Endoscopic resection of third ventricle colloid cysts using an ultrasonic aspirator.

An important step in the performance of endoscopic resection of colloid cysts of the third ventricle is the forced aspiration of cyst contents. The different consistencies these cysts may have can limit their complete resection and increase the likelihood of complications. The introduction of the ultrasonic neuroendoscopic aspirator allows cysts to be emptied more easily than with a conventional rigid aspirator, improving the feasibility of resection even in more solid cysts. The ability to regulate ultrasound and aspiration increases safety in a reduced and highly morbid space such as the third ventricle. Our objective was to determine the safety and efficiency of the ultrasonic aspirator for endoscopic resection of colloid cysts of the third ventricle. This was a retrospective descriptive study of patients with colloid cysts of the third ventricle undergoing neuroendoscopic resection using an ultrasonic aspirator between 2016-2023. Clinical, radiological, and procedural variables were studied. Mean, median and range were analyzed for quantitative variables and percentages and frequencies for qualitative variables. We present a series of 11 patients with colloid cysts of the third ventricle. The mean age was 44 years (27-69). All had biventricular hydrocephalus, with a mean cyst diameter of 15 mm (9-20). The lateral ventricle was accessed using the transforaminal approach in seven patients and the transchoroidal approach in three patients. All patients underwent septostomy. The mean endoscopy time was 40 min (29-68). Complete resection was possible in 10 patients. Median follow-up was 16 months (1-65) with 100% clinical improvement. At the end of follow-up, no patient had recurrence of the lesion. Based on our experience, the ultrasonic aspirator can be used safely and effectively for the resection of colloid cysts of the third ventricle, achieving high rates of complete resection with minimal postoperative complications.

Suprasellar masquerader: Chordoid glioma.

BACKGROUND: Chordoid glioma is a rare well-circumscribed glial neoplasm arising in adults and predominantly affects females. Tanycytes of the third ventricle have been proposed as the cell of origin owing to its location. It is characterized by chordoid features with myxoid and inflammatory stroma and recurrent PRKCA p.D463H missense mutation. CASE REPORT: We present two cases (30-year-old female and 45-year-old male) with similar complaints of behavioral change and headache. Midline suprasellar homogeneously enhancing mass was seen on contrast-enhanced magnetic resonance imaging. Histopathology and immunohistochemistry was characteristic of chordoid glioma with cords and clusters of epithelioid cells arranged in a solid pattern. There were variable amounts of myxoid stroma and lymphoplasmacytic infiltrate. No mitosis, necrosis, or brain invasion was noted. The cells expressed strong diffuse positivity for glial fibrillary acid protein (GFAP) and weak nuclear thyroid transcription factor (TTF-1). Epithelial membrane antigen (EMA)and brachyury were negative. Subsequently, the lady underwent gross total excision and died soon after the operation. The male patient received radiotherapy and is currently doing well after 6 months of follow-up. CONCLUSION: The rare occurrence as well as the radiological and morphological overlaps in chordoid gliomas make them a true masquerader. Combination of GFAP and TTF-1 in the immunohistochemical panel can be useful in differential diagnosis. Mainstay of treatment is complete surgical excision, with adjuvant radiotherapy becoming increasingly important.

Aberrant Arterial Anatomy at the Floor of the Third Ventricle: Video Case Report.

A 65-year-old woman presented with a 2-month progressive history of forgetfulness, headaches, and decline in mobility. Imaging showed a large, enhancing pineal region tumor with triventricular hydrocephalus. She underwent an endoscopic third ventriculostomy and biopsy after appropriate consent was gained. Video 1 demonstrates the endoscopic procedure during which 2 aberrant arteries were identified at the floor of the third ventricle. The endoscopic third ventriculostomy was performed between these 2 arteries with great care to preserve them. The patient improved postoperatively with resolution of the hydrocephalus. Histology showed a metastatic malignant melanoma. To the best of our knowledge, no similar anatomy has been shown in an endoscopic procedure. We speculate that these are perforating arteries from the posterior communicating artery (premamillary artery) or a branch from the first part of the posterior cerebral artery P1 (thalamoperforators). Other options include perforators from the ophthalmic segment of the internal carotid artery, the communicating segment of the internal carotid artery, the superior hypophyseal artery, or a branch of the medial posterior choroidal arteries. We look at each in turn.

Considerations on surgical strategies and associated risk profiles for endoscopic tumor biopsies within the third ventricle and periaqueductal region.

INTRODUCTION: Neuroendoscopic techniques have proven to be a successful and minimally-invasive technique for tumor biopsies within the third ventricle in pediatric patients. However, a comprehensive assessment of associated surgical strategies, techniques, and morbidity is essential to optimize patient outcomes. METHODS: This retrospective study analyzed full endoscopic tumor biopsies in pediatric patients with tumors in the third ventricle and periaqueductal region. Data from 1995 to 2022 were collected from medical records, imaging, and intraoperative video documentation. RESULTS: In this study, 16 shear endoscopic tumor biopsies were performed using the transventricular transforaminal approach. Tumors were located in the anterior or mid part of the third ventricle (50%) or in the periaqueductal and pineal recess region (50%). Preoperative hydrocephalus was seen in 81.25%. Tumor biopsies were harvested successfully in all cases. Simultaneous ETV was performed in 12 (75%) cases and additional septostomy in 3 (18.75%). Significant intraoperative bleeding occurred in 3 cases (18.75%). All bleeding situations could be successfully managed with continuous irrigation. Histopathology revealed astrocytoma as the predominant diagnosis (75%). No new neurologic deficits were observed, except for one case of transient oculomotor nerve paralysis after ETV. Hydrocephalus persisted in 18.6% of all cases with the need of urgent ventriculoperitoneal shunting in two patients. CONCLUSION: In conclusion, neuroendoscopy emerges as an effective technique for tumor biopsies within the third ventricle in pediatric patients, offering the added advantage of simultaneous treatment of obstructive hydrocephalus. However, it is essential to acknowledge the specific intra- and postoperative risks associated with various surgical strategies. The safe management and achievement of favorable clinical results demand extensive experience and expertise.

Neurosurgical application of pineal region tumor resection with 3D 4K exoscopy via infratentorial approach: a retrospective cohort study.

BACKGROUND: The pineal region tumors are challenging for neurosurgeons and can lead to secondary hydrocephalus. The introduction of the exoscope has provided clinical interventions with high image quality and an ergonomic system for pineal region tumor operations. In this study, the authors describe the exoscopic approach used to facilitate the surgical resection of pineal region tumors and relieve hydrocephalus. MATERIALS AND METHODS: In this retrospective cohort study, we consecutively reviewed the clinical and radiological data of 25 patients with pineal region lesions who underwent three-dimensional exoscopic tumor resection at a single center. RESULTS: The patient cohort consisted of 16 males and 9 females, with an average age of 34.6 years (range, 6-62 years; 8 cases aged ≤18). Pathological examination confirmed eight pineal gland tumors, four gliomas, nine germ cell neoplasms, two ependymomas, and two metastatic tumors. Preoperative hydrocephalus was present in 23 patients. Prior to tumor resection, external ventricular drainage (EVD) with Ommaya reservoir implantation was performed in 17 patients. Two patients received preoperative endoscopic third ventriculostomy (ETV), and five patients received a ventriculoperitoneal (VP) shunt, including one who received both procedures. Gross total resection was achieved in 19 patients (76%) in the 'head-up' park bench position using the exoscope. Eight patients (31.6%) with third ventricle invasion received subtotal resection, mainly in glioma cases, which was higher than those without invasion (0%), but not statistically significant ( P =0.278, Fisher's exact test). No new neurological dysfunction was observed after surgery. Two patients (8%) developed intracranial and pulmonary infections, and two patients (8%) suffered from pneumothorax. Hydrocephalus was significantly relieved in all patients postoperatively, and four patients with relapse hydrocephalus were cured during the long-term follow-up. Postoperative adjuvant management was recommended for indicated patients, and a mean follow-up of 24.8±14.3 months showed a satisfied outcome. CONCLUSIONS: The exoscope is a useful tool for pineal region tumor resection and hydrocephalus relief, particularly with posterior third ventricle invasion, as total resection could be achieved without obvious complication. The special superiority of the exoscope for the indicated pineal region tumors should be highlighted.

Role of endoscopic third ventriculostomy in patients undergoing resection of pulvinar area lesions: Preliminary clinical results.

BACKGROUND: Patients with pulvinar area lesions may develop hydrocephalus at any stage. The role of endoscopic third ventriculostomy (ETV) in this setting remains unclear. METHOD: We retrospectively enrolled 15 patients with a mean age of 43 years who underwent endoscopic resection of pulvinar area lesions using the supracerebellar infratentorial approach (SCITA). We compared the different modalities of hydrocephalus management and their outcomes. RESULTS: Nine of 15 patients (60.0%) had preoperative obstructive hydrocephalus. Five patients underwent ETV before tumor resection, and none developed postoperative hydrocephalus. Four patients underwent one-stage surgery for tumor removal, and one patient with a polymorphous low-grade neuroepithelial tumor of the young required postoperative ETV. Another patient with diffuse astrocytoma and hydrocephalus underwent concurrent lamina terminalis fenestration and endoscopic resection via the SCITA, which resulted in the resolution of hydrocephalus. The preoperative ETV group had no major postoperative complications, while the non-ETV group had three (0/5 vs. 3/4, P = 0.048). The ETV group also had a shorter intensive care unit stay; however, the difference was not significant (1.2 vs. 2.8; P = 0.188). ETV was effective in alleviating symptoms of postoperative hydrocephalus in patients with midbrain-invading tumors. CONCLUSION: Endoscopic surgery via the SCITA can address both tumor and hydrocephalus issues in some cases but has a higher surgical risk and postoperative hydrocephalus rate. Preoperative ETV can prevent these complications and improve postoperative outcomes.

Cytological features of chordoid glioma: A case report with summary of prior published cases.

Chordoid glioma is an uncommon low-grade glioma and is a CNS WHO grade 2 tumour in the current WHO 2021 classification. Predominantly it is seen in the third ventricle and in young adults. Although the histological features of chordoid glioma are well documented, there is sparse literature describing its cytological features. Here we describe the squash cytological features of a case of chordoid glioma along with summary of prior published cases. The smears tend to be quite cellular, the cells show mild pleomorphism, anisonucleosis, and absent mitotic activity. The background shows a distinctive bluish myxoid stroma. It can be mistaken for high grade glioma on squash cytology.

Endoscope-assisted microsurgical resection of a third ventricular immature teratoma.

BACKGROUND: Reaching a tumor within the third ventricle is challenging, and planning an accessible trajectory is crucial without injuring the surrounding structures. We report a 5-year-old boy presented with headache and a seizure where sequential MRI brain studies in a short time period revealed a rapid growing immature teratoma within the third ventricle with hydrocephalic changes. Several management procedures were performed for CSF diversion and medical treatment of the tumor with chemotherapy and stem cell therapy. The tumor was rapidly growing, and surgical excision was decided. Total resection was achieved via endoscope-assisted microsurgical transcallosal approach. Seven years after surgery, the patient experienced no recurrence of the tumor with a favorable clinical condition. CONCLUSION: We report a rare case of posterior third ventricular immature teratoma where the endoscope-assisted microsurgical technique was implemented with favorable long-term postoperative outcome.

Granular cell tumor of the neurohypophysis presenting as a third ventricle mass.

Granular cell tumors of the neurohypophysis (GCT) are rare benign neoplasms belonging, along with pituicytoma and spindle cell oncocytoma, to the family of TTF1-positive low-grade neoplasms of the posterior pituitary gland. GCT usually present as a solid sellar mass, slowly growing and causing compressive symptoms over time, occasionally with suprasellar extension. They comprise polygonal monomorphous cells with abundant granular cytoplasm, which is ultrastructurally filled with lysosomes. Here we report the case of a GCT presenting as a third ventricle mass, radiologically mimicking chordoid glioma, with aberrant expression of GFAP and Annexin-A, which lends itself as an example of an integrated diagnostic approach to sellar/suprasellar and third ventricle masses.

Endoscopic trans-septal interforniceal approach for excision of colloid cysts of the third ventricle using the rotational technique.

Colloid cysts of the third ventricle are benign intracranial lesions that account for 0.5 to 2% of all brain tumors and are even rarer in pediatric population. Dandy was the first to successfully excise a colloid cyst of the third ventricle via a transcortical transventricular approach in 1921. For several decades to follow, the transcortical transventricular and transcallosal microsurgical approaches remained the cornerstone of surgical management of these lesions. With time and refinements in endoscopic equipment and techniques, endoscopic resection of colloid cysts evolved into a currently well-established and appealing minimally invasive alternative to microsurgery. Endoscopic endochannel techniques for colloid cysts of the third ventricle may either be transforaminal or trans-septal interforniceal, depending on the pathoanatomical features of the colloid cyst and its relation to the juxtaposed anatomical structures. The endoscopic trans-septal interforniceal approach is required to access the rare subset of colloid cysts that extend superior to the roof of the third ventricle between the two fornices insinuating themselves between the leaflets of the septum pellucidum. In this article, the surgical technique of the endochannel endoscopic trans-septal interforniceal approach is elaborated upon. A representative case is presented along with an operative video.

Pure endoscopic ultrasonic removal of choroid plexus papillomas of the third ventricle: technical report of two cases.

BACKGROUND: Tumors of the choroid plexus of the third ventricle are uncommon. Surgical excision is technically challenging because of the rich vascularisation, central location, and high incidence in young children. Open microsurgical resection is considered the standard treatment. However, attempts at purely endoscopic removal of choroid plexus tumors of the third ventricle have also been made in the past, with encouraging results. CASE REPORTS: We report our experience with endoscopic ultrasonic removal of two cases of tumors of the third ventricular choroid plexus. The first case was a large atypical choroid plexus papilloma (WHO grade 2) in the anterior third ventricle associated with hydrocephalus; the second case was a smaller choroid plexus papilloma (WHO grade 1) in the middle/posterior third ventricle without overt hydrocephalus requiring a more anterior neuronavigation guided approach. DISCUSSION AND CONCLUSION: Choroid plexus papillomas of the third ventricle can be safely treated by a purely endoscopic approach because they are usually smaller than their counterparts in the lateral ventricle and often have a recognizable vascular pedicle. Early detection and control of the vascular pedicle at the choroidal border is key to success. The use of ultrasonic aspirator facilitates and expedites endoscopic access. By alternating surface coagulation with fragmentation and aspiration with the ultrasonic aspirator, the tumor can be removed without difficult dissection maneuvers.

Endoscopic ultrasonic aspirator-assisted removal of a third ventricular colloid cyst.

BACKGROUND: Colloid cysts are benign tumors usually located on the roof of the third ventricle. Cyst removal is the treatment of choice. It can be accomplished microsurgically through a transcortical- or transcallosal approach, or endoscopically. There is a lack of consensus regarding the best strategy for cyst removal. One of the challenges of the traditional endoscopic technique is dealing with the cyst content density. Hyperdensity on computed tomography scan and low signal on T2-weighted magnetic resonance imaging (MRI) cyst are correlated with high viscosity cystic content. CASE REPORTS: We present a case of a colloid cyst of the third ventricle in a 15-year-old boy removed through a pure endoscopic transventricular approach. The cyst presented a low signal on T2 MRI; nevertheless, it was easily removed with the help of an endoscopic ultrasonic aspirator. DISCUSSION AND CONCLUSION: The colloid cyst of the third ventricle can be safely treated by a purely endoscopic approach. The rationale of the use of the ultrasonic aspirator relies on the facilitation of aspiration of the content even when the consistency is extremely firm.

Endoscopic endonasal approach to remove pediatric intraventricular tumors of the third ventricle.

PURPOSE: Pediatric intraventricular tumors of the third ventricle are among the most difficult-to-treat brain tumors. Recently, endonasal endoscopic surgery for suprasellar, third ventricle, and median clivus lesions has become the common procedure, and its indications are expanding to pediatric cases. We describe our strategy for endonasal endoscopic surgery for pediatric third ventricle tumors. METHOD: We report on surgical anatomies and our surgical procedures in detail, including case presentations. RESULT: Endoscopic endonasal surgery has the advantage of providing a wider view of the tumor site, hypothalamus, optic chiasm, and other critical structures. Good indications for the endoscopic endonasal approach for intra-third ventricular tumors are those arising from the floor of the third ventricle. In particular, craniopharyngioma, a typical pediatric suprasellar tumor, sometimes extends into the third ventricle, causing great operative difficulty. However, aggressive removal for long-term control while preserving memory and visual function is important. We perform surgery with a strategy of radically removing tumors without causing damage to visual or brain function, and we adopt the "4-hands technique by two neurosurgeons" in full endoscopic surgery to remove tumors safely and aggressively. CONCLUSION: We describe our strategy for endonasal endoscopic surgery for pediatric third ventricle tumors, especially those extending from the suprasellar region into the third ventricle, and present a representative case.

Spontaneous Third Ventriculostomy in Cases of Aqueductal Stenosis: A Retrospective Case Series.

BACKGROUND: Spontaneous third ventriculostomy (STV) is a rare occurrence in cases of obstructive hydrocephalus where the walls of the third ventricle rupture, communicating the ventricular system, and the subarachnoid space leading to arrest of active hydrocephalus. We aim to review our series of STVs while reviewing previous reports. METHODS: A retrospective review of cases undergoing cine phase-contrast magnetic resonance imaging (PC-MRI) from 2015 to 2022 of any age with imaging evidence of arrested obstructive hydrocephalus was performed. Patients in which aqueductal stenosis was radiologically evident and the presence of third ventriculostomy through which cerebrospinal fluid flow was detectable were included. Patients who previously underwent endoscopic third ventriculostomy were excluded. Data on patient demographics, presentation, and imaging details of STV and aqueductal stenosis were collected. We searched the PubMed database using the following keyword combination: ((("spontaneous ventriculostomy") OR ("spontaneous third ventriculostomy")) OR ("spontaneous ventriculocisternostomy")) including English reports of STV published between 2010 and 2022. RESULTS: Fourteen cases were included (7 adults, 7 pediatrics), all with history of hydrocephalus. STV occurred in the floor of the third ventricle in 57.1% of the cases, at the lamina terminalis in 35.7%, and at both sites in 1 case. Eleven publications reporting 38 cases of STV were identified from 2009 to date. Minimum follow-up period was 10 months and maximum follow-up is 77 months. CONCLUSIONS: In cases of chronic obstructive hydrocephalus, neurosurgeons should be minded with the possibility of the presence of an STV on cine phase-contrast magnetic resonance imaging leading to arrested hydrocephalus. The delayed flow at the aqueduct of Sylvius might not be the only determinant of the necessity of cerebrospinal fluid diversion and the presence of an STV should be factored into the neurosurgeon's decision considering the patient's clinical picture.

Extra-axial Endoscopic Third Ventriculostomy: A Novel Treatment for Managing Hydrocephalus Due to Vertebrobasilar Dolichoectasia.

BACKGROUND: Vertebrobasilar dolichoectasia, a rare vascular anomaly, rarely presents with hydrocephalus. The traditional treatment for hydrocephalus is a ventriculoperitoneal shunt. Conventional endoscopic third ventriculostomy can avoid shunt-related complications but is considered risky due to the presence of the dolichoectatic vessel. A subfrontal extra-axial fenestration of the lamina terminalis can circumvent this anatomic constraint and establish cerebrospinal fluid communication between the third ventricle and subarachnoid space. METHODS: We performed an extra-axial endoscopic third ventriculostomy to manage hydrocephalus due to vertebrobasilar dolichoectasia in a 26-year-old male. The clinical description, surgical technique, outcome, and rationale are described. RESULTS: The patient had symptomatic improvement in his headaches and vision. There was also improvement in the postoperative ventricular indices: Evans index-19% reduction, frontal occipital horn ratio-14.1% reduction, and third ventricle index-39.5% reduction. A cine-phase magnetic resonance image showed cerebrospinal fluid flow void through the lamina terminalis fenestration, suggesting patency. CONCLUSIONS: Extra-axial endoscopic third ventriculostomy may be a suitable treatment alternative to circumvent anatomic constraints produced by vertebrobasilar dolichoectasia in performing conventional endoscopic third ventriculostomy.

Third Ventricular Subependymomas: Clinical Features and Outcomes Over Two Decades.

BACKGROUND: Subependymomas are uncommon, benign slow-growing neoplasms of the central nervous system preferentially arising within the fourth and lateral ventricles. Third ventricle involvement has been described rarely. The aim of this study is to provide the first systematic review of third ventricular subependymomas (TVSE) by analyzing all reported cases over 2 decades and describing a case example. METHODS: MEDLINE and Embase databases were searched for the 20 years ending January 1, 2022, using relevant MeSH and non-MeSH terms, including "subependymoma" and "third ventricle." Methodology followed PRISMA guidelines. RESULTS: Of 804 identified studies, 131 met inclusion eligibility. The literature yielded 17 patients with TVSE plus our example (18 total). Of these patients, 83% (15/18) presented in adulthood (average age, 42 ± 19 years), of whom 73% were women. The pediatric cohort age was 5 ± 1 years, 67% (4/6) of whom were girls. The most common presenting symptom in both cohorts was headache (80%), followed by memory disturbances and vomitus. In adults, symptomatic tumors were approached by open craniotomy in all but 1 case, most using a transcallosal approach. Gross total resection was obtained in 73%. A ventriculoperitoneal shunt was inserted in 2/15 adult and 4/6 pediatric patients. Overall, both cohorts showed symptomatic improvement without disease recurrence. One patient died perioperatively. CONCLUSIONS: Subependymomas should be considered in the differential diagnosis of third ventricular tumors. The clinical presentation of TVSE mainly parallels hydrocephalus symptoms and, hence, awareness is of vital importance for timely treatment. The surgical goal should be gross total resection, which can be curative and offers greatest clinical improvement across the population.

Concomitant, Single Burr Hole Endoscopic Third Ventriculostomy and Tumor Biopsy for Pineal Lesions: Feasibility, Safety, and Benefits.

Obtaining a prompt diagnosis, avoiding indwelling ventriculoperitoneal shunt, and enhancing the predictive value of pathologic examinations are only some of the advantages conferred by a simultaneous third ventriculostomy and tumor biopsy in patients with pineal region tumors. The objective of this study was to retrospectively search the literature on concomitant, single burr hole endoscopic third ventriculostomy (ETV) and tumor biopsy (TB) for pineal region tumors and to analyze the feasibility, surgical safety, and benefits of these 2 combined procedures. Consequently, a comprehensive, systematic literature search was performed in compliance with the updated PRISMA 2020 guidelines within electronic databases MEDLINE/PubMed, EMBASE, PLOS, and Cochrane Library. Statistical analysis was performed with IBM SPSS 28.0.1.1(14), using Kendall's and Spearman's tests, with a P < 0.05 considered significant. A total of 25 studies were selected and included in this review, for a total of 368 patients (mean age 20.6 years; range 1-86 years; SD 17.5). More than two-thirds of the procedures were operated with a rigid endoscope and 27.6% were performed with either a flexible endoscope, a combination of the 2, or not otherwise specified. Germinoma represented the most frequent diagnosis (20.1%) followed by astrocytoma (12.9%) and pineocytoma (9.9%). The single-entry approach allowed a correct histologic diagnosis in 88.7% of the examined cases. Summing up, concomitant ETV and TB represent a valuable option for the management of non-communicating hydrocephalus and the initial assessment of pineal region tumors. The histologic confirmation rate was 88.7% in the examined cohort, with only 10% of the biopsies yielding inconclusive results.

Perioperative external ventricular drainage vs. no-EVD strategy in pediatric posterior fossa tumors-pilot study results.

INTRODUCTION: Pediatric brain tumors of the posterior fossa often present with occlusive hydrocephalus. Endoscopic third ventriculostomy (ETV) or ventriculoperitoneal shunting (VPS) has been established for definite hydrocephalus treatment. The aim of the study was to analyze the impact and safety of perioperative temporary external ventricular CSF drainage (EVD) placement on postoperative hydrocephalus outcome compared to a no-EVD strategy. PATIENTS AND METHODS: In a prospective database, 36 posterior fossa tumor patients of 2-18 years were included with a follow-up of 1 year. Fifty-eight percent presented with preoperative hydrocephalus. Patients were assigned to non-hydrocephalus group: group I (n = 15) and to preoperative hydrocephalus, group IIa with EVD placement (n = 9), and group IIb without EVD (n = 12). RESULTS: Median age of patients was 8.1 years (range 3.17 to 16.58 years). One-third of 21 hydrocephalus patients required ETV or VPS (n = 7). Occurrence of de novo hydrocephalus in group I after surgery was not observed in our cohort. Age and histology were no confounding factor for EVD placement between group IIa and IIb (p = 0.34). The use of EVD did not result in better control of hydrocephalus compared to no-EVD patients considering pre- and postoperative MRI ventricular indices (p = 0.4). Perioperative placement of an EVD resulted in a threefold risk for subsequent VPS or ETV (group IIa 55.5% vs group IIb 16.6%): relative risk for EVD patients compared to no-EVD patients with hydrocephalus was 3.3 (CI = 1.06-13.43, p = 0.09). CONCLUSION: Perioperative EVD placement appears to harbor a threefold relative risk of requiring subsequent permanent CSF diversion in children above 2 years. EVD was not more effective to control ventricular enlargement compared to tumor removal alone. The no-EVD strategy was safe and did not result in postoperative complications. Thus, to evaluate potential adverse effects on hydrocephalus outcome by EVD placement, a prospective study is warranted to falsify the results.