Silicone elastomer cerebrospinal fluid shunt systems. Council on Scientific Affairs, American Medical Association

Ventriculoatrial shunt remains a safe surgical alternative for hydrocephalus: a systematic review and meta-analysis

Hydrocephalus is a commonly encountered pathology in the neurosurgical practice. Since the first permanent ventriculo-subarachnoid-subgaleal shunt described by Mikulicz in 1893, there were multiple attempts to find solutions for draining the excess production/less reabsorption of the cerebrospinal fluid (CSF) from the brain. Nowadays, the most common technique is the ventriculoperitoneal shunt (VPS), whereas the ventriculoatrial shunt (VAS) is applied only in some rare conditions. To date there are still no specific guidelines or strong evidence in literature that guide the surgeon in the choice between the two methods, and the decision usually relies on the confidence and expertise of the surgeon. Considering the lack of established recommendations, this systematic review and meta-analysis aims to evaluate the effectiveness and safety of these two shunting techniques. This systematic review was conducted following the PRISMA protocol (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). No chronological limits of study publications were included. Prospective and retrospective clinical studies, and reports of case series with at least five patients per group and reporting data on comparison between VAS and VPS techniques were eligible for inclusion. Nine studies reporting 3197 patients meeting the inclusion and exclusion criteria were identified and included in the quantitative synthesis. The risk of shunt dysfunction/obstruction was significantly lower in the VAS group [odds ratio (OR) 0.49, 95%-CI 0.34-0.70, I2 0%]. The risk of infection was not significantly different between the two groups (OR 1.02, 95%-CI 0.59-1.74, I2 0%). The risk of revision was not significantly different between the two groups; however, the heterogeneity between the studies was significant (OR 0.73, 95%-CI 0.36-1.49, I2 91%). Additionally, the risk of death was not significantly different between the two groups; however, the heterogeneity between the studies was high (OR 1.93, 95%-CI 0.81-4.62, I2 64%). VAS remains a safe surgical alternative for hydrocephalus. The results of this study highlight a lower risk of shunt dysfunction/obstruction variable in the VAS group, with no significant statistical differences regarding the occurrence of at least one infection-related complication. In consequence, the choice between these two techniques must be tailored to the specific characteristics of the patient.Protocol Registration: The review protocol was registered and published in Prospective Register of Systematic Reviews (PROSPERO) ( www.crd.york.ac.uk/PROSPERO ) website with registration number: CRD42023479365.

In vitro and in vivo assessment of a novel ultra-flexible ventriculoamniotic shunt for treating fetal hydrocephalus

Fetal aqueductal stenosis (AS) is one of the most common causes of congenital hydrocephalus, which increases intracranial pressure due to partial or complete obstruction of cerebrospinal fluid (CSF) flow within the ventricular system. Approximately 2-4 infants per 10,000 births develop AS, which leads to progressive hydrocephalus, which enlarges the head often necessitating delivery by cesarean section. Most babies born with AS are severely neurologically impaired and experience a lifetime of disability. Therefore, a new device technology for venticuloamniotic shunting is urgently needed and has been studied to ameliorate or prevent fetal hydrocephalus development, which can provide a significant impact on patients and their family's quality of life and on the decrease of the healthcare dollars spent for the treatment. This study has successfully validated the design of shunt devices and demonstrated the mechanical performance and valve functions. A functional prototype shunt has been fabricated and subsequently used in multiple in vitro tests to demonstrate the performance of this newly developed ventriculoamniotic shunt. The shunt contains a main silicone-nitinol composite tube, a superelastic 90° angled dual dumbbell anchor, and an ePTFE valve encased by a stainless-steel cage. The anchor will change its diameter from 1.15 mm (collapsed state) to 2.75 mm (deployed state) showing up to 1.4-fold diameter change in human body temperature. Flow rates in shunts were quantified to demonstrate the valve function in low flow rates mimicking the fetal hydrocephalus condition showing "no backflow" for the valved shunt while there is up to 15 mL/h flow through the shunt with pressure difference of 20 Pa. In vivo ovine study results show the initial successful device delivery and flow drainage with sheep model.

Intraventricular Hemorrhage in Premature Infants: A Historical Review

Intraventricular hemorrhage (IVH) is common in premature newborns and poses a high risk for morbidity with lifelong disability. We searched the available literature for original and secondary literature regarding the epidemiology, pathogenesis, and treatment of IVH in order to trace changes in the management of this disease over time. We examined IVH pathogenesis and epidemiology and reviewed the history of medical and surgical treatment for intraventricular hemorrhage in preterm children. Initial medical management strategies aimed at correcting coagulopathy and eventually targeted mediators of perinatal instability including respiratory distress. Surgical management centered around cerebrospinal fluid diversion, initially through serial lumbar punctures, progressing to ventriculoperitoneal shunting, with more recent interventions addressing intraventricular clot burden. We provide a historical review of the evolution of treatment for IVH in newborns. While the management of IVH has grown significantly over time, IVH remains a common neurosurgical disease that continues to affect patient and caregiver quality of life and health care costs. Despite advances in treatment over more than a century, IVH remains a significant cause of morbidity and mortality in premature infants, and an understanding of past approaches may inform the development of new treatments.

Analysis of N-acetyl cysteine modified polydimethylsiloxane shunt for improved treatment of hydrocephalus

A major cause of hydrocephalus shunt failure is cell adhesion and obstruction of shunt catheter holes. An estimated 50% of pediatric shunts fail in the first 2 years of insertion, decreasing cell attachment and catheter obstruction can prolong the lifetime and effectiveness of the device. From previous studies, it was shown that treatment of the polydimethylsiloxane (PDMS) surface of a standard catheter with an N-acetyl-cysteine (NAC/1-ethyl-3-(3-dimethylanimopropyl)carbodiimide hydrochloride/N-hydroxysuccinimide) layer increases the wettability of the surface and has been shown to decrease cell adhesion. Other studies indicate that NAC's antioxidant behavior induces glutathione and in turn modulates cell inflammatory pathways. The current study explores the longevity of the NAC coating from the surface of the catheter over time and shows its effect on valve function. Using SEM imaging, contact angle testing, and nanodrop spectrophotometry, this release was quantified for shunt samples incubated for 0, 10, 30, 60, and 90 days. Contact angle showed a significant increase in wettability of the surface when shunts were treated with NAC, confirming successful surface modification. Pressure assays determined that if the coating is release it had no detrimental downstream effects, such as on the shunt valve mechanism. SEM imaging revealed slight deformations in surface coating indicative of salt deposition on the modified shunt samples, while nanodrop spectrophotometry and contact angle data trends suggested some discharge of the NAC coating from the catheter surfaces. The effects of NAC on cell activity may transform the way hydrocephalus is treated in the future by increasing the longevity of the shunt to protect from obstruction.

Case report: the unexpected culprit for multiple shunt revisions

Silicone allergy in patients with ventricular shunts is uncommon hence easily missed. However, there are clinical features that could assist in identifying and diagnosing this condition. We discuss a case where a patient with a ventriculoperitoneal (VP) shunt presented to us with features suggestive of silicone allergy.

Silicone implants and lymphoma: The role of inflammation

The risk of hematological malignancies is mainly determined by genetic background, age, sex, race and ethnicity, geographic location, exposure to certain chemicals and radiation; along with the more recently proposed immune factors such as chronic inflammation, immunodeficiencies, autoimmunity, and infections. Paradigmatic examples include the development of lymphoma in Sjögren's syndrome and Hashimoto thyroiditis, gastric MALT lymphoma in Helicobacter pylori infection, or lymphomas associated with infections by Epstein-Barr virus, human herpes virus 8 (HHV 8) and leukemia/lymphoma virus 1 (HTLV-1). A growing number of reports indicates an increased risk of lymphoma, particularly of the anaplastic large cell (ALCL) type. The implants, specifically those used in the past, elicit chronic stimulation of the immune system against the prosthetic material. This is particularly the case in genetically susceptible hosts. We suggest that polyclonal activation may result in monoclonality in those at risk hosts, ultimately leading to lymphoma. We suggest that patients with an inflammatory response against silicone implants be monitored carefully.

Endoscopic observations of blocked ventriculoperitoneal (VP) shunt: a step toward better understanding of shunt obstruction and its removal

OBJECTIVES

Most of our understanding of ventriculoperitoneal (VP) shunt blockage (ventricular end) is based on in vitro studies of blocked VP shunts. Not much information is available regarding the in vivo changes that occur in the tube and in the surrounding ventricle. The primary aim of our study was to observe and analyse these changes, directly, through the endoscope, in patients with blocked shunts undergoing an endoscopic third ventriculostomy (ETV). Based on these findings, we have also suggested criteria for safe removal of the VP shunt tube following ETV.

MATERIAL AND METHODS

ETV was performed with standard technique in patients with blocked VP shunt. The ventricular end of the shunt tube was inspected through the endoscope, for changes in ventricle linings as well as in the shunt tube. These changes were correlated with the age of the patient, etiology of HC, type or make of the shunt tube, duration of shunt placement to ETV and the CSF findings.

RESULTS

Fifty-three patients of blocked VP shunt underwent ETV from July 2006 to April 2010. Thirty patients had Chhabra (CH) V P Shunt (Surgiwear, India) and 23 had ceredrain (CD) shunt (Hindustan Latex, India). The age of the patients ranged from 2 months to 60 years (mean--13.33 years.). Various causes of hydrocephalus (HC) included congenital hydrocephalus (aqueductal stenosis) in 18 patients, post-meningitis hydrocephalus (PMH) in 32 cases, neuro-cysticercosis (NCC) in 2 patients and intraventricular haemorrhagic (IVH) in 1 patient. Clinical and radiological improvement occurred in 33 (62.21%), and 24 (45%) patients, respectively. Freedom from shunt was attained in 20 (38%) patients. The changes around the shunt tube were seen in 41 (77%). Hyperaemia and neovascularised ependyma was seen in 20 (37%) and 15 (28%) patients. Encasement of the tube was seen in 41%. Ependymal growth and neovascularised shunt tubes were noticed in 15% each. Choroid plexus blocking the tube was seen in only four cases (7%). VP shunt was revised in 14 patients (26.4%). Patient with infective etiology had more changes (p < 0.005). Age, CSF findings and make of shunt tube had no relation with endoscopic observations (p< 0.02).

CONCLUSIONS

ETV has a role in shunt failures. It can offer patient a chance of shunt free life. Endoscopic observation of shunt tube and ventricle can unfold several interesting in vivo findings pertaining to shunt obstruction. Shunt should only be removed if there are no adhesions and neovascularisation.

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.

Improved delineation of ventricular shunt catheters using fast steady-state gradient recalled-echo sequences in a rapid brain MR imaging protocol in nonsedated pediatric patients

BACKGROUND AND PURPOSE

Rapid brain MR imaging is often substituted for head CT in multiply imaged patients with shunted hydrocephalus. Fast TSE-T2 sequences are commonly used in these protocols. One limitation of TSE-T2 sequences is the decreased catheter delineation compared with CT. The aim of this study was to compare fast TSE-T2 with rapid SS-GRE sequences in the evaluation of intracranial shunt catheter delineation as part of a rapid nonsedated pediatric brain MR imaging protocol.

MATERIALS AND METHODS

We evaluated the findings from 179 consecutive patients who underwent routine clinical imaging according to the rapid nonsedated pediatric brain MR imaging protocol. Comparison of the quality of intracranial shunt catheter localization on SS-GRE versus TSE-T2 was performed.

RESULTS

Of the total of 179 rapid nonsedated pediatric brain MR images that were reviewed, 62 (35%) had an intracranial shunt catheter. The shunt catheter tip was better localized on the SS-GRE than on the TSE-T2 images in 49/62 (79%) of these patients. Of the remaining 13/62 (21%), the TSE-T2 was either better or equivalent in localizing the shunt catheter tip.

CONCLUSIONS

Our study shows that rapid SS-GRE sequences can provide better delineation of standard intracranial shunt catheters than standard rapid MR imaging protocols containing only fast TSE-T2 sequences.

Biomaterials for the central nervous system

Biomaterials are widely used to help treat neurological disorders and/or improve functional recovery in the central nervous system (CNS). This article reviews the application of biomaterials in (i) shunting systems for hydrocephalus, (ii) cortical neural prosthetics, (iii) drug delivery in the CNS, (iv) hydrogel scaffolds for CNS repair, and (v) neural stem cell encapsulation for neurotrauma. The biological and material requirements for the biomaterials in these applications are discussed. The difficulties that the biomaterials might face in each application and the possible solutions are also reviewed in this article.

Have we made progress in preventing shunt failure? A critical analysis

OBJECT

The goal of this study was to determine whether failure rates of hydrocephalus shunts have fallen over the years as a result of experience or technical improvements.

METHODS

A structured search was performed of the English language literature for case series reporting failure rates after shunt insertion. A metaanalytic model was constructed to pool data from multiple studies and to analyze failure rates statistically for temporal trends. Separate models were used for children (< 17 years old) and adults.

RESULTS

In children, the shunt failure rate was 31.3% for the 1st year and 4.5% per year thereafter. There were no significant changes in either rate over time. Although 1st-year failure rates in adults have fallen slightly over time, late failure rates have risen.

CONCLUSIONS

Progress in preventing shunt failures has not been made over the last several decades. Any improvements made in shunt materials or insertion techniques have been overshadowed by biological and other factors.

Effect of surface modification of siliconeon Staphylococcus epidermidis adhesion and colonization

Cerebrospinal fluid (CSF) shunts for the treatment of hydrocephalus are generally made of silicone rubber. The growth of bacterial colonies on the silicone surface leads to frequent CSF shunt complications. A systematic study of the effect of the surface modification of silicone on Staphylococcus epidermidis adhesion and colonization was performed for different incubation times by means of colony counting and scanning electron microscopy (SEM). Silicone was modified with different biopolymers and silanes, including heparin, hyaluronan, octadecyltrichlorosilane (OTS), and fluoroalkylsilane (FAS) to provide a stable and biocompatible surface with different surface functional groups and degrees of hydrophobicity. The modified silicone surfaces were studied by using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). After 4 and 8 h of incubation, the FAS- and OTS-coated silicone and the hyaluronan coated OTS/silicone surfaces showed significantly reduced bacterial adhesion and colonization compared to blank silicone by both quantification methods. However, the heparin coated OTS/silicone showed significantly increased bacterial adhesion. These results indicate that the nature of the surface functional group and surface roughness determine the extent of bacterial adhesion and colonization. However, the degree of hydrophobicity of the surface did not appear to play a determining role in bacterial adhesion and colonization.

Nonfunctional abdominal complications of the distal catheter on the treatment of hydrocephalus: an inflammatory hypothesis? Experience with six cases

INTRODUCTION

The peritoneal cavity is the most common site of cerebrospinal fluid absorption in hydrocephalus treatment. Many distal catheter complications are the result of this type of treatment, and these have been extensively described in the neurosurgical literature.

MATERIALS AND METHODS

In our study, six cases of distal catheter migration with visceral perforation and/or extrusion are presented: three through the umbilicus, two through the scrotum, and one through the anus. An extensive review of the literature was performed.

RESULTS

The studies of peritoneal dialysis models for the treatment of chronic renal failure patients provide important data about solute absorption in the peritoneal cavity and reactivity of the peritoneal membrane.

CONCLUSION

This model, when compared to distal catheter complications on a ventriculoperitoneal (VP) shunt, presents similarities that could help understand the mechanism of the nonfunctional complications of the distal VP catheter (complication with functional shunt), providing valuable data to support an inflammatory mechanism.