Immune reactions associated with silicone-based ventriculo-peritoneal shunt malfunctions in children

Ventriculoperitoneal Shunt Failure and Cerebrospinal Fluid Protein: A Meta-Analysis and Systematic Review

Ventriculoperitoneal shunts (VPS) are used to manage hydrocephalus but suffer from high failure rates. Our objectives were to (1) conduct a meta-analysis to objectively weigh this conflicting evidence, and (2) conduct a systematic review compiling and synthesizing what is known about the association between CSF proteins and shunt failure. A literature search was performed in compliance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The Embase, PubMed, and CENTRAL databases were searched from inception to June 2023. The articles were screened based on the inclusion criteria. A meta-analysis was conducted using R statistical software (R Foundation for Statistical Computing, Vienna, Austria); heterogeneity, subgroup, sensitivity, risk of bias, and publication bias analyses were performed. Thirty-one studies were selected for the systematic review, of which eight were selected for the meta-analysis. Perioperative CSF protein level was compared between 351 shunt failures and 1,094 shunt survivals; the mean difference of 24.37 mg/dL favoring shunt failure was significant (95% confidence interval=2.44-46.29 mg/dL). Our systematic review yielded a hypothesized pathogenesis: proteins attached to imperfections in the shunt surface lead to secondary attachment of cells, particularly astrocytes, and tertiary attachment of ependymal cells and the choroid plexus. Owing to the limitations of this meta-analysis, including lack of robustness due to missing data, heterogeneity, and certainty of the evidence, future research is needed to better understand the relationship between perioperative CSF protein levels and shunt failure.

Repeated shunt dysfunction due to Barium allergy that was difficult to differentiate from shunt infection

We encountered a case of repeated shunt dysfunction caused by barium allergy. The patient was a 60-year-old male who underwent ventricular peritoneal shunting for hydrocephalus following subarachnoid hemorrhage due to a ruptured aneurysm;however, it malfunctioned many times. A patch test performed after the third reconstruction was positive for barium. To the best of our knowledge, this is the first case report of shunt malfunction due to barium allergy. The patch test is useful in cases of suspected allergy-related dysfunction. We recommend the introduction of barium into antigen testing using the patch test. J. Med. Invest. 70 : 521-523, August, 2023.

The surface topography of silicone breast implants mediates the foreign body response in mice, rabbits and humans

Silicone is widely used in chronic implants and is generally perceived to be safe. However, textured breast implants have been associated with immune-related complications, including malignancies. Here, by examining for up to one year the foreign body response and capsular fibrosis triggered by miniaturized or full-scale clinically approved breast implants with different surface topography (average roughness, 0-90 μm) placed in the mammary fat pads of mice or rabbits, respectively, we show that surface topography mediates immune responses to the implants. We also show that the surface surrounding human breast implants collected during revision surgeries also differentially alters the individual's immune responses to the implant. Moreover, miniaturized implants with an average roughness of 4 μm can largely suppress the foreign body response and fibrosis (but not in T-cell-deficient mice), and that tissue surrounding these implants displayed higher levels of immunosuppressive FOXP3⁺ regulatory T cells. Our findings suggest that, amongst the topographies investigated, implants with an average roughness of 4 μm provoke the least amount of inflammation and foreign body response.

A multicenter retrospective study of heterogeneous tissue aggregates obstructing ventricular catheters explanted from patients with hydrocephalus

BACKGROUND

Implantation of ventricular catheters (VCs) to drain cerebrospinal fluid (CSF) is a standard approach to treat hydrocephalus. VCs fail frequently due to tissue obstructing the lumen via the drainage holes. Mechanisms driving obstruction are poorly understood. This study aimed to characterize the histological features of VC obstructions and identify links to clinical factors.

METHODS

343 VCs with relevant clinical data were collected from five centers. Each hole on the VCs was classified by degree of tissue obstruction after macroscopic analysis. A subgroup of 54 samples was analyzed using immunofluorescent labelling, histology and immunohistochemistry.

RESULTS

61.5% of the 343 VCs analyzed had tissue aggregates occluding at least one hole (n = 211) however the vast majority of the holes (70%) showed no tissue aggregates. Mean age at which patients with occluded VCs had their first surgeries (3.25 yrs) was lower than in patients with non-occluded VCs (5.29 yrs, p < 0.02). Mean length of time of implantation of occluded VCs, 33.22 months was greater than for non-occluded VCs, 23.8 months (p = 0.02). Patients with myelomeningocele had a greater probability of having an occluded VC (p = 0.0426). VCs with occlusions had greater numbers of macrophages and astrocytes in comparison to non-occluded VCs (p < 0.01). Microglia comprised only 2-6% of the VC-obstructing tissue aggregates. Histologic analysis showed choroid plexus occlusion in 24%, vascularized glial tissue occlusion in 24%, prevalent lymphocytic inflammation in 29%, and foreign body giant cell reactions in 5% and no ependyma.

CONCLUSION

Our data show that age of the first surgery and length of time a VC is implanted are factors that influence the degree of VC obstruction. The tissue aggregates obstructing VCs are composed predominantly of astrocytes and macrophages; microglia have a relatively small presence.

A new inflammatory parameter can predict delayed intracranial hemorrhage following ventriculoperitoneal shunt

Delayed intracerebral hemorrhage (DICH) secondary to ventriculoperitoneal (VP) shunt is considered to be a potentially severe event. This study aimed to investigate the association between a ratio of postoperative neutrophil-to-lymphocyte ratio to preoperative neutrophil-to-lymphocyte ratio (NLRR) and DICH secondary to VP shunt. We performed a retrospective review of patients who underwent VP shunt between January 2016 and June 2020. Multivariable logistic regression analysis was used to assess the association of DICH and NLRR. Then patients were divided into two groups according to the optimal cut-off point of NLRR, propensity score matching (PSM) method was performed to reconfirm the result. A total of 130 patients were enrolled and DICH occurred in 29 patients. Elevated NLRR and history of craniotomy were independent risk factors for DICH secondary to VP shunt. The optimal cut off point of NLRR was 2.05, and the sensitivity was 89.7%, the specificity was 63.4%. Patients with NLRR > 2.05 had much higher incidence of DICH (40.6% vs 4.5%). Our finding suggested that DICH following VP shunt was not a rare complication and elevated NLRR could independently predict DICH. Inflammatory responses might play an important role in the development of DICH following VP shunt.

GAVCA Study: Randomized, Multicenter Trial to Evaluate the Quality of Ventricular Catheter Placement with a Mobile Health Assisted Guidance Technique

BACKGROUND

Freehand ventricular catheter placement may represent limited accuracy for the surgeon's intent to achieve primary optimal catheter position.

OBJECTIVE

To investigate the accuracy of a ventricular catheter guide assisted by a simple mobile health application (mhealth app) in a multicenter, randomized, controlled, simple blinded study (GAVCA study).

METHODS

In total, 139 eligible patients were enrolled in 9 centers. Catheter placement was evaluated by 3 different components: number of ventricular cannulation attempts, a grading scale, and the anatomical position of the catheter tip. The primary endpoint was the rate of primary cannulation of grade I catheter position in the ipsilateral ventricle. The secondary endpoints were rate of intraventricular position of the catheter's perforations, early ventricular catheter failure, and complications.

RESULTS

The primary endpoint was reached in 70% of the guided group vs 56.5% (freehand group; odds ratio 1.79, 95% confidence interval 0.89-3.61). The primary successful puncture rate was 100% vs 91.3% (P = .012). Catheter perforations were located completely inside the ventricle in 81.4% (guided group) and 65.2% (freehand group; odds ratio 2.34, 95% confidence interval 1.07-5.1). No differences occurred in early ventricular catheter failure, complication rate, duration of surgery, or hospital stay.

CONCLUSION

The guided ventricular catheter application proved to be a safe and simple method. The primary endpoint revealed a nonsignificant improvement of optimal catheter placement among the groups. Long-term follow-up is necessary in order to evaluate differences in catheter survival among shunted patients.

Soluble membrane attack complex is diagnostic for intraventricular shunt infection in children

BACKGROUND

Children treated with cerebrospinal fluid (CSF) shunts to manage hydrocephalus frequently develop shunt failure and/or infections, conditions that present with overlapping symptoms. The potential life-threatening nature of shunt infections requires rapid diagnosis; however, traditional microbiology is time consuming, expensive, and potentially unreliable. We set out to identify a biomarker that would identify shunt infection.

METHODS

CSF was assayed for the soluble membrane attack complex (sMAC) by ELISA in patients with suspected shunt failure or infection. CSF was obtained at the time of initial surgical intervention. Statistical analysis was performed to assess the diagnostic potential of sMAC in pyogenic-infected versus noninfected patients.

RESULTS

Children with pyogenic shunt infection had significantly increased sMAC levels compared with noninfected patients (3,211 ± 1,111 ng/ml vs. 26 ± 3.8 ng/ml, P = 0.0001). In infected patients undergoing serial CSF draws, sMAC levels were prognostic for both positive and negative clinical outcomes. Children with delayed, broth-only growth of commensal organisms (P. acnes, S. epidermidis, etc.) had the lowest sMAC levels (7.96 ± 1.7 ng/ml), suggesting contamination rather than shunt infection.

CONCLUSION

Elevated CSF sMAC levels are both sensitive and specific for diagnosing pyogenic shunt infection and may serve as a useful prognostic biomarker during recovery from infection.

FUNDING

This work was supported in part by the Impact Fund of Children's of Alabama.

Biodegradable Mineralized Collagen Plug for the Reconstruction of Craniotomy Burr-Holes: A Report of Three Cases

Objectives

In this case report, we describe the design, fabrication and clinical outcomes of a novel bioresorbable, mineralized collagen burr-hole plug for the reconstruction of craniotomy burr-holes.

Methods

Mineralized collagen burr-hole plugs were fabricated via a biomimetic mineralization process. The biomimetic mineralized collagen has a similar chemical composition and microstructure to natural bone tissue, thereby possessing good biocompatibility and osteoconductivity. The mineralized collagen burr-hole plugs were implanted into three patients, and clinical outcomes were evaluated at one-year follow-ups.

Results

All bone defects healed very well using the mineralized collagen burr-hole plugs, and there were no adverse reactions at the surgical sites.

Conclusions

The clinical outcomes indicated that the mineralized collagen was effective for reconstructing burr-holes in the skull after craniotomy.

Pathophysiology of shunt dysfunction in shunt treated hydrocephalus

BACKGROUND

We hypothesized that shunt dysfunction in the ventricular catheter and the shunt valve is caused by different cellular responses. We also hypothesized that the cellular responses depend on different pathophysiological mechanisms.

METHODS

Removed shunt material was collected. Macroscopic tissue in the catheters was paraffin-embedded and HE-stained. Valves were incubated with trypsin-EDTA in order to detach macroscopically invisible biomaterial, which was then cytospinned and HE-stained. Associated aetiological and surgical data were collected by reviewing patient files, and ventricular catheter position was examined using preoperative radiology (CT scans).

RESULTS

We examined eleven ventricular catheters and ten shunt valves. Catheters: 6/11 catheters contained intraluminal tissue consisting of vascularised glial tissue and inflammatory cells (macrophages/giant cells and a few eosinophils). Catheter adherence correlated with the presence of intraluminal tissue, and all tissue containing catheters had some degree of ventricle wall contact. All obstructed catheters contained intraluminal tissue, except one catheter that was dysfunctional because of lost ventricular contact. Valves: Regardless of intraoperative confirmation of valve obstruction, all ten valves contained an almost uniform cellular response of glial cells (most likely ependymal cells), macrophages/giant cells, and lymphomonocytic cells. Some degree of ventricle wall catheter contact was present in all examined valves with available radiology (9/10).

CONCLUSIONS

The same cellular responses (i.e., glial cells and inflammatory cells) cause both catheter obstruction and valve obstruction. We propose two synergistic pathophysiological mechanisms. (1) Ventricle wall/parenchymal contact by the catheter causes mechanical irritation of the parenchyma including ependymal exfoliation. (2) The shunt material provokes an inflammatory reaction, either nonspecific or specific. In combination, these mechanisms cause obstructive tissue ingrowth (glial and inflammatory) in the catheter and clogging of the valve by exfoliated glial cells and reactive inflammatory cells.

Foreign body granuloma secondary to ventriculo-peritoneal shunt: a rare scenario with a new insight

Ventriculo-peritoneal shunts are used extensively for the management of hydrocephalus and frequently present with complications such as shunt blockage and infection. Cerebrospinal fluid (CSF) eosinophilia and allergic responses to the shunt itself are rare, poorly understood but increasingly recognised complications. Here, the authors describe a child who required multiple shunt revision surgeries due to extensive scalp tenderness overlying the shunt tubing and persistent severe headaches despite having a normal working shunt and no CSF infection or eosinophilia. Histological investigation of excised tissue during the last shunt revision demonstrated fibrosis with scar tissue and chronic inflammatory infiltrate with foreign body giant cells and few abortive granulomata. This was felt to represent a foreign body reaction to the shunt. A hypoallergenic 'extracted' shunt was trialled (extracted Delta® valve and extracted ventricular and peritoneal catheters; Medtronic) and the child has had no further shunt revisions and is currently asymptomatic 1 year after the insertion.

Is the elapsed time following the placement of a ventriculoperitoneal shunt catheter an individual risk factor for shunt fractures?

In this study, we examined whether the resistance of peritoneal catheters against the retraction force changed over time following shunt placement, and the role of this resistance in shunt fracture is discussed. We investigated peritoneal catheters removed from patients treated with a ventriculoperitoneal shunt because of hydrocephalus; previously, patients underwent shunt revision. The maximum tension, maximum elongation and elongation percentages of the peritoneal catheters were measured. The mean and maximum tension values of the revised peritoneal catheters were increased compared to the unused catheters. The maximum elongation and elongation rates were significantly decreased. The changes in the maximum elongation, elongation rate and tension values were unrelated to the time elapsed after catheter insertion. This finding indicates that the time elapsed following peritoneal catheter placement was not an individual factor based on the strength of the response of the organism to the foreign body and the mechanical trauma exposed in shunt fractures.

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.

Cerebrospinal fluid eosinophilia associated with intraventricular shunts

CSF eosinophilia (CSF-eo) is uncommon and is usually caused by helminthic infections. However, it has also been found in ∼30% of patients experiencing intraventricular shunt malfunctions. We present a case report and review the conditions associated with CSF-eo and their prophylaxis. An 8 year-old boy with tetraventricular hydrocephalus has had several shunt malfunctions over the last three years. During hospitalization in January 2009 for shunt revision, a transient 30% eosinophilia was detected in his cerebral spinal fluid (CSF) concomitant with Staphylococcus epidermidis infection and long term vancomycin administration. After several shunt replacements and antibiotic treatment, CSF-eo eventually disappeared with good overall clinical response. CSF-eo is a transient and focal event mainly associated with infection, reactions to foreign substances, particles or blood, or obstruction of tubing by normal or fibro-granulomatous tissues. Infection associated with CSF-eo is usually caused by S. epidermidis and Propioniumbacterium acnes. In addition to infection, allergy to silicone and other foreign materials may also be a cause of CSF-eo. We review the diversity of conditions and proposed mechanisms associated with CSF-eo, as well as recommendations for the care of patients with shunts. Detection of CSF-eo has been shown to be a useful indicator of shunt malfunction. As such, it provides physicians with an indicator of a hypersensitivity reaction that is underway or the need to identify bacterial infection. We also highlight the need for improved biocompatibility of shunt hardware and describe strategies to avoid conditions leading to shunt malfunction.

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.

Antipolymer antibody in Italian fibromyalgic patients

The objectives of the present study were to evaluate the presence of antipolymer antibody (APA) seropositivity in 285 Italian patients affected by primary fibromyalgia (FM) and to verify whether APA levels correlate with disease severity and with cytokine levels.APA levels were determined on serum samples by an indirect ELISA kit that detects IgG APA. Cytokines (IL-1, IL-6, IL-8, IL-10 and TNFalpha) were measured by ELISA in plasma. The impact of FM on the quality of life was estimated using the Fibromyalgia Impact Questionnaire, while pain severity was evaluated using a visual analogic scale. Patients were also characterized by the presence of tiredness, stiffness, nonrestorative sleep, anxiety, depression, tension headache, irritable bowel syndrome, temporomandibular dysfunction and Raynaud's phenomena. Using a cut-off value of 30 U, APA-positive values were detected in 60 FM patients (21.05%) and in 15 healthy control individuals (15.00%) without significant differences among their levels or the percentage of seropositivity. FM patients with moderate and severe symptoms had slightly higher APA levels with respect to patients with mild symptoms. APA-seropositive patients exhibited significant correlations between APA levels and the Fibromyalgia Impact Questionnaire estimate (P = 0.042), tiredness (P = 0.003) and IL-1 levels (P = 0.0072). In conclusion, APA cannot be considered a marker of disease in Italian FM patients. The presence of APA, however, might permit the identification of a subset of FM patients with more severe symptoms and of patients who may respond differently to different therapeutic strategies.

Treatment of recurrent ventriculoperitoneal shunt failure associated with persistent cerebrospinal fluid eosinophilia and latex allergy by use of an "extracted" shunt

Shunt failure is commonly associated with infection or mechanical obstruction of the shunt system. The presence of eosinophilia in the cerebrospinal fluid (CSF) has been associated with CSF shunt failure and may be related to both latex and shunt allergies. The authors describe the case of a child with a latex allergy who presented with 10 episodes of shunt failure over a period of 93 months. Cerebrospinal fluid sampling demonstrated persistent eosinophilia (3-36%) and negative cultures. Pathological examination of the ventricular catheter on 3 occasions demonstrated mechanical obstruction by inflammatory debris consisting largely of eosinophils and multinucleated giant cells. On the suspicion that the child might have some uncharacterized allergy to the shunt hardware, shunt replacement was performed using an "extracted" shunt system. The child has remained free of shunt malfunction for > 2 years since the last surgery. Immune responses to unpolymerized silicone are discussed.

Simultaneous analysis of multiple serum proteins adhering to the surface of medical grade polydimethylsiloxane elastomers

Although polydimethylsiloxane (PDMS, silicone) elastomers are presumed to be chemically inert and of negligible toxicity, they induce a prompt acute inflammatory response with subsequent fibrotic reactions. Since local inflammatory and fibrotic side effects are associated with the proteinaceous film on the surface of silicone implants, the process of protein adherence to silicone is of practical medical relevance, and interesting from theoretical, clinical and biotechnological perspectives. It is hypothesized that the systemic side effects resembling rheumatoid and other connective tissue diseases may be triggered by local immunological changes, but this functional relationship has yet to be defined. Because the proteinaceous film on the surface of silicone has been identified as a key player in the activation of host defense mechanisms, we propose a test system based on a proteomics screen to simultaneously identify proteins adsorbed from serum to the surface of silicone. Herein, we describe protein adsorption kinetics on the surface of silicone implants, correlate the adhesion properties of serum proteins with the occurrence of adverse reactions to silicone, and successfully discriminate their signature on the silicone surface in a blinded study of patients suffering from fibrotic reactions (as determined by Baker scale) to silicone implants.

Immune response against polyester implants is influenced by the coating substances

The aim of this study was to evaluate the influence of the coating of polymer implants upon the individual humoral immune response to the polymer matrix. Intramuscular implantation and explantation of samples from three different polyester vascular prostheses coated with collagen, gelatin, or human serum albumin was performed in LEW.1A rats and subsequently compared to sham operated control animals. Antibodies in serum samples were detected by means of enzyme immunoassays employing particles of pure polyester and the respective prosthesis, or solid phase bound coating substances as targets. In contrast to the controls, all animals with implants demonstrated a high antipolyester antibody response with a broad individual variability graduated according to the prosthesis coatings: gelatin > albumin > collagen. This was further significantly increased after the second implantation/first explantation and declined following the last explantation. Only animals with albumin-coated implants revealed specific antibodies to the coating as well as the strongest overall immunological reaction against the prosthesis already on day 8. Specificity of polymer antibodies was demonstrated by competitive inhibition of median antibody binding. Our results showed a specific immune reaction as a result of the applied polymer, which varied due to the surface-coating and individual factors.

Shunt revisions in children--can they be avoided? Experiences from a population-based study

BACKGROUND

Shunt failure is by far the most frequent problem in children with shunts, and most of them will experience this condition at some point in their lives. In order to identify causes of shunt failure, and to compare multi-component and one-piece shunt systems, we analyzed retrospectively all pediatric shunt procedures in our Department during an 11-year period. The study does not deal with shunt infections.

METHODS

We reviewed the records of all pediatric shunting procedures between January 1986 and December 1996.

RESULTS

The study included 161 children operated for hydrocephalus with a total of 431 procedures. The procedures included 124 (29%) primary insertions, 10 (2%) reinsertions and 297 (69%) revisions; 206 (69%) of the revisions were due to shunt failures, of which 74 (36%) were caused by the failure of the surgical technique (misplaced ventricular catheters, disconnected shunts, or misplaced peritoneal catheters).

CONCLUSIONS

Improvement of the surgical technique may reduce the incidence of shunt failures and revisions. The results obtained in a small department like ours do not seem to differ substantially from those obtained in more specialized departments with a larger patient group. Practical measures that may reduce the risk of shunt failures are suggested.

Hospitalist care of the medically complex child

The nature of inpatient pediatrics is changing. Over the past decade, several factors have converged to influence the kinds of children currently being hospitalized. There has been a shift in the relative proportion of otherwise healthy children with acute illnesses being hospitalized to children with increasing medical complexity. This article focuses on hospitalist care of medically complex children and provides an overview on (1) the challenges in defining this population, (2) the unique issues surrounding their inpatient care (using a family-centered care approach that includes coordinated care, minimizing secondary complications, nutritional needs, functional limitations, transdisciplinary collaboration, and primary care issues), (3) technology devices commonly found, and (4) a proposal for a research agenda regarding medically complex children.

Highly active, lipase silicone elastomers

Lipase Candida rugosa was entrapped in silicone rubber via condensation-cure room temperature vulcanization of silanol-terminated poly(dimethylsiloxane) with tetraethyl orthosilicate as a crosslinker, to give a highly active silicone-enzyme elastomer. The effect on enzyme activity of addition of water and hydrophilic polymeric moieties based on poly(ethylene oxide) 2 was examined, as were crosslinker concentration, enzyme concentration, and elastomer thickness. It was demonstrated that lipase is most active in silicone elastomers and more active in silicone oils than simple hydrocarbons. Crosslink density in these elastomers was not an important factor in the reactivity of the rubber. However, the addition of hydrophilic species prior to elastomer formation decreased the efficiency both of the dispersion of the enzyme and the resulting activity of the elastomer. This effect could be moderated by prior exposure of the lipase to silicone oil. Thus, hydrophobic silicones play a protective/activating role for lipase.