Single burr hole endoscopic biopsy with third ventriculostomy-measurements and computer-assisted planning

Tailored Concept for Accurate Neuroendoscopy: A Comparative Retrospective Single-Center Study on Image-Guided Neuroendoscopic Procedures

OBJECTIVE

Precise planning and execution is key for neuroendoscopic interventions, which can be based on different available aiding technologies. The aim of this retrospective study is to report a case-based use of guided neuroendoscopy and to develop a stratification algorithm for the available technologies.

METHODS

We reviewed consecutive neuroendoscopic cases performed at our center from 2016 to 2018. We distinguished between patients receiving a new burr hole (group A) and those with a preexisting burr hole (group B). Case-specific technical requirements for procedure planning and execution, complication rate, surgical outcome, and possible subsequent surgery were evaluated. From this experience, a stratification system was developed to tailor the available guiding technologies.

RESULTS

A total of 309 neuroendoscopic interventions in 243 patients were included in the present study. The cases included hydrocephalic (81.6%) and nonhydrocephalic (18.4%) conditions. The interventions were supported by coordinate-based (group A, n = 49; group B, n = 67), guide-based (group A, n = 42; group B, n = 0), ultrasound-guided (group A, n = 50; group B, n = 7), or navigated augmented reality-guided (group A, n = 85; group B, n = 9) techniques. The overall complication rate was 4.5%. Stratified by the surgical indication, fontanel status, entry point localization, presence of a preexisting burr hole, ventricular size, and number of targets, an approach toward image-guided neuroendoscopy is suggested.

CONCLUSIONS

Planning and technical guidance is essential in neuroendoscopic procedures. The stratified decision-making algorithm for different available technologies aims to achieve lower cost and time consumption, which was found to be safe and efficient. Further investigations are warranted to deliver solid data on procedure efficiency.

Intraventricular Tumors: Surgical Considerations in Lateral and Third Ventricular Tumors

Management of lateral and third ventricular tumors has been a challenge for neurosurgeons. Advances in imaging and pathology have helped in a better understanding of the treatment options. Technical refinement of microsurgical technique and addition of endoscopy has enabled more radical excision of tumors, when indicated, and added more safety.A proper understanding of the pathology at various ages and treatment options is continuously evolving. Many pediatric tumors are amenable to conservative surgical methods with effective complementary treatments. However, radical surgery is required in many adults as the main treatment and for many benign tumors. Various intraventricular lesions encountered and their surgical management is reviewed here for their efficacy, safety, and outcome, encompassing changes in our practice over the last 20 years.

Endoscopic extended transforaminal approach (medial subchoroid) as an alternative to the classical transchoroidal approach: Technical note

The extended transforaminal endoscopic approaches allows visualization and manipulation of the middle and posterior third of the III ventricle. In selected cases where the venous anatomy is favorable, the medial subchoroidal approach can be performed as an alternative to the classic transchoroidal approach (via trans-taenia fornicis) with increased protection over the fornix and without the need to sacrifice the septal vein. We present a 14-year-old male with history of Neurofibromatosis type 1 referred for two weeks of clinical evolution with headache, dizziness, gait instability and appearance of a right VI nerve palsy. Magnetic resonance imaging showed obstructive tri-ventricular hydrocephalus due to stenosis of the aqueduct of Sylvius with suspicion of an underlying tumor. An endoscopic surgical procedure was performed through a single approach with III cisternostomy and resection of the tissue that produced the stenosis. The anatomopathological diagnosis showed reactive glial tissue with no signs of malignancy. In conclusion, the medial subchoroidal approach is a plausible alternative in the endoscopic approach to the III ventricle structures in a safe and comfortable manner.

Simultaneous single-trajectory endoscopic biopsy and third ventriculostomy in pediatric pineal region tumors

Pineal region tumors have different pathological tumors and their optimal management remains controversial. Advancements in neuroendoscopy have led to the ability to simultaneously treat the hydrocephalus and obtain a tissue diagnosis. A retrospective review of 34 patients with pineal region tumors in Beijing Tiantan hospital from the year 2016 to 2018 was undertaken. A single bur hole for both procedures was used successfully in all patients. Once pathologic diagnosis is made, the subsequent management of different tumors is dependent on response to therapy, the tumor markers and original pathology. Follow-up period was 4-26 months. All 34 cases presented with hydrocephalus and increased intracranial pressure manifestations. Elevated blood tumor markers were found in seven cases. The neuroendoscopic biopsy was diagnostic in 32 samples (94.1%) and nondiagnostic (gliosis) in two patients. 21 cases were germinomas, five cases were tectal astrocytomas, two cases were pineoblastomas, two cases were non-germinomatous germ-cell tumours (NG-GCTs) and 1 case immature teratoma and glioblastoma respectively. During the follow-up period, all germinomas but one case with elevated blood α-fetoprotein received craniotomy with a final diagnosis of NG-GCT received radiotherapy and chemotherapy. Four tectal astocytomas, two pineoblastomas and two NG-GCTs received subsequent open surgery due to progressive development, the pathological data was concordant with the initial endoscopic biopsy sample. An additional VP shunt was inserted in one tectal astrocytoma who have hydrocephalus after craniotomy. Except for 18 cases of transient fever and a case with intratumoral hemorrhage, there was no other significant complications, cognitive disorder and no death. The simultaneous single-trajectory endoscopic technique permits not only to control hydrocephalus but also to obtain histological diagnosis with a low incidence of complication and higher safety. Providing meaningful pathological data, endoscopic biopsies could lead to an appropriate management decision. Especially, it is favored as an early step in the management of patients with marker-negative tumors.

Endoscopic Third Ventriculostomy for Obstructive Hydrocephalus and Ventriculocystostomy for Intraventricular Arachnoid Cysts

OBJECTIVE

To evaluate and discuss the outcomes of a combination of ventriculocystostomy (VC) and endoscopic third ventriculostomy (ETV) for obstructive hydrocephalus (HCP) due to ventricular/cisternal arachnoid cysts, and only ETV for obstructive HCP due to different etiologies.

METHODS

We retrospectively reviewed all 40 symptomatic patients (aged 4 months - 61 years) of obstructive HCP treated by ETV or VC+ETV during October 2014 - April 2019. VC+ETV was performed in 7 patients with intraventricular/cisternal arachnoid cyst and obstructive HCP. Only ETV was performed in 33 patients with obstructive HCP due to other etiologies.

RESULTS

Successful ETV or VC+ETV surgery was performed in 35 patients. The procedure failed in 5 patients aged 90 percentile at the time of surgery. Another 5 patients aged 90 percentile).

Single Burr-Hole Extended Transforaminal Approach for Concurrent Endoscopic Surgery in the Third Ventricle Posterior to the Foramen of Monro and Ventriculostomy: Clinical Series and Planning Steps

OBJECTIVE

For endoscopic surgery of third ventricular lesions posterior to the foramen of Monro that frequently require a third ventriculostomy during the same procedure, the extended transforaminal approach (ETFA) through the choroid fissure has been proposed. This study reports clinical results and provides anatomic background and guidelines for individual planning of a single burr-hole approach and a safe transchoroid entry zone.

METHODS

A retrospective review was undertaken of 25 cases of concurrent third ventricle surgery and third ventriculostomy via ETFA. Assessment was made of a safe transchoroidal entry zone on cadavers (6 hemispheres) and of planning guidelines on magnetic resonance imaging showing occlusive hydrocephalus (30 sides).

RESULTS

ETFA was feasible in all 25 cases. The safe transchoroid entry zone was sufficient in 16 cases; in 9 cases, additional transchoroid opening with transection of the anterior septal vein was required without clinical consequences. The anatomic study showed a safe transchoroid entry zone of 5 mm (3-6 mm) for posterior enlargement of the foramen of Monro. Individual planning on magnetic resonance imaging of patients with enlarged third ventricles showed an optimal burr-hole position 22 mm (10-30 mm) lateral to the midline and 8 mm (27 to -23 mm) precoronal; a foramen of Monro diameter of 7 mm (3-11 mm) and a safe transchoroid entry zone of 6 mm (3-12 mm).

CONCLUSIONS

According to our data, concurrent endoscopic surgery of third ventricular lesions posterior to the foramen of Monro and ventriculostomy are feasible through a single burr hole and a transchoroid extension of the transforaminal approach. Precise preoperative planning is recommended for anticipating the individual anatomic nuances.

Integrated understanding of hydrocephalus - a practical approach for a complex disease

Most of childhood hydrocephalus are originating during infancy. It is considered to be a complex disease since it is developed on the basis of heterogeneous pathophysiological mechanisms and different pathological conditions as well as during different age groups. Hence, it is of relevant importance to have a practical concept in mind, how to categorize hydrocephalus to surgically better approach this disease. The current review should offer further basis of discussion on a disease still most frequently seen in Pediatric Neurosurgery. Current literature on pathophysiology and classification of pediatric hydrocephalus has been reviewed to integrate the different published concepts of hydrocephalus for pediatric neurosurgeons. The current understanding of infant and childhood hydrocephalus pathophysiology is summarized. A simplified concept based on seven factors of CSF dynamics is elaborated and discussed in the context of recent discussions. The seven factors such as pulsatility, CSF production, major CSF pathways, minor CSF pathways, CSF absorption, venous outflow, and respiration may have different relevance and may also overlap for the individual hydrocephalic condition. The surgical options available for pediatric neurosurgeons to approach hydrocephalus must be adapted to the individual condition. The heterogeneity of hydrocephalus causes mostly developing during infancy warrant a simplified overview and understanding for an everyday approach. The proposed guide may be a basis for further discussion and may serve for a more or less simple categorization to better approach hydrocephalus as a pathophysiological complex disease.

Endoscopic Third Ventriculostomy and Simultaneous Tumor Biopsy in Pineal Region Tumors using the "Single Burr Hole" Technique: An Analysis of 34 Cases

Background

Pineal region tumors often present with hydrocephalus. Endoscopic third ventriculostomy (ETV) and simultaneous tumor biopsy remain a minimally invasive procedure offering both diagnostic and therapeutic advantages in the management of these tumors. However, different operative techniques have been described in the literature.

Aim

The aim is to study the ETV success rate, diagnostic rate of simultaneous tumor biopsy, complications, and follow-up of patients of pineal region tumors managed with ETV and simultaneous tumor biopsy using the single burr hole technique.

Methods

The study was performed by retrospectively reviewing the records of patients of pineal region tumors managed by simultaneous ETV and tumor biopsy using a "single burr hole" technique from January 2012 to December 2019.

Results

Thirty-four patients (22 males and 12 females) with a mean age of 28.7 years were analyzed. ETV was successful in relieving hydrocephalus in 29 (87.8%) patients. Three patients needed a ventriculoperitoneal shunt, and one required Ommaya reservoir placement for persistent hydrocephalus. Histological diagnosis was successfully established in 26 (78.8%) patients. There were two procedure-related mortalities. Two patients underwent craniotomy and tumor excision subsequently. Radiotherapy was given to 11 patients, and 9 patients were managed by observation alone. The mean follow-up of our study was 15.8 months.

Conclusions

Simultaneous ETV and tumor biopsy using a single burr hole technique is a safe, minimally invasive procedure for the management of pineal region tumors.

A Review of Common Endoscopic Intracranial Approaches

With the evolution of surgical techniques, endoscopy has emerged as a suitable alternative to many instances of more invasive methods. In this review article, we aim to discuss the endoscopic advancements, procedural details, indications, and outcomes of the most commonly practiced neuroendoscopic procedures. We have also summarized the uses, techniques, and challenges of neuroendoscopy in select neurosurgical pathologies.

One- vs Two-Burr-Hole Technique for Combined Endoscopic Third Ventriculostomy and Pineal Region Biopsy: Volumetric Analysis of Brain at Risk

BACKGROUND

Pineal region tumors are associated with the ventricular system. Endoscopic third ventriculostomy (ETV) is often performed at the same time as tumor biopsy.

OBJECTIVE

To investigate the volume of brain possibly undergoing injury and forniceal stretching during ETV and tumor biopsy.

METHODS

We performed a retrospective review of preoperative magnetic resonance imagings (MRIs) and computed tomography (CTs) of patients with pineal region masses and used volumetric image-guided navigation to simulate a 1-burr-hole vs a 2-burr-hole approach through the brain parenchyma. We compared the volumes of parenchyma and fornix at the risk of injury.

RESULTS

The ideal entry point for ETV using 2 burr holes was a mean ± standard deviation (SD) of 25.8 ± 6 mm from the midline and 11.4 ± 9 mm behind the coronal suture. The ideal entry point using 2 burr holes for tumor biopsy was 25.7 ± 8 mm from the midline and 53.7 ± 14 mm anterior to the coronal suture. With 1 burr hole, the mean ± SD volume of brain parenchyma at risk was 852 ± 440 mm3. The volume of brain parenchyma at risk with 2 burr holes was 2159 ± 474 mm3 (P < .001; paired t-test). The use of 1 burr hole predisposed the fornix to 14 ± 3 mm of possible stretch, which was minimized with the 2-burr-hole approach.

CONCLUSION

Using 1 burr hole for both the ETV and tumor biopsy is less likely to traumatize the brain parenchyma than using 2 burr holes. However, 1 burr hole predisposes the fornix to stretch injury. We recommend tailoring the entry to each patient according to their anatomy rather than using a 1-size-fits-all approach.

Management of pineal region tumors in a pediatric case series

Pineal region tumors commonly present with non-communicating hydrocephalus. These heterogeneous histological entities require different therapeutic regimens. We evaluated our surgical experience concerning procurance of a histological diagnosis, management of hydrocephalus, and choice of antitumoral treatment. We analyzed the efficacy of neuroendoscopic biopsy and endoscopic third ventriculocisternostomy (ETV) in patients with pineal region tumors between 2006 and 2019 in a single-center retrospective cross-sectional study with regard to diagnostic yield, hydrocephalus treatment, as well as impact on further antitumoral management. Out of 28 identified patients, 23 patients presented with untreated hydrocephalus and 25 without histological diagnosis. One patient underwent open biopsy, and 24 received a neuroendoscopic biopsy with concomitant hydrocephalus treatment if necessary. Eighteen primary ETVs, 2 secondary ETVs, and 2 ventriculoperitoneal shunts (VPSs) were performed. Endoscopic biopsy had a diagnostic yield of 95.8% (23/24) and complication rates of 12.5% (transient) and 4.2% (permanent), respectively. ETV for hydrocephalus management was successful in 89.5% (17/19) with a median follow-up of more than 3 years. Following histological diagnosis, 8 patients (28.6%) underwent primary resection of their tumor. Another 9 patients underwent later-stage resection after either adjuvant treatment (n = 5) or for progressive disease during observation (n = 4). Eventually, 20 patients received adjuvant treatment and 7 were observed after primary management. One patient was lost to follow-up. Heterogeneity of pineal region tumor requires histological confirmation. Primary biopsy of pineal lesions should precede surgical resection since less than a third of patients needed primary surgical resection according to the German pediatric brain tumor protocols. Interdisciplinary decision making upfront any treatment is warranted in order to adequately guide treatment.

A Steerable Neuroendoscopic Instrument Using Compliant Contact-Aided Joints and Monolithic Articulation

This work presents the design of an articulate neuroendoscopic instrument (ANI), a handheld tool for use in minimally invasive neurosurgery. The instrument consists of a handle and a steerable tube-shaft with a distal end-effector. The design aims to increase the reach of surgeons operating through narrow channels within the center of the brain when approaching multiple targets from a single incision point. The steerable tube-shaft consists of a 1.6- mm notch-tube compliant joint mechanism augmented with contact-aids modeled after a gear geometry. The contact-aid geometry aims to address the performance tradeoff between stiffness, range-of-motion (RoM), and joint compactness for millimeter-scale notched-tube joints; it increases blocking force without sacrificing RoM. Finite element modeling (FEM) was used to refine design features, and the joint stiffness and RoM are assessed experimentally for three prototypes. The joint is incorporated into a tube-shaft instrument, and the assembled tool's stiffness properties are characterized. The prototype was then assessed in a validated neurosurgical simulator. An individual 1.24-mm outer-diameter notch-tube compliant joint with gear contact-aids is capable of 30 deg maximum bending and can sustain a 0.55 N blocking force with 0.5 mm displacement. A functional instrument shaft with a 15.5- mm-long articulating section was constructed from three joints in series with an external flexible stainless-steel sheath. It achieves a 6.7-mm bending radius at 75 deg maximum bending angle. In preclinical testing with an endoscopic third ventriculostomy and endoscopic tumor biopsy (ETV-ETB) simulator, the tool successfully completes the biopsy and fenestration maneuvers from a single burr-hole entry point. The ANI prototype uses contact-aid geometry incorporated into a compliant nitinol notched-tube joint to produce an articulate biopsy instrument for minimally invasive neurosurgical applications.

Continuum Robot With Follow-the-Leader Motion for Endoscopic Third Ventriculostomy and Tumor Biopsy

BACKGROUND

In a combined endoscopic third ventriculostomy (ETV) and endoscopic tumor biopsy (ETB) procedure, an optimal tool trajectory is mandatory to minimize trauma to surrounding cerebral tissue.

OBJECTIVE

This paper presents wire-driven multi-section robot with push-pull wire. The robot is tested to attain follow-the-leader (FTL) motion to place surgical instruments through narrow passages while minimizing the trauma to tissues.

METHODS

A wire-driven continuum robot with six sub-sections was developed and its kinematic model was proposed to achieve FTL motion. An accuracy test to assess the robot's ability to attain FTL motion along a set of elementary curved trajectory was performed. We also used hydrocephalus ventricular model created from human subject data to generate five ETV/ETB trajectories and conducted a study assessing the accuracy of the FTL motion along these clinically desirable trajectories.

RESULTS

In the test with elementary curved paths, the maximal deviation of the robot was increased from 0.47 mm at 30 ° turn to 1.78 mm at 180 ° in a simple C-shaped curve. S-shaped FTL motion had lesser deviation ranging from 0.16 to 0.18 mm. In the phantom study, the greatest tip deviation was 1.45 mm, and the greatest path deviation was 1.23 mm.

CONCLUSION

We present the application of a continuum robot with FTL motion to perform a combined ETV/ETB procedure. The validation study using human subject data indicated that the accuracy of FTL motion is relatively high. The study indicated that FTL motion may be useful tool for combined ETV and ETB.

An anatomical study of the foramen of Monro: implications in management of pineal tumors presenting with hydrocephalus

BACKGROUND

For pineal tumors presenting with hydrocephalus, simultaneous endoscopic third ventriculostomy (ETV) and tumor biopsy is commonly used as the initial step in management. To analyze the restriction which the foramen of Monro poses to this procedure, one must start with a detailed description of the microsurgical anatomy of the foramen in living subjects. However, the orientation and shape of the foramen of Monro make this description difficult with conventional imaging techniques.

METHOD

Virtual reality technology was applied on MRIs on living subject without hydrocephalus, as well as patients with hydrocephalus, to generate precise anatomical models with sub-millimeter accuracy. The morphometry of the foramen of Monro was studied in each group. In addition, displacement of the margins of the foramen was studied in detail for simultaneous ETV and pineal tumor biopsy through a single burr hole.

RESULTS

In 30 normal subjects, the foramen of Monro had oval-shaped openings averaging 5.23 mm². The foramen was larger in people above age 55 (p = 0.007) and on the left side compared to the right (p = 0.002). For patients with clinical presentation of hydrocephalus, the average opening was 32.6 mm². Simulated single burr hole simultaneous ETV and pineal tumor biopsy was performed in 10 specimens. Average displacement of the posterior and anterior margins of the foramen was 5.71 mm and 5.76 mm, respectively. However, maximum displacement reached 9.3 mm posteriorly and 10 mm anteriorly.

CONCLUSIONS

The foramen of Monro is an oval-shaped cylinder that changes in size and orientation in the hydrocephalic patient. If universally applied to all patients regardless of foramen and tumor size, ETV/biopsy can displace structures around the Foramen of Monro up to 1 cm, which can potentially lead to neurological damage. Careful pre-operative assessment is critical to determine if a single burr hole approach is safe.

Visual-Controlled Endoscopic Biopsy of Paraventricular Intraparenchymal Tumors

OBJECTIVE

Frame-based stereotaxy represents the gold standard for biopsy of deep-seated lesions. Visual control of possible bleeding in these lesions is not possible. Neuroendoscopic biopsy represents an alternative procedure for tissue sampling in deep-seated intraventricular lesions. The authors present a technique for transventricular-navigated endoscopic biopsy of lesions that are located in the paraventricular region.

METHODS

Biopsy of paraventricular pathologies was performed in 6 male and 6 female patients between March 2013 and September 2018. The patient age ranged from 18 to 82 years. All patients underwent a pure endoscopic procedure over a burr hole trepanation supported by frameless navigation of the sedan probe.

RESULTS

Histologic diagnoses were established in all biopsies. In all patients, a direct control of the biopsy area was feasible, and hemostasis could be obtained. In 5 patients, endoscopic third ventriculostomy was performed first due to obstructive hydrocephalus. In 1 patient suffering from obstructive hydrocephalus, a pellucidotomy was performed. In 9 cases, the initial postoperative course was uneventful. Three patients suffered from persistent hydrocephalus and had to be treated with ventriculoperitoneal shunt insertion.

CONCLUSIONS

Endoscopically conducted biopsies with the aid of navigated tracking of the probe represent a possible additional technique in selected paraventricular intraparenchymal pathologies. The endoscopic approach enables the direct visualization of the intraventricular surface and its vessels. In contrast to standard stereotactic biopsy, direct visual control of hemostasis can be obtained even in paraventricular tumors.

Clinical Management of Prostate Cancer Metastasis to Pineal Gland: Case Report and Review of Literature

BACKGROUND

Prostate cancer is the most common cancer among American men, with an incidence of approximately 233,000 cases per year. Intracranial metastases are rare and, specifically, metastasis to the pineal gland has only been reported in 2 postmortem cases in the literature.

CASE DESCRIPTION

We present the first documented case of confirmed prostate cancer metastasis to the pineal gland in a living patient. The patient underwent an endoscopic third ventriculostomy and pineal lesion biopsy with complete resolution of his hydrocephalus and presenting symptoms. His biopsy results confirmed the prostate origin of the metastasis, and he subsequently underwent stereotactic radiosurgery for treatment of this lesion.

CONCLUSIONS

This is the first report of the clinical management of metastatic prostate cancer to the pineal region and description of the clinical outcome. Although prostate cancer is the most common cancer in American men, metastasis to the pineal has only been reported twice from autopsy examinations. Overall, pineal tumors in the geriatric population are exceedingly rare and the age and comorbidities in this patient made management quite unique.

The effect and evolution of patient selection on outcomes in endoscopic third ventriculostomy for hydrocephalus: A large-scale review of the literature

Endoscopic third ventriculostomy (ETV) has become a popular technique for the treatment of hydrocephalus, but small sample size has limited the generalizability of prior studies. We performed a large-scale review of all available studies to help eliminate bias and determine how outcomes have changed and been influenced by patient selection over time. A systematic literature search was performed for studies of ETV that contained original, extractable patient data, and a meta-analytic model was generated for correlative and predictive analysis. A total of 130 studies were identified, which included 11,952 cases. Brain tumor or cyst was the most common hydrocephalus etiology, but high-risk etiologies, post-infectious or post-hemorrhagic hydrocephalus, accounted for 18.4%. Post-operative mortality was very low (0.2%) and morbidity was only slightly higher in developing than in industrialized countries. The rate of ETV failure was 34.7% and was higher in the first months and plateaued around 20months. As anticipated, ETV is less successful in high-risk etiologies of hydrocephalus and younger patients. Younger patient age and high-risk etiologies predicted failure. ETVs were performed more often in high-risk etiologies over time, but, surprisingly, there was no overall change in ETV success rate over time. This study should help to influence optimal patient selection and offer guidance in predicting outcomes.

Augmented reality in intraventricular neuroendoscopy

BACKGROUND

Individual planning of the entry point and the use of navigation has become more relevant in intraventricular neuroendoscopy. Navigated neuroendoscopic solutions are continuously improving.

OBJECTIVE

We describe experimentally measured accuracy and our first experience with augmented reality-enhanced navigated neuroendoscopy for intraventricular pathologies.

PATIENTS AND METHODS

Augmented reality-enhanced navigated endoscopy was tested for accuracy in an experimental setting. Therefore, a 3D-printed head model with a right parietal lesion was scanned with a thin-sliced computer tomography. Segmentation of the tumor lesion was performed using Scopis NovaPlan navigation software. An optical reference matrix is used to register the neuroendoscope's geometry and its field of view. The pre-planned ROI and trajectory are superimposed in the endoscopic image. The accuracy of the superimposed contour fitting on endoscopically visualized lesion was acquired by measuring the deviation of both midpoints to one another. The technique was subsequently used in 29 cases with CSF circulation pathologies. Navigation planning included defining the entry points, regions of interests and trajectories, superimposed as augmented reality on the endoscopic video screen during intervention. Patients were evaluated for postoperative imaging, reoperations, and possible complications.

RESULTS

The experimental setup revealed a deviation of the ROI's midpoint from the real target by 1.2 ± 0.4 mm. The clinical study included 18 cyst fenestrations, ten biopsies, seven endoscopic third ventriculostomies, six stent placements, and two shunt implantations, being eventually combined in some patients. In cases of cyst fenestrations postoperatively, the cyst volume was significantly reduced in all patients by mean of 47%. In biopsies, the diagnostic yield was 100%. Reoperations during a follow-up period of 11.4 ± 10.2 months were necessary in two cases. Complications included one postoperative hygroma and one insufficient fenestration.

CONCLUSIONS

Augmented reality-navigated neuroendoscopy is accurate and feasible to use in clinical application. By integrating relevant planning information directly into the endoscope's field of view, safety and efficacy for intraventricular neuroendoscopic surgery may be improved.

Endoscopic Third Ventriculostomy: Outcome Analysis of an Anterior Entry Point

BACKGROUND

Endoscopic third ventriculostomy (ETV) is a safe and effective treatment for hydrocephalus. An entry point located 4 cm anterior to the coronal suture, 3 cm anterior to Kocher point, and approximately 9 cm from the pupil at the midpupillary line has been used successfully for the last 20 years in our center. We aimed to evaluate this alternative anterior entry point routinely used for ETV, with or without concurrent endoscopic biopsy.

METHODS

Patients undergoing this proposed entry point were examined to evaluate its safety and efficacy. Factors such as patients' age, sex, hydrocephalus etiology, tumor location and pathology, and complication rate were examined through regression analyses to evaluate their impact on tumor biopsy and ETV success rates, and the need for subsequent ventricular shunting.

RESULTS

A total of 131 patients were included in the study. ETV was successful in 125 (95.4%) patients. Of these, 26 (19.8%) patients required a biopsy, which was successful in 21 (80.8%) cases. A complication was observed in 10 (7.6%) patients, with a trend toward complications occurring after ETV failure. There was no association between ETV success rate and patients' age (P = 0.5) or sex (P = 0.99).

CONCLUSIONS

The anterior entry point is a safe and effective method for ETV, especially when considering concurrent ventricular tumor biopsy. This entry point may be considered as a more minimally invasive procedure when using rigid endoscopy and may also eliminate the need for a flexible scope.

Third Ventricular Cerebrospinal Fluid Cysts of Thalamic Origin: Review of Embryologic Origin, Presentation, and Management Strategies with a Case Series

OBJECTIVE

Third ventricular cerebrospinal fluid (CSF) cysts of thalamic origin are rare. The objective of this study is to review their possible pathogenesis, clinical presentation, and management strategies with a case series describing management via an endoscopic approach with fenestration using a single burr-hole technique.

METHODS

A systematic literature review of reported cases of thalamic cysts was conducted with further meta-analysis of CSF cysts that involve the third ventricle. The mode of presentation, pathologic analysis, surgical management, and outcomes were analyzed.

RESULTS

Twenty-two studies reported between 1990 and 2013 described 42 cases of thalamic cyst. Of those cases, 13 were consistent with CSF cyst that originated in the thalamus and involved the third ventricle. Eight cases (61.5%) were treated via endoscopic fenestration, 2 cases (15.4%) were surgically drained, 2 cases (15.4%) were stereotactically aspirated, and 1 case (7.69%) was observed. The most common presenting symptoms were gait disturbance (26.3%) and headaches (26.3%) followed by tremors (15.8%) and weakness (15.8%). In our series, a single burr-hole technique was a successful definitive treatment, with an average period of 23 months.

CONCLUSIONS

Third ventricular CSF cysts of thalamic origin most commonly present with hydrocephalus. They can be safely definitively treated via endoscopic fenestration to the CSF circulation using a single burr-hole technique. Long-term follow-up shows lasting improvement in symptoms without reaccumulation of the cyst.

A multiport MR-compatible neuroendoscope: spanning the gap between rigid and flexible scopes

OBJECTIVE Rigid endoscopes enable minimally invasive access to the ventricular system; however, the operative field is limited to the instrument tip, necessitating rotation of the entire instrument and causing consequent tissue compression while reaching around corners. Although flexible endoscopes offer tip steerability to address this limitation, they are more difficult to control and provide fewer and smaller working channels. A middle ground between these instruments-a rigid endoscope that possesses multiple instrument ports (for example, one at the tip and one on the side)-is proposed in this article, and a prototype device is evaluated in the context of a third ventricular colloid cyst resection combined with septostomy. METHODS A prototype neuroendoscope was designed and fabricated to include 2 optical ports, one located at the instrument tip and one located laterally. Each optical port includes its own complementary metal-oxide semiconductor (CMOS) chip camera, light-emitting diode (LED) illumination, and working channels. The tip port incorporates a clear silicone optical window that provides 2 additional features. First, for enhanced safety during tool insertion, instruments can be initially seen inside the window before they extend from the scope tip. Second, the compliant tip can be pressed against tissue to enable visualization even in a blood-filled field. These capabilities were tested in fresh porcine brains. The image quality of the multiport endoscope was evaluated using test targets positioned at clinically relevant distances from each imaging port, comparing it with those of clinical rigid and flexible neuroendoscopes. Human cadaver testing was used to demonstrate third ventricular colloid cyst phantom resection through the tip port and a septostomy performed through the lateral port. To extend its utility in the treatment of periventricular tumors using MR-guided laser therapy, the device was designed to be MR compatible. Its functionality and compatibility inside a 3-T clinical scanner were also tested in a brain from a freshly euthanized female pig. RESULTS Testing in porcine brains confirmed the multiport endoscope's ability to visualize tissue in a blood-filled field and to operate inside a 3-T MRI scanner. Cadaver testing confirmed the device's utility in operating through both of its ports and performing combined third ventricular colloid cyst resection and septostomy with an endoscope rotation of less than 5°. CONCLUSIONS The proposed design provides freedom in selecting both the number and orientation of imaging and instrument ports, which can be customized for each ventricular pathological entity. The lightweight, easily manipulated device can provide added steerability while reducing the potential for the serious brain distortion that happens with rigid endoscope navigation. This capability would be particularly valuable in treating hydrocephalus, both primary and secondary (due to tumors, cysts, and so forth). Magnetic resonance compatibility can aid in endoscope-assisted ventricular aqueductal plasty and stenting, the management of multiloculated complex hydrocephalus, and postinflammatory hydrocephalus in which scarring obscures the ventricular anatomy.

Operative planning aid for optimal endoscopic third ventriculostomy entry points in pediatric cases

OBJECT

Endoscopic third ventriculostomy (ETV) uses anatomical spaces of the ventricular system to reach the third ventricle floor and create an alternative pathway for cerebrospinal fluid flow. Optimal ETV trajectories have been previously proposed in the literature, designed to grant access to the third ventricle floor without a displacement of eloquent periventricular structures. However, in hydrocephalus, there is a significant variability to the configuration of the ventricular system, implying that the optimal ETV trajectory and cranial entry point needs to be planned on a case-by-case basis. In the current study, we created a mathematical model, which tailors the optimal ETV entry point to the individual case by incorporating the ventricle dimensions.

METHODS

We retrospectively reviewed the imaging of 30 consecutive pediatric patients with varying degrees of ventriculomegaly. Three dimensional radioanatomical models were created using preoperative MRI scans to simulate the optimal ETV trajectory and entry point for each case. The surface location of cranial entry points for individual ETV trajectories was recorded as Cartesian coordinates centered at Bregma. The distance from the Bregma in the coronal plane represented as "x", and the distance from the coronal suture in the sagittal plane represented as "y". The correlation between the ventricle dimensions and the x, y coordinates were tested using linear regression models.

RESULTS

The distance of the optimal ETV entry point from the Bregma in the coronal plane ("x") and from the coronal suture in the sagittal plane ("y") correlated well with the frontal horn ratio (FHR). The coordinates for x and y were fitted along the following linear equations: x = 85.8 FHR-13.3 (r ² = 0.84, p < 0.001) and y = -69.6 FHR + 16.7 (r ² = 0.83, p < 0.001).

CONCLUSION

The surface location of the optimal cranial ETV entry point correlates well with the ventricle size. We provide the first model that can be used as a surgical planning aid for a case specific ETV entry site with the incorporation of the ventricle size.

Three-Dimensional Simulation of Collision-Free Paths for Combined Endoscopic Third Ventriculostomy and Pineal Region Tumor Biopsy: Implications for the Design Specifications of Future Flexible Endoscopic Instruments

BACKGROUND

Recent innovations to expand the scope of intraventricular neuroendoscopy have focused on transitioning multiple-incision procedures into single-corridor approaches. However, the successful adoption of these combined procedures requires minimizing the unwanted torques applied to surrounding healthy structures.

OBJECTIVE

To define the geometry of relevant anatomical structures in endoscopic third ventriculostomy (ETV) and pineal region tumor biopsy (ETB). Second, to determine the optimal instrument shaft path required for collision-free single burr hole combined ETV/ETB.

METHODS

Magnetic resonance and computed tomography data from 15 pediatric patients who underwent both ETV and ETB procedures between 2006 and 2014 was segmented by using the 3DSlicer software package to create virtual 3-D patient models. Anatomical regions of interest were measured including the foramen of Monro, the massa intermedia, the floor of the third ventricle, and the tumor margin. Utilizing the MATLAB software package, virtual dexterous instruments were inserted into the models and optimal dimensions were calculated.

RESULTS

The diameters of the foramen of Monro, massa intermedia (anterior-posterior, superior-inferior), anterior third ventricle, and tumor margin are 6.85, 4.01, 5.05, 14.2, and 28.5 mm, respectively. The average optimal burr placement was determined to be 22.5 mm anterior to the coronal and 30 mm lateral to the sagittal sutures. Optimal flexible instrument geometries for novel instruments were calculated.

CONCLUSION

We have established a platform for estimating the shape of novel curved dexterous instruments for collision-free targeting of multiple intraventricular points, which is both patient and tool specific and can be integrated with image guidance. These data will aid in developing novel dexterous instruments.

Endoscopic Histologic Mapping of a Mixed Germ Pineal Tumor

BACKGROUND

The accurate histologic diagnosis of germ cell tumors in the pineal region is a keystone for determining the best treatment strategy and prognosis. This situation poses a challenge for the neuropathologist, considering the lack of a standarized procedure to obtain biopsy samples, which results in few and small specimens, which are not suitable for diagnosis.

CASE DESCRIPTION

We report a case in which a pineal region mixed germ cell tumor was accurately diagnosed by performing histologic mapping through a dual burr-hole endoscopic approach. The technical pitfalls and other considerations necessary for obtaining an accurate diagnosis in this tumor subgroup are specified. In addition, the histologic analysis regarding the sampling technique used is described.

CONCLUSIONS

The supraorbital frontal endoscopic approach enables the surgeon to perform histologic mapping of pineal region tumors, allowing standarization of the procedure used to obtain the specimens. This approach could result in a more accurate diagnosis, especially in mixed germ cell neoplasms.

Endoscopic Versus Stereotactic Procedure for Pineal Tumor Biopsies: Focus on Overall Efficacy Rate

OBJECTIVE

The management of pineal region tumors depends on the histologic subtypes. Two minimally invasive techniques are available: endoscopic intraventricular biopsies and stereotactic biopsies. The recent Southampton and Lille series are the largest endoscopic and stereotactic series of pineal region tumors reporting both diagnosis rate and accuracy rate, respectively; we elaborated on these results in the light of other recent studies.

METHODS

We compared the Southampton endoscopic series with the Lille series, reflecting our 25-year experience of stereotactic biopsies, and the metadata of the literature for both approaches, as reported in the 2013 Report of the French-Speaking Society of Neurosurgery on tumors of the pineal region.

RESULTS

The results of the Southampton series match the endoscopic literature, in particular regarding the diagnosis rate (81.2%) and the perioperative morbidity (25.0%), and provide a rarely reported accuracy rate (78.6%), giving access to the overall efficacy rate (63.8%). The results of the Lille series match the stereotactic literature and show better results than endoscopic biopsies concerning the diagnosis rate (98.9%), accuracy rate (100%), resulting overall efficacy rate (98.9%), and perioperative morbidity (6.4%).

CONCLUSIONS

The Southampton and Lille series provide a unique opportunity to compare the overall efficacy rates of endoscopic and stereotactic biopsies, respectively. The stereotactic approach is safer and more effective for biopsies of pineal region tumors. To improve the safety and reliability of endoscopic biopsies, various methods have to be evaluated: alternative burr-hole strategies, use of neuronavigation, and a combination of flexible and rigid endoscopes.

Design optimization of neuroendoscopic continuum instruments for third ventriculostomy and tumor biopsy

A simulation-based approach to the design of procedure-specific dexterous neuroendoscopic continuum instruments for endoscopic third ventriculostomy and tumor biopsy is proposed. Given pre-operative CT and MRI images, the algorithm returns instrument design specifications including lengths, curvatures and alternative positions for the surgical incision while respecting anatomical boundaries. This methodology proposes a novel clinically-guided geometric representation of surgical targets specific to this indication. The additional constraints imposed by the presence of surgical trocars and endoscopes are also considered. Finally, we conclude with a clinical example to demonstrate the proposed approach.

Comparative analysis of endoscopic third ventriculostomy trajectories in pediatric cases

OBJECT

Endoscopic third ventriculostomy (ETV) has become a widely used method for CSF diversion when treating obstructive hydrocephalus. There are multiple recommendations on the transcortical ETV entry points, and some are specifically designed to provide a trajectory that avoids displacement to the eloquent periventricular structures. However, the morphology of the ventricular system is highly variable in hydrocephalus, and therefore a single best ETV trajectory may not be applicable to all cases. In the current study, 3 frequently quoted ETV entry points are compared in a cohort of pediatric cases with different degrees of ventriculomegaly.

METHODS

The images of 30 consecutive pediatric patients with varying degrees of ventriculomegaly were reviewed. Three-dimensional models were created using radiological analysis of anatomical detail and preoperative MRI scans in order to simulate 3 frequently quoted ETV trajectories for rigid neuroendoscopes. These trajectories were characterized based on the frequency and depth of tissue displacement to structures such as the fornix, caudate nucleus, genu of the internal capsule, and thalamus. The results are stratified based on ventricle size using the frontal horn ratio (FHR).

RESULTS

Eloquent areas were displaced in nearly all analyzed entry points (97%-100%). Stratifying the data based on ventricle size revealed that (1) lateral structures were more likely to be displaced in cases of intermediate ventriculomegaly (FHR < 0.4) using all 3 trajectories, whereas (2) the fornix was less likely to be displaced using more posteriorly placed trajectories for severe ventriculomegaly (FHR > 0.4). Allowing for minimal (2.4 mm) tissue displacement, a more posterior entry point was less traumatic for severe ventriculomegaly.

CONCLUSIONS

There is no single best ETV trajectory that fully avoids displacement of the eloquent periventricular structures. Larger ventricles require a more posteriorly placed entry point in order to reduce injury to the eloquent structures, and intermediate ventricles would dictate a medial entry point. These results suggest that the optimal entry point should be selected on a case-by-case basis after incorporating ventricle size.

Strategies to improve the quality of survival for childhood brain tumour survivors

BACKGROUND

Tumours of the central nervous system (CNS) are the most frequent solid tumours and the second most frequent type of cancer in children and adolescents. Overall survival has continuously improved in Germany, since an increasing number of patients have been treated according to standardised, multicentre, multimodal treatment recommendations, trials of the German Paediatric Brain Tumour Consortium (HIT-Network) or the International Society of Paediatric Oncology-Europe (SIOP-E) during the last decades. Today, two out of three patients survive. At least 8000 long-term childhood brain tumour survivors (CBTS) are currently living in Germany. They face lifelong disease- and treatment-related late effects (LE) and associated socioeconomic problems more than many other childhood cancer survivors (CCS).

METHOD

We review the LE and resulting special needs of this particular group of CCS.

RESULTS

Despite their increasing relevance for future treatment optimisation, neither the diversity of chronic and cumulative LE nor their pertinent risk factors and subsequent impact on quality of survival have yet been comprehensively addressed for CBTS treated according to HIT- or SIOP-E-protocols. Evidence-based information to empower survivors and stakeholders, as well as medical expertise to manage their individual health care, psychosocial and educational/vocational needs must still be generated and established.

CONCLUSION

The establishment of a long-term research- and care network in Germany shall contribute to a European platform, that aims at optimising CBTSs' transition into adulthood as resilient individuals with high quality of survival including optimal levels of activity, participation and acceptance by society.

Combined rigid and flexible endoscopy for tumors in the posterior third ventricle

OBJECT

Tumors leading to occlusion of the sylvian aqueduct include those of pineal, thalamic, and tectal origins. These tumors cause obstructive hydrocephalus and thus necessitate a CSF diversion procedure such as an endoscopic third ventriculostomy (ETV), often coupled with an endoscopic biopsy (EBX). Lesions located posterior to the massa intermedia pose a technical challenge, as the use of a rigid endoscope for performing both an ETV and EBX is limited. The authors describe their experience using a combined rigid and flexible endoscopic procedure through a single bur hole for both procedures in patients with posterior third ventricular tumors.

METHODS

Since January 2012, patients with posterior third ventricular tumors causing hydrocephalus underwent dual ETV and EBX procedures using the combined rigid-flexible endoscopic technique. Following institutional review board approval, data from clinical, radiological, surgical, and pathological records were retrospectively collected.

RESULTS

Six patients 3.5-53 years of age were included. Lesion locations included pineal (n = 3), fourth ventricle (n = 1), aqueduct (n = 1), and tectum (n = 1). The ETV and EBX were successful in all cases. Pathologies included pilocytic astrocytoma, pineoblastoma, ependymoma Grade II, germinoma, low-grade glioneural tumor, and atypical choroid plexus papilloma. One patient experienced an immediate postoperative intraventricular hemorrhage necessitating evacuation of the clots and resection of the tumor, eventually leading to the patient's death.

CONCLUSIONS

The authors recommend using a combined rigid-flexible endoscope for endoscopic third ventriculostomy and biopsy to approach posterior third ventricular tumors (behind the massa intermedia). This technique overcomes the limitations of using a rigid endoscope by reaching 2 distant regions.

Third ventricular schwannoma with hydrocephalus

Intraventricular schwannomas are rare, with only 20 cases reported in the literature to our knowledge, including two cases of schwannomas in the third ventricle. We report a 23-year-old man with a mass in the posterior portion of the third ventricle and obstructive hydrocephalus. The intraventricular mass was clearly visualized and removed by neuroendoscopic surgery, and endoscopic third ventriculostomy was simultaneously performed for the hydrocephalus. Histological and immunohistochemical assays of the surgical sample established a diagnosis of intraventricular schwannoma. The patient had a favourable outcome and no neurological deficits 1 year later. The schwannoma was distant from the choroid plexus, which supports the hypothesis that the schwannoma originated from ectopic neural crest cells that were displaced during embryogenesis.

A Novel Protocol of Continuous Navigation Guidance for Endoscopic Third Ventriculostomy

BACKGROUND:

Although considered a standard neurosurgical procedure, endoscopic third ventriculostomy (ETV) is associated with a relatively high complication rate that is predominantly related to malpositioning of the trajectory.

OBJECTIVE:

To develop an advanced navigation protocol for ETV, assess its possible benefits over commonly used ETV trajectories, and apply this protocol during surgery.

METHODS:

After development of our advanced protocol, the imaging data of 59 patients who underwent ETV without navigation guidance was transferred to our navigation software. An individualized endoscope trajectory was created according to our protocol in all cases. This trajectory was compared with 2 standard trajectories, especially with regard to the distance to relevant neuronal structures: a trajectory manually measured on preoperative radiological images, as performed in all 59 cases, and a trajectory resulting from a commonly used fixed coronal burr hole. Subsequently, we applied the protocol in 15 ETVs to assess the feasibility and procedural complications.

RESULTS:

Our individualized trajectory resulted in a significantly greater distance to the margins of the foramen of Monro, and the burr hole was located more posteriorly from the coronal suture in comparison with the standard trajectories. The advanced ETV technique was feasible in all 15 procedures, and no major complications occurred in any procedure. In 1 patient, a fornix contusion without clinical correlation was observed.

CONCLUSION:

Our data indicate that the proposed navigation protocol for ETV optimizes the distance of the endoscope to important neuronal structures. Continuous endoscope and puncture device guidance may further add to the safety of this procedure.

Endoscopic third ventriculostomy

Endoscopic third ventriculostomy (ETV) is considered as a treatment of choice for obstructive hydrocephalus. It is indicated in hydrocephalus secondary to congenital aqueductal stenosis, posterior third ventricle tumor, cerebellar infarct, Dandy-Walker malformation, vein of Galen aneurism, syringomyelia with or without Chiari malformation type I, intraventricular hematoma, post infective, normal pressure hydrocephalus, myelomeningocele, multiloculated hydrocephalus, encephalocele, posterior fossa tumor and craniosynostosis. It is also indicated in block shunt or slit ventricle syndrome. Proper Pre-operative imaging for detailed assessment of the posterior communicating arteries distance from mid line, presence or absence of Liliequist membrane or other membranes, located in the prepontine cistern is useful. Measurement of lumbar elastance and resistance can predict patency of cranial subarachnoid space and complex hydrocephalus, which decides an ultimate outcome. Water jet dissection is an effective technique of ETV in thick floor. Ultrasonic contact probe can be useful in selected patients. Intra-operative ventriculo-stomography could help in confirming the adequacy of endoscopic procedure, thereby facilitating the need for shunt. Intraoperative observations of the patent aqueduct and prepontine cistern scarring are predictors of the risk of ETV failure. Such patients may be considered for shunt surgery. Magnetic resonance ventriculography and cine phase contrast magnetic resonance imaging are effective in assessing subarachnoid space and stoma patency after ETV. Proper case selection, post-operative care including monitoring of ICP and need for external ventricular drain, repeated lumbar puncture and CSF drainage, Ommaya reservoir in selected patients could help to increase success rate and reduce complications. Most of the complications develop in an early post-operative, but fatal complications can develop late which indicate an importance of long term follow up.