Historical trends of neuroendoscopic surgical techniques in the treatment of hydrocephalus

Recapitulation of physiologic and pathophysiologic pulsatile CSF flow in purpose-built high-throughput hydrocephalus bioreactors

BACKGROUND

Hydrocephalus, an accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain, is often treated via a shunt system to divert the excess CSF to a different compartment; if left untreated, it can lead to serious complications and permanent brain damage. It is estimated that one in every 500 people are born with hydrocephalus. Despite more than 60 years of concerted efforts, shunts still have the highest failure rate of any neurological device requiring follow-up shunt revision surgeries and contributing to the $2 billion cost of hydrocephalus care in the US alone. The absence of a tested and validated long-term in-vitro model that can incorporate clinically relevant parameters has limited hypothesis-driven studies and, in turn, limited our progress in understanding the mechanisms of shunt obstruction in hydrocephalus. Testing clinical parameters of flow, pressure, shear, catheter material, surface modifications, and others while optimizing for minimal protein, cellular, and blood interactions has yet to be done systematically for ventricular catheters. Several studies point to the need to not only understand how cells and tissues have occluded these shunt catheters but also how to stop the likely multi-faceted failure. For instance, studies show us that tissue occluding the ventricular catheter is primarily composed of proliferating astrocytes and cells of the macrophage lineage. Cell reactivity has been observed to follow flow gradients, with elevated levels of typically pro-inflammatory interleukin-6 produced under shear stress conditions greater than 0.5 dyne/[Formula: see text]. But also, that shear can shift cellular attachment. The Automated, In vitro Model for hydrocephalus research (AIMS), presented here, improves upon our previous long-term in vitro systems with specific goals of recapitulating bulk pulsatile cerebrospinal fluid (CSF) waveforms and steady-state flow directionality relevant to ventricular catheters used in hydrocephalus.

METHODS

The AIMS setup was developed to recapitulate a wide range of physiologic and pathophysiologic CSF flow patterns with varying pulse amplitude, pulsation rate, and bulk flow rate with high throughput capabilities. These variables were specified in a custom-built user interface to match clinical CSF flow measurements. In addition to flow simulation capabilities, AIMS was developed as a modular setup for chamber testing and quality control. In this study, the capacity and consistency of single inlet resin chambers (N = 40), multidirectional resin chambers (N = 5), silicone chambers (N = 40), and PETG chambers (N = 50) were investigated. The impact of the internal geometry of the chamber types on flow vectors during pulsatile physiologic and pathophysiologic flow was visualized using Computational Fluid Dynamics (CFD). Dynamic changes in ventricular volume were investigated by combining AIMS with MRI-driven silicone model of a pediatric patient's ventricles. Parametric data were analyzed using one-way analysis of variance (ANOVA) or repeated measures ANOVA tests. Non-parametric data were analyzed using Kruskal-Wallis test. For all tests, a confidence interval was set at 0.95 (α = 0.05). In a subset of experiments, AIMS was also tested for its capability to measure the flow of florescent microspheres through the holes of unused and explanted ventricular catheters.

RESULTS

The analysis of peak amplitude through chambers indicated no statistically significant differences between the chamber batches. This high throughput setup was able to reproduce clinical measurements of bulk CSF flow tested in up to 50 independent pump channels such that there was no exchange of solution or flow interference between adjacent channels. Physiologic and pathophysiologic clinical measurements of CSF flow patterns were recapitulated in all four chamber types of the AIMS setup with and without augmented compliance. The AIMS setup's automated priming feature facilitated constant fluid contact throughout the study; no leaks or ruptures were observed during short- (up to 24 h) or long-term (30 days) experiments. Finally, qualitative microscopy long-exposure image capture revealed microsphere movement under steady-state and pulsatile flow of spheres moving into the shunt catheter.

CONCLUSION

AIMS successfully simulates clinical measurements of physiologic and pathophysiologic CSF pulsation amplitude and frequency, as exemplified using clinical data of CSF exiting an externalized ventricular drain in four distinct chamber types, as well as flow patterns from a valve. This provides a promising platform for investigating the direct interaction between CSF, immune cells, and shunt hardware under relevant flow conditions when both the source of bulk flow and pulsatility are coupled. The implementation of this system in conjunction with a previously reported three-dimensional hydrogel scaffold in future work will enhance our understanding of shunt-related complications and improve treatment strategies by reducing the obstruction rate.

Biomechanics of brain tissue damage caused by fiber endoscope penetration in third ventriculostomy surgery

Third ventriculostomy is the preferred treatment for obstructive hydrocephalus, but the biomechanics of brain tissue damage caused by fiber endoscopes remains unclear. In this study, brain tissue material parameters were tested based on the Ogden model to simulate needle puncture mechanics, and replicated the entire fiber endoscope advancement process during third ventriculostomy. It was found that a smaller diameter fiber endoscope, a perpendicular puncture angle, and a faster puncture speed would decrease the damage of brain tissue caused by the fiber endoscope. This study provides valuable insights for optimizing the instrumentation and surgical process of third ventriculostomy.

The Role of Ventriculocisternostomy in the Management of Hydrocephalus in Mali and the Democratic Republic of the Congo

BACKGROUND

 Hydrocephalus continues to pose significant clinical challenges in neurosurgery. The primary goal of this study is to assess the feasibility of ventriculocisternostomy (VCS) within the provincial city of Kinshasa and Mali to optimize the management of patients afflicted with hydrocephalus.

METHODS

 This investigation was hosted at two major urban healthcare facilities: the Initiative Plus Hospital Center, positioned in the bustling metropolis of Kinshasa, Democratic Republic of the Congo (DRC), and the Bamako Hospital, Republic of Mali. A prospective, analytical cohort study was executed from December 2022 to June 2023.

RESULTS

In the Mali group, seven patients underwent VCS, four patients were treated with VCS and spinal surgery, and one case was treated with VCS and biopsy. Similarly, in the Kinshasa group, 25 patients underwent VCS, whereas four patients were treated with VCS and spinal surgery. The median hospital stay was eight and 10 days for the Mali and the Kinshasa groups, respectively.

CONCLUSION

VCS emerges as a formidable alternative for hydrocephalus management in Mali and DRC, showcasing the potential to markedly ameliorate patient outcomes, economize healthcare expenditures, and fortify the local neurosurgical capacity.

Neuroendoscopy: history, endoscopes, and instrumentation

INTRODUCTION

Endoscopy was first employed in the surgical treatment of neurosurgical diseases early in the twentieth century, but did not become an established practice for a long time, mainly because of poor technology and clinical results. After a slow re-appearance in the 1980s, the 1990s saw an explosion of techniques and instrumentation. Continuing technological improvement has led to further expansion of surgical techniques and indications for use of neuroendoscopy.

DISCUSSION

The expansion of ventricular endoscopy has led to significant understanding of CSF disorders. Aqueduct stenosis as cause of hydrocephalus and arachnoid cysts are an example of pathologies, the concept and understanding of which now is considerably enhanced, due to the application of neuroendoscopy in their treatment. Management of loculated hydrocephalus has been facilitated considerably with the use of the endoscope. The concepts of aqueductoplasty, septostomy, and foraminoplasty of the foramina of Monro and Magendie emerged, which were previously unknown. Skull base surgery, especially surgery for craniopharyngioma, has seen dramatic improvement in results with the use of the endoscope. Coupling of the endoscope with neuronavigation has expanded technical capabilities even further. Overall, we can do a lot more with the endoscope now in comparison to 30 years ago.

CONCLUSION

We should always remember that the endoscope is only a tool. Its use has indications and limitations related to its design and our ability to extract the maximum, in the context of its shortcomings. Further technological advances will push surgical frontiers even more in years to come.

Testing and validation of reciprocating positive displacement pump for benchtop pulsating flow model of cerebrospinal fluid production and other physiologic systems

BACKGROUND

The flow of physiologic fluids through organs and organs systems is an integral component of their function. The complex fluid dynamics in many organ systems are still not completely understood, and in-vivo measurements of flow rates and pressure provide a testament to the complexity of each flow system. Variability in in-vivo measurements and the lack of control over flow characteristics leave a lot to be desired for testing and evaluation of current modes of treatments as well as future innovations. In-vitro models are particularly ideal for studying neurological conditions such as hydrocephalus due to their complex pathophysiology and interactions with therapeutic measures. The following aims to present the reciprocating positive displacement pump, capable of inducing pulsating flow of a defined volume at a controlled beat rate and amplitude. While the other fluidic applications of the pump are currently under investigation, this study was focused on simulating the pulsating cerebrospinal fluid production across profiles with varying parameters.

METHODS

Pumps were manufactured using 3D printed and injection molded parts. The pumps were powered by an Arduino-based board and proprietary software that controls the linear motion of the pumps to achieve the specified output rate at the desired pulsation rate and amplitude. A range of 0.01 [Formula: see text] to 0.7 [Formula: see text] was tested to evaluate the versatility of the pumps. The accuracy and precision of the pumps' output were evaluated by obtaining a total of 150 one-minute weight measurements of degassed deionized water per output rate across 15 pump channels. In addition, nine experiments were performed to evaluate the pumps' control over pulsation rate and amplitude.

RESULTS

Volumetric analysis of a total of 1200 readings determined that the pumps achieved the target output volume rate with a mean absolute error of -0.001034283 [Formula: see text] across the specified domain. It was also determined that the pumps can maintain pulsatile flow at a user-specified beat rate and amplitude.

CONCLUSION

The validation of this reciprocating positive displacement pump system allows for the future validation of novel designs to components used to treat hydrocephalus and other physiologic models involving pulsatile flow. Based on the promising results of these experiments at simulating pulsatile CSF flow, a benchtop model of human CSF production and distribution could be achieved through the incorporation of a chamber system and a compliance component.

Outcome of Initial 3 Years of Cranial Endoscopy at DG Khan Medical College and Teaching Hospital, Dera Ghazi Khan

OBJECTIVE

With the evolution of surgical approaches, endoscopic skull base surgery has emerged as a suitable alternative to many other invasive methods. The aim of this study was to investigate the efficacy and outcome of cranial endoscopy in treating various neurosurgical intracranial pathologies in terms of procedural success and complications.

METHODS

This observational, prospective case series was conducted at the Department of Neurosurgery of DG Khan Medical College from November 2017 to October 2020. The study enrolled 74 patients with indications for cranial neuroendoscopy. Clinical examination was performed, and a detailed history of the disease was obtained. Follow-up was conducted in the outpatient department. The collected data were analyzed using statistical analysis software.

RESULTS

Of 77 procedures performed, endoscopic third ventriculostomy, arachnoid cyst fenestration, septostomy, colloid cyst excision, endoscopic assisted ventricular catheter placement, and intraventricular tumor biopsy were performed in 53.3%, 18.2%, 10.4%, 7.8%, 6.5%, and 3.9% of patients. Aqueductal stenosis was identified as the most common cause of obstructive hydrocephalus. Seizures and cerebrospinal fluid leaks were the most commonly reported complications (12% and 8.1%, respectively). The observed mortality rate was 2.7%.

CONCLUSIONS

Neuroendoscopic surgery has become safe and effective, as surgeon experience and learning have lowered the risk of complications, and offers a low-cost alternative intervention.

Ventricular volume changes after successful shunting in hydrocephalic infants

Objectives

Due to increased number of patients suffering from hydrocephalus (HCP) and lack of data concerning volumetric changes after shunting operations, this study aims to assess the volumetric changes in brain ventricles after successful ventriculoperitoneal (VP) shunt surgery in correlation with clinical improvement.

Patient and methods

This study included 20 patients; all of them are below the age of 2 years. All the patients had hydrocephalus, were treated surgically with VP shunts, and have clinically improved over the period of study. We measured the volumetric changes radiologically using the fronto-occipital horn ratio (FOHR) over a period of 6 months postoperatively.

Results

The frontal and occipital horn ratio was calculated in all these patients both pre and postoperatively. There was a significant radiological improvement in the majority of children after the shunt operation. One month postoperatively, the FOHR decreased to about 85% of its preoperative value in average. The FOHR was found to be significantly improving with time over a period of 6 months reaching 63% of its preoperative value.

Conclusion

Successful treatment of HCP in infants via VPS seems to be of benefit in decreasing the ventricular size gradually to a near normal FOHR with clinical improvement.

Functional and Radiological Parameters to Assess Outcome of Endoscopic Third Ventriculostomy in Shunt Failure Patients

Background:

Placement of ventriculoperitoneal shunt is a standard treatment for hydrocephalus. The risk of shunt malfunction in the first year is 25%–40% making endoscopic third ventriculostomy (ETV) a feasible option in those patients with shunt failure.

Aim:

The aim of this study was to evaluate ETV as a viable option in patients with shunt malfunction and to correlate the clinical outcome following successful ETV with functional and radiological outcomes.

Materials and Methods:

All patients who underwent ETV as a diversion procedure for hydrocephalus following shunt failure or malfunction over 1 year were studied. Functional outcome was evaluated by Wee function independence measure score carried out preoperatively, postoperatively, and at 6-month follow-up. Similar comparison was carried out for radiological parameters such as effacement of gyri, periventricular lucency, frontal horn diameter (maximum), Evans’ index, and third ventricular diameter.

Results:

Of 15 patients, 61.5% were shunt free after ETV. All the failures were noted in the first month following the procedure. The factors, which showed statistically significant correlation with the outcome of ETV, included age (P = 0.030), preoperative functional score (P = 0.006), and all the three components of the functional scoring, namely self-care score (P = 0.087), motor control score (P = 0.035), and neurocognitive score (P = 0.003). Parameters such as Evans’ index, maximum frontal horn diameter, and third ventricular diameter showed no significant difference between preoperative and postoperative scans. In follow-up imaging, only the frontal horn diameter showed a significant improvement (P = 0.047).

Conclusion:

ETV leads to significant neurocognitive improvement and postoperative functional status making it a viable option in patients who present with shunt malfunction.

Low-cost endoscopic third ventriculostomy simulator with mimetic endoscope

OBJECTIVE Hydrocephalus affects approximately 1 in 500 people in the US, yet ventricular shunting, the gold standard of treatment, has a nearly 85% failure rate. Endoscopic third ventriculostomy (ETV) is an alternative surgical approach for a specific subset of hydrocephalic patients, but can be limited by the inability of neurosurgical residents to practice prior to patient contact. The goal of this study was to create an affordable ETV model and endoscope for resident training. METHODS Open-source software was used to isolate the skull and brain from the CT and MR images of a 2-year-old boy with hydrocephalus. A 3D printer created the skull and a 3D mold of the brain. A mixture of silicone and silicone tactile mutator was used to cast the brain mold prior to subsequent compression and shearing modulus testing. A mimetic endoscope was then created from basic supplies and a 3D printed frame. A small cohort of neurosurgical residents and attending physicians evaluated the ETV simulator with mimetic endoscope. RESULTS The authors successfully created a mimetic endoscope and ETV simulator. After compression and shearing modulus testing, a silicone/Slacker ratio between 10:6 and 10:7 was found to be similar to that of human brain parenchyma. Eighty-seven percent of participants strongly agreed that the simulator was useful for resident training, and 93% strongly agreed that the simulator helped them understand how to orient themselves with the endoscope. CONCLUSIONS The authors created an affordable (US$123, excluding 3D printer), easy-to-use ETV simulator with endoscope. Previous models have required expensive software and costly operative endoscopes that may not be available to most residents. Instead, this attempt takes advantage of open-source software for the manipulation and fabrication of a patient-specific mold. This model can assist with resident development, allowing them to safely practice use of the endoscope in ETV.

Neuroendoscopic septostomy: Indications and surgical technique

BACKGROUND

Endoscopic septostomy is the treatment of choice for monolateral obstruction of the foramen of Monro. Common causes of this condition include: neoplasms, hemorrages, infections, congenital atresia, idiopathic occlusion.

METHOD

All the steps for performing a safe endoscopic pellucidotomy are presented. A brief discussion about the most common technical variations and their rationale is added.

CONCLUSION

Endoscopic pellucidotomy is a safe and effective treatment when a thorough understanding of anatomy is achieved.

The view through the ventricle catheter - The new ShuntScope for the therapy of pediatric hydrocephalus

PURPOSE

Correct placement of the ventricle catheter directly influences the function of cerebral shunt systems. The incidence of proximal catheter misplacement reaches up to 45%. To avoid misplacements and revisions a new intra-catheter endoscope for precise ventricle catheter placement in children was evaluated.

METHODS

The semi-rigid ShuntScope (Karl Storz GmbH & Co.KG, Tuttlingen, Germany) with an outer diameter of 1.0 mm and an image resolution of 10,000 pixels was used in a series of 27 children and adolescents (18 males, 9 females, age range 2 months-18 years). Indications included catheter placement in aqueductal stenting (n = 4), first time shunt placement (n = 5), burr hole reservoir insertion (n = 4), catheter placement after endoscopic procedures (n = 7) and revision surgery of the ventricle catheter (n = 7).

RESULTS

ShuntScope guided precise catheter placement was achieved in 26 of 27 patients. In one case of aqueductal stenting, the procedure had to be abandoned. One single wound healing problem was noted as a complications. Intraventricular image quality was always sufficient to recognize the anatomical structures. In case of catheter removal, it was helpful to identify adherent vessels or membranes. Penetration of small adhesions or thin membranes was feasible. Postoperative imaging studies demonstrated catheter tip placements analogous to the intraoperative findings.

CONCLUSIONS

Misplacements of shunt catheters are completely avoidable with the presented intra-catheter technique including slit ventricles or even aqueductal stenting. Potential complications can be avoided during revision surgery. The implementation of the ShuntScope is recommended in pediatric neurosurgery.

Avoiding the pocket: A case report of coiling of distal shunt catheter into subcutaneous pocket

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Recognize patients with previous surgeries, especially those involving subcutaneous implants.

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Distal shunt catheters must be passed around potential spaces to avoid coiling leading to shunt malfunction.

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Note that if a peritoneal catheter does not pass easily a different approach should be considered.

Introduction

Hydrocephalus is one of the most common disorders of neurosurgery and ventricular shunting, the primary surgical intervention, malfunctions in 85% of patients by 10 years.

Presentation of case

Here we present a case of a 12-year-old girl with history of a vagal nerve stimulator (VNS) and ventricular shunt, most recently revised from ventriculoatrial (VA) to ventriculoperitoneal (VP) shunt at an outside hospital. The patient presented with a new left chest bulge, nausea, emesis, and seizures. Imaging revealed the patient’s distal shunt catheter to have completely migrated and coiled into the VNS subcutaneous pocket. Subsequently, the patient’s distal shunt catheter was externalized, and later internalized back to a VA shunt.

Discussion

Potential spaces from previous surgeries such as VNS can lead to coiling of distal shunt catheters. In this case, the coiled distal shunt catheter led to hydrocephalus and the patient’s presenting symptoms.

Conclusion

It is imperative to recognize patients with previous surgeries, especially those involving subcutaneous implants and to avoid passing of distal shunt catheters through these potential spaces.

Choroid plexus cauterization on treatment of hydranencephaly and maximal hydrocephalus

INTRODUCTION

The standard treatment for hydranencephaly and maximal hydrocephalus consists of inserting shunts, although complications frequently occur. Choroid plexus cauterization (CPC) is an alternative, but its long-term efficacy and the factors associated with the success and failure of controlling head circumference (HC) are not well defined.

OBJECTIVE

This study aims to evaluate the long-term efficacy and factors related to the success rate of CPC in the treatment of hydranencephaly and maximal hydrocephalus.

METHOD

Forty-two children with maximal hydrocephalus and hydranencephaly underwent CPC from 2006 to 2014 and were retrospectively evaluated. Children with less than 3 months of follow-up were excluded. The long-term efficacy and success rate of possible variables (i.e., sex, type of malformation, type of surgery performed, treatment hospital, age, and HC at the time of surgery and birth) were evaluated.

RESULTS

Thirty-four children were considered for the effectiveness analysis. Treatment was successful in 24 children (70.6%), and failure occurred in 10 children (29.4%). Failure was detected soon after the endoscopic procedure (average 116 days). There was no difference in effectiveness when comparing the age at the moment of surgery (p = 0.473), type of malformation (p = 1), HC at birth (0.699), and HC at the time of surgery (p = 0.648). The surgical death rate was 7.14%.

CONCLUSION

Endoscopic CPC was a valid procedure used to treat hydranencephaly and maximal hydrocephaly, and it was effective in 70.6% of cases, with an average follow-up period of 32 months. When failures occurred, they occurred early. None of the analyzed variables interfered with the success of the treatment.

Anesthesia for Endoscopic Third Ventriculostomy in Children

Neuroendoscopy has established itself as a routine neurosurgical procedure in pediatric population. To have an uneventful smooth perioperative course, it is important for anesthesiologist to know about the key steps, possible complications, and specific anesthetic requirements. Among neuroendoscopies, endoscopic third ventriculostomy is the commonly performed one.

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

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

Conversion technique from neuroendoscopy to microsurgery in ventricular tumors: Technical note

BACKGROUND

Ventricular tumors represent a major neurosurgical challenge, making endoscopic approach an invaluable tool as it gained importance due to technological advances. Nevertheless, the method is not exempt of risk and limitations, sometimes requiring an open surgery. Thus, initial measurements must be adopted in order to simplify an eventual need for conversion to open craniotomy.

METHODS

Here, we describe a series of 6 patients with ventricular tumors approached by neuroendoscopy where the conversion to microsurgery turned out to be necessary. Patients' average age was 59.5 years (39-75 years). Average tumoral size was 17.8 mm (15-21 mm). There were 2 cases of lateral ventricle subependymoma and 4 cases of third ventricle colloid cysts. A standard surgical incision was performed in the coronal direction, allowing lateral expansion to 10 cm. Moreover, the endoscopic burr hole was enlarged to a 5 cm craniotomy. A small enlargement of the endoscopic cortical access was performed to gain a transcortical microsurgical corridor to the ventricular cavity. The need for conversion arose due to high consistency of the tumor (3 cases), technical problems (2 cases), and cortical collapse (1 case).

RESULTS

There was one case of cerebrospinal fluid fistula and infection and one case of transitory memory disturbance. In both the cases, we obtained a complete functional recovery. Clinical and radiological follow-up showed total tumor removal with no recurrences.

CONCLUSIONS

The technique herein described was easy to perform, promptly bypassed the endoscopic limitations, and gathered excellent surgical results. The possibility of adapting the method to other tumor locations may be considered.

Aqueductal stenting with an intra-catheter endoscope--a technical note

INTRODUCTION

Aqueductoplasty as well as aqueductal stenting is an accepted therapy option in short-segment aqueductal stenosis and isolated fourth ventricle. Over the years, different techniques with only slight modifications by using a conventional neuroendoscope with a working sheath to introduce different instruments have been presented. In summary, the use of Fogarty balloon catheters or flexible endoscopes to pass the narrowed aqueduct is recommended.

METHODS

This technical report describes a substantially new technique for this purpose. Six patients underwent aqueductal stenting with a new intracatheter endoscope.

RESULTS

Aqueductal stenting was possible in 4 out of 6 cases. No complications occurred. Handling of this new technique was good and easy without a prolonged learning curve. All four stents did work appropriately, and the procedure was considered to be successful. Of the two failures, the technique was abandoned and endoscopic third ventriculostomy (ETV) was performed in one. In the other case, suboccipital shunting was done.

CONCLUSION

This technical report describes a substantially new technique for aqueductal stenting. The combination of an intracatheter miniature endoscope and a prepared ventricular catheter enables careful and elegant aqueductal stenting. Large or flexible endoscopes, balloons, or special instruments to place a stent have become completely obsolete in selected cases.

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.

Comparison of Intracranial Neuroendoscopic Procedures in Children versus Adults

BACKGROUND

The emphasis regarding intracranial neuroendoscopy has been traditionally advocated and focused on the role in pediatric patients, although a significant usage has developed in adult patients. In this study, we examine and contrast the role of predominantly intracranial neuroendoscopy in both a pediatric and adult population with a minimum postprocedure follow-up of 5 years.

METHODS

A retrospective review was conducted for patients in the two hospitals that manage neurosurgical care for Southern Alberta, Canada, undergoing neuroendoscopic surgery between 1994 and 2008. The pediatric group was defined as age ≤17 years and the adult group as age ≥18 years.

RESULTS

A total of 273 patients who underwent a total of 330 procedures with a mean postprocedure follow-up of 12.9 years were identified. There were 161 adult and 112 pediatric patients, and both groups underwent surgery by the same surgeons. The most common procedure was endoscopic third ventriculostomy, accounting for 55% of procedures. One postoperative death occurred in an adult patient. Endoscopic third ventriculostomy success 1-year postprocedure was 81%, with only three late-term failures. Postoperative infection was the most common serious complication (two pediatric/four adult patients). Adult and pediatric patients had similar major complication rates (4.2% vs 5.7%, p=0.547).

CONCLUSIONS

Neuroendoscopy overall had a similar role in both pediatric and adult neurosurgical populations, with the most commonly associated complication being infection. Neuroendoscopy is an important therapeutic modality in the management of appropriate adult patients.

Volumetric analysis of cerebrospinal fluid and brain parenchyma in a patient with hydranencephaly and macrocephaly--case report

The aim of this study was to perform for the first time the intracranial volumetric analysis of cerebrospinal fluid (CSF) and brain parenchyma in the supratentorial and infratentorial space in a 30-year-old female patient with hydranencephaly and macrocephaly. A head scan performed using a 3T magnetic resonance was followed by manual segmentation of the brain parenchyma and CSF on T2 coronal brain sections. The volume of CSF and brain parenchyma was measured separately for the supratentorial and infratentorial space. The total volume of the intracranial space was 3645.5 cm³. In the supratentorial space, the volume of CSF was 3375.2 cm³ and the volume of brain parenchyma was 80.3 cm³. In the infratentorial space, the volume of CSF was 101.3 cm³ and the volume of the brain parenchyma was 88.7 cm³. In the supratentorial space, there was severe malacia of almost all brain parenchyma with no visible remnants of the choroid plexuses. Infratentorial structures of the brainstem and cerebellum were hypoplastic but completely developed. Since our patient had no choroid plexuses in the supratentorial space and no obstruction between dural sinuses and CSF, development of hydrocephalus and macrocephaly cannot be explained by the classic hypothesis of CSF physiology with secretion, unidirectional circulation, and absorption as its basic postulates. However, the origin and turnover of the enormous amount of intracranial CSF volume, at least 10-fold larger than normal, and the mechanisms of macroencephaly development could be elucidated by the new hypothesis of CSF physiology recently published by our research team.

Ventricular endoscopy in the pediatric population: review of indications

INTRODUCTION

Neuroendoscopy has greatly impacted pediatric neurosurgery over the past few decades. Improved optics and microsurgical tools have allowed neuroendoscopes to be used for a multitude of neurosurgical procedures.

DISCUSSION

In this review article, we present the breadth of intraventricular neuroendoscopic procedures for the treatment of conditions ranging from hydrocephalus and brain tumors to congenital cysts and other pathologies. We critically discuss treatment indications and reported success rates for neuroendoscopic procedures. We also present novel approaches, technical nuances, and variations from recently published literature and as practiced in the authors' institution.

New endoscopic route to the temporal horn of the lateral ventricle: surgical simulation and morphometric assessment

Object

The temporal horn of the lateral ventricle is a complex structure affected by specific pathological conditions. Current approaches to the temporal horn involve a certain amount of corticotomy and white matter disruption. Surgeons therefore set aside anterior temporal lobectomy as a last resource and avoid it in the dominant hemisphere. The authors propose a minimally invasive endoscopic intraventricular approach to the temporal horn and describe a standardized analysis and technical assessment of the feasibility of this approach.

Methods

To determine the best trajectory, angulation, and entry point to the temporal horn of the lateral ventricle, the authors evaluated 50 cranial MRI studies (100 temporal lobes) from healthy patients. They studied and systematized the neurosurgical endoscopic anatomy. They also simulated the proposed approach in 9 cadaveric specimens (18 approaches).

Results

Mean scalp entry point coordinates (± SD) were 2.7 ± 0.28 cm lateral to the inion and 5.6 ± 0.41 cm superior to the inion. The mean total distance from the uncal recess to the scalp (± SD) was 10.64 ± 0.6 cm. The mean total intraparenchymal distance crossed by the endoscope was 3.76 ± 0.36 cm. The approach was successfully completed in all studied specimens.

Conclusions

In this study, the endoscopic intraventricular approach to the temporal horn is standardized. The morphometric analysis makes this approach anatomically feasible and replicable. This approach provides minimally invasive endoscopic access to the uncal recess, amygdala, hippocampus, fornix, and paraventricular temporal lobe structures. The following essential strategies enabled access to and maneuverability inside the temporal horn: tailored preoperative planning of the trajectory and use of anatomical and radiological references, constant irrigation, and an angled endoscopic lens. Safety assessment and novel instruments and techniques may be proposed to advance this very promising route to pathological changes in the temporal lobe.

Neuroendoscopic biopsy of pediatric brain tumors with small ventricle

PURPOSE

Intraventricular endoscopic procedures to resect or biopsy peri- or intraventricular tumors may have not been used in patients with small ventricles due to the presumed difficulties with ventricular cannulation and the perceived risk of morbidity. The purpose of this study is to review the feasibility and safety of neuroendoscopic procedures in the biopsy of pediatric brain tumors with a small ventricle.

METHODS

Between January 2006 and January 2013, 72 children were identified with brain tumors confirmed by transventricular endoscopic biopsy. Patients were divided into non-hydrocephalus and hydrocephalus groups, and the ratio of the two groups was 20:52.

RESULTS

In 20 pediatric brain tumors with small ventricle, the targeted lesion was successfully approached under the guidance of neuronavigation. Navigational tracking was especially helpful in entering small ventricles and in approaching the third ventricle through the narrow foramen of Monro. The histopathologic diagnosis was established in all 20 patients: nine germinomas, three mixed germ cell tumors, two pilomyxoid astrocytomas, and two pilocytic astrocytomas. The tumor biopsy sites were the suprasellar area (n = 10), pineal area (n = 4), lateral ventricular wall (n = 4), and mammillary body (n = 1). There were no major morbidities related to the endoscopic procedure.

CONCLUSION

Neuroendoscopic biopsy or resection of peri- or intraventricular tumors in pediatric patients without hydrocephalus is feasible. Navigation-guided neuroendoscopic procedures improved the accuracy of the neuroendoscopic approach and minimized brain trauma. The absence of ventriculomegaly in patients with brain tumor may not serve as a contraindication to neuroendoscopic tumor biopsy.

A comparison of costs associated with endoscope-assisted craniectomy versus open cranial vault repair for infants with sagittal synostosis

OBJECT

The surgical management of infants with sagittal synostosis has traditionally relied on open cranial vault remodeling (CVR) techniques; however, minimally invasive technologies, including endoscope-assisted craniectomy (EAC) repair followed by helmet therapy (HT, EAC+HT), is increasingly used to treat various forms of craniosynostosis during the 1st year of life. In this study the authors determined the costs associated with EAC+HT in comparison with those for CVR.

METHODS

The authors performed a retrospective case-control analysis of 21 children who had undergone CVR and 21 who had undergone EAC+HT. Eligibility criteria included an age less than 1 year and at least 1 year of clinical follow-up data. Financial and clinical records were reviewed for data related to length of hospital stay and transfusion rates as well as costs associated with physician, hospital, and outpatient clinic visits.

RESULTS

The average age of patients who underwent CVR was 6.8 months compared with 3.1 months for those who underwent EAC+HT. Patients who underwent EAC+HT most often required the use of 2 helmets (76.5%), infrequently required a third helmet (13.3%), and averaged 1.8 clinic visits in the first 90 days after surgery. Endoscope-assisted craniectomy plus HT was associated with shorter hospital stays (mean 1.10 vs 4.67 days for CVR, p < 0.0001), a decreased rate of blood transfusions (9.5% vs 100% for CVR, p < 0.0001), and a decreased operative time (81.1 vs 165.8 minutes for CVR, p < 0.0001). The overall cost of EAC+HT, accounting for hospital charges, professional and helmet fees, and clinic visits, was also lower than that of CVR ($37,255.99 vs $56,990.46, respectively, p < 0.0001).

CONCLUSIONS

Endoscope-assisted craniectomy plus HT is a less costly surgical option for patients than CVR. In addition, EAC+HT was associated with a lower utilization of perioperative resources. Theses findings suggest that EAC+HT for infants with sagittal synostosis may be a cost-effective first-line surgical option.

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.

Application of phase-contrast cine magnetic resonance imaging in endoscopic aqueductoplasty

The aim of this study was to evaluate the application of phase-contrast cine magnetic resonance imaging (MRI) in endoscopic aqueductoplasty (EA) for patients with obstructive hydrocephalus. The clinical diagnosis of hydrocephalus caused by aqueduct obstruction in 23 patients was confirmed by phase-contrast cine MRI examination. The patients were treated with EA and MRI was repeated during the follow-up. The cerebrospinal fluid (CSF) flow velocity in the aqueduct was measured to determine whether the aqueduct was obstructed. The results of phase-contrast cine MRI examinations indicated that there was no CSF flow in the aqueduct for all patients prior to surgery. Aqueductoplasty was successfully performed in all patients. The results of phase-contrast cine MRI examinations performed a week after surgery demonstrated an average CSF flow velocity of 4.74±1.77 cm/sec. During the follow-up, intracranial hypertension recurred in two patients in whom CSF flow was not observed in the aqueduct by the phase-contrast cine MRI scan. Aqueduct re-occlusion was revealed by an endoscopic exploration. By measuring the CSF flow velocity, phase-contrast cine MRI accurately identifies aqueduct obstruction. Cine MRI is a nontraumatic, simple and reliable method for determining whether the aqueduct is successfully opened following aqueductoplasty.

Neuroendoscopic surgery in children: an analysis of 200 consecutive procedures

OBJECTIVE

Neuroendoscopic surgery in children has particular features and is associated with different success rates (SR). The aim of this study was to identify putative factors that could influence the outcome in pediatric patients.

METHODS

Clinical data of 177 patients under 18 years of age submitted to 200 consecutive neuroendoscopic procedures from January 2000 to January 2010 were reviewed.

RESULTS

The overall success rate was 77%. Out of the patients with successful outcomes, 46% were under six months, 68% were between six months and one year of age, and 85% older than one year. Neuroendoscopic techniques provide very good results for a wide number of indications in children. Tumor-related cerebrospinal fluid (CSF) circulation problems and aqueductal stenosis seem to be particularly well suited to neuroendoscopic treatment regardless of the patient's age.

CONCLUSION

Patients' age and etiology of hydrocephalus were associated with a different outcome. In all cases, surgical experience is extremely important to reduce complications.

Neuroendoscopic surgery in hydrocephalus

Hydrocephalus represents one of the most frequent pathologic entities requiring neurosurgical intervention. Even in present times the treatment of hydrocephalus is a highly debated subject. Neuroendoscopy is one of the technique posibility. The present study includes patients with different types of hydrocephalus classified according to imagistic criteria (MRI). Neuroendoscopic therapeutic options are presented for different types of hydrocephalus and the postoperative results of these procedures are revealed by imaging. In conclusion, we consider neuroendoscopy useful in each type of hydrocephalus.

Ventriculoperitoneal shunt surgery outcome in adult transition patients with pediatric-onset hydrocephalus

BACKGROUND

Ventriculoperitoneal shunting remains the most widely used neurosurgical procedure for the management of hydrocephalus, albeit with many complications.

OBJECTIVE

To review and assess the long-term clinical outcome of ventriculoperitoneal shunt surgery in adult transition patients with pediatric-onset hydrocephalus.

METHODS

Patients 17 years or older who underwent ventriculoperitoneal shunt placement for hydrocephalus during their pediatric years (younger than 17 years) were included. Medical charts, operative reports, imaging studies, and clinical follow- up evaluations were reviewed and analyzed retrospectively.

RESULTS

A total of 105 adult patients with pediatric-onset hydrocephalus were included. The median age of the patients was 25.9 years. The median age at the time of the initial ventriculoperitoneal shunt placement was 1.0 year. The median follow-up time for all patients was 17.7 years. The incidence of shunt failure at 6 months was 15.2%, and the overall incidence of shunt failure was 82.9%. Single shunt revision occurred in 26.7% of the patients, and 56.2% had multiple shunt revisions. The cause of hydrocephalus was significantly associated with shunt survival for patients who had shunt failure before the age of 17 years. Being pediatric at first shunt revision, infection, proximal shunt complication, and other causes were independently associated with multiple shunt failures.

CONCLUSION

The findings of this retrospective study show that the long-term ventriculoperitoneal shunt survival remains low in adult transition patients with pediatric-onset hydrocephalus.

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.

The dedicated endoscopic operating room

BACKGROUND

The establishment of neuroendoscopy has been one of the major achievements in neurosurgery in the last 2 decades. The use of the endoscope increases efficacy and safety in each procedure.

METHODS

The integration of endoscopy with other operating techniques or imaging technologies enhances the safety and reliability of the technique.

RESULTS

The efficacy of the procedures, patient safety, and extent of resection have been increased by the integration of endoscopy with all of these sophisticated operative tools and imaging sources. Endoscopy has led to shortening of operative time and of the duration of hospital stay.

CONCLUSIONS

A dedicated endoscopic operating room should provide workflow optimization, ergonomic solutions, and highest safety standards for the patient.

Endoscopic third ventriculostomy and posterior fossa tumors

BACKGROUND

The management of hydrocephalus associated with a posterior fossa tumor is debated. Some authors emphasize the advantages of an immediate tumor removal that may normalize the cerebrospinal fluid (CSF) dynamics. However, in clinical practice, the mere excision of the lesion has been demonstrated to be accompanied by a persisting hydrocephalus in about one third of the cases. Preoperative endoscopic third ventriculostomy (ETV) offers several advantages. It may control the intracranial pressure (ICP), avoid the necessity of an emergency procedure, allow appropriate scheduling of the operation for tumor removal, and eliminate the risks related to the presence of an external drainage. The procedure also reduces the incidence of postoperative hydrocephalus. A final advantage, more difficult to weight, but obvious to the neurosurgeon, is the possibility to remove the lesion with a relaxed brain and normal ICP. In the postoperative phase, ETV can be used in case of persisting hydrocephalus, both in patients who underwent only the excision of the tumor and in those whose preoperative ETV failed as a consequence of intraventricular bleeding with secondary closure of the stoma (redoETV). The main advantage of postoperative ETV is that the procedure is carried out only in case of persisting hydrocephalus; its use is consequently more selective than preoperative ETV. The disadvantage consists in the common use of an external CSF drainage in the first few postoperative days, which is necessary to control the pressure and for ruling out those cases that reach a spontaneous cure of the hydrocephalus.

METHODS

The authors review the criteria for patient selection and the results of ETV performed in case of hydrocephalus secondary to a posterior fossa tumor.

RESULTS AND CONCLUSIONS

Preoperative ETV constitutes an effective procedure for controlling the hydrocephalus associated with posterior fossa tumors. It might lower the rate of persistent postoperative hydrocephalus and result in a short hospital stay. Low rates of patients requiring an extrathecal-CSF shunt device are also reported by authors who utilize ETV postoperatively. As, however, the assessment of the persistent hydrocephalus in these children is based on prolonged ICP monitoring through an external CSF drainage, their results are weighted by a major risk of infective complications and longer hospital stay.

Actual state of EndActive ventricular endoscopy

PURPOSE

We assessed usability and applicability of a rigid, multidirectional steerable videoendoscope (EndActive, Karl Storz GmbH, Tuttlingen, Germany) for endoscopic third ventriculostomy and compared our experience with reports about other multidirectional endoscopes.

METHODS

The prototype is a 4-mm-diameter rigid videoendoscope with an integrated image sensor comprising an embedded light source, offering a free viewing direction in a range of 160° while the tip itself does not move. In five specimens (ten sides), we introduced the endoscope via precoronal burr holes through the lateral ventricle and foramen of Monro into the third ventricle. The endoscope's tip was positioned at the level of the mamillary bodies and the previously defined anatomical target structures; anteriorly, the optic chiasm, anterior commissure, infundibulum, tuber cinereum and posteriorly, the entrance to the mesencephalic aqueduct and posterior commissure were inspected.

RESULTS

A single insertion of the videoendoscope was sufficient to explore with the multiplanar viewing mechanism the entire third ventricle. The prototype videoendoscope may be held like a microsurgical instrument in one hand. It is feasible to control movements precisely due to the reduced weight and ergonomic shape of the device.

CONCLUSIONS

The prototype EndActive has the potential to fit in the current concept of ETV and enrich the setting adding working economy and viewing variability.

The success of endoscopic third ventriculostomy in children: analysis of prognostic factors

OBJECTIVE

The treatment of hydrocephalus in children with endoscopic third ventriculostomy (ETV) has particular features and is associated with different success rates (SR). The aim of this study was to identify putative factors that could influence the outcome of ETV in children.

METHODS

Clinical data of 114 consecutive patients under 18 years of age who underwent 116 consecutive ETVs from January 2000 to January 2010 were reviewed. Data were analyzed with regards to clinical and radiological SR. The actual long-term SR was compared to that predicted by the ETV Success Score (ETVSS) model.

RESULTS

The study group included 49 males (43%) and 65 females (57%) with a mean age of 6.17 ± 1.02 years (ranging from 11 days to 18 years) at surgery. Concerning the etiology of hydrocephalus, tumors and aqueductal stenosis (AS) were the most frequently observed, with each occurring in 33 cases (29%), followed by malformations in 24 (21%), cystic lesions in 6 (5%) and other etiologies in 18 patients (16%). The overall SR at the first ETV attempt was 80% (91/114), compared to 74.8% (variance 14.35, 95% CI 69.37-78.22) predicted by the ETVSS. Regarding age, SR was 58% in patients under 6 months of age, 65% in children between 6 months and 1 year, and 86% in children older than 1 year. SR for AS and hydrocephalus associated with posterior fossa tumors were 88 and 90%, respectively. Unsatisfactory results were related to previous intraventricular hemorrhage and infection. The overall complication rate in this series was 13%.

CONCLUSION

ETV is safe and effective in children. In this series, the age of the patient and etiology of hydrocephalus were related to SR. Also, the ETVSS was accurate to predict outcome. In a long-term follow-up, surgical experience was statistically significant in reducing complications.

What We Should Know About the Cellular and Tissue Response Causing Catheter Obstruction in the Treatment of Hydrocephalus

The treatment of hydrocephalus by cerebrospinal fluid shunting is plagued by ventricular catheter obstruction. Shunts can become obstructed by cells originating from tissue normal to the brain or by pathological cells in the cerebrospinal fluid for a variety of reasons. In this review, the authors examine ventricular catheter obstruction and identify some of the modifications to the ventricular catheter that may alter the mechanical and chemical cues involved in obstruction, including alterations to the surgical strategy, modifications to the chemical surface of the catheter, and changes to the catheter architecture. It is likely a combination of catheter modifications that will improve the treatment of hydrocephalus by prolonging the life of ventricular catheters to improve patient outcome.

Development of hydrocephalus and classical hypothesis of cerebrospinal fluid hydrodynamics: facts and illusions

According to the classical hypothesis of the cerebrospinal fluid (CSF) hydrodynamics, CSF is produced inside the brain ventricles, than it circulates like a slow river toward the cortical subarachnoid space, and finally it is absorbed into the venous sinuses. Some pathological conditions, primarily hydrocephalus, have also been interpreted based on this hypothesis. The development of hydrocephalus is explained as an imbalance between CSF formation and absorption, where more CSF is formed than is absorbed, which results in an abnormal increase in the CSF volume inside the cranial CSF spaces. It is believed that the reason for the imbalance is the obstruction of the CSF pathways between the site of CSF formation and the site of its absorption, which diminishes or prevents CSF outflow from the cranium. In spite of the general acceptance of the classical hypothesis, there are a considerable number of experimental results that do not support such a hypothesis and the generally accepted pathophysiology of hydrocephalus. A recently proposed new working hypothesis suggests that osmotic and hydrostatic forces at the central nervous system microvessels are crucial for the regulation of interstial fluid and CSF volume which constitute a functional unit. Based on that hypothesis, the generally accepted mechanisms of hydrocephalus development are not plausible. Therefore, the recent understanding of the correlation between CSF physiology and the development of hydrocephalus has been thoroughly presented, analyzed and evaluated, and new insights into hydrocephalus etiopathology have been proposed, which are in accordance with the experimental data and the new working hypothesis.

Endoscopic third ventriculostomy in patients with shunt malfunction

OBJECTIVE

This paper presents data from a retrospective study of endoscopic third ventriculostomy (ETV) in patients with shunt malfunction and proposes a simple and reasonable post-operative protocol that can detect ETV failure.

METHODS

We enrolled 19 consecutive hydrocephalus patients (11 male and 8 female) who were treated with ETV between April 2001 and July 2010 after failure of previously placed shunts. We evaluated for correlations between the success rate of ETV and the following parameters : age at the time of surgery, etiology of hydrocephalus, number of shunt revisions, interval between the initial diagnosis of hydrocephalus or the last shunt placement and ETV, and the indwelling time of external ventricular drainage.

RESULTS

At the time of ETV after shunt failure, 14 of the 19 patients were in the pediatric age group and 5 were adults, with ages ranging from 14 months to 42 years (median age, 12 years). The patients had initially been diagnosed with hydrocephalus between the ages of 1 month 24 days and 32 years (median age, 6 years 3 months). The etiology of hydrocephalus was neoplasm in 7 patients; infection in 5; malformation, such as aqueductal stenosis or megacisterna magna in 3; trauma in 1; and unknown in 3. The overall success rate during the median follow-up duration of 1.4 years (9 days to 8.7 years) after secondary ETV was 68.4%. None of the possible contributing factors for successful ETV, including age (p=0.97) and the etiology of hydrocephalus (p=0.79), were statistically correlated with outcomes in our series.

CONCLUSION

The use of ETV in patients with shunt malfunction resulted in shunt independence in 68.4% of cases. Age, etiology of hydrocephalus, and other contributing factors were not statistically correlated with ETV success. External ventricular drainage management during the immediate post-ETV period is a good means of detecting ETV failure.

Stereotactic versus endoscopic surgery in periventricular lesions

OBJECT

Endoscopic and stereotactic surgery have gained widespread acceptance as minimally invasive tools for the diagnosis of intracerebral pathologies. We investigated the specific advantages and disadvantages of each technique in the assessment of periventricular lesions.

METHOD

This study included a retrospective series of 70 patients with periventricular lesions. Endoscopic surgery was performed in 17 patients (mean age, 37 years; range, 4 months-78 years) and stereotactic biopsy in 55 patients (mean age, 63 years; range, 23-80 years), including two patients who underwent both procedures.

RESULTS

Hydrocephalus was present in 13/17 patients in the endoscopic group (77%) and in 11/55 patients in the stereotactic group (20%). Diagnosis was achieved in all patients in the endoscopic group and in all but one patient in the stereotactic group, in whom histological diagnosis was obtained by endoscopic biopsy during a second operation. In the endoscopic group, additional procedures performed included ventriculostomy (2/17), cyst fenestration (3/17), endoscopic shunt revision (3/17) and placement of Rickham reservoirs or external cerebrospinal fluid drains (6/17). Adverse events occurred in one patient after endoscopy (chronic subdural hematoma) and in two patients after stereotactic surgery (one mild hemiparesis and one transitory paresis of the contralateral leg).

CONCLUSIONS

Endoscopic and stereotactic surgery have distinct advantages and disadvantages in approaching periventricular lesions. The advantages of endoscopy encompass the possibility to perform additional surgical procedures during the same session (e.g. tumour reduction, third ventriculostomy, fenestration of a cyst). The visual control reduces the hazard of injury to anatomical structures and allows for a better control of bleeding although there is a considerable blind-out in such situations. The advantages of stereotactic surgery include a smaller approach and precise planning of the trajectory. It is usually performed under local anaesthesia. Both methods provide a safe and efficient therapeutic option in periventricular lesions with low surgical-related morbidity.

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.

Endoscopic minimally invasive neurosurgery: emerging techniques and expanding role through an extensive review of the literature and our own experience - part I: intraendoscopic neurosurgery

BACKGROUND/AIMS

Minimally invasive neurosurgery is a growing field, more so in recent decades. The modernization of tools, especially the endoscope, has allowed for critical improvements and crucial advancements in minimally invasive neurosurgery. The current classification scheme for endoscopic procedures needs to be updated to reflect these advancements.

METHODS

Although the field of neuroendoscopy is continually evolving, the terminologies utilized to describe endoscopic procedures reflect and favor its use as mostly an assisting device complementing the microscope. Even though the classification was adequate for its time, it has become inexact and therefore confusing. We therefore propose a new classification scheme that encompasses the growing independence of endoscopic minimally invasive neurosurgery (EMIN) as well as the changing landscape within EMIN procedures.

RESULTS

We have classified our EMIN procedures, since 2002, as either 'intraendoscopic' (IEN) or 'extraendoscopic' (XEN) in relation to the endoscope's axis. Exemplary cases of IEN and a review of the literature are presented as well.

CONCLUSION

Our proposed classification scheme for solely endoscopic procedures is presented. The role of the endoscope as an independent tool is clarified.

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.

Pressure inside the neuroendoscope: correlation with epidural intracranial pressure during neuroendoscopic procedures

BACKGROUND

During neuroendoscopic procedures, pressure inside the neuroendoscope (PIN) monitored through the irrigation channel correlates with the occurrence of postoperative complications. Our aim was to analyze the reliability of PIN measurement as a surrogate for intracranial pressure (ICP) by comparing PIN with simultaneously epidural ICP measurement as the standard.

METHODS

Seventeen consecutive patients undergoing neuroendoscopy were studied prospectively. Type and length of procedure and PIN and epidural ICP values during neuroendoscopy were recorded. Lin's concordance coefficient and Bland-Altman analysis of agreement were used to assess correspondence between the 2 systems.

RESULTS

A consistent relation between PIN and epidural ICP waveforms was observed during neuroendoscopic navigation. A strong Pearson correlation between PIN and epidural ICP data were found in 15 patients. Epidural ICP values were systematically higher than PIN values in 15 patients. Lin concordance coefficients showed moderate global agreement between the 2 methods, at 0.58 (95% confidence interval, 0.577-0.592). In 6 cases (35.2%) concordance was good according to this analysis, in 7 cases (41.2%) agreement was moderate/fair, and in 4 cases (23.5%) agreement was poor. The Bland-Altman analysis of patient data showed good agreement between the PIN and epidural ICP measurements for most patients, although discrepancies were greater at higher ICP values for 11 patients. Bland-Altman analysis of the complete dataset, after the normalization of individual's measurements, showed good overall agreement.

CONCLUSIONS

PIN measurement seems useful for evaluating ICP changes related to neuroendoscopic procedures and seems to be more consistent than epidural ICP at high pressures.