ventricle. Once the important landmarks were visualized, the third ventricular floor was bluntly perforated, followed by dilatation of the stoma with a Fogarty balloon catheter. The prepontine cistern was then inspected to rule out persistent arachnoid webs. If pulsation of the cerebrospinal fluid through the stoma was observed and a free connection to the prepontine cistern was evident, the endoscope was removed. The burr hole was closed using Spongostan or a borehole plate. For minimal-invasive treatment, an internal shunt catheter was implanted stereotactically (STS) to connect the lateral ventricles with the basal cisterns 10 – 12 . For this, surgical planning (iPlan stereotaxy; Brainlab, Munich, Germany) was based on a stereotactically localized contrast-enhanced computed tomography (CT) scan (0.6 mm slice thickness) and the preoperative MRI data (T1-weighted with and without contrast, T2-weighted/CISS sequences, contrast-enhanced magnetic resonance angiography), which were co-localized with the CT scan. A 1.3 mm diameter catheter (Becker EDMS ventricular catheter; Medtronic Inc, Dublin, Ireland) was stereotactically implanted via a 2 mm burr hole. Additional catheter perforations were added manually to achieve optimal up- and downstream drainage. The catheter was fixed extracranially with a hemoclip (Titanium Ligation-Clip, 150mm length, B Braun, Melsungen, Germany) placed orthogonally on the catheter on the calvaria preventing the catheter from sliding into the brain. Above this, a sponge sealant patch (TachoSil®, Takeda Pharmaceuticals, Konstanz, Germany) was attached for adequate closure and additional fixation.” Fig. 2 shows the preoperative trajectory planning for an STS in a patient with aqueductal stenosis due to an arachnoid web via a left frontal trajectory (A and B) and the postoperative cCT with the internal shunt catheter (C and D). Symptom Assessment Headache, gait disturbance, and urinary incontinence were documented from neurological examinations and clinical records at baseline and postoperatively. Cognitive impairment was evaluated using age-appropriate neuropsychological or clinical assessments, and papilledema was assessed by ophthalmological fundoscopy at both time points. Calculation of Evans index Preoperative cMRI (1.5- or 3.0-T scanners: Magnetom Symphony, Siemens, Erlangen; Signa HDxt; GE Healthcare, Little Chalfont, United Kingdom) routinely included axial T2-weighted sequences (with slice thickness of 2 mm), 3-dimensional T1-weighted sequences before and after intravenous administration of gadopentetate dimeglumine (0.1 mmol/kg body weight; Magnevist; Schering Corporation, Kenilworth, NJ), as well as constructive interference in steady-state (CISS) sequences (with slice thickness of 1 mm). The Evans index (EI) was determined as a marker of pre- and postoperative hydrocephalus on the basis of the performed cMRI images. The EI is calculated as the ratio between the maximum width of the lateral ventricular anterior horns and the maximum inner diameter of the skull on the same slice level with values > 0.3 representing an enlarged ventricular system 13 , 14 . Statistical analysis The ETVSS was calculated for the ETV and STS groups and compared using Student´s t-test. A calibration plot was used to estimate the predictive power. For risk factor analyses uni- and multivariate tests were conducted. For correlation analyses Pearson´s coefficient r was determined. In addition, a receiver operator characteristics (ROC) analysis was performed and the area under the curve (AUC) was calculated to compare the performance of the score for both treatment modalities with GraphPad PRISM 8.0 software (GraphPad, San Diego, CA, USA). Statistical significance was set at p < 0.05. In an effort to create an alternative score, uni- and multivariable logistic regression models with odds ratios and 95% CI were computed. Additionally, gradient boosted trees, decision trees, support vector machines, nearest neighbours classifiers, random forest models, Bayes classifiers and multilayer perceptron neural networks were applied. 10-fold cross-validation was used for model training using 10% of training data as validation set each. A ‘reject option’ was applied, i.e., instead of one cut-off, two cut-offs were applied to the a posteriori probabilities, allowing the models to reject to make a prediction. Statistical significance for all reported tests was determined using two-sided tests and the significance level was set to 5%. Analyses were conducted using STATISTICA 13 (Hill, T. & Lewicki, P. Statistics: Methods and Applications. StatSoft, Tulsa, OK) and MATHEMATICA 13.0 (Wolfram Research, Inc., Mathematica, Version 13.0, Champaign, IL, USA, 2021) Results In total, 147 patients underwent surgery for aqueductal stenosis (AS). In 60/147 patients (40.8%) stenosis was caused by tumor formations (33 gliomas, 18 pineal tumors and 9 metastases). 50/147 (34.0%) patients were treated by STS and 97/147 (66.0%) patients by ETV, respectively. The main symptoms of headache, cognitive impairment, gait disorder, urinary incontinence and papilledema have improved remarkably well both in the ETV and STS group (Table 1). In the overall cohort, correlation analyses displayed a significant association of an older patient age (r=0.3, p=0.01), an enlarged clivus to basilar artery distance (r=0.3, p=0.002) and a decreased postoperative EI (r=0.2, p=0.04) with higher ETVSS scores suggesting successful hydrocephalus treatment. Evaluation of the ETVSS in the STS group 50 patients with a mean age of 45.5 ± 22.3 years underwent STS. The gender distribution was balanced, with 52% male patients. 33/50 (66.0%) patients had a solid tumor and 4/50 (8.0%) patients had a cystic tumor that led to aqueductal stenosis, while 13/50 (26%) patients had an aqueductal arachnoidal web causing the aqueductal stenosis. There were no patients with previous shunts, infections or bleedings in the STS group. Only 4/50 patients (8%) were below the age of 10 years. The mean follow-up period was 29.4 ± 27.4 months, with 2/50 patients (4.0%) undergoing revision surgery due to inadequate hydrocephalus treatment. The mean ETVSS was 88.2 ± 3.9% for the whole STS cohort. The 2 patients undergoing revision surgery had a mean ETVSS of 81.7 ± 4.1% compared with 89.1 ± 2.9% in successfully treated patients (p=0.23). In univariate analysis, younger patient age (p<0.05) and male sex (p=0.04), were associated with a lower ETVSS. Age was confirmed as risk factor for treatment failure in the multivariate analysis (Table 2). ROC analysis revealed an AUC of 0.553 (Figure 3A). Therefore, the ETVSS could not reliably predict treatment success in our cohort of patients undergoing STS. Comparison of the ETV cohort with the STS cohort 97 patients underwent ETV. Tumors as the underlying pathology for aqueductal stenosis occurred more frequently in the STS group (STS 22.4% vs. ETV 13.6%, p < 0.0001). In addition, there were significantly more infants and newborns in the ETV group, resulting in a significantly lower mean age of 35.6 ± 24.1 years in the ETV group (p=0.02). Apart from these differences, the demographic data of both cohorts were comparable. In the ETV group, there were two neonates with previous infections, but no patients with previous shunts or bleeding. The mean ETVSS in the ETV cohort was 81.8 ± 16.7% and was thus significantly lower than in the STS cohort (p < 0.01). In the ETV cohort, there were 13/97 revision surgeries (13.4%) due to inadequate hydrocephalus drainage. In the univariate analysis, younger patient age (p=0.04) and a reduced distance between the basilar artery and clivus (p=0.02) were associated with a lower ETVSS, while younger patient age was significantly striking in the multivariate analysis (Table 3). The mean ETVSS for successful ETV was 84.1 ± 13.5% compared to 71.7 ± 24.8% for failed ETV (p = 0.1). The ROC analysis yielded an AUC value of 0.766 for the ETVSS in the ETV group (Figure 3B). Exploration of new scoring systems Despite using different statistical approaches, it was not possible to develop an alternative scoring system especially for the group of STS patient. Since only young patient age could be identified as risk factor for treatment failure, different models failed to predict treatment success. Discussion The ETVSS has been developed to predict the probability of successful treatment in patients with ETV for aqueductal stenosis 5 , 7 . The aim of this study was to evaluate the predictive value of ETVSS for STS in patients with aqueductal stenosis in order to facilitate the decision regarding the treatment modality. We found that the ETVSS was unable to predict successful ETV in our STS cohort. In the ETV cohort, ROC analysis showed better sensitivity and specificity with an AUC value of 0.766, which is comparable to previous studies describing moderate predictive power of ETVSS. Ferreira Furtado et al. 15 report an AUC value of 0.668 in a large cohort of pediatric patients. Given that age has a major influence on ETVSS and the number of children under 10 years of age in the STS cohort was very low, the negative results could also be due to the characteristics of the cohort. Although frame-based stereotactic surgery has been shown to be safe in children 16 – 18 , endoscopic surgery is often preferred to avoid the stereotactic frame. In addition, there were no previous shunts or hydrocephalus due to infection or hemorrhage in the STS cohort, and the number of failed STS was very low at only 4%, which could also have an impact on the statistics. To confirm that the ETVSS is not suitable for patient selection, the score needs to be evaluated in a more heterogeneous cohort. Uni- and multivariate analyses were performed to determine possible influencing factors associated with reduced ETVSS in the respective cohorts. In the ETV group, we found a small clivus to basilar artery diameter to be associated with treatment failure. This could reflect the surgical challenge of safely creating an adequate stoma in a very small and delicate area. However, even with an adequate stoma, the anatomy of a small prepontine cistern itself may influence CSF dynamics. Preoperative imaging should be studied in detail in this regard. Additionaly, younger patient age was associated with a lower ETVSS. In the STS cohort, also patient age was associated with a lower ETVSS. These results are consistent with the strong influence that age has on the calculation of the ETVSS and appear to be relevant for both ETV and STS. This may reflect the complexity of hydrocephalus in young children and also suggest that catheter placement does not necessarily overcome the suspected underlying problems of new arachnoid membrane formation, new ependymal or gliotic tissue formation in these young patients 19 . When considering other risk factors for stoma failure in ETV patients, these may also apply to STS patients. Posthemorrhagic hydrocephalus carries the risk of malabsorption and occlusion of catheter perforations after STS, and postinfectious hydrocephalus may be associated with a higher risk of delayed infection due to the use of foreign material. In contrast, STS can be a good alternative for non-tectal brain tumors, allowing stereotactic biopsy and treatment of hydrocephalus to be performed in a single stereotactic procedure, as Niedermeyer et al. have already reported in a cohort of 38 patients 20 . This procedure led to a low ventriculoperitoneal shunt dependency during follow-up period and carried a remarkably low rate of surgical morbidity of only 2.6%. Despite extensive statistical efforts, we were unable to find an alternative scoring system that would be suitable for STS patients or for both STS and ETV patients. This is most likely due to the small number of unsuccessful operations and the homogeneity of the cohort, in which only the young age of the patients was a preoperative risk factor for treatment failure. Future studies must aim to identify additional risk factors for treatment failure in STS patients in order to develop and validate an alternative scoring system. For patient selection, we must therefore adhere to our previously published scheme 4 and take into account the individual preferences of the neurosurgeons. Conclusion The ETVSS did not enable prediction of successful treatment of hydrocephalus by STS in our cohort, whereas prediction was good in the ETV cohort. Therefore, individual decision-making is essential, especially in patients with low ETVSS. Evaluation of the ETVSS in a more heterogeneous and larger cohort might lead to different results and may provide an opportunity to develop a new scoring system for patients who are eligible for STS. Declarations Human Ethics and Consent to Participate declaration Informed consent was obtained from all individual participants included in the study.The Ethics Committee of the University Hospital Munich (LMU) approved the study in accordance with the Declaration of Helsinki (reference number 22–0511). Conflicts of interest/Competing interests Funding The authors did not receive support from any organization for the submitted work. Author Contribution All authors contributed to the study conception and design. Data collection and analysis were performed by M. U., K. W. and M. S.-S. The first draft of the manuscript was written by M. U. and M. S.-S.. M. U. and M. S.-S. and all authors commented on the previous versions of the manuscript. All authors read and approved the final manuscript. Data Availability Data can be offered to reviewers on reasonable request. References Cinalli G et al (2011) Hydrocephalus in aqueductal stenosis. Childs Nerv Syst 27:1621–1642 Jiang L, Gao G, Zhou Y (2018) Endoscopic third ventriculostomy and ventriculoperitoneal shunt for patients with noncommunicating hydrocephalus: A PRISMA-compliant meta-analysis. Med (Baltim) 97:e12139 Bergsneider M, Miller C, Vespa PM, Hu X (2008) Surgical management of adult hydrocephalus. Neurosurgery 62 Suppl 2, 643–659; discussion 659–660 Ueberschaer M et al (2025) Comparison of endoscopic third ventriculostomy with stereotactic prepontine stenting in patients with aqueductal stenosis. J Neurosurg, 1–9 Kulkarni AV et al (2009), Endoscopic third ventriculostomy in the treatment of childhood hydrocephalus. J Pediatr 155, 254–259 e251 Labidi M et al (2015) Predicting success of endoscopic third ventriculostomy: validation of the ETV Success Score in a mixed population of adult and pediatric patients. J Neurosurg 123:1447–1455 Kulkarni AV et al (2010) Predicting who will benefit from endoscopic third ventriculostomy compared with shunt insertion in childhood hydrocephalus using the ETV Success Score. J Neurosurg Pediatr 6:310–315 Krause M, Grafe D, Metzger R, Griessenauer CJ, Gburek-Augustat J (2024) Evaluation of the ETV success score and its predictive value in pediatric occlusive hydrocephalus: implications for patient counseling. Childs Nerv Syst 41:72 Adil SM et al (2025) Revisiting the Endoscopic Third Ventriculostomy Success Score using machine learning: can we do better? J Neurosurg Pediatr 35:246–254 Schmutzer-Sondergeld M et al (2024) Evaluation of surgical treatment strategies and outcome for cerebral arachnoid cysts in children and adults. Acta Neurochir 166:39 Schmutzer-Sondergeld M et al (2025) Comparison of surgical approaches and outcome for symptomatic pineal cysts: microscopic/endoscopic fenestration vs. stereotactic catheter implantation. Acta Neurochir 167:27 Niedermeyer S et al (2024) Efficacy and safety of cysto-ventricular catheter implantation for space-occupying cysts arising from glioma and brain metastasis: a retrospective study. Acta Neurochir 166:36 Neikter J et al (2020) Ventricular Volume Is More Strongly Associated with Clinical Improvement Than the Evans Index after Shunting in Idiopathic Normal Pressure Hydrocephalus. AJNR Am J Neuroradiol 41:1187–1192 Toma AK, Holl E, Kitchen ND, Watkins LD (2011) Evans' index revisited: the need for an alternative in normal pressure hydrocephalus. Neurosurgery 68:939–944 Furtado LMF, da Costa Val Filho JA (2021) Dos Santos Junior, E.C. External validation of the ETV success score in 313 pediatric patients: a Brazilian single-center study. Neurosurg Rev 44:2727–2734 Furlanetti LL, Monaco BA, Cordeiro JG, Lopez WO, Trippel M (2015) Frame-based stereotactic neurosurgery in children under the age of seven: Freiburg University's experience from 99 consecutive cases. Clin Neurol Neurosurg 130:42–47 Schmutzer-Sondergeld M et al (2024) Risk-benefit analysis of surgical treatment strategies for cystic craniopharyngioma in children and adolescents. Front Oncol 14:1274705 Kirchleitner SV et al (2025) Leksell G frame in pediatric neurosurgery: experiences from 73 stereotactic procedures. J Neurosurg Pediatr, 1–8 Mohanty A, Vasudev MK, Sampath S, Radhesh S (2002) Sastry Kolluri, V.R. Failed endoscopic third ventriculostomy in children: management options. Pediatr Neurosurg 37:304–309 Niedermeyer S et al (2023) Minimally invasive third ventriculostomy with stereotactic internal shunt placement for the treatment of tumor-associated noncommunicating hydrocephalus. Acta Neurochir (Wien) Tables Tables 1 to 3 are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Tables.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8628583","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":582050830,"identity":"c4d64608-aa91-43a5-9c4e-93db40e95d08","order_by":0,"name":"Moritz Ueberschaer","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIiWNgGAWjYJACZjApASIqGBj4eEjTcoaBgQ2k5QDRWhjbiNCi28Bj+Lig4p49/+zmh48r59XJs/EcYPz8AY8WswM8xsYzzhQnzrhzzNjw7LbDhm28DcwS+GwBajGT5m1LSDCQSDCTbNx2gLGNH+hIAlrMf/P+S7A3kEj//rNxTp09UAvzD0K2MPM2JDBukMgxY2xsYE4EOowNvy2H2YqlZxxLSJxxI6dYsuHY4eQ2noNtFmfwaTnevPFzQU2CPf+M9I0fG2rqbPt5kg/fqMCjBRopKICxAZ+GUTAKRsEoGAVEAAAf4kpGz6T5XgAAAABJRU5ErkJggg==","orcid":"","institution":"Paracelsus Medical University","correspondingAuthor":true,"prefix":"","firstName":"Moritz","middleName":"","lastName":"Ueberschaer","suffix":""},{"id":582050831,"identity":"87cbf4ff-7a4b-44a0-9e0f-888a87e1bdc0","order_by":1,"name":"Katja Wirtensohn","email":"","orcid":"","institution":"LMU Klinikum","correspondingAuthor":false,"prefix":"","firstName":"Katja","middleName":"","lastName":"Wirtensohn","suffix":""},{"id":582050832,"identity":"16d42b67-2770-43c7-9439-18dbbea51939","order_by":2,"name":"Sebastian Niedermeyer","email":"","orcid":"","institution":"Ruhr University Bochum","correspondingAuthor":false,"prefix":"","firstName":"Sebastian","middleName":"","lastName":"Niedermeyer","suffix":""},{"id":582050833,"identity":"da472388-62c9-4556-aaf7-174920190500","order_by":3,"name":"Robert Forbrig","email":"","orcid":"","institution":"LMU Klinikum","correspondingAuthor":false,"prefix":"","firstName":"Robert","middleName":"","lastName":"Forbrig","suffix":""},{"id":582050834,"identity":"6b0fd807-91cb-4de3-afb7-a77550b7ab17","order_by":4,"name":"Niklas Thon","email":"","orcid":"","institution":"Ruhr University Bochum","correspondingAuthor":false,"prefix":"","firstName":"Niklas","middleName":"","lastName":"Thon","suffix":""},{"id":582050835,"identity":"52dd59f2-8656-4c97-b195-05db3b80b3a9","order_by":5,"name":"Sabrina Viktoria Kirchleitner","email":"","orcid":"","institution":"Philipps University of Marburg","correspondingAuthor":false,"prefix":"","firstName":"Sabrina","middleName":"Viktoria","lastName":"Kirchleitner","suffix":""},{"id":582050836,"identity":"4322acf8-318e-4717-8caf-66f70319d66e","order_by":6,"name":"Mathias Kunz","email":"","orcid":"","institution":"LMU Klinikum","correspondingAuthor":false,"prefix":"","firstName":"Mathias","middleName":"","lastName":"Kunz","suffix":""},{"id":582050837,"identity":"aea98820-97f7-455a-8e65-1855b070d558","order_by":7,"name":"Wolfgang Hitzl","email":"","orcid":"","institution":"Paracelsus Medical University","correspondingAuthor":false,"prefix":"","firstName":"Wolfgang","middleName":"","lastName":"Hitzl","suffix":""},{"id":582050838,"identity":"f6b306da-461b-4a06-ba96-73d35845355f","order_by":8,"name":"Michael Schmutzer-Sondergeld","email":"","orcid":"","institution":"LMU Klinikum","correspondingAuthor":false,"prefix":"","firstName":"Michael","middleName":"","lastName":"Schmutzer-Sondergeld","suffix":""}],"badges":[],"createdAt":"2026-01-18 00:23:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8628583/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8628583/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101499743,"identity":"2f6e504e-8b59-4362-a972-2e25c04c50f6","added_by":"auto","created_at":"2026-01-30 13:12:40","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":77011,"visible":true,"origin":"","legend":"\u003cp\u003eETV success score, published by Kulkarni et al. in 2009\u003csup\u003e5\u003c/sup\u003e. The higher the score, the higher the probability of successful ETV.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8628583/v1/1faa3eb60107d307fc7e0feb.jpg"},{"id":101499792,"identity":"5ab14167-ad9c-4d3d-b836-297688ef00d2","added_by":"auto","created_at":"2026-01-30 13:12:50","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":800817,"visible":true,"origin":"","legend":"\u003cp\u003eT1-weighted with contrast cMRI scans of the preoperative trajectory planning for an STS in a patient with aqueductal stenosis due to an arachnoid web vie a left frontal trajectory (sagittal and coronal, A and B). Postoperative cCT with the internal shunt catheter tip in the prepontine cistern (sagittal and coronal, C and D).\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8628583/v1/2cb464028522c04a21274562.jpeg"},{"id":101499595,"identity":"d25e8660-fbe8-4337-9476-c3d931bd1ddf","added_by":"auto","created_at":"2026-01-30 13:12:10","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":92695,"visible":true,"origin":"","legend":"\u003cp\u003eA: ROC analysis for the STS group. B: ROC analysis for the ETV group.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8628583/v1/25e131cb3cb93e6386cfdebb.jpeg"},{"id":101563535,"identity":"c78781f3-2df6-499e-8019-cdf1f37c7e1f","added_by":"auto","created_at":"2026-01-31 12:40:17","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1439555,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8628583/v1/e4f3c14a-16a3-42bd-a53e-06ccca0abe5d.pdf"},{"id":101499642,"identity":"4015b510-1a0d-47a6-a46b-bf4f524dd592","added_by":"auto","created_at":"2026-01-30 13:12:23","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":25130,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-8628583/v1/0ebbd2f08fe4d40c43bf3305.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of the Endoscopic Third Ventriculostomy Success Score for Stereotactic Prepontine Stenting in Patients with Aqueductal Stenosis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAqueductal stenosis (AS) is a common pathology leading to hydrocephalus \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. The treatment of choice in symptomatic patients is endoscopic third ventriculostomy (ETV), which has been shown to be safe and effective \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. In a recent publication, our group compared outcomes and complications in a cohort of patients who underwent either ETV or stereotactic prepontine stenting as an alternative treatment that may reduce the risk of stoma occlusion. We found that both treatment modalities had comparable clinical outcomes and complication rates with slightly lower rates of stoma occlusion after STS not reaching statistical significance\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe choice of treatment method therefore remains a challenge. A success score for ETV (ETVSS) has previously been developed to predict the risk of treatment failure \u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Age, etiology of the aqueductal stenosis and a previous shunt contribute to the probability of a successful ETV. While this scoring system has been validated several times in different cohorts \u003csup\u003e\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e, we wondered whether it is also applicable to STS. Therefore, we sought to evaluate the score in our own cohort of patients with aqueductal stenosis who underwent STS and compare its performance with that of patients who underwent ETV.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eWe performed a retrospective single center study including all consecutive patients who underwent an ETV or STS procedure due to symptomatic AS between January 2013 and July 2024. Patients had either aqueductal stenosis caused by an arachnoid web or aqueductal stenosis caused by compression of a tumor or a cystic lesion. In order to be able to assess individual ETV success scores, patient age, reason for aqueductal stenosis and previous shunt were documented and scores were calculated as previously described \u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. The primary outcome (treatment success) was defined as no revision surgery being performed within 6 months due to inadequate treatment of the hydrocephalus. Inadequate treatment was considered as persisting or worsened symptoms and/or absence of flow void signal on MRI after ETV. The local ethics committee approved the study (reference number 22\u0026ndash;0511). Surgical treatment decision was made according to the preferences of the surgeon and the patient. As already published by our group either ETV or STS was performed \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. \u0026ldquo;For ETV either the Lotta or the little Lotta endoscopes (Karl Storz SE \u0026amp; Co. KG) were used. The Minop \u0026reg; endoscope (B.Braun SE) was used for the last patients in the series (2023\u0026ndash;2024), as the little Lotta was no longer available. After puncturing the ventricle, the endoscope was advanced into the lateral ventricle and further through the foramen of Monro into the third ventricle. Once the important landmarks were visualized, the third ventricular floor was bluntly perforated, followed by dilatation of the stoma with a Fogarty balloon catheter. The prepontine cistern was then inspected to rule out persistent arachnoid webs. If pulsation of the cerebrospinal fluid through the stoma was observed and a free connection to the prepontine cistern was evident, the endoscope was removed. The burr hole was closed using Spongostan or a borehole plate.\u003c/p\u003e \u003cp\u003eFor minimal-invasive treatment, an internal shunt catheter was implanted stereotactically (STS) to connect the lateral ventricles with the basal cisterns \u003csup\u003e\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. For this, surgical planning (iPlan stereotaxy; Brainlab, Munich, Germany) was based on a stereotactically localized contrast-enhanced computed tomography (CT) scan (0.6 mm slice thickness) and the preoperative MRI data (T1-weighted with and without contrast, T2-weighted/CISS sequences, contrast-enhanced magnetic resonance angiography), which were co-localized with the CT scan. A 1.3 mm diameter catheter (Becker EDMS ventricular catheter; Medtronic Inc, Dublin, Ireland) was stereotactically implanted via a 2 mm burr hole. Additional catheter perforations were added manually to achieve optimal up- and downstream drainage. The catheter was fixed extracranially with a hemoclip (Titanium Ligation-Clip, 150mm length, B Braun, Melsungen, Germany) placed orthogonally on the catheter on the calvaria preventing the catheter from sliding into the brain. Above this, a sponge sealant patch (TachoSil\u0026reg;, Takeda Pharmaceuticals, Konstanz, Germany) was attached for adequate closure and additional fixation.\u0026rdquo; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the preoperative trajectory planning for an STS in a patient with aqueductal stenosis due to an arachnoid web via a left frontal trajectory (A and B) and the postoperative cCT with the internal shunt catheter (C and D).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSymptom Assessment\u003c/p\u003e \u003cp\u003eHeadache, gait disturbance, and urinary incontinence were documented from neurological examinations and clinical records at baseline and postoperatively. Cognitive impairment was evaluated using age-appropriate neuropsychological or clinical assessments, and papilledema was assessed by ophthalmological fundoscopy at both time points.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eCalculation of Evans index\u003c/h2\u003e \u003cp\u003ePreoperative cMRI (1.5- or 3.0-T scanners: Magnetom Symphony, Siemens, Erlangen; Signa HDxt; GE Healthcare, Little Chalfont, United Kingdom) routinely included axial T2-weighted sequences (with slice thickness of 2 mm), 3-dimensional T1-weighted sequences before and after intravenous administration of gadopentetate dimeglumine (0.1 mmol/kg body weight; Magnevist; Schering Corporation, Kenilworth, NJ), as well as constructive interference in steady-state (CISS) sequences (with slice thickness of 1 mm). The Evans index (EI) was determined as a marker of pre- and postoperative hydrocephalus on the basis of the performed cMRI images. The EI is calculated as the ratio between the maximum width of the lateral ventricular anterior horns and the maximum inner diameter of the skull on the same slice level with values\u0026thinsp;\u0026gt;\u0026thinsp;0.3 representing an enlarged ventricular system \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe ETVSS was calculated for the ETV and STS groups and compared using Student\u0026acute;s t-test. A calibration plot was used to estimate the predictive power. For risk factor analyses uni- and multivariate tests were conducted. For correlation analyses Pearson\u0026acute;s coefficient \u003cem\u003er\u003c/em\u003e was determined. In addition, a receiver operator characteristics (ROC) analysis was performed and the area under the curve (AUC) was calculated to compare the performance of the score for both treatment modalities with GraphPad PRISM 8.0 software (GraphPad, San Diego, CA, USA). Statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05. In an effort to create an alternative score, uni- and multivariable logistic regression models with odds ratios and 95% CI were computed. Additionally, gradient boosted trees, decision trees, support vector machines, nearest neighbours classifiers, random forest models, Bayes classifiers and multilayer perceptron neural networks were applied. 10-fold cross-validation was used for model training using 10% of training data as validation set each. A \u0026lsquo;reject option\u0026rsquo; was applied, i.e., instead of one cut-off, two cut-offs were applied to the a posteriori probabilities, allowing the models to reject to make a prediction. Statistical significance for all reported tests was determined using two-sided tests and the significance level was set to 5%. Analyses were conducted using STATISTICA 13 (Hill, T. \u0026amp; Lewicki, P. Statistics: Methods and Applications. StatSoft, Tulsa, OK) and MATHEMATICA 13.0 (Wolfram Research, Inc., Mathematica, Version 13.0, Champaign, IL, USA, 2021)\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eIn total, 147 patients underwent surgery for aqueductal stenosis (AS). In 60/147 patients (40.8%) stenosis was caused by tumor formations (33 gliomas, 18 pineal tumors and 9 metastases). 50/147 (34.0%) patients were treated by STS and 97/147 (66.0%) patients by ETV, respectively. The main symptoms of headache, cognitive impairment, gait disorder, urinary incontinence and papilledema have improved remarkably well both in the ETV and STS group (Table 1). In the overall cohort, correlation analyses displayed a significant association of an older patient age (r=0.3, p=0.01), an enlarged clivus to basilar artery distance (r=0.3, p=0.002) and a decreased postoperative EI (r=0.2, p=0.04) with higher ETVSS scores suggesting successful hydrocephalus treatment.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEvaluation of the ETVSS in the STS group\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e50 patients with a mean age of 45.5 \u0026plusmn; 22.3 years underwent STS. The gender distribution was balanced, with 52% male patients. 33/50 (66.0%) patients had a solid tumor and 4/50 (8.0%) patients had a cystic tumor that led to aqueductal stenosis, while 13/50 (26%) patients had an aqueductal arachnoidal web causing the aqueductal stenosis. There were no patients with previous shunts, infections or bleedings in the STS group. Only 4/50 patients (8%) were below the age of 10 years. The mean follow-up period was 29.4 \u0026plusmn; 27.4 months, with 2/50 patients (4.0%) undergoing revision surgery due to inadequate hydrocephalus treatment. The mean ETVSS was 88.2 \u0026plusmn; 3.9% for the whole STS cohort. The 2 patients undergoing revision surgery had a mean ETVSS of 81.7 \u0026plusmn; 4.1% compared with 89.1 \u0026plusmn; 2.9% in successfully treated patients (p=0.23). In univariate analysis, younger patient age (p\u0026lt;0.05) and male sex (p=0.04), were associated with a lower ETVSS. Age was confirmed as risk factor for treatment failure in the multivariate analysis (Table 2). ROC analysis revealed an AUC of 0.553 (Figure 3A). Therefore, the ETVSS could not reliably predict treatment success in our cohort of patients undergoing STS.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eComparison of the ETV cohort with the STS cohort\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e97 patients underwent ETV. Tumors as the underlying pathology for aqueductal stenosis occurred more frequently in the STS group (STS 22.4% vs. ETV 13.6%, p \u0026lt; 0.0001). In addition, there were significantly more infants and newborns in the ETV group, resulting in a significantly lower mean age of 35.6 \u0026plusmn; 24.1 years in the ETV group (p=0.02). Apart from these differences, the demographic data of both cohorts were comparable. In the ETV group, there were two neonates with previous infections, but no patients with previous shunts or bleeding. The mean ETVSS in the ETV cohort was 81.8 \u0026plusmn; 16.7% and was thus significantly lower than in the STS cohort (p \u0026lt; 0.01). In the ETV cohort, there were 13/97 revision surgeries (13.4%) due to inadequate hydrocephalus drainage. In the univariate analysis, younger patient age (p=0.04) and a reduced distance between the basilar artery and clivus (p=0.02) were associated with a lower ETVSS, while younger patient age was significantly striking in the multivariate analysis (Table 3). The mean ETVSS for successful ETV was 84.1 \u0026plusmn; 13.5% compared to 71.7 \u0026plusmn; 24.8% for failed ETV (p = 0.1). The ROC analysis yielded an AUC value of 0.766 for the ETVSS in the ETV group (Figure 3B).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eExploration of new scoring systems\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eDespite using different statistical approaches, it was not possible to develop an alternative scoring system especially for the group of STS patient. Since only young patient age could be identified as risk factor for treatment failure, different models failed to predict treatment success.\u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe ETVSS has been developed to predict the probability of successful treatment in patients with ETV for aqueductal stenosis \u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. The aim of this study was to evaluate the predictive value of ETVSS for STS in patients with aqueductal stenosis in order to facilitate the decision regarding the treatment modality.\u003c/p\u003e \u003cp\u003eWe found that the ETVSS was unable to predict successful ETV in our STS cohort. In the ETV cohort, ROC analysis showed better sensitivity and specificity with an AUC value of 0.766, which is comparable to previous studies describing moderate predictive power of ETVSS. Ferreira Furtado et al.\u003csup\u003e15\u003c/sup\u003e report an AUC value of 0.668 in a large cohort of pediatric patients. Given that age has a major influence on ETVSS and the number of children under 10 years of age in the STS cohort was very low, the negative results could also be due to the characteristics of the cohort. Although frame-based stereotactic surgery has been shown to be safe in children \u003csup\u003e\u003cspan additionalcitationids=\"CR17\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e, endoscopic surgery is often preferred to avoid the stereotactic frame. In addition, there were no previous shunts or hydrocephalus due to infection or hemorrhage in the STS cohort, and the number of failed STS was very low at only 4%, which could also have an impact on the statistics. To confirm that the ETVSS is not suitable for patient selection, the score needs to be evaluated in a more heterogeneous cohort.\u003c/p\u003e \u003cp\u003eUni- and multivariate analyses were performed to determine possible influencing factors associated with reduced ETVSS in the respective cohorts. In the ETV group, we found a small clivus to basilar artery diameter to be associated with treatment failure. This could reflect the surgical challenge of safely creating an adequate stoma in a very small and delicate area. However, even with an adequate stoma, the anatomy of a small prepontine cistern itself may influence CSF dynamics. Preoperative imaging should be studied in detail in this regard. Additionaly, younger patient age was associated with a lower ETVSS. In the STS cohort, also patient age was associated with a lower ETVSS. These results are consistent with the strong influence that age has on the calculation of the ETVSS and appear to be relevant for both ETV and STS. This may reflect the complexity of hydrocephalus in young children and also suggest that catheter placement does not necessarily overcome the suspected underlying problems of new arachnoid membrane formation, new ependymal or gliotic tissue formation in these young patients \u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eWhen considering other risk factors for stoma failure in ETV patients, these may also apply to STS patients. Posthemorrhagic hydrocephalus carries the risk of malabsorption and occlusion of catheter perforations after STS, and postinfectious hydrocephalus may be associated with a higher risk of delayed infection due to the use of foreign material. In contrast, STS can be a good alternative for non-tectal brain tumors, allowing stereotactic biopsy and treatment of hydrocephalus to be performed in a single stereotactic procedure, as Niedermeyer et al. have already reported in a cohort of 38 patients \u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. This procedure led to a low ventriculoperitoneal shunt dependency during follow-up period and carried a remarkably low rate of surgical morbidity of only 2.6%.\u003c/p\u003e \u003cp\u003eDespite extensive statistical efforts, we were unable to find an alternative scoring system that would be suitable for STS patients or for both STS and ETV patients. This is most likely due to the small number of unsuccessful operations and the homogeneity of the cohort, in which only the young age of the patients was a preoperative risk factor for treatment failure. Future studies must aim to identify additional risk factors for treatment failure in STS patients in order to develop and validate an alternative scoring system. For patient selection, we must therefore adhere to our previously published scheme \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e and take into account the individual preferences of the neurosurgeons.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe ETVSS did not enable prediction of successful treatment of hydrocephalus by STS in our cohort, whereas prediction was good in the ETV cohort. Therefore, individual decision-making is essential, especially in patients with low ETVSS. Evaluation of the ETVSS in a more heterogeneous and larger cohort might lead to different results and may provide an opportunity to develop a new scoring system for patients who are eligible for STS.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003e \u003cb\u003eHuman Ethics and Consent to Participate declaration\u003c/b\u003e \u003c/h2\u003e\u003cp\u003eInformed consent was obtained from all individual participants included in the study.The Ethics Committee of the University Hospital Munich (LMU) approved the study in accordance with the Declaration of Helsinki (reference number 22\u0026ndash;0511).\u003c/p\u003e \u003c/p\u003e\u003cb\u003eConflicts of interest/Competing interests\u003c/b\u003e\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThe authors did not receive support from any organization for the submitted work.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Data collection and analysis were performed by M. U., K. W. and M. S.-S. The first draft of the manuscript was written by M. U. and M. S.-S.. M. U. and M. S.-S. and all authors commented on the previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData can be offered to reviewers on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCinalli G et al (2011) Hydrocephalus in aqueductal stenosis. Childs Nerv Syst 27:1621\u0026ndash;1642\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJiang L, Gao G, Zhou Y (2018) Endoscopic third ventriculostomy and ventriculoperitoneal shunt for patients with noncommunicating hydrocephalus: A PRISMA-compliant meta-analysis. Med (Baltim) 97:e12139\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBergsneider M, Miller C, Vespa PM, Hu X (2008) Surgical management of adult hydrocephalus. \u003cem\u003eNeurosurgery\u003c/em\u003e 62 Suppl 2, 643\u0026ndash;659; discussion 659\u0026ndash;660\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUeberschaer M et al (2025) Comparison of endoscopic third ventriculostomy with stereotactic prepontine stenting in patients with aqueductal stenosis. J Neurosurg, 1\u0026ndash;9\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKulkarni AV et al (2009), \u003cem\u003eEndoscopic third ventriculostomy in the treatment of childhood hydrocephalus. J Pediatr 155, 254\u0026ndash;259 e251\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLabidi M et al (2015) Predicting success of endoscopic third ventriculostomy: validation of the ETV Success Score in a mixed population of adult and pediatric patients. J Neurosurg 123:1447\u0026ndash;1455\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKulkarni AV et al (2010) Predicting who will benefit from endoscopic third ventriculostomy compared with shunt insertion in childhood hydrocephalus using the ETV Success Score. J Neurosurg Pediatr 6:310\u0026ndash;315\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKrause M, Grafe D, Metzger R, Griessenauer CJ, Gburek-Augustat J (2024) Evaluation of the ETV success score and its predictive value in pediatric occlusive hydrocephalus: implications for patient counseling. Childs Nerv Syst 41:72\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdil SM et al (2025) Revisiting the Endoscopic Third Ventriculostomy Success Score using machine learning: can we do better? J Neurosurg Pediatr 35:246\u0026ndash;254\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmutzer-Sondergeld M et al (2024) Evaluation of surgical treatment strategies and outcome for cerebral arachnoid cysts in children and adults. Acta Neurochir 166:39\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmutzer-Sondergeld M et al (2025) Comparison of surgical approaches and outcome for symptomatic pineal cysts: microscopic/endoscopic fenestration vs. stereotactic catheter implantation. Acta Neurochir 167:27\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNiedermeyer S et al (2024) Efficacy and safety of cysto-ventricular catheter implantation for space-occupying cysts arising from glioma and brain metastasis: a retrospective study. Acta Neurochir 166:36\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNeikter J et al (2020) Ventricular Volume Is More Strongly Associated with Clinical Improvement Than the Evans Index after Shunting in Idiopathic Normal Pressure Hydrocephalus. AJNR Am J Neuroradiol 41:1187\u0026ndash;1192\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eToma AK, Holl E, Kitchen ND, Watkins LD (2011) Evans' index revisited: the need for an alternative in normal pressure hydrocephalus. Neurosurgery 68:939\u0026ndash;944\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFurtado LMF, da Costa Val Filho JA (2021) Dos Santos Junior, E.C. External validation of the ETV success score in 313 pediatric patients: a Brazilian single-center study. Neurosurg Rev 44:2727\u0026ndash;2734\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFurlanetti LL, Monaco BA, Cordeiro JG, Lopez WO, Trippel M (2015) Frame-based stereotactic neurosurgery in children under the age of seven: Freiburg University's experience from 99 consecutive cases. Clin Neurol Neurosurg 130:42\u0026ndash;47\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmutzer-Sondergeld M et al (2024) Risk-benefit analysis of surgical treatment strategies for cystic craniopharyngioma in children and adolescents. Front Oncol 14:1274705\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKirchleitner SV et al (2025) Leksell G frame in pediatric neurosurgery: experiences from 73 stereotactic procedures. J Neurosurg Pediatr, 1\u0026ndash;8\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMohanty A, Vasudev MK, Sampath S, Radhesh S (2002) Sastry Kolluri, V.R. Failed endoscopic third ventriculostomy in children: management options. Pediatr Neurosurg 37:304\u0026ndash;309\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNiedermeyer S et al (2023) Minimally invasive third ventriculostomy with stereotactic internal shunt placement for the treatment of tumor-associated noncommunicating hydrocephalus. Acta Neurochir (Wien)\u003c/span\u003e\u003c/li\u003e \u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 3 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"ETVSS, hydrocephalus, aqueductal stenosis, ETV, stereotaxy, endoscopy","lastPublishedDoi":"10.21203/rs.3.rs-8628583/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8628583/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose:\u003c/h2\u003e \u003cp\u003eStereotactic prepontine stenting (STS) has been shown to be a safe and effective alternative treatment to standard endoscopic third ventriculostomy (ETV) for the treatment of triventricular hydrocephalus. For ETV a success score (ETVSS) allows risk stratification for treatment failure. We sought to evaluate this score for patients undergoing STS.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003ePatients with hydrocephalus due to obstruction of the aqueductal outflow tract undergoing either ETV or STS between January 2013 and July 2024 were retrospectively analyzed. Treatment failure was defined as absence of symptomatic and/or imaging improvement. ETVSS were calculated for each group and correlated with outcome. Predictive power of the score was compared. Various statistical approaches were applied in order to create an alternative score.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003e50 STS patients had a mean ETVSS of 88.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9% versus a mean ETVSS of 81.8\u0026thinsp;\u0026plusmn;\u0026thinsp;16.7% in 97 patients undergoing ETV (p\u0026thinsp;=\u0026thinsp;0.009). Successful treatment of hydrocephalus was achieved in 87% of ETV and 96% of STS patients (p\u0026thinsp;=\u0026thinsp;0.09). Mean ETVSS of patients with successful STS was 89.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9% compared to 81.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1% with STS failure and 84.1\u0026thinsp;\u0026plusmn;\u0026thinsp;13.5% versus 71.7\u0026thinsp;\u0026plusmn;\u0026thinsp;24.8% in the ETV group (p\u0026thinsp;=\u0026thinsp;0.02 for successful treatment). ROC analysis showed poor performance of ETVSS in the STS (AUC\u0026thinsp;=\u0026thinsp;0.553) and good performance in the ETV cohort (AUC 0.766). Univariate analysis and the importance plot showed significant influence of the clivus-basilar artery diameter on successfull ETV. The risk factors identified in our cohort did not allow for the establishment of a new scoring system.\u003c/p\u003e\u003ch2\u003eConclusion:\u003c/h2\u003e \u003cp\u003eThe ETVSS did not enable prediction of successful treatment of hydrocephalus by STS in our cohort, whereas prediction was good for ETV. Therefore, individual decision-making remains essential. Future studies must aim to identify additional risk factors to develop new scoring systems specifically for patients who are eligible for STS.\u003c/p\u003e","manuscriptTitle":"Evaluation of the Endoscopic Third Ventriculostomy Success Score for Stereotactic Prepontine Stenting in Patients with Aqueductal Stenosis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-30 13:08:53","doi":"10.21203/rs.3.rs-8628583/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c33fcc1b-50bd-4bef-8999-614abe357501","owner":[],"postedDate":"January 30th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-31T12:40:04+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-30 13:08:53","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8628583","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8628583","identity":"rs-8628583","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}