Anomalies and variants of the endoscopic anatomy for third ventriculostomy

Stereotactic anatomy of the third ventricle

PURPOSE

Endoscopic third ventriculostomy (ETV) is a surgical procedure that can lead to complications and requires detailed preoperative planning. This study aimed to provide a more accurate understanding of the anatomy of the third ventricle and the location of important structures to improve the safety and success of ETV.

METHODS

We measured the stereotactic coordinates of six points of interest relative to a predefined stereotactic reference point in 23 cadaver brain hemi-sections, 200 normal brain magnetic resonance imaging (MRI) scans, and 24 hydrocephalic brain MRI scans. The measurements were statistically analyzed, and comparisons were made.

RESULTS

We found some statistically significant differences between genders in MRIs from healthy subjects. We also found statistically significant differences between MRIs from healthy subjects and both cadaver brains and MRIs with hydrocephalus, though their magnitude is very small and not clinically relevant. Some stereotactic points were more posteriorly and inferiorly located in cadaver brains, particularly the infundibular recess and the basilar artery. It was found that all stereotactic points studied were more posteriorly located in brains with hydrocephalus.

CONCLUSION

The study describes periventricular structures in cadaver brains and MRI scans from healthy and hydrocephalic subjects, which can guide neurosurgeons in planning surgical approaches to the third ventricle. Overall, the study contributes to understanding ETV and provides insights for improving its safety and efficacy. The findings also support that practicing on cadaveric brains can still provide valuable information and is valid for study and training of neurosurgeons unfamiliar with the ETV technique.

Minimally invasive third ventriculostomy with stereotactic internal shunt placement for the treatment of tumor-associated noncommunicating hydrocephalus

BACKGROUND

Intracranial tumors can cause obstructive hydrocephalus (OH). Most often, symptomatic treatment is pursued through ventriculoperitoneal shunt (VS) or endoscopic third ventriculostomy (ETV). In this study, we propose stereotactic third ventriculostomy with internal shunt placement (sTVIP) as an alternative treatment option and assess its safety and efficacy.

METHODS

In this single-center, retrospective analysis, clinical symptoms, procedure-related complications, and revision-free survival of all patients with OH due to tumor formations treated by sTVIP between January 2010 and December 2021 were evaluated.

RESULTS

Clinical records of thirty-eight patients (11 female, 27 male) with a mean age of 40 years (range 5-88) were analyzed. OH was predominantly (in 92% of patients) caused by primary brain tumors (with exception of 3 cases with metastases). Following sTVIP, 74.2% of patients experienced symptomatic improvement. Preoperative headache was a significant predictor of postoperative symptomatic improvement (OR 26.25; 95% CI 4.1-521.1; p = 0.0036). Asymptomatic hemorrhage was detected along the stereotactic trajectory in 2 cases (5.3%). One patient required local revision due to CSF fistula (2.6%); another patient had to undergo secondary surgery to connect the catheter to a valve/abdominal catheter due to CSF malabsorption. However, in the remaining 37 patients, shunt independence was maintained during a median follow-up period of 12 months (IQR 3-32 months). No surgery-related mortality was observed.

CONCLUSIONS

sTVIP led to a significant symptom control and was associated with low operative morbidity, along with a high rate of ventriculoperitoneal shunt independency during the follow-up period. Therefore, sTVIP constitutes a highly effective and minimally invasive treatment option for tumor-associated obstructive hydrocephalus, even in cases with a narrow prepontine interval.

Extra-Axial Third Ventriculostomy Through Lamina Terminalis with Multiple Cisternostomies - Rescue Surgery for Patients with Failed Shunt Surgeries and Hydrocephalus

Background and Aim

Contemporary management of hydrocephalus involves various modes of cerebrospinal fluid (CSF) diversion, including shunt surgery and endoscopic ventriculostomy. However, there are times when either of these procedures have either failed or are not feasible. Highly invasive procedures aimed at internal CSF have been described previously, which, with the aid of modern microsurgical techniques, can be attempted in cases with very limited options. Our aim was to study the utility of extra-axial third ventriculostomy via lamina terminalis fenestration with multiple cisternostomies in the treatment of failed hydrocephalus.

Materials and Methods

Forty-five patients with hydrocephalus were operated for extra-axial trans-lamina terminalis third ventriculostomy with multiple cisternostomies from January 2017 to January 2019. A minimally invasive supraorbital craniotomy was performed with subfrontal fenestration of the lamina terminalis and trans-lamina terminalis fenestration of the floor of the third ventricle with multiple cisternostomies including the optico-carotid cistern and opening of the Liliequist membrane.

Results

Tuberculous meningitis was the most common etiology in the series, and multiple shunt procedures and incompatible CSF profiles were the most common reasons that necessitated this alternate rescue procedure. At a mean follow-up of 6 months, no patient required a revision shunt surgery. There was one death due to cardiac failure with anasarca, unrelated to the procedure.

Conclusions

Extra-axial trans-lamina terminalis ventriculostomy with cisternostomies can safely be performed using minimally invasive micro-neurosurgical techniques, adding to the armamentarium of neurosurgeons in the management of complex cases of hydrocephalus.

Endoscopic third ventriculostomy complications: avoidance and management in a stepwise manner

Background

Various complications of endoscopic third ventriculostomy (ETV) have been described. One has to recognize these complications and learn how to avoid them.

Methods

We performed a literature review regarding the reported complications of ETV procedures discussed in a correlated manner with the surgical steps. Furthermore, we reviewed the technical notes described by experienced neuroendoscopists, including surgical indications, choice of the endoscopic entry point and trajectory, anatomic orientation, proper bleeding control and tight closure, to prevent and deal with such complications.

Results and conclusion

A lesson learned that comprehensive knowledge of ventricular anatomy with proper orientation by studying the preoperative images is mandatory and one should be aware of all complication types and rates.

Anatomic variations of the floor of the third ventricle: Surgical implications for endoscopic third ventriculostomy

Background:

Endoscopic third ventriculostomy (ETV) is currently used as a treatment for different types of hydrocephalus. However, the anatomical endoscopic variants of the third ventricle floor (3VF), as well as their surgical implications, have been underrated. The anatomic variations of the 3VF can influence the technique and the success rate of the ETV. The purpose of this article is to describe the anatomical variations of 3VF, assess their incidence, and discuss the implications for ETV.

Methods:

Intraoperative videos of 216 patients who underwent ETV between January 2012 and February 2020 at Hospital Infantil Universitario de San José, Bogotá, Colombia were reviewed. One hundred and eighty patients who met the criteria to demonstrate the type of 3VF were selected.

Results:

3VF types were classified as follows: (1) Thinned, (2) thickened, (3) partially erased, (4) globular or herniated, and (5) narrowed.

Conclusion:

Knowledge of anatomical variations of the 3VF is paramount for ETV and it influences the success rate of the procedure.

Endoscopic third ventriculostomy in obstructive hydrocephalus: A case report and analysis of operative technique

BACKGROUND

The endoscopic third ventriculostomy (ETV) is a neuroendoscopical procedure that represents a more suitable alternative to the extracranial shunting. It consists of fenestrating the floor of the third ventricle and thus establishing a free flow of the cerebrospinal fluid from the ventricles to the site of resorption in the subarachnoid space. It offers a more physiological solution and a chance at a shunt-free life for children with hydrocephalus. The main indication for the procedure is obstructive hydrocephalus, however, it can also be useful in patients with other forms of hydrocephalus.

CASE SUMMARY

We present a treatment flow of a 9-year-old patient, diagnosed with an obstructive hydrocephalus due to tectal glioma that was successfully treated with an ETV. We review the important factors influencing the success rate such as age, aetiology, shunt history, preoperative planning and visualisation of the basilar artery.

CONCLUSION

Even though the ETV effectively controls obstructive hydrocephalus in more than 75% of all cases, the overall success rate of the procedure varies and could be approved by the correct preoperative patient selection.

[Neuroendoscopic interventions using an Nd-YAG laser for multilevel hydrocephalus: treatment results for 10 patients]

INTRODUCTION

Treatment or multilevel hydrocephalus is a complex problem. Neuroendoscopic interventions, make it possible to combine minimal invasiveness with the possibility of fenestration of several cysts during one procedure and thereby eliminate multi-level occlusion. We present our the experience of using a neodymium YAG laser (Nd-YAG laser) as an additional tool to improve the treatment results of patients with non-communicating hydrocephalus.

MATERIAL AND METHODS

This study included 10 patients aged from 5 months to 8 years who underwent endoscopic interventions with the use of rigid endoscope with frameless navigation. A surgical laser with a radiation wavelength of 1.064 μm was used as the main tool for fenestrating the walls of the cysts.

RESULTS

13 endoscopic laser interventions were performed in 10 patients with multilevel hydrocephalus. In 3 children, the two-stage treatment was chosen in due to the impossibility of simultaneous fenestration of all cysts. The interval between procedures was 1 month in two cases and 11 months in one case. We managed to compensate for cerebrospinal fluid disturbances in each patient, positive dynamics in the condition was noted. The duration of postoperative stay averaged 8 days (from 4 to 13 days). There were no deaths in the study group. All patients were discharged in good condition. Average follow-up duration was 14 months (from 8 to 25 months). During the observation, the condition of the patients remained stable; there was no need for repeated operations.

CONCLUSION

Combined use of bypass operations, endoscopic techniques and neural navigation may improve the results of treatment of patients with multilevel hydrocephalus. Data presented in this article demonstrates the safety and effectiveness of the clinical use of laser radiation as an additional tool for interventions in patients with this condition.

Interhypothalamic adhesion as a cause of aborted third-ventriculostomy: neuroradiological and neuroendoscopic considerations in a pediatric case

BACKGROUND

Interhypothalamic adhesions (IHA) are horizontally oriented parenchymal bands of tissue connecting the medial hypothalamic regions across the third ventricle. They can be assessed with high resolution magnetic resonance (MR) techniques.

CASE DESCRIPTION

We report MR and neuroendoscopic features of IHA in a 3-year old boy without symptoms referable to the hypothalamus. He presented with obstructive hydrocephalus secondary to posterior fossa tumor. An endoscopic third ventriculostomy (ETV) was attempted but was not performed because of the presence of a very thick IHA, that prevented approach to the floor of the third ventricle. During the procedure the patient also experienced supraventricular tachicardia. The procedure was aborted and an external ventricular drainage was left in the ventricles, until resolution of hydrocephalus after posterior fossa surgery. To the best of our knowledge, no study has previously described in detail endoscopic images of IHA.

CONCLUSIONS

MR imaging allows to preoperatively identify most anatomic anomalies of the ventricular system and of the floor of the third ventricle. However an IHA that may prevent an approach to the floor of the third ventricle due to his thickness, may be missed. This can be recognized only on direct vision, underlining the importance of endoscopy in neurosurgery.

Lo studio neuroradiologico dell'idrocefalo Valutazione pre- e post-chirurgica con particolare riguardo all'approccio endoscopico

La studio neuroradiologico dell'idrocefalo nell'epoca dei trattamenti chirurgici endoscopici si arricchisce di nuovi quesiti e di nuovi segni.

Se la TC mantiene la sua validità nella prima diagnosi di idrocefalo e nello studio delle complicanze immediate dei trattamenti endoscopici, perde il ruolo preminente che aveva nei controlli post-operatori a medio e lungo termine.

La RM è l'esame di scelta in fase prechirurgica, per la pianificazione dell'intervento endoscopico, con lo studio dell'anatomia della regione del III ventricolo. Lo stesso discorso vale per i controlli post-chirurgici delle terzoventricolostomie, vista la maggiore importanza del dato funzionale della pervietà della stomia rispetto al semplice dato morfologico della variazione della volumetria ventricolare.

Gli studi quantitativi con sequenze specifiche per il flusso e con sincronizzazione cardiaca, eventualmente abbinati alla funzione cine, sono indubbiamente accurati, raffinati ed eleganti, ma non indispensabili, nella pratica clinica, per lo studio del flusso liquorale; infatti non si è ancora dimostrata una loro significativa maggiore sensibilità rispetto ai dati qualitativi (flusso si/flusso no) ottenibili con normali sequenze FSE e TSE T2 w.

Visualization of Liliequist's membrane prior to endoscopic third ventriculostomy

PURPOSE

Endoscopic third ventriculostomy (ETV) is an effective treatment in patients with obstructive hydrocephalus caused by aqueductal stenosis. Operative failure may occur if an unnoticed membrane below the floor of the third ventricle is present, such as Liliequist's membrane (LM). To analyze how often LM can be visualized by high-resolution heavily T2-weighted 3D-MRI prior to ETV, and to find out potential reasons for diagnostic failure.

MATERIALS AND METHODS

Preoperative 3D-MR images of 37 consecutive patients (19 female, median 42 years) were retrospectively analyzed. Visualization of three LM segments (sellar, diencephalic, mesencephalic), dimensions of the space below the third ventricle, and extent of hydrocephalus were measured. Image quality was scored (score 1[poor] to 3[excellent]). Preoperative imaging findings were compared with intraoperative findings.

RESULTS

Patients were subdivided into group 1 (no segment of LM identified, n = 18), and group 2 (at least one segment of LM was identified, n = 19). The sellar segment of LM was most often positively identified (10 out of 19 cases). The mean distance between the pons and the sella/clivus was significantly shorter in group 1 than in group 2 (3.7 vs. 6.2 mm; p < 0.01). Other variables, such as the distance between tip of the pons and the mamillary bodies as well as the image quality, were not significantly different between both groups. Intraoperatively, LM was present in 78 % of group 2 patients, and in 28 % of group 1 patients, respectively (p < 0.03).

CONCLUSIONS

LM can be detected in about half of patients prior to ETV. Reduced PSD influences visualization of LM.

Endoscopic third ventriculostomy - effectiveness of the procedure for obstructive hydrocephalus with different etiology in adults

Introduction

After a time of domination of shunt placement, endoscopic third ventriculostomy (ETV) has been increasingly applied in treatment of obstructive hydrocephalus.

Aim

To assess the effectiveness of ETV in treatment of adults with three-ventricle hydrocephalus of different etiology.

Material and methods

Ninety-six patients with obstructive hydrocephalus were studied: 24 with primary aqueductal stenosis, 61 with brain tumor, and 2 with basilar tip aneurysm. In 9 patients the etiology of hydrocephalus remained undetermined. The assessment of treatment results was based on clinical and radiological criteria.

Results

Clinical improvement was observed in 74 (77.1%) patients, and radiological improvement in 52 (54.2%). One patient died. Follow-up of 24 patients with primary aqueductal stenosis has shown that in 20 (83.3%) of them clinical improvement has been stable, and in 14 (58.3%) radiological improvement has been observed. Two patients required shunt placement due to hydrocephalus recurrence 12–24 months after the ETV procedure. Among 9 patients with undefined hydrocephalus, 3 required shunt placement within 6 months after ETV (2 shunted previously). Endoscopic third ventriculostomy treatment in a patient with hydrocephalus caused by basilar tip aneurysm succeeded. The assessment of ETV effectiveness in oncological patients has been indirect in view of the underlying disease.

Conclusions

The best results of ETV treatment have been demonstrated for patients with primary aqueductal stenosis. Ventricle size cannot determine the effectiveness of treatment as an individual requirement. Endoscopic third ventriculostomy is effective in previously shunted patients although the prediction of outcome should be cautious. Endoscopic third ventriculostomy enables preparation for further therapy and is palliative treatment in oncological patients with secondary hydrocephalus.

Indocyanine green angiography in endoscopic third ventriculostomy

BACKGROUND

Endoscopic third ventriculostomy (ETV) has become a well-established method for the treatment of noncommunicating hydrocephalus with a high success rate and a relatively low morbidity rate. However, vessel injury has been repeatedly reported, often with a fatal outcome. Vessel injury is considered to be the most threatening complication. The use of indocyanine green (ICG) angiography has become an established tool in vascular microneurosurgery.

OBJECTIVE

We report our initial experience with endoscopic ICG angiography in ETV for intraoperative visualization of the basilar artery and its perforators to reduce the risk of vascular injury.

METHODS

Eleven patients with noncommunicating hydrocephalus underwent ETV. Before opening of the third ventricular floor, ICG angiography was performed using a prototype neuroendoscope for intraoperative visualization of ICG fluorescence.

RESULTS

In 10 patients, ETV and ICG angiography were successfully performed. In 1 case, ICG angiography failed. Even in the presence of an opaque floor of the third ventricle (n = 5), ICG angiography clearly demonstrated the course of the basilar artery and its major branches and was considered useful.

CONCLUSION

ICG angiography has the potential to become a useful adjunct in ETV for better visualization of vessel structures, especially in the presence of aberrant vasculature, a nontranslucent floor of the third ventricle, or in case of reoperations.

Fluorescein-Enhanced Characterization of Additional Anatomical Landmarks in Cerebral Ventricular Endoscopy

BACKGROUND:

Fluorescein enhancement to detect retinal disorder or differentiate cancer tissue in situ is a well-defined diagnostic procedure. It is a visible marker of where the blood-brain barrier is absent or disrupted. Little is reported in the contemporary literature on endoscopic fluorescein-enhanced visualization of the circumventricular organs, and the relevance of these structures as additional markers for safe ventricular endoscopic navigation remains an unexplored field.

OBJECTIVE:

To describe fluorescein sodium–enhanced visualization of circumventricular organs as additional anatomic landmarks during endoscopic ventricular surgery procedures.

METHODS:

We prospectively administered intravenously 500 mg fluorescein sodium in 12 consecutive endoscopic surgery patients. A flexible endoscope equipped with dual observation modes for both white light and fluorescence was used. During navigation from the lateral to the fourth ventricle, the endoscopic anatomic landmarks were first inspected under white light and then under the fluorescent mode.

RESULTS:

After a mean of 20 seconds in the fluorescent mode, the fluorescein enhanced visualization of the choroid plexus of the lateral ventricle, median eminence–tuber cinereum complex, organum vasculosum of the lamina terminalis, choroid plexus of the third and fourth ventricles, and area postrema.

CONCLUSION:

Fluorescein-enhanced visualization is a useful tool for helping neuroendoscopists recognize endoscopic anatomic landmarks. It could be adopted to guide orientation when the surgeon deems an endoscopic procedure unsafe or contraindicated because of unclear or subverted anatomic landmarks. Visualization of the circumventricular organs could add new insight into the functional anatomy of these structures, with possible implications for the site and safety of third ventriculostomy.

Endoscopic third ventriculostomy in obstructive hydrocephalus: surgical technique and pitfalls

BACKGROUND

Reviewing our experience in the variety of pathological entities causing obstructive hydrocephalous, we evaluate the effectiveness of endoscopic treatment, with particular attention to surgical technique, nuances, and pitfalls.

MATERIALS AND METHODS

We reviewed the cases of 57 consecutive patients with obstructive hydrocephalus of various origins in the last 9 years. They were treated by endoscopic third ventriculostomy (ETV). A septostomy was also performed in ten cases. Operative videos were reassessed, and surgical nuances reconsidered.

RESULTS

ETV was accomplished in all but three cases. The overall rate of good results (shunt-independent patients with clinical remission or improvement) was 81.5% (44/54). From ten patients with ETV failure, five were re-ETVed successfully, and five were shunted. Patients with benign aqueductal stenosis and tumor compressing the aqueduct received the greatest benefit from the ETV. There were no permanent morbidities or any mortality. Fundamentals of preoperative planning, postoperative evaluation, and technical pitfalls have been considered.

CONCLUSION

ETV for obstructive hydrocephalus of various origins is safe and effective, and should be considered as a first-line treatment. Familiarity with the ventricular anatomy and its variations in hydrocephalus is key to success. Preoperative planning is mandatory. Awareness of potential pitfalls minimizes the risk.

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.

The distance between the posterior communicating arteries and their relation to the endoscopic third ventriculostomy in adults: An anatomic study

BACKGROUND

The diencephalic leaf of the Liliequist's membrane is a continuous structure that should be perforated in the endoscopic third ventriculostomy. Its lateral borders are penetrated by the third cranial nerve and the posterior communicating arteries. The most important complication of endoscopic third ventriculostomy is the vascular injury, such as the posterior communicating artery. The purpose of this study is to measure the distance between posterior communicating arteries located below the third ventricle floor and anterior of the mammillary bodies.

METHODS

In this observational prospective study 20 fresh brains from cadavers were utilized to measure the distance between the posterior communicating arteries in April 2008 at the Death Check Unit of our Institution. A digital photograph of the posterior communicating arteries was taken and the distance between the arteries was measured. The measurement was analyzed using descriptive statistics.

RESULTS

In the descriptive analysis of the 20 specimens, the posterior communicating arteries distance was 9 to 18.9 mm, a mean of 12.5 mm, median of 12.2 mm, standard deviation of 2.3 mm.

CONCLUSION

The detailed knowledge of vascular structures involved in the endoscopic third ventriculostomy as to the posterior communicating arteries distance provides a safe lateral vascular border when performing such procedure.

Endoscopic third ventriculostomy in adults: a technique for dealing with the neural (opaque) floor

Object

An opaque (neural) floor of the third ventricle is considered an obstacle to safe penetration of the floor of the third ventricle in endoscopic third ventriculostomy (ETV). The direct technique of endoscopic coring (“cookie cut”) of the opaque (neural) floor of the third ventricle is described in 41 cases among a total of 101 consecutive adult ETVs.

Methods

A 0° endoscope in a 4.6-mm irrigating sheath was used to press and core (“cookie cut”) a section of the tuber cinereum, thereby exposing the underlying membranes and vasculature. Thereafter, the endoscopic apparatus was used to penetrate the membrane into the prepontine space.

Results

Among 101 consecutive ETVs performed in adults, there were 41 instances of an opaque floor in which the coring technique was used. The basilar artery (BA) complex was in the intended path of penetration in 13 cases. There were no perioperative deaths or vascular injuries. No cases were aborted because of the opaque floor or the configuration of the BA complex. The clinical success rate in the opaque floor group was 80% (33 of 41 patients).

Conclusions

An opaque (neural) floor is frequently seen in adults during ETV. Removing the floor by the core (“cookie cut”) method is a safe means of revealing the underlying BA complex and membranous structures prior to penetration into the prepontine cistern. On occasion, the BA complex may be in the path of penetration, and one can maneuver the endoscope to displace the vasculature to successfully accomplish the ETV.

Endoscopic third ventriculostomy versus ventriculoperitoneal shunt in the treatment of obstructive hydrocephalus due to posterior fossa tumors in children

OBJECT

This study compares endoscopic third ventriculostomy (ETV) and ventriculoperitoneal shunt (VPS) in the treatment of pediatric patients with marked obstructive hydrocephalus due to midline posterior fossa tumors.

METHODS

Fifty-three pediatric patients with a midline posterior fossa tumor (32 medulloblastomas and 21 ependymomas) associated with marked hydrocephalus were studied. Patients were divided into two groups: group A (32 patients) operated by ETV with a mean follow-up of 27.4 months and group B (21 patients) operated by VPS with a mean follow-up of 25 months.

RESULTS

Both procedures proved to be effective clinically and radiologically. In group A, intraoperative bleeding occurred in two cases (6.2%) and cerebrospinal fluid leakage in one case (3.1%). In group B, shunt infection occurred in two cases (9.4%), one of these two cases died 4.5 months postoperatively from ventriculitis. Subdural collection occurred in two cases (9.4%), epidural hematoma in one case (4.7%), and upward brain herniation in one case (4.7%). Endoscopic third ventriculostomy proved to be superior due to shorter duration of surgery (15 min versus 35 min), lower incidence of morbidity (9.3% versus 38%), no mortality (0% versus 4.7%), and lower incidence of procedure failure (6.2% versus 38%).

CONCLUSION

The shorter duration of surgery, the lower incidence of morbidity, the absence of mortality, the lower incidence of procedure failure, and the significant advantage of not becoming shunt dependent make ETV be recommended as the first choice in the treatment of pediatric patients with marked obstructive hydrocephalus due to midline posterior fossa tumors.

Is the distance between mammillary bodies predictive of a thickened third ventricle floor?

Object

The aim of this study was to correlate intraoperative endoscopic third ventriculostomy (ETV) findings in hydrocephalic patients with the MR imaging appearance of the mammillary bodies (MBs), the fundamental anatomical landmarks of the third ventricle floor (TVF) region.

Methods

The authors reviewed brain MR images and intraoperative ETV records in 23 patients with hydrocephalus as well as MR imaging data from 120 randomized control volunteers of various ages to define the normal intermammillary distance (IMD).

Results

In control volunteers, no measurable IMD (“kissing” configuration) was observed in 91 (85%) of 107 cases, and there was mild MB splitting (mean ± standard deviation, 0.18 ± 0.12 cm) in only 16 cases with age-related cerebral atrophy. Among the 21 patients with complete MR imaging and ETV data sets, 12 ETV procedures were hindered by anatomical anomalies such as a thickened TVF or an “upward ballooning” phenomenon. On preoperative MR imaging in these 12 patients, there was an increased IMD (0.55 ± 0.41 cm) compared with that in the remaining 9 patients (0.27 ± 0.25 cm) who had a normal thin TVF during ETV and in the control group (0.03 ± 0.08 cm). Magnetic resonance imaging and ETV data concordantly displayed nonsplit MBs in 6 of 9 cases with a thin TVF and split MBs in 10 of 12 cases with a thick TVF.

Conclusions

The normal configuration of MBs is no measurable IMD, with mild splitting occurring in patients with age-related brain atrophy. In hydrocephalic patients, a thickened TVF was present almost exclusively with an increased IMD on preoperative MR imaging and separated MBs on endoscopic viewing. Large retrospective series are needed to confirm that a preoperative increased IMD is predictive of a thickened TVF during ETV.

Three-dimensional constructive interference in steady-state magnetic resonance imaging in obstructive hydrocephalus: relevance for endoscopic third ventriculostomy and clinical results

Object

Endoscopic third ventriculostomy is the treatment of choice in patients with obstructive hydrocephalus caused by aqueductal stenosis. The authors examined the clinical course and results of surgical treatment for obstructive hydrocephalus with pre- and postoperative refined constructive interference in steady-state (CISS) MR imaging.

Methods

Forty patients with obstructive hydrocephalus underwent pre- and postoperative 3D-CISS imaging and clinical evaluation. Radiological findings were correlated with intraoperative observations of the thickness and transparency of the floor of the third ventricle and the patient's postoperative clinical course.

Results

Three-dimensional CISS MR imaging provides precise visualization of the basilar/posterior cerebral artery, its distance to the clivus, the diameter of the foramen of Monro, and the extension of and thickness of the floor of the third ventricle. In 71% of patients a flow void was detectable postoperatively on the ventriculostomy. In this group 81.5% had strong and 14.8% moderate clinical benefit, and 3.7% required secondary shunt placement. In the remaining 29% of the patients without a visible flow void, strong improvement was seen in 54.5%, moderate improvement in 18.2%, and stoma failure occurred in 27.3% (p = 0.094). Radiological measurements of the thickness of the third ventricle floor correlated with intraoperative findings (r = 0.35, p = 0.029). Comparison of outcomes showed a statistically significant tendency for a better outcome in patients with thin and easily perforated third ventricle floors (p = 0.04).

Conclusions

Endoscopic ventriculostomy in patients with obstructive hydrocephalus is safe and mostly successful, and 3D-CISS MR imaging seems to be a valuable diagnostic method for precisely identifying the anatomy of relevant structures. Furthermore, 3D-CISS MR imaging allows judgment of the thickness of the third ventricle floor and display of the ventriculostomy/flow void, which are predictive for intraoperative course and clinical outcome.

Intraoperative assessment of endoscopic third ventriculostomy success

OBJECT

The authors' aim in this study was to determine if standardizing the evaluation of intraoperative findings during endoscopic third ventriculostomy (ETV) could predict patients with hydrocephalus in whom endoscopic treatment will fail and require ventriculoperitoneal shunt treatment. The creation of a uniform scale with predictive outcomes may reduce returns to the operating room for shunt treatment and reliance on postoperative externalized ventricular monitoring and MR imaging.

METHODS

The authors evaluated the preoperative history, intraoperative findings, and postoperative monitoring and imaging findings in 109 consecutive patients undergoing 112 consecutive attempted ETVs for obstructive hydrocephalus. A 5-grade scale was developed to assess preoperative risk factors and intraoperative evaluation to unify criteria that have been suspected to influence outcome independently. A grade of 0 was assigned to patients with no negative predictors, whereas increasing scores were assigned to patients who had multiple preoperative and intraoperative risks identified. Patients' grades were compared with outcome of the procedure, utility of externalized ventricular monitoring, and results of postoperative MR imaging.

RESULTS

Of 112 ETVs, 77 were successful and 35 were unsuccessful. Fifty-nine patients received a grade of 0, 27 received a grade of 1, 11 received a grade of 2, and 15 received a grade of > or = 3. In all 15 patients receiving a grade > or = 3 attempted ETV procedures failed, and the patients required a ventriculoperitoneal shunt. Postoperative monitoring with externalized ventricular drains and MR images demonstrating radiographic evidence of flow was independently less reliable than intraoperative grading in predicting success. Patients with a grade of 0 almost uniformly had successful surgery, independent of MR imaging findings. Patients with a grade of 1 or 2 who had successful surgery almost always lacked negative intraoperative predictive findings.

CONCLUSIONS

Despite reliance in recent years on post-ETV MR images and externalized ventricular monitoring, these modalities, although often useful adjuncts, appear less reliable as predictive tests than a simple assessment at the time of endoscopic fenestration. By using a uniform grading scale, the authors have introduced a novel means through which intraoperative and postoperative decision making can be aided, with the goal of reducing unnecessary procedures and tests and preventing unnecessary returns to the operating room.

Complications of endoscopic third ventriculostomy

OBJECTS

Although endoscopic third ventriculostomy (ETV) is considered as the first choice in the management of noncommunicating hydrocephalus, it is not without risk or complication.

METHODS

The patients who had undergone ETV only between 1998 and 2005 were retrospectively reviewed. There were 85 males and 70 females, and 173 ETVs were performed in 155 patients. The patients' age ranged from 2 months to 77 years. Complications were categorized as (1) intraoperative, (2) early postoperative (<1 month), and (3) late postoperative (>1 month). Follow-up of the patients ranged from 1 to 86 months.

RESULTS

Overall complication rate per patient was 15.4%, and complication per procedure was 18%. Complication rate significantly varied with the etiology of hydrocephalus (P = 0.013). The patients with Chiari type I malformation and tumor had no or very low complication rates. The complication risk was significantly higher in repeat endoscopic procedure (55.5%) than in the first procedure (10%; P = 0.0001).

CONCLUSION

ETV should be the first choice in the management of noncommunicating hydrocephalus. Training, experience, and meticulous technique will decrease the complication rate. Patients undergoing ETV should be followed in a similar manner to patients with cerebrospinal fluid shunts.

Microsurgical third ventriculocisternostomy as an alternative to ETV: report of two cases

OBJECTIVE

To describe a microsurgical alternative to endoscopic third ventriculocisternostomy.

METHODS

Two children with shunt-dependent hydrocephalus and multiple shunt revisions were considered candidates for third ventriculocisternostomy (TVS). Because of slit ventricles, an endoscopic approach was not possible and, therefore, both patients received a microsurgical TVS by a supraorbital approach.

RESULTS

In both cases, microsurgical TVS was successful and the patients became shunt free.

CONCLUSION

Microsurgical TVS by a supraorbital craniotomy is a viable alternative to endoscopic TVS in selected cases.

First experiences with a 2.0-μm near infrared laser system for neuroendoscopy

Nd:YAG, argon and diode lasers have been used in neurosurgical procedures including neuroendoscopy. However, many neurosurgeons are reluctant to use these lasers because of their inappropriate wavelength and uncontrollable tissue interaction, which has the potential to cause serious complications. Recently, a 2.0-microm near infrared laser with adequate wavelength and minimal tissue penetration became available. This laser was developed for endoscopic neurosurgical procedures. It is the aim of the study to report the initial experiences with this laser in neuroendoscopic procedures. We have performed 43 laser-assisted neuroendoscopic procedures [multicompartmental congenital, posthaemorrhagic or postinfectious hydrocephalus (n = 17), tumour biopsies (n = 6), rescue of fixed and allocated ventricular catheters (n = 2), endoscopic third ventriculostomy (ETV, n = 17) and aqueductoplasty (n = 1)] in 41 patients aged between 3 months and 80 years. The laser beam was delivered through a 365-microm bare silica fibre introduced through the working channel of a rigid endoscope. It was used for the opening of cysts, perforating the third ventricular floor, and for coagulation prior to and after biopsy. The therapeutic goals [creating unhindered cerebrospinal fluid (CSF) flow between cysts, ventricles and cisterns, sufficient tissue samples for histopathological diagnosis and catheter rescue] were achieved in 40 patients by the first and in 2 patients by a second neuroendoscopic operation. In one child, a CSF shunt was later required despite patency of the created stoma proven by magnetic resonance imaging (MRI). In another patient ETV was abandoned due to a tiny third ventricle. There was neither mortality nor transient or permanent morbidity. The authors conclude that the use of the 2.0-microm near infrared laser enables safe and effective procedures in neuroendoscopy.

Endoscopic opening of the foramen of Magendie using transaqueductal navigation for membrane obstruction of the fourth ventricle outlets

✓A membrane obstruction of the foramina of Magendie and Luschka is an uncommon origin of hydrocephalus characterized by unusual clinical symptoms of rhomboid fossa hypertension. Various surgical approaches have been proposed to alleviate this obstruction, including opening the obstructed foramen of Magendie using suboccipital craniectomy, shunting procedures, and more recently, endoscopic third ventriculostomy (ETV). In some cases, however, reshaping of the posterior fossa due to the collapse of the prepontine cistern could make ETV difficult for the surgeon and dangerous to the patient. In these cases, endoscopic opening of the foramen of Magendie by transaqueductal navigation of the fourth ventricle is a suitable and feasible therapeutic option.

The role of different imaging modalities: is MRI a conditio sine qua non for ETV?

OBJECTIVE

To describe the different imaging modalities used for the diagnosis and classification of hydrocephalus, their role in defining the optimal treatment of hydrocephalus and to define the optimal preoperative diagnostics for endoscopic third ventriculocisternostomy (ETV).

METHODS

An overview on available imaging modalities for hydrocephalus will be given and their pros and cons discussed. In addition, different aspects of the treatment of hydrocephalus by shunts and by ETV will be highlighted.

DISCUSSION

The role of the technical aspects of performing an ETV, the role of the surgeon's philosophy, the role of the urgency of the procedure, and the role of informed consent on the requirements for the imaging of the hydrocephalus will be discussed.

CONCLUSION

The authors conclude that MRI is a conditio sine qua non for ETV in elective surgical cases.

Shunts vs endoscopic third ventriculostomy in infants: are there different types and/or rates of complications? A review

INTRODUCTION

The decision-making process when we compare endoscopic third ventriculostomy (ETV) with shunts as surgical options for the treatment of hydrocephalus in infants is conditioned by the incidence of specific and shared complications of the two surgical procedures.

REVIEW

Our literature review shows that the advantages of ETV in terms of complications are almost all related to two factors: (a) the avoidance of a foreign body implantation and (b) the establishment of a 'physiological' cerebrospinal fluid (CSF) circulation. Both these kinds of achievements are particularly important in infants because of the relative high rate of some intraoperative (i.e. abdominal) and late (secondary craniosynostosis, slit-ventricle syndrome) shunt complications in this specific subset of patients. On the other side, the main factor which is claimed against ETV is the relatively high risk of immediate mortality and neurological complications. Clinical manifestations of neurological structure damage seem to be more frequent in infants, probably due to the more relevant effect of parenchymal and vascular damage in this age group; however, both the immediate mortality and neurological damage risk of ETV procedures should be weighted against the long-term mortality and the late neurological damage which is not infrequently described as a consequence of shunt malfunction and proximal shunt revision procedures. Infections are possible in both ETV and extrathecal CSF procedures, especially in infants. However, the incidence of infective complications is significantly lower in case of ETV (1-5% vs 1-20%). Moreover, different from shunting procedures, infections in children with third ventriculostomy have a more benign course, being generally controlled by antibiotic treatment alone.

Transparent endoscopic sheath and rigid-rod endoscope used in endoscopic third ventriculostomy for hydrocephalus in the presence of deformed ventricular anatomy

OBJECT

Endoscopic third ventriculostomy (ETV) has been widely performed for the treatment of noncommunicating hydrocephalus. In cases of hydrocephalus in conjunction with deformed and complex ventricular anatomy, it is preferable to use a rigid-rod endoscope for ETV, because the excellent visibility provided by this instrument yields a smooth and correct orientation in the ventricle. The authors report on ETV procedures in which they used a transparent endoscopic sheath that has a common channel in which a rigid-rod endoscope and an instrument can be inserted.

METHODS

In 15 cases of noncommunicating hydrocephalus, a transparent endoscopic sheath and a rigid endoscope were used for ETV. In 11 of the 15 patients, the diameter of the foramen of Monro and the width of the third ventricle were greater than 5 mm, and thus a transparent endoscopic sheath and a rigid endoscope could be smoothly introduced through the foramen of Monro and an ETV successfully performed. Four patients had congenital or acquired narrowing of the foramen of Monro and an anatomically deformed ventricular system. In three of the patients, opening of the narrowed foramen and an ETV were successfully performed using the transparent endoscopic sheath under direct visualization through the rigid-rod endoscope.

CONCLUSIONS

A transparent endoscopic sheath increases safety by offering a corridor to the third ventricle. It also provides excellent visibility without troublesome bleeding from tissues surrounding the foramen of Monro during endoscopic procedures in which a rigid endoscope is used.

Hemodynamic and electrolyte changes in patients undergoing neuroendoscopic procedures

OBJECTS

Intraoperative hemodynamic alterations and postoperative electrolyte disturbances related to endoscopic third ventriculostomy (E3V) have been reported. We aimed to evaluate prospectively those changes in patients undergoing neuroendoscopic procedures.

METHODS

This study was carried out in 24 patients who underwent neuroendoscopic intervention. Sevoflurane was used for the induction and maintenance of anesthesia. Heart rate (HR), mean arterial pressure (MAP), peripheral oxygen saturation, end-tidal CO2, and body temperature values were recorded according to the stages of the operation. Blood gas and blood chemistry analyses were performed before and after endoscopic procedure and were repeated on the third postoperative day.

CONCLUSIONS

There were no significant differences in intraoperative HR and MAP. Bradycardia occurred only in 1 of the 24 patients during the dilatation. In conclusion, we suggest the use of 0.9% NaCl for intravenous fluid replacement and a warm lactated ringer solution for ventricular irrigation during E3V to prevent intraoperative hemodynamic changes and postoperative electrolyte disturbances.

Endoscopic third ventriculostomy in the treatment of hydrocephalus in pediatric patients

Advances in surgical instrumentation and technique have lead to an extensive use of endoscopic third ventriculostomy in the management of pediatric hydrocephalus. The aim of this work was to point out the leading aspects related to this technique. After a review of the history, which is now almost one century last, the analysis of the endoscopic ventricular anatomy is aimed to detail normal findings and possible anatomic variations which might influence the correct conclusion of the procedure. The overview of modern endoscopic instrumentation helps to understand the technical improvements that have contributed to significantly reduce the operative invasiveness. Indications are analysed from a pathogenetic standpoint with the intent to better understand the results reported in the literature. A further part of the paper is dedicated to the neuroradiological and clinical means of outcome evaluation, which are still a matter of debate. Finally a review of transient and permanent surgical complications is performed looking at their occurrence in different hydrocephalus etiologies.

Endoscopic transtentorial ventriculocystostomy and cystoventriculoperitoneal shunt in a neonate with Dandy-Walker malformation and associated aqueductal obstruction

OBJECTIVE

Shunting of the lateral ventricle and the posterior fossa cyst is the advocated surgical therapy for children with Dandy-Walker malformation (DWM) and associated aqueductal obstruction. The high rate of complications of combined shunting stimulated the authors to search for an alternative surgical solution.

CLINICAL PRESENTATION/INTERVENTION

After transtentorial endoscopic ventriculocystostomy, a cystoventricular catheter, connected to a peritoneal shunt, was placed in a neonate with DWM and associated aqueductal obstruction. Immediately prior to ventriculocystostomy, the presence of a blocked third ventricular outflow was reconfirmed by contrast medium injection. Neuronavigation was required to define the surgical path from the lateral ventricle through the tentorium and the overlying small rim of brain parenchyma into the posterior fossa cyst. The postoperative clinical course was uneventful with radiologically proven reduction of the size of the ventricular system and the cyst.

CONCLUSION

Cystoventriculoperitoneal shunt placement after transtentorial endoscopic ventriculostomy is a surgical alternative in very young children with DWM and associated aqueductal obstruction.

Endoscopic third ventriculostomy for obstructive hydrocephalus

The indications for neuroendoscopy are not only constantly increasing, but even the currently accepted indications are constantly being adjusted and tailored. This is also true for one of the most frequently used neuroendoscopic procedures, the endoscopic 3rd ventriculostomy (ETV) for obstructive hydrocephalus. ETV has gained popularity and widespread acceptance during the past few years, but little attention has been paid to the techniques of the procedure. After a short introduction describing the history of ETV, an overview is given of all the different techniques that have been and still are employed to open the floor of the 3rd ventricle. The spectrum of indications for ETV has been widely enlarged over the last years. Initially, the use of this procedure was restricted to patients older than 2 years, to patients with an obvious triventricular hydrocephalus, and to those with a bulging, translucent floor of the 3rd ventricle. Nowadays, indications include all kinds of obstructive hydrocephalus but also communicating forms of hydrocephalus. The results of endoscopic procedures in treating these pathologies are given under special consideration of shunt technologies. In summary, from the review of the publications since the first ETV performed by Mixter in 1923, this technique is the treatment of choice for obstructive hydrocephalus caused by different etiologies and is an alternative to cerebrospinal fluid shunt application.

Endoscopic anatomic features of the triangular recess

OBJECTIVE

To describe the morphological and topographic features of the triangular recess (TR) in the anterior wall of the third ventricle and the pathological conditions that allow its observation during ventricular endoscopic neuronavigation.

METHODS

A systematic review of records and operative videotapes for 145 patients who underwent endoscopic third ventriculostomy was performed.

RESULTS

The TR could be recognized in five cases of hydrocephalus, each caused by a different underlying pathological condition. The approach was precoronal in four cases and suboccipital in one. The morphological and topographic features of the TR and adjacent structures varied among the different cases.

CONCLUSION

Although it is seldom reported in neuroanatomy handbooks and is not readily accessible under normal conditions, the TR is a characteristic structure of the third ventricle, which might become apparent in several conditions that produce hydrocephalus. Neurosurgeons who perform neuroendoscopy should be aware of this structure and of the situations that cause its deformation and allow its observation during endoscopic neuronavigation.

Stereotactic neuroendoscopic management of hydrocephalus: a three-year follow-up and analysis of Malaysian children with aqueduct stenosis

The beneficial effects of stereotactic third ventriculostomy versus ventriculoperitoneal shunt were evaluated in 62 paediatric patients and analysed in relation to age, sex, clinical history, presence of meningomyelocele, magnetic resonance imaging measurements of hydrocephalus and third ventricle floor size. The third ventriculostomy were done on 50 patients using the Richard-Wolf Caemaert Endoscope and the Leksell Stereotactic Frame Model G. These patients were operated using the 4-French Fogarty catheter to open the base of the third ventricle. During the same period of study 12 paediatric patients with aqueduct stenosis who were managed by ventriculoperitoneal shunt were included. Both surgical procedures were compared. Statistically univariate analysis revealed that those patient with an age group of more than six months undergoing ventriculostomy had good outcome. Multivariate analysis revealed that past history of haemorrhage and/or meningitis were predictors of poor outcome. Sex, size of lumbar meningocele at birth, abnormal ventricular anatomy or narrow third ventricular floor size were non predictors of bad outcome in these patients. There was no difference in outcome in both the shunt or ventriculostomy group.

Complications of endoscopic third ventriculostomy

OBJECT

The purpose of this prospective investigation was to determine the rate of complications associated with endoscopic third ventriculostomy (ETV).

METHODS

Between March 1993 and October 2001, 193 ETVs were performed in 188 patients at a single institution. The age of the patients ranged from 1 month to 85 years (mean age 39 years). One procedure had to be abandoned because a severe venous hemorrhage blurred the surgeon's view; however, third ventriculostomy was successfully accomplished in that patient 14 days later. In addition, there were two cases in which significant venous hemorrhages could be controlled endoscopically by using irrigation. Postoperative imaging revealed three subdural collections, one tiny thalamic contusion, one cortical hemorrhage at the puncture site, and one severe subarachnoid hemorrhage (SAH). There were two deaths (1% mortality rate) related to the endoscopic procedure; causes of death were one SAH from a torn basilar perforating artery and one wound infection leading to meningitis and septic multiorgan failure. Three permanent deficits occurred (confusion, oculomotor palsy, and diabetes insipidus [1.6% permanent morbidity rate]). Transient deficits included four cases of meningitis, three cases of cerebrospinal fluid leak, two cases of herniation syndrome, two cases of confusion, one case in which there was a decrease of consciousness, two cases of oculomotor palsy, and one case in which there was loss of thirst (7.8% transient morbidity rate). Misplacement of the fenestration was the main reason for severe complications. During the course of the study, the complication rate dropped significantly (no incidences of mortality or permanent morbidity occurred during the last 100 procedures).

CONCLUSIONS

All permanent and fatal complications occurred during the authors' very early experience, indicating that a steep learning curve was associated with the procedure. Endoscopic third ventriculostomy, if performed correctly, is a safe, simple, and effective treatment option for various forms of noncommunicating hydrocephalus.

Acute distortion of the anatomy of the third ventricle during third ventriculostomy. Report of four cases

The authors report on four third ventriculostomy procedures in which upward ballooning of the third ventricular floor occurred immediately after perforation of the floor and withdrawal of a Fogarty catheter. The floor herniated into the third ventricle, hindering the endoscopic view. Preoperative magnetic resonance imaging demonstrated a similar anatomy in all four cases, consisting of hydrocephalus, extreme dilation of the third ventricle, and disappearance of the interpeduncular cistern due to a very thin, membranous floor of the third ventricle, which herniated downward, draping over the basilar artery. The authors suggest that excessive rinsing in combination with this anatomical configuration provoked the phenomenon of upward ballooning of the third ventricular floor, which is described in this report.