Frameless neuronavigation in intracranial endoscopic neurosurgery

Hydrocephalus despite extra ventricular drainage in adults: a new description of multiloculated hydrocephalus

Multiloculated hydrocephalus constitutes a challenging pathology due to intracerebral haemorrhage or ventriculitis leading to iterative shunt revision frequently described in paediatric neurosurgery, but poorly reported in adults. Nevertheless, this potential complication of intraventricular haemorrhage, already drained in emergency, should be considered with special interest, as ideal management of cerebrospinal drainage remains debated in such situation. We thus report herein the case of intraventricular haemorrhage in an adult complicated of multiloculated hydrocephalus, as an illustrative plea for endoscopic surgery.

Exclusively endoscopic management of complicated pineal cysts in young children: Definitive treatment through single burr-hole technique

Background:

The management of complicated symptomatic pineal cysts in the pediatric population is challenging and variable. Surgical management may include treatment of hydrocephalus alone, or direct treatment of the cyst with or without direct hydrocephalus management. This is typically done through craniotomy-based microsurgical approaches to the pineal region or an endoscopic transventricular approach.

Methods:

We present a stepwise minimally invasive technique to treat complicated pineal cysts in young children associated with an obstructive hydrocephalus in a single procedure through third ventriculostomy combined with an intraventricular marsupialization of the pineal cyst through a single burr-hole using stereotactic navigation.

Results:

Two young patients with over 2 years of follow-up have done well without complication using this technique. Other literature reports for complex pineal cysts in pediatric patients are reviewed and this technique is not previously described for this population.

Conclusion:

Endoscopic third ventriculostomy and cyst marsupialization using a single burr-hole and stereotactic navigation for symptomatic or enlarging pineal cysts in children allow for minimally invasive management, a rapid recovery, short hospital stay, and durable outcome owed to redundant CSF flow pathways.

Management of Complex Hydrocephalus

Background

Management of complex/multiloculated/septated hydrocephalus is challenging. Neuroendoscopy has been well-established when compared to multiple shunt placements in management of multiloculated hydrocephalus (MH). The main aim of neuroendoscopy is to convert multiple locules into a single locule and drain it by either third ventriculostomy or ventriculoperitoneal shunt.

Objective

The objective is to reduce the number of surgical procedures and improve the quality of life. Neuroendoscopy avoids multiple shunt placement and need for revision of shunt.

Methods

Literature review regarding natural history, pathogenesis, classification and management of complex/uni/multiloculated hydrocephalus was extensively done and our minimal experience with these cases has been taken into consideration.

Conclusion

Neuroendoscopy when combined with frameless neuronavigation is reliable, accurate, and extremely useful in maintaining orientation and localizing the appropriate fenestration site in MH where anatomical landmarks are grossly distorted.

Augmented reality navigation for cranial biopsy and external ventricular drain insertion

OBJECTIVE

The aim of this study was to evaluate the accuracy (deviation from the target or intended path) and efficacy (insertion time) of an augmented reality surgical navigation (ARSN) system for insertion of biopsy needles and external ventricular drains (EVDs), two common neurosurgical procedures that require high precision.

METHODS

The hybrid operating room-based ARSN system, comprising a robotic C-arm with intraoperative cone-beam CT (CBCT) and integrated video tracking of the patient and instruments using nonobtrusive adhesive optical markers, was used. A 3D-printed skull phantom with a realistic gelatinous brain model containing air-filled ventricles and 2-mm spherical biopsy targets was obtained. After initial CBCT acquisition for target registration and planning, ARSN was used for 30 cranial biopsies and 10 EVD insertions. Needle positions were verified by CBCT.

RESULTS

The mean accuracy of the biopsy needle insertions (n = 30) was 0.8 mm ± 0.43 mm. The median path length was 39 mm (range 16-104 mm) and did not correlate to accuracy (p = 0.15). The median device insertion time was 149 seconds (range 87-233 seconds). The mean accuracy for the EVD insertions (n = 10) was 2.9 mm ± 0.8 mm at the tip with a 0.7° ± 0.5° angular deviation compared with the planned path, and the median insertion time was 188 seconds (range 135-400 seconds).

CONCLUSIONS

This study demonstrated that ARSN can be used for navigation of percutaneous cranial biopsies and EVDs with high accuracy and efficacy.

Benefits of Endoscopic Sheath in Intraventricular Neuroendoscopy: Technical Note

BACKGROUND

 The usefulness of the endoscopic sheath is underreported in the literature.

OBJECTIVE AND METHODS

 To explain the use of an endoscopic sheath and to highlight its benefits.

RESULTS

 In addition to protecting the surrounding brain parenchyma when inserting the endoscope, the endoscopic sheath is a very useful tool to retract neurovascular structures, achieve hemostasis, and create adequate working space within narrow ventricles. The sheath can be moved within the ventricular system, and the endoscope can be moved independently within the sheath. These movements represent all the advantages of the endoscopic sheath.

CONCLUSIONS

 We used an endoscopic sheath in ∼ 300 intraventricular neuroendoscopic procedures and consider the sheath an essential part of a ventriculoscopic system. Proper use of the sheath can help avoid or manage endoscopic complications.

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.

Robot-assisted procedures in pediatric neurosurgery

OBJECTIVE

During the last 3 decades, robotic technology has rapidly spread across several surgical fields due to the continuous evolution of its versatility, stability, dexterity, and haptic properties. Neurosurgery pioneered the development of robotics, with the aim of improving the quality of several procedures requiring a high degree of accuracy and safety. Moreover, robot-guided approaches are of special interest in pediatric patients, who often have altered anatomy and challenging relationships between the diseased and eloquent structures. Nevertheless, the use of robots has been rarely reported in children. In this work, the authors describe their experience using the ROSA device (Robotized Stereotactic Assistant) in the neurosurgical management of a pediatric population.

METHODS

Between 2011 and 2016, 116 children underwent ROSA-assisted procedures for a variety of diseases (epilepsy, brain tumors, intra- or extraventricular and tumor cysts, obstructive hydrocephalus, and movement and behavioral disorders). Each patient received accurate preoperative planning of optimal trajectories, intraoperative frameless registration, surgical treatment using specific instruments held by the robotic arm, and postoperative CT or MR imaging.

RESULTS

The authors performed 128 consecutive surgeries, including implantation of 386 electrodes for stereo-electroencephalography (36 procedures), neuroendoscopy (42 procedures), stereotactic biopsy (26 procedures), pallidotomy (12 procedures), shunt placement (6 procedures), deep brain stimulation procedures (3 procedures), and stereotactic cyst aspiration (3 procedures). For each procedure, the authors analyzed and discussed accuracy, timing, and complications.

CONCLUSIONS

To the best their knowledge, the authors present the largest reported series of pediatric neurosurgical cases assisted by robotic support. The ROSA system provided improved safety and feasibility of minimally invasive approaches, thus optimizing the surgical result, while minimizing postoperative morbidity.

Neuroendoscopy via an Extremely Narrow Foramen of Monro: A Case Report

Herein, safe and reliable neuroendoscopic biopsy via an extremely narrow foramen of Monro (ENFM) for a non-hydrocephalic patient with hypothalamic and pineal region tumors was successfully applied. A 17-year-old boy presented with hypothalamic manifestations attributed to hypothalamic and pineal region tumors. Small ventricles were seen. Intraoperatively, to advance different diameter steerable fiberscopes via ENFM, the third ventricle was flushed to induce a moment increase in the intraventricular pressure with subsequent dilatation of FM. Postoperative course was uneventful. Histopathological studies revealed a yolk sac tumor. Adjuvant therapy was applied. Follow-up neuroimaging disclosed marvellous improvement of the condition. His symptoms gradually improved.

Neuronavigation-guided endoscopy for intraventricular tumors in adult patients without hydrocephalus

Introduction

Intraventricular endoscopic operations are usually undertaken in patients with an enlarged ventricular system that provides good access to the ventricles, proper anatomic orientation and safety of maneuvers within the ventricles.

Aim

The preliminary assessment of the feasibility of endoscopic procedures in cases occurring without hydrocephalus.

Material and methods

Eleven patients with intraventricular tumor diagnosed in neuroimaging studies were included in the study. None of these cases was accompanied by hydrocephalus. Surgery was performed with a rigid neuroendoscope using a neuronavigation system. The purpose of the operation was tumor removal or histological verification.

Results

The colloid cyst of the third ventricle was removed in 5 patients. In 1 patient a glial-derived tumor adjacent to the interventricular foramen was partially resected. In 1 case a tumor of the lateral ventricle was totally removed, and in another case the resection of such a tumor was partial. In 2 cases, a biopsy of the tumor of the posterior portion of the third ventricle was undertaken, while in 1 case the biopsy was abandoned due to the risk of injury of structures surrounding interventricular foramen. There were no intraoperative or postoperative complications. None of the patients developed hydrocephalus in the long-term follow-up. The results of treatment in the study group did not differ from those obtained in patients operated on with hydrocephalus.

Conclusions

The presence of hydrocephalus is not necessary to perform endoscopic surgery. However, in each case it should be preceded by a thorough analysis of the feasibility of the endoscopic procedure and should be supported by a neuronavigation system.

Neuroendoscopic Intraventricular Biopsy in Children with Small Ventricles Using Frameless VarioGuide System

Endoscopic biopsy for intraventricular tumors in pediatric patients with small ventricles is a challenging procedure because of the risk of morbidity during the intraventricular approach. We describe the use of the VarioGuide system for intraventricular endoscopic biopsy in 9 consecutive pediatric patients with intraventricular lesions and small ventricular size. All patients had lesions in the anterior part of the third ventricle with a median frontal and occipital horn ratio of 0.33. Patients presented with growth failure (n = 4), visual disturbances (n = 4), and seizures (n = 1). The VarioGuide system consists of an ergonomic arm with 3 joints for gross adjustment. The 3 rotational joints on the distal side of the system are adjusted according to the angles of the planned trajectory. The endoscope is adjusted to the distal side of the VarioGuide and inserted through the ring, previously set for the diameter of the endoscope and for the planned trajectory. The accuracy of the trajectory and correct ventricular cannulation are confirmed under endoscopic guidance. The biopsy is carried out according to the standard technique. In all cases, the biopsy sample provided the definitive diagnosis. Diagnoses included germinomas in 4 patients, hamartoma in 1 patient, hypothalamic astrocytoma in 2 patients, and craniopharyngioma in 2 patients. The use of the VarioGuide system for intraventricular endoscopic biopsy is highly recommended for pediatric patients with small ventricle size. This technique may help minimize the risk of unnecessary brain damage during the entrance to small ventricles.

Dual-trajectory Approach for Simultaneous Cyst Fenestration and Endoscopic Third Ventriculostomy for Treatment of a Complex Third Ventricular Arachnoid Cyst

Objectives: We present a case of a multiloculated third ventricular arachnoid cyst to describe a novel technique for definitive management of these lesions via direct endoscopic fenestration and CSF diversion utilizing separate trajectories that offers superior visualization and avoids forniceal injury.

Methods and Results: We present a case of a 33-year-old woman with progressive headache and worsened vision, a known history of a multiloculated third-ventricular arachnoid cyst, and imaging findings consistent with cyst expansion and worsened obstructive hydrocephalus. We then describe the dual-trajectory approach for simultaneous cyst fenestration and endoscopic third ventriculostomy that ultimately resulted in successful treatment of her cyst and hydrocephalus.

Conclusions: Dual-trajectory endoscopic approach utilizing double burr holes should be considered when addressing lesions of the third ventricle causing obstructive hydrocephalus.

Intraoperative Conversion from Endoscopic to Open Transcortical-Transventricular Removal of Colloid Cysts as a Salvage Procedure

OBJECTIVE

 To describe the transcortical-transventricular as an intraoperative salvage procedure and its effect of operative time and outcome.

METHODS

 Thirty-three patients were included in the study. Twenty patients had an endoscopic operation, five had a transcortical-transventricular approach, and eight underwent an interhemispheric approach for resection. Based on common cyst location in the roof of the third ventricle, we propose a simple classification of surgical operative zones based on relationships defined by the anterior column of the fornix, the septal vein, and the medial atrial vein.

RESULTS

 Complete capsule removal was achieved in 35% of endoscopic operations, 100% of transcortical-transventricular operations, and 63% of the interhemispheric operations. Operative time was 176 minutes for endoscopic operations, whereas the operative time for cases that converted to the transcortical-transventricular approach was 190 minutes (p=0.39).

CONCLUSION

 A surgical-based classification of zones within the roof of the third ventricle that can be accessed with microsurgical techniques is proposed. Both endoscopic and microsurgical cyst aspiration and excision remain options. We believe that younger patients, patients with large cysts that fill the third ventricle, or those with recurrence after prior treatment would benefit from open transcortical excision as a safe and effective operative approach using modern image-guided systems. Consent was formally obtained or waived for all subjects present within this study.

Flexible endoscopy for management of intraventricular brain tumors in patients with small ventricles

OBJECT

Endoscopic surgery is generally withheld in patients with small ventricles due to difficulties in ventricular cannulation and intraventricular manipulation. The effectiveness of flexible endoscopy for management of intraventricular brain tumors in patients with small ventricles was evaluated.

METHODS

Forty-five patients who underwent endoscopic surgery with a flexible endoscope for intraventricular brain tumors were divided into small-ventricle and ventriculomegaly groups according to the frontal and occipital horn ratio (FOR). Retrospective review of these cases was performed and achievement of surgical goals and morbidity were assessed.

RESULTS

Among the 45 patients, there were 14 with small ventricles and 31 with ventriculomegaly. In the smallventricle group, targeted tumors were located in the suprasellar region in 12 patients and in the pineal region in 2. In the ventriculomegaly group, tumors were located in the pineal region in 15 patients, in the suprasellar region in 9, in the lateral ventricle in 4, in the midbrain in 2, and in the fourth ventricle in 1. In the small-ventricle group, ventricular cannulation was successful and the surgical goals were accomplished in all patients. In ventriculomegaly group, sampling of the tumor was not diagnostic due to intraoperative hemorrhage in 1 patient. There were no significant differences in the rate of achieving the surgical goals or the morbidity between the 2 groups.

CONCLUSIONS

Endoscopic surgery using a flexible endoscope is useful for management of intraventricular brain tumors in patients with small ventricles. A flexible endoscope allows excellent maneuverability in introducing the device into the lateral ventricle and manipulating through small ventricles.

Endoscopic fenestration at the splenial-habenular junctional area for symptomatic cavum and tumor at the foramen of Monro: case reports and anatomical review

The splenial-habenular junctional area is an alternative site for neuroendoscopic fenestration to divert CSF flow into the quadrigeminal cistern in cases in which endoscopic third ventriculostomy is not amenable. In some patients with obstructive hydrocephalus, the splenium of the corpus callosum can be elevated from the habenular complex. This exposes the membranous connection between the splenium and habenula, which can be fenestrated to divert the CSF flow into the quadrigeminal cistern. This technique can be performed in patients in whom the foramen of Monro or the third ventricle is blocked by a lesion. Here, the authors present 3 complex cases that were managed by neuronavigation-guided transventricular transcavum endoscopic fenestration of the splenial-habenular junctional area. These cases may increase the knowledge and understanding of the anatomy of this region.

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.

Neurosurgical oncology: advances in operative technologies and adjuncts

Modern glioma surgery has evolved around the central tenet of safely maximizing resection. Recent surgical adjuncts have focused on increasing the maximum extent of resection while minimizing risk to functional brain. Technologies such as cortical and subcortical stimulation mapping, intraoperative magnetic resonance imaging, functional neuronavigation, navigable intraoperative ultrasound, neuroendoscopy, and fluorescence-guided resection have been developed to augment the identification of tumor while preserving brain anatomy and function. However, whether these technologies offer additional long-term benefits to glioma patients remains to be determined. Here we review advances over the past decade in operative technologies that have offered the most promising benefits for glioblastoma patients.

Update on the management of pineal cysts: Case series and a review of the literature

OBJECTIVE

The natural history of pineal cysts still remains unclear. Incidental pineal cysts have become more common which raises the question of their management. Symptomatic pineal cysts may require a surgical solution but therapeutic indications have not yet been clearly established.

METHOD

From 1986 to 2012, 26 patients with pineal cysts were identified. Their medical records were retrospectively assessed focusing on the initial symptoms, imaging characteristics of the cyst, management strategy, operative technique and their complications, as well as the latest follow-up. A systematic review of the literature is also presented.

RESULTS

Twenty-six patients with pineal cysts were identified. The mean age was 23.5 years ranging from 7 to 49 years. Symptoms included intracranial hypertension with obstructive hydrocephalus in 18 cases and oculomotor anomalies in 12 cases. Two adult cases presented with non-specific headaches and did not require surgery. Twenty patients were operated via a suboccipital transtentorial approach with total removal of the cyst in 70% of the cases, while the remaining 4 cases were treated with an intraventricular endoscopic marsupialization associating a third ventriculostomy. Four patients required a preoperative ventriculo-peritoneal shunt due to life-threatening obstructive hydrocephalus. Overall, peri-operative mortality was nil. In the two non-operated patients, the cyst remained stable and no recurrences were observed in all operated patients with a mean follow-up of 144 months.

CONCLUSION

In the majority of incidental pineal cysts, a clinical and imaging follow-up is sufficient but occasionally not required especially in adults as very rare cases of increase in size have been reported.

An overview of the current surgical options for pineal region tumors

BACKGROUND

The list of pineal region tumors comprises an extensive array of pathological entities originating within one of the most complex areas of the intracranial cavity. With the exception of germ cell tumors, microsurgical excision is still nowadays the mainstay of management for most pineal region tumors.

METHODS

A search of the medical literature was conducted for publications addressing surgical options for management of pineal region tumors.

RESULTS

The infratentorial supracerebellar and the occipital transtentorial approaches are currently the most frequently used approaches for pineal region tumors. Endoscopic tumor biopsy with simultaneous endoscopic third ventriculostomy has emerged as a minimally invasive and highly effective strategy for initial management since it addresses the issue of tissue diagnosis and offers a solution for the associated hydrocephalus frequently encountered in these patients. Endoscope-assisted microsurgery and purely endoscopic excision have been reported in few reports and are likely to be more utilized in the future.

CONCLUSION

Preoperative planning is very crucial and should most importantly be individualized according to the anatomical features of the lesion and structures encountered during the procedure.

Neuroendoscopic resection of intraventricular tumors: a systematic outcomes analysis

Introduction. Though traditional microsurgical techniques are the gold standard for intraventricular tumor resection, the morbidity and invasiveness of microsurgical approaches to the ventricular system have galvanized interest in neuroendoscopic resection. We present a systematic review of the literature to provide a better understanding of the virtues and limitations of endoscopic tumor resection. Materials and Methods. 40 articles describing 668 endoscopic tumor resections were selected from the Pubmed database and reviewed. Results. Complete or near-complete resection was achieved in 75.0% of the patients. 9.9% of resected tumors recurred during the follow-up period, and procedure-related complications occurred in 20.8% of the procedures. Tumor size ≤ 2cm (P = 0.00146), the presence of a cystic tumor component (P < 0.0001), and the use of navigation or stereotactic tools during the procedure (P = 0.0003) were each independently associated with a greater likelihood of complete or near-complete tumor resection. Additionally, the complication rate was significantly higher for noncystic masses than for cystic ones (P < 0.0001). Discussion. Neuroendoscopic outcomes for intraventricular tumor resection are significantly better when performed on small, cystic tumors and when neural navigation or stereotaxy is used. Conclusion. Neuroendoscopic resection appears to be a safe and reliable treatment option for patients with intraventricular tumors of a particular morphology.

3D preoperative planning in the ER with OsiriX®: when there is no time for neuronavigation

The evaluation of patients in the emergency room department (ER) through more accurate imaging methods such as computed tomography (CT) has revolutionized their assistance in the early 80s. However, despite technical improvements seen during the last decade, surgical planning in the ER has not followed the development of image acquisition methods. The authors present their experience with DICOM image processing as a navigation method in the ER. The authors present 18 patients treated in the Emergency Department of the Hospital das Clínicas of the University of Sao Paulo. All patients were submitted to volumetric CT. We present patients with epidural hematomas, acute/subacute subdural hematomas and contusional hematomas. Using a specific program to analyze images in DICOM format (OsiriX^®), the authors performed the appropriate surgical planning. The use of 3D surgical planning made it possible to perform procedures more accurately and less invasively, enabling better postoperative outcomes. All sorts of neurosurgical emergency pathologies can be treated appropriately with no waste of time. The three-dimensional processing of images in the preoperative evaluation is easy and possible even within the emergency care. It should be used as a tool to reduce the surgical trauma and it may dispense methods of navigation in many cases.

Pineal cysts in children: case-based update

PURPOSE

Pineal cysts (PC) are found in children as often asymptomatic and without change in their size over the time. However, there are some debatable issues about their evolution and management in the pediatric population. The aim of the present paper is to update the information regarding pathogenesis, clinical presentation, and management of these lesions.

METHODS

All the pertinent literature was reviewed, and a meta-analysis of operated on cases was carried out. An illustrative case regarding the clinical evolution of a 13-year-old girl is also presented.

RESULTS AND CONCLUSIONS

PC are often asymptomatic and do not evolve over the time. However, since there is a certain risk of clinical and/or radiological progression, or even sudden and severe clinical onset (apoplexy), both a clinical and radiological follow-up is recommended in the pediatric age. The surgical excision is usually limited to symptomatic patients or to cases with clear radiological evolution.

The usefulness of electromagnetic neuronavigation in the pediatric neuroendoscopic surgery

OBJECTIVE

Neuroendoscopy is applied to various intracranial pathologic conditions. But this technique needs informations for the anatomy, critically. Neuronavigation makes the operation more safe, exact and lesser invasive procedures. But classical neuronavigation systems with rigid pinning fixations were difficult to apply to pediatric populations because of their thin and immature skull. Electromagnetic neuronavigation has used in the very young patients because it does not need rigid pinning fixations. The usefulness of electromagnetic neuronavigation is described through our experiences of neuroendoscopy for pediatric groups and reviews for several literatures.

METHODS

Between January 2007 and July 2011, nine pediatric patients were managed with endoscopic surgery using electromagnetic neuronavigation (AxiEM, Medtronics, USA). The patients were 4.0 years of mean age (4 months-12 years) and consisted of 8 boys and 1 girl. Totally, 11 endoscopic procedures were performed. The cases involving surgical outcomes were reviewed.

RESULTS

The goal of surgery was achieved successfully at the time of surgery, as confirmed by postoperative imaging. In 2 patients, each patient underwent re-operations due to the aggravation of the previous lesion. And one had transient mild third nerve palsy due to intraoperative manipulation and the others had no surgery related complication.

CONCLUSION

By using electromagnetic neuronavigation, neuroendoscopy was found to be a safe and effective technique. In conclusion, electromagnetic neuronavigation is a useful adjunct to neuroendoscopy in very young pediatric patients and an alternative to classical optical neuronavigation.

Neuronavigational neuroendoscopy--to be or not to be? An international pilot questionnaire-based study

OBJECTIVE

The almost age-old neuroendoscopy (NE) and neuronavigation (NN) in its twenties independently and indisputably have proved their high value as neurosurgical armamentarium and became even indispensable in some pathologies. However, nowadays the effectiveness of their simultaneous and combined application still is a matter of debate. The purpose of our pilot international, questionnaire-based survey was to assess the position of the opinion leaders in the field of neuroendoscopy worldwide toward the neuronavigational neuroendoscopy (NNNE).

METHODS

Within 3 months, a questionnaire with 17 questions was emailed repeatedly to 55 leading academic neuroendoscopic neurosurgeons from 50 institutions in 24 countries. The questionnaire covered aspects of personal and institutional experience in NE, NN, and NNNE, the most frequently treated pathologies by NNNE as well as inquiring the neurosurgeons' opinion for the importance and future of NNNE.

RESULTS

Forty-one questionnaires were returned (response rate = 74.6%). Six questionnaires were excluded because of incomplete or incorrect answers, leaving in the survey 35 respondents from 35 institutions in 18 countries. The less experienced neurosurgeons rely in higher degree on NNNE. Most frequently, NNNE is performed for hydrocephalus (procedures other than third ventriculostomy), transsphenoidal surgery, tumor biopsy, and cyst fenestration. Regardless their neurosurgical and NE experience, more than 75% of the respondents state that NNNE extends the range of neuroendoscopic procedures in their neurosurgical departments.

CONCLUSION

NNNE represents a valuable operative technique with excellent future prospects. NNNE extends the range of neuroendoscopic procedures, transforming some number of patients from "nonoperable" neuroendoscopically to suitable for neuroendoscopy.

Multiloculated hydrocephalus: a review of current problems in classification and treatment

PURPOSE

Loculated hydrocephalus is a condition in which discrete fluid-filled compartments form in or in relation to the ventricular system of the brain. Both uni- and multiloculated variants exist, with marked differences in outcome. However, several competing and seemingly interchangeable nomenclatures exist, and none address the pathophysiological basis of the condition. To clarify current treatment options, we carried out a review of the literature.

METHODS

A protocol describing search strategy and inclusion criteria was prepared in advance, and a search of MEDLINE, the Cochrane Database of Systematic Reviews, and the U.S. NIH ClinicalTrials.gov database was carried out with the search terms: "multicystic," "multiloculated," "multicompartment," "uniloculated," and "loculated." All were used in conjunction with the search term "hydrocephalus."

RESULTS

A single study with a control group was found. Remaining reports are purely case series. Research efforts are hampered by unclear and seemingly interchangeable nomenclatures, which makes comparison between studies difficult. There is a paucity of studies of high methodological quality concerning choice of treatment. At the case series level, evidence is in favor of the neuroendoscopic approach.

CONCLUSIONS

In order to ensure a consistent nomenclature as well as to guide future research, we propose a new system of classification for loculated hydrocephalus. It acknowledges the differences between uniloculated and multiloculated hydrocephalus, and goes beyond a pure anatomical model. For future research, it enables us to clearly characterize subgroups, which is essential if we are to advance our understanding and level of care for this challenging group of patients.

Pineal region tumors: simultaneous endoscopic third ventriculostomy and tumor biopsy

OBJECTIVE

Advances in neuroendoscopy have accommodated the development of intraventricular techniques that enhance the management of multiple disease processes. Tumors of the pineal region are amenable to endoscopic management in that they are accessible through the third ventricle and commonly cause hydrocephalus that can be alleviated by endoscopic third ventriculostomy (ETV). We describe the indications for and procedure of simultaneous ETV and biopsy of pineal region tumors, as well as the clinical features favoring different approaches to this procedure.

METHODS

The current literature on endoscopic management of pineal region tumors and the senior author's clinic experience with current techniques are reviewed.

RESULTS

Simultaneous tumor biopsy with ETV following initial evaluation with tumor markers and imaging can be accomplished using a single or dual entry approach. The choice of approach is dependent on multiple clinical factors including massa intermedia size, goals of surgery, degree of hydrocephalus, and the relationship between the tumor and massa intermedia.

CONCLUSIONS

Simultaneous ETV and tumor biopsy is a valuable technique that can be used to manage hydrocephalus and establish diagnosis in patients with newly diagnosed pineal region tumors, potentially avoiding traditional craniotomy and ventriculoperitoneal shunt placement. It is favored as an early step in the management of patients with marker-negative tumors.

Endoscopic management of complex hydrocephalus

BACKGROUND

The management of complex hydrocephalus is challenging. There is no consensus of the best treatment for isolated fourth ventricles, arachnoid cysts, and multiloculated hydrocephalus, although the avoidance of multiple shunts is desirable. We reviewed our experience with the use of endoscopic techniques to simplify complex multicompartmental hydrocephalus to determine its efficacy and safety.

METHODS

We performed a retrospective study of 114 consecutive adults and children undergoing endoscopic management of hydrocephalus by a single surgeon. The type of hydrocephalus and endoscopic procedure performed were recorded. The management algorithm for simplification of complex hydrocephalus is reviewed. All patients were followed up in the office or by telephone.

RESULTS

A total of 143 endoscopic procedures were performed on 114 patients with a mean age of 4.4 years (4 weeks to 32 years). The endoscopic procedures performed included cyst fenestration, septum pellucidotomy, endoscopic third ventriculostomy, aqueductal plasty with and without stent, and removal of cystercicotic cysts. Twenty-two (19.3%) patients had planned staged endoscopic procedures. Mean follow up was 65 months (range 33-122 months). Eighty-two (72%) patients were reduced to 1 shunt, shunt independence was achieved in 32 (28%) patients, and only 8 (11%) patients required shunt revision in the follow-up period.

CONCLUSIONS

Endoscopic simplification of complex hydrocephalus enables dependence on only a single shunt in the majority of patients, and a significant proportion achieve shunt independence. Endoscopic management should be considered before the placement of a second shunt, and some cases require staged endoscopic procedures to adequately communicate multicompartmental hydrocephalus.

The role of neuronavigation in intracranial endoscopic procedures

In occlusive hydrocephalus, cysts and some ventricular tumours, neuroendoscopy has replaced shunt operations and microsurgery. There is an ongoing discussion if neuronavigation should routinely accompany neuroendoscopy or if its use should be limited to selected cases. In this prospective clinical series, the role of neuronavigation during intracranial endoscopic procedures was investigated. In 126 consecutive endoscopic procedures (endoscopic third ventriculostomy, ETV, n = 65; tumour biopsy/resection, n = 36; non-tumourous cyst fenestration, n = 23; abscess aspiration and hematoma removal, n = 1 each), performed in 121 patients, neuronavigation was made available. After operation and videotape review, the surgeon had to categorize the role of neuronavigation: not beneficial; beneficial, but not essential; essential. Overall, neuronavigation was of value in more than 50% of the operations, but its value depended on the type of the procedure. Neuronavigation was beneficial, but not essential in 16 ETVs (24.6%), 19 tumour biopsies/resections (52.7%) and 14 cyst fenestrations (60.9%). Neuronavigation was essential in 1 ETV (2%), 11 tumour biopsies/resections (30.6%) and 8 cyst fenestrations (34.8%). Neuronavigation was not needed/not used in 48 ETVs (73.9%), 6 endoscopic tumour operations (16.7%) and 1 cyst fenestration (4.3%). For ETV, neuronavigation mostly is not required. In the majority of the remaining endoscopic procedures, however, neuronavigation is at least beneficial. This finding suggests integrating neuronavigation into the operative routine in endoscopic tumour operations and cyst fenestrations.

Supracerebellar infratentorial endoscopically controlled resection of pineal lesions: case series and operative technique

OBJECT

The heterogeneous clinical manifestations and operative characteristics of pathological entities in the pineal region represent a significant challenge in terms of patient selection and surgical approach. Traditional surgical options have included endoscopic transventricular resection; open supratentorial microsurgical approaches through the midline, choroidal fissure, lateral ventricle, and tentorium; and supracerebellar infratentorial (SCIT) approaches through the posterior fossa. The object of the current study was to review the preoperative characteristics and outcomes for a cohort of patients treated purely via the novel endoscopically controlled SCIT approach.

METHODS

A single-institution series of 9 consecutive patients (4 male and 5 female patients [10 total cases]; mean age 21 years, range 6-37 years) treated via the endoscopically controlled SCIT approach for a pathological entity in the pineal region was retrospectively reviewed. The mean follow-up time was 13.2 months.

RESULTS

The endoscopically controlled SCIT approach was successfully used to approach a variety of pineal lesions, including pineal cysts (6 patients), epidermoid tumor, WHO Grade II astrocytoma (initial biopsy and recurrence), and malignant mixed germ cell tumor (1 patient each). Gross-total resection and/or adequate cyst fenestration was achieved in 8 cases. Biopsy with conservative debulking was performed for the single case of low-grade astrocytoma and again at the time of recurrence. The mean preoperative tumor and cyst volumes were 9.9 ± 4.4 and 3.7 ± 3.2 cm(3), respectively. The mean operating times were 212 ± 71 minutes for tumor cases and 177 ± 72 minutes for cysts. Estimated blood loss was less than 150 ml for all cases. A single case (pineal cyst) was converted to an open microsurgical approach to enhance visualization. There were no operative complications, as well as no documented CSF leaks, additional CSF diversion procedures, or air emboli. Seven patients underwent concomitant third ventriculostomy into the quadrigeminal cistern. At the time of the last follow-up evaluation, all patients had a stable or improved modified Rankin Scale score.

CONCLUSIONS

The endoscopically controlled SCIT approach may be used for the biopsy and resection of appropriately selected solid tumors of the pineal region, in addition to the fenestration and/or resection of pineal cysts. Preoperative considerations include patient presentation, anticipated disease and vascularity, degree of local venous anatomical distortion, and selection of optimal paramedian trajectory.

Endoscopic Treatment of Isolated Fourth Ventricle

BACKGROUND:

Treatment of an isolated fourth ventricle should be considered when clinical symptoms or a significant mass effect occur.

OBJECTIVE:

To report clinical and radiographic outcomes after endoscopic transaqueductal or transcisternal stent placement into the fourth ventricle.

METHODS:

In 19 patients (age, 34th week of gestation-20 years; median age, 17.5 months), 22 endoscopic procedures were performed. Either an aqueductoplasty or, in cases with a supratentorially extended fourth ventricular component, an interventricular fenestration was performed. In all patients, a stent connected to the cerebrospinal fluid--diverting shunt was placed through the fenestration. Surgical complications and radiological and clinical outcomes are reported.

RESULTS:

All 19 patients had a mean follow-up of 26.9 ± 18.2 months. No persisting neurological complications were observed; 27.3% of patients experienced complete resolution of presenting symptoms, whereas 68.3% demonstrated partial resolution. Symptoms with short duration (&lt; 4 weeks) resolved completely, whereas long-standing symptoms partially improved. Short-term shunt complications (n = 2; insufficient catheter placement and subdural hygroma) and a need for long-term stent revisions (n = 3; stent retraction and shunt revision for other causes) were observed. The mean fourth ventricular volume was reduced after surgery (44.2 ± 25.8 to 23.1 ± 21.9 mL; P &lt; .01). Pontine diameter increased from 0.9 ± 0.3 to 1.2 ± 0.3 cm (P &lt; .01) after surgery. Both effects were still demonstrated on later radiological follow-up of 24.4 ± 14.2 months (fourth ventricular size, 24.7 ± 28.1 mL; P &lt; .01; pontine diameter, 1.3 ± 0.3 cm; P &lt; .01).

CONCLUSION:

The clinical and radiological outcomes after endoscopic aqueductoplasty and interventriculostomy in children with an isolated fourth ventricle indicate that this procedure is feasible, effective, and safe.

Supraorbital endoscopic approach to colloid cysts

BACKGROUND

Surgical approaches to colloid cysts of the third ventricle have evolved over time. In recent years, endoscopy has been recognized as an effective alternative to open surgery. The disadvantage of endoscopic treatment is the difficulty in controlling the adhesion of the cyst to the roof of the third ventricle and in obtaining complete removal of the cyst.

OBJECTIVE

To design and carry out a supraorbital approach to obtain a better viewing angle of the cyst and better control of the adhesion of the cyst to the roof of the third ventricle.

METHODS

From September 2005 to February 2008, we operated on 7 consecutive patients with colloid cysts in the third ventricle. All procedures were performed with the endoscopic supraorbital approach. The endoscopic procedure was performed with a rigid STORZ endoscope with 3 working channels. In 4 patients, the surgical supraorbital trajectory was planned with the help of a navigator.

RESULTS

The procedures lasted between 60 and 110 minutes, including the registration on the navigation system. Near-total removal of the cyst was achieved in 6 patients. All patients were discharged within 6 days.

CONCLUSION

Endoscopic treatment may be an effective and safe alternative to open surgical craniotomy. Our series shows that the endoscopic supraorbital endoscopic resection is a valuable approach to colloid cysts of the third ventricle.

Intracranial migration of bone dust after intraventricular neuroendoscopy complicating acute hydrocephalus and removal of bone dust: case report

OBJECTIVE

To present the first case of neuroendoscopic removal of migrated intraventricular bone dust and gel foam after intraventricular endoscopic surgery.

CLINICAL PRESENTATION

A 37-year-old man was admitted with a 2-year history of headache. Brain computed tomography (CT) scan and magnetic resonance imaging revealed a cavum vergae cyst. The patient was operated on by stereotactically guided endoscopic cyst fenestration with no intraoperative complications. Postoperative CT scan demonstrated regression of the cyst with no other pathological findings. Because of a postoperative fever, a lumbar puncture was performed after the brain CT scan to eliminate meningitis as a differential diagnosis. After the lumbar puncture, the patient complained of severe headache and vomiting followed by depression of consciousness. The follow-up CT scan showed the migration of bone dust from the burr hole site to the ventricular system and acute hydrocephalus. It is thought that the negative pressure gradient generated after the lumbar puncture might have been transmitted through the cerebrospinal fluid pathway, resulting in a suction effect and migration of the bone dust from the burr hole to the ventricle.

INTERVENTION

An urgent reexplorative endoscopic procedure was performed, and most of the bone dust and gel foam were removed. The patient recovered with complete resolution of the previous symptoms.

CONCLUSION

We propose not using autologous bone dust for closure of the burr holes after endoscopic intraventricular procedures; instead, alloplastic materials designed especially for burr hole closure may be used. However, our main recommendation is to use an external ventricular drainage, which is maintained closed but can be opened if necessary. In addition, lumbar puncture should be avoided in cases in which bone dust is used for the burr hole reconstruction without dural closure.

Small-ventricle neuroendoscopy for pediatric brain tumor management

OBJECT

The use of intraventricular endoscopy to achieve diagnosis or to resect accessible intraventricular or paraventricular tumors has been described in the literature in both adults and children. Traditionally, these techniques have not been used in patients with small ventricles due to the perceived risk of greater morbidity. The authors review their experience with the effectiveness and safety of endoscopic brain tumor management in children with small ventricles.

METHODS

Between July 2002 and December 2009, 24 children with endoscopically managed brain tumors were identified. Radiological images were reviewed by a radiologist blinded to study goals and clinical setting. Patients were categorized into small-ventricle and ventriculomegaly groups based on frontal and occipital horn ratio. Surgical success was defined a priori and analyzed between groups. Trends were identified in selected subgroups, including complications related to pathological diagnosis and surgeon experience.

RESULTS

Six children had small ventricles and 18 had ventriculomegaly. The ability to accomplish surgical goals was statistically equivalent in children with small ventricles and those with ventriculomegaly (83% vs 89%, respectively, p = 1.00). There were no complications in the small-ventricle cohort, but in the ventriculomegaly cohort there were 2 cases of postoperative hemorrhages and 1 case of infection. All hemorrhagic complications occurred in patients with high-grade tumor histopathological type and were early in the surgeon's endoscopic career.

CONCLUSIONS

Based on our experience, endoscopy should not be withheld in children with intraventricular tumors and small ventricles. Complications appear to be more dependent on tumor histopathological type and surgeon experience than ventricular size.

Stereotactically guided endoscopic port surgery for intraventricular tumor and colloid cyst resection

BACKGROUND

Intraventricular lesions are challenging entities that may be difficult to resect completely and safely, especially larger lesions with high vascularity or firm consistency.

OBJECTIVE

To assess the results of stereotactically guided endoscopic port (SEP) surgery for resection of colloid cysts and intraventricular tumors.

METHODS

The authors developed a minimally invasive microsurgical technique for intraventricular surgery using parallel endoscopy to visualize the lesion. Surgical resection was performed via an 11.5-mm transparent conduit (Neuroendoport) deployed under stereotactic guidance. Forty-seven consecutive cases were performed, and all had a minimum 1-year follow-up to assess the efficacy of the technique.

RESULTS

For colloid cysts, gross total resection was achieved in 31 (96.9%) of the 32 cases. The transient neurologic morbidity rate was 9.4%; no permanent neurologic morbidity occurred. For intraventricular tumors, gross or near total resection was achieved in 80% of cases. The transient neurological morbidity rate was 6.7%, and no permanent neurological morbidity occurred.

CONCLUSION

SEP surgery for colloid cysts and intraventricular tumors proved to be a safe and effective alternative to conventional microsurgical resection. This technique was not limited by the vascularity, friability, or size of any of the lesions.

Small ventricular access prior to rigid neuroendoscopy

The authors describe a new technique that may be used in conjunction with neuronavigation or freehand techniques for obtaining small ventricular access. Using this modification, the introducer sheath and trocar can be guided down a ventriculostomy tract with endoscopic visual control. With increasing focus on endoscopic therapies in patients without hydrocephalus, this adjunct, based on the authors' experience, may provide an additional technique for safely treating patients.

Pinless frameless electromagnetic image-guided neuroendoscopy in children

OBJECTIVES

Frameless imaged-guided neuronavigation is a useful adjunct to neuroendoscopy in paediatric patients, especially those with abnormal or complex ventricular or cyst anatomy. The development of electromagnetic neuronavigation has allowed the use of image-guided navigation in the very young patient in whom rigid fixation in cranial pins is contraindicated. The technique and the authors' experience of its use in a series of paediatric patients are described.

MATERIALS AND METHODS

Nineteen paediatric patients were treated with endoscopic surgery at two paediatric neurosurgery centres over a period of 18 months. A total of 29 endoscopic procedures were performed. The cases were reviewed and surgical outcomes assessed. In all of the cases, the goal of surgery was realised successfully at the time of surgery, as confirmed by post-operative imaging. No technical failures were encountered. None of the patients suffered worsened neurological function as a result of their procedures.

CONCLUSION

Pinless, frameless electromagnetic neuronavigation was found to be a safe technique that can supplement endoscopic surgery in the very young patient. It allows the use of direct navigation of the endoscope in patients that are unable safely to undergo rigid cranial fixation in pins due to young age or thin skull vaults. This has proven to be a useful adjunct to neuroendoscopy in the subset of infants who have complicated or distorted ventricular anatomy and can improve the safety and accuracy of this type of surgery. It is also an alternative to optical neuronavigation in conjunction with neuroendoscopy in patients of any age.

Transventricular Biopsy of Brain Tumor without Hydrocephalus Using Neuroendoscopy with Navigation

OBJECTIVE

It is usually difficult to perform the neuroendoscopic procedure in patients without hydrocephalus due to difficulties with ventricular cannulation. The purpose of this study was to find out the value of navigation guided neuroendoscopic biopsy in patients with peri- or intraventricular tumors without hydrocephalus.

METHODS

Six patients with brain tumors without hydrocephalus underwent navigation-guided neuroendoscopic biopsy. The procedure was indicated for verification of the histological diagnosis of the neoplasm, which was planned to be treated by chemotherapy and/or radiotherapy as the first line treatment, or establishment of the pathological diagnosis for further choice of the most appropriate treatment strategy.

RESULTS

Under the guidance of navigation, targeted lesion was successfully approached in all patients. Navigational tracking was especially helpful in entering small ventricles and in approaching the third ventricle through narrow foramen Monro. The histopathologic diagnosis was established in all of 6 patients : 2 germinomas, 2 astrocytomas, 1 dysembryoplastic neuroepithelial tumor and 1 pineocytoma. The tumor biopsy sites were pineal gland (n = 2), suprasellar area (n = 2), subcallosal area (n = 1) and thalamus (n = 1). There were no operative complications related to the endoscopic procedure.

CONCLUSION

Endoscopic biopsy or resection of peri- or intraventricular tumors in patients without hydrocephalus is feasible. Image-guided neuroendoscopic procedure improved the accuracy of the endoscopic approach and minimized brain trauma. The absence of ventriculomegaly in patients with brain tumor may not be served as a contraindication to endoscopic tumor biopsy.

Navigated endoscopic surgery for multiloculated hydrocephalus in children

OBJECT

Multiloculated hydrocephalus remains a challenging condition to treat in the pediatric hydrocephalic population. In a retrospective study, the authors reviewed their experience with navigated endoscopy to treat multiloculated hydrocephalus in children.

METHODS

Between April 2004 and September 2008, navigated endoscopic procedures were performed in 16 children with multiloculated hydrocephalus (median age 8 months, mean age 16.1 +/- 23.3 months). In all patients preoperative MR imaging was used for planning entry sites and trajectories of the endoscopic approach for cyst perforation and catheter positioning. Intraoperatively, a rigid endoscope was tracked by the navigation system. For all children the total number of operative procedures, navigated endoscopic procedures, implanted ventricular catheters, and drained compartments were recorded. In addition, postoperative complications and radiological follow-up data were analyzed.

RESULTS

In 16 children, a total of 91 procedures were performed to treat multiloculated hydrocephalus, including 29 navigated endoscopic surgeries. Finally, 21 navigated procedures involved 1 ventricular catheter and 8 involved 2 catheters for CSF diversion via the shunt. The average number of drained compartments in a shunt was 3.6 +/- 1.7 (range 2-9 compartments). In 9 patients (56%) a navigated endoscopic procedure constituted the last procedure within the follow-up period. One additional surgery was necessary in 3 patients (19%) after navigated endoscopy, and in 4 patients (25%) 2 further procedures were necessary after navigated endoscopy. Serial follow-up MR imaging demonstrated evidence of sufficient CSF diversion in all patients.

CONCLUSIONS

Navigated endoscopic surgery is a safe and effective treatment option for multiloculated hydrocephalus. The combination of the endoscopic approach and neuronavigation further refines preoperative planning and intraoperative orientation. The aim of treatment is to drain as many compartments as possible and as soon as possible, thereby establishing sufficient CSF drainage with few ventricular catheters in single shunt systems. Close clinical and radiological follow-up is mandatory because multiple revisions are likely.

Treatment of colloid cysts of the third ventricle through neuroendoscopic Nd: YAG laser stereotaxis

OBJECTIVE: Colloid cysts (IIIVT CC) are benign neuroepithelial cysts located in the anterior third ventricle. The authors propose the use of Nd:YAG laser stereotactic neuroendoscopic for guided resection of the third ventricle colloid cysts. METHOD: Eleven patients presented third ventricle colloid cysts and were treated by Nd:YAG laser guided with stereotactic endoscopy (n=7) , stereotactic endoscopy (n=3) or stereotactly guided puncture (n=1). The patients were followed prospectively (average 33 months, range 19-64 months). The clinical data, neuroimaging findings, hospitalization stay, outcomes and complications of the method were evaluated. RESULTS: All patients presented headache; six had papilledema, one had gait disturbance and one had third-nerve palsy. Neuroimaging showed hydrocephalus and a IIIVT CC with 14.4-mm mean diameter. After surgery all patients presented clinical and image improvement. Only two patients presented transient morbidities that were easily treated: One had diabetes insipidus that lasted for two days and was treated with a single dose of DDAVP, and another had chemical aseptic meningitis, probably due to the contact of the cyst content with the CSF. This patient was treated with antibiotics and corticosteroids with complete resolution of the problem without sequels. The other patients were discharged from the hospital 48 h after surgery. CONCLUSION: The stereotactic neuroendoscopy-guided procedure with Nd:YAG laser allowed the complete removal of the third ventricle colloid cysts, without definitive morbidities, sequels or recurrence of the lesion.

Application of electromagnetic technology to neuronavigation: a revolution in image-guided neurosurgery

Object

The authors investigated the practicality of electromagnetic neuronavigation in routine clinical use, and determined the applications for which it is at the advantage compared with other systems.

Methods

A magnetic field is generated encompassing the surgical volume. Devices containing miniaturized coils can be located within the field. The authors report on their experience in 150 cases performed with this technology.

Results

Electromagnetic neuronavigation was performed in 44 endoscopies, 42 ventriculoperitoneal shunt insertions for slit ventricles, 21 routine shunt insertions, 6 complex shunt insertions, 14 external ventricular drain placements for traumatic brain injury, 5 awake craniotomies, 5 Ommaya reservoir placements, and for 13 other indications. Satisfactory positioning of ventricular catheters was achieved in all cases. No particular changes to the operating theater set-up were required, and no significant interference from ferromagnetic instruments was experienced. Neurophysiological monitoring was not affected, nor did it affect electromagnetic guidance.

Conclusions

Neuronavigation enables safe, accurate surgery, and may ultimately reduce complications and improve outcome. Electromagnetic technology allows frameless, pinless, image-guided surgery, and can be used in all procedures for which neuronavigation is appropriate. This technology was found to be particularly advantageous compared with other technologies in cases in which freedom of head movement was helpful. Electromagnetic neuronavigation was therefore well suited to CSF diversion procedures, awake craniotomies, and cases in which rigid head fixation was undesirable, such as in neonates. This technology extends the application of neuronavigation to routine shunt placement and ventricular catheter placement in patients with traumatic brain injury.

Primary ventriculitis caused byStreptococcus intermedius

Streptococcus intermedius is increasingly being recognised as an aetiological agent in central nervous system infections. Primary ventriculitis caused by this organism has not been reported so far. We present a case of primary ventriculitis, which resulted in adhesions and multiloculated hydrocephalus, necessitating numerous surgical procedures to control it. No predisposing factor(s) could be identified. Although the organism could not be cultured from CSF, as he was already on antibiotic treatment, it could, however, be identified by 16S rDNA polymerase chain reaction on the CSF sample. It appears important to recognise this condition and to treat it aggressively to prevent complications such as adhesions and multiloculated hydrocephalus.

Electromagnetic-guided neuroendoscopy in the pediatric population

OBJECT

Image-guided neuroendoscopy is being increasingly used in an attempt to reduce the morbidity associated with surgery and to make navigation easier. It has a particularly useful application in the pediatric population for the treatment of conditions such as complex hydrocephalus and arachnoid cysts. However, its use has been limited by the requirement for rigid head fixation, which may be difficult in infants because of the immaturity of the skull. In addition there can be line-of-sight issues, which can be a problem with optical-based systems. Electromagnetic navigation has eliminated the requirement for head immobilization, and its successful use in the infant population has been reported. The authors present their series to date, define its role, and discuss its advantages over other forms of image-guided navigation.

METHODS

The authors used the electromagnetic StealthStation and software (Medtronic) for neuronavigation. A dynamic reference frame was attached to the head using an adhesive dressing. The patient was positioned without rigid fixation and was registered using a specially designed stylet. Navigation was through a stylet, which could be placed within the endoscope. Direct advantages were no rigid head fixation, the ability to maneuver the endoscope without the requirement for a bulky optical attachment, and no loss of navigation caused by user obstruction of reflective fiducial markers. The authors performed a total of 28 procedures in 23 patients. There were 9 arachnoid cyst marsupializations, 4 multiple fenestrations for multiloculated hydrocephalus, 4 aqueductal stenting procedures for encysted fourth ventricles, 5 endoscopic third ventriculostomies, 3 septum pellucidotomies, 2 tumor biopsies, and 1 tumor cyst decompression.

RESULTS

Electromagnetic navigation was successful in all cases. Two complications were reported: a subdural collection, requiring bur hole drainage after a successful fenestration of the arachnoid cyst and failed treatment of complex hydrocephalus requiring subsequent placement of a ventriculoperitoneal shunt.

CONCLUSIONS

The electromagnetic technology provides reliable image-guided endoscopy. It has several advantages over alternative forms of stereotaxy, and the ability to use it without the need for rigid head fixation makes it eminently suitable for the pediatric population. Its use and application in the treatment of a variety of different conditions has been demonstrated successfully.

A restricted neuroendoscopic approach for pathological diagnosis of intraventricular and paraventricular tumours

BACKGROUND

There is increasing interest in the use of neuroendoscopic techniques in neuro-oncology. We report our experience of endoscopic biopsy in patients harbouring intraventricular and paraventricular brain tumours in order to define criteria for the use of this technique.

METHODS

We identified 23 patients (aged 7-78 years) who underwent endoscopic biopsy for intraventricular or paraventricular lesions considered not suitable for surgical removal and too risky for a stereotactical approach. All of the biopsies were obtained with a flexible endoscope using a free-hand technique.

FINDINGS

In 16 patients specimens were adequate and led to a diagnosis; in three patients they were informative but not completely diagnostic; a pathological diagnosis was unavailable in four patients. In 13 patients with a lesion causing an obstruction of the aqueduct, a third ventriculostomy was performed during the same procedure; in one patient with a lesion occluding the Monro foramen, a septostomy was done, while in another case multiple cystostomies were required. No specific complications were observed, either clinically or radiologically, in particular no major bleeding occurred.

CONCLUSIONS

In our experience, endoscopic biopsy could provide a pathological diagnosis in 19 of 23 patients. Endoscopic biopsy sampling sufficient tissue should be considered as the first choice in selected lesions that are otherwise difficult to approach.

Chiari I malformation without hydrocephalus: acute intracranial hypertension managed with endoscopic third ventriculostomy (ETV)

INTRODUCTION

In a small subset of patients, a Chiari malformation can present with signs of raised intracranial pressure due to obstruction of cerebrospinal fluid flow or with the raised intracranial pressure as the primary pathological driving force resulting in tonsillar herniation.

CASE REPORT

The authors report a unique case in a 14-year-old boy with a Chiari malformation type 1-syringomyelia complex with slit-like ventricles. We have successfully managed the acute presentation of raised intracranial pressure, mimicking idiopathic intracranial hypertension, utilizing a frameless stereotactic image-navigated endoscopic third ventriculostomy alone. We present the preoperative and postoperative radiological and ophthalmological findings and discuss the possible mechanisms related to the pathophysiology and treatment in this case. The patient's symptoms resolved immediately postoperatively with resolution of papilledema. At 18-month follow-up, the patient remains entirely asymptomatic and the need for craniovertebral decompression appears to have been obviated.

CONCLUSION

We advocate that in the Chiari malformation type 1-syringomyelia complex with normal or small ventricles, patients presenting with isolated signs and symptoms of raised intracranial pressure alone can be safely and effectively managed with an electromagnetic-guided stereotactic endoscopic third ventriculostomy as a primary treatment option.

Neuroendoscopic foraminal plasty of foramen of Monro

OBJECTIVES

The aims of this study were to describe and analyze the technique of neuroendoscopic foraminal plasty of foramen of Monro (NEFPFMO) in the treatment of isolated unilateral hydrocephalus (IUH) due to membranous occlusion, to evaluate its efficacy and safety, and to define the benefits of neuronavigational guidance of the procedure.

MATERIALS AND METHODS

Two symptomatic neonates with IUH, as a result of congenital atresia of foramen of Monro, underwent NEFPFMO plus neuroendoscopic septostomy in the first case and neuronavigational guidance in the second one. Clinical results were excellent in both neonates. The postoperative ventricular size decreased and the progressive IUH changed to the state of arrested hydrocephalus. The neuronavigation was precise.

CONCLUSION

NEFPFMO should be the primary treatment option in patients with IUH due to membranous occlusion of foramen of Monro. It reestablishes natural anatomical communication and provides real physiological cerebrospinal fluid flow. Neuronavigation is a useful adjunct of NEFPFMO.

2D/3D registration of endoscopic ultrasound to CT volume data

This paper describes a computer-aided navigation system using image fusion to support endoscopic interventions such as the accurate collection of biopsy specimens. An endoscope provides the physician with real-time ultrasound (US) and a video image. An image slice that corresponds to the corresponding image from the US scan head is derived from a preoperative computed tomography (CT) or magnetic resonance image volume data set using oblique reformatting and displayed side by side with the US image. The position of the image acquired by the US scan head is determined by a miniaturized electromagnetic tracking system (EMTS) after calibrating the endoscope's scan head. The transformation between the patient coordinate system and the preoperative data set is calculated using a 2D/3D registration. This is achieved by calibrating an intraoperative interventional CT slice with an optical tracking system (OTS) using the same algorithm as for the US calibration. The slice is then used for 2D/3D registration with the coordinate system of the preoperative volume. The fiducial registration error (FRE) for the US calibration was 2.0 mm +/- 0.4 mm; the interventional CT FRE was 0.36 +/- 0.12 mm; and the 2D/3D registration target registration error (TRE) was 1.8 +/- 0.3 mm. The point-to-point registration between the OTS and the EMTS had an FRE of 0.9 +/- 0.4 mm. Finally, we found an overall TRE for the complete system to be 3.9 +/- 0.6 mm.

Endoscopic resection of cavernoma of foramen of Monro in a patient with familial multiple cavernomatosis

Intraventricular cavernomas are extremely infrequent and only 11 cases of cavernous hemangioma to occur at the foramen of Monro have been reported in the literature. This 56 years old patient was admitted with progressive and intractable headache of 10 days of evolution. He was known to suffer familial multiple cavernomatosis. Magnetic resonance imaging (MRI), revealed obstructive hydrocephalus due to a cavernoma located in the area of the left foramen of Monro. Under neuronavigation guidance, complete endoscopic resection of the cavernoma was performed and normal ventricular size achieved. The patient experienced transient recent memory loss that resolved within a month after surgery. In the literature attempted endoscopic resection is reported to be abandoned due to bleeding and ineffectiveness of piecemeal endoscopic resection. In this case, the multiplicity of the lesions made it advisable to resect the lesion endoscopically, to avoid an open procedure in a patient with multiple potentially surgical lesions. Endoscopic resection was uneventful with easy control of bleeding with irrigation, suction, and bipolar coagulation despite dense vascular appearance of the lesion. During the procedure, precise visualization of the vascular structures around the foramen of Monro allowed complete resection with satisfactory control of the instruments. To the best of the authors' knowledge, this is the first published cavernoma of foramen of Monro successfully resected using an endoscopic approach.

Endoscopic management of arachnoid cysts: an advancing technique

OBJECT

Neuroendoscopy is increasingly used in neurosurgery. The authors report their evolving experience in the management of arachnoid cysts using endoscopic techniques and, more recently, the use of these techniques in combination with neuronavigation systems. The aim of this study was to assess the efficacy of this approach and the factors influencing the final outcome of treatment.

METHODS

The authors reviewed 39 cases in which patients were treated endoscopically for intracranial arachnoid cysts over a period of 8 years. The indications and techniques used were reviewed and the surgical outcomes assessed. There was no death or significant morbidity associated with the procedure. Thirty-six patients had resolution or improvement of symptoms and only three required insertion of a shunt.

CONCLUSIONS

The treatment of arachnoid cysts has been revolutionized by the introduction of endoscopic techniques. The authors conclude on the basis of their experience that in most cases the combination of neuroendoscopy and frameless navigation represents a safe and reliable modality for treating this benign intracranial entity with minimal surgical trauma. The specific approach should be based on the individual characteristics of each cyst and the surgeon's experience.