What is the risk of infecting a cerebrospinal fluid-diverting shunt with percutaneous tapping?

Superb microvascular ultrasound is a promising non-invasive diagnostic tool to assess a ventriculoperitoneal shunt system function: a feasibility study

The objective of this pilot study was to assess the reliability of superb microvascular ultrasound (SMI) for the measurement of the cerebrospinal fluid (CSF) flow within VPS systems as an indirect sign for shunt dysfunction. Asymptomatic hydrocephalus patients, with a VPS system implanted between 2017 and 2021, were prospectively enrolled in the study. Using SMI, the CSF flow within the proximal and distal catheters were analysed. Before and after pumping the shunt reservoir, intraabdominal free fluid, optical nerve sheath diameter (ONSD), and papilla diameter (PD) were evaluated and correlated with the amount of valve activation. Nineteen patients were included. A flow was detectable in 100% (N = 19) patients in the proximal and in 89.5% (N = 17) in the distal catheter. The distal catheter tip was detectable in 27.7% (N = 5) patients. Free intraabdominal fluid was initially detected in 21.4% (N = 4) patients and in 57.9% (N = 11) at the end of the examination (P = 0.049). ONSD was significantly lower after pump activation (4.4 ± 0.9 mm versus 4.1 ± 0.8 mm, P = 0.049). Both peak velocity and flow volume per second were higher in proximal compared to distal catheters (32.2 ± 45.2 versus 5.6 ± 3.7 cm/sec, P = 0.015; 16.6 ± 9.5 ml/sec versus 5.1 ± 4.0 ml/sec, P = 0.001, respectively). No correlation was found between the number of pump activations and the changes in ONSD (P = 0.975) or PD (P = 0.820). SMI appears to be a very promising non-invasive diagnostic tool to assess CSF flow within the VPS systems and therefore affirm their function. Furthermore, appearance of free intraperitoneal fluid followed by repeated compression of a shunt reservoir indicates an intact functioning shunt system.

Cerebrospinal fluid shunt infections in children

Cerebrospinal fluid (CSF) shunts are commonly used for the long-term management of hydrocephalus in children. Shunt infection remains a common complication, occurring in about 5%-15% of CSF shunts. This narrative review summarises key evidence from recent literature on the epidemiology, pathogenesis, clinical presentation, diagnosis, management, outcomes and prevention of CSF shunt infections in children. The majority of shunt infections occur due to contamination at the time of surgery, with coagulase-negative staphylococci and Staphylococcus aureus being the most common infecting organisms. Clinical presentations of shunt infection can be varied and difficult to recognise. CSF cultures are the primary test used for diagnosis. Other CSF and blood parameters may aid in diagnosis but lack sensitivity and specificity. Core aspects of management of shunt infections include systemic antimicrobial therapy and surgical removal of the shunt. However, many specific treatment recommendations are limited by a lack of robust evidence from large studies or controlled trials. Shunt infections may result in long hospital stays, worsening hydrocephalus, neurological sequelae and other complications, as well as death. Therefore, reducing the incidence of infection and optimising management are high priorities. Antibiotic prophylaxis at the time of shunt placement, improved surgical protocols and antibiotic-impregnated shunts are key strategies to prevent shunt infections. Nevertheless, further work is needed to identify additional strategies to prevent complications and improve outcomes.

Ventriculoperitoneal Shunt Tap Task Trainer: A Technical Report

This technical report describes the creation of a model of an infant with a ventriculoperitoneal shunt (VPS). This model is authentic, assembled easily, and reusable which allows for pediatric and neurosurgical practitioners to gain experience in performing VPS taps. Learning objectives have been provided to guide task training.

Cerebral spinal fluid overdrainage from shunt tap using large bore coring needle: A case report

Background

Tapping a ventriculoperitoneal shunt percutaneously using a coring needle, such as a butterfly needle, is a common neurosurgical practice despite manufacturers' recommendation to use a Huber type non-coring needle.

Case Description

A 26-year-old woman, with congenital hydrocephalus and history of multiple shunt revision and shunt taps, presented with symptoms consistent with intracranial hypotension. During her shunt revision, cerebrospinal fluid (CSF) was found to be leaking from her shunt reservoir defects which were believed to be caused by prior shunt taps. An in vitro study duplicated this finding in which several areas of leak were observed from the valve tapped using the coring needle, while none was observed from the valve tapped using the non-coring needle.

Conclusion

Taping a shunt using a coring needle can damage the shunt reservoir and cause CSF overdrainage.

Challenges in the Management of Gram-Negative Bacterial Infections in Patients With Ventriculoperitoneal Shunt

Gram-negative bacterial infections of the central nervous system (CNS) have worse clinical outcomes. The most common bacteria include Escherichia Coli, Citrobacter species, Enterobacter species, Serratia species, and Pseudomonas aeruginosa. There are multiple risk factors for CNS infection after shunt insertion, including younger age, obstructive hydrocephalus, shunt revision surgery, and trauma. The clinical presentation of a ventriculoperitoneal (VP) shunt infection includes the signs and symptoms of meningitis to fever with abdominal pain and peritonitis. Apart from cerebrospinal fluid (CSF) analysis, microbiological cultures and radiological studies are key diagnostic tools. Initial empirical intravenous antimicrobial therapy is preferably broad spectrum with appropriate coverage for resistant Gram-negative pathogens and the duration of treatment depends upon pathogenesis, host factors, and clinical response to the therapy.

Considering the importance of this disease and associated clinical outcomes, in this review article, we have summarized the epidemiology, clinical features, management, and prevention of Gram-negative VP shunt infections in adults.

Global trends in the evaluation and management of cerebrospinal fluid shunt infection: a cooperative ISPN survey

INTRODUCTION

Ventriculoperitoneal shunts (VPS) is commonly performed by pediatric neurosurgeons and there is no consensus in management of VPS infection as it relates to diagnosis and treatment.

OBJECTIVE

We utilized an international practitioner-based survey to study the variability in VPS infection diagnostic and therapeutic measures.

METHODS

A survey gauging practice patterns of pediatric neurosurgeons regarding VPS and its complication management was distributed. Survey endpoints were analyzed by VPS case volume and pediatric-focused case volume regarding diagnostic measures, use of cerebrospinal fluid (CSF) profile, microbiology, and treatment.

RESULTS

A total of 439 surveys were distributed, with a response rate of 31%. Responders ranged from Americas (44.9%), European (31.4%), Asian (18.6%), African (2.5%), to Australian continents (2.5%). Practitioners were stratified based on number and percentage pediatric VPS performed. Institutions performing highest VPS and percentage pediatric case volumes had lower rate of VPS infection. Shunt tap was the most widely used diagnostic study. Overall CSF profile did not affect decision making towards VPS internalization, except for leukocyte count ≤ 20 × 10⁹/L. Practitioners utilized 3 negative cultures prior to VPS internalization. Discrepancies in surgical management were noted amongst centers with high versus low VPS volume and proportion of pediatric-focused case volume. Practice patterns were not noted to be organism dependent. Antibiotic-impregnated shunts were utilized in the Americas and Europe over other regions but only in one third of all initial VPS or as a preventive strategy after a VPS infection has been resolved respectively.

DISCUSSION

Survey results from 6 continents in VPS management revealed patterns of lower infection in high-volume centers, 3 negative cultures prior to internalization and aggressive surgical VPS infection management in high-volume institutions.

Reliability of the radiopharmaceutical shunt flow study for the detection of a CSF shunt malfunction in the presence of stable ventricular size

OBJECTIVE

The authors sought to determine the reliability of a radiopharmaceutical (RP) shunt flow study for the detection of a CSF-diverting shunt malfunction in the presence of stable ventricular size.

METHODS

After the authors obtained IRB approval, all CSF RP shunt flow studies done between January 1, 2014, and January 1, 2019, in pediatric patients at Children's Hospital Los Angeles were identified. Included in the study were only those patients in whom an MRI or CT scan was done during the hospital admission for shunt malfunction and showed no increase in ventricular size compared with the most recent prior MRI or CT scan when the patient was asymptomatic. Data recorded for analysis were patient age and sex, etiology of the hydrocephalus, shunt distal site, nonprogrammable versus programmable valve, operative findings if the shunt was revised, and follow-up findings for a minimum of 90 days after admission. The RP shunt flow study consisted of tapping the reservoir and injecting technetium-99m DTPA according to a set protocol.

RESULTS

The authors identified 146 RP flow studies performed in 119 patients meeting the above criteria. Four of the 146 RP studies (3%) were nondiagnostic secondary to technical failure and were excluded from statistical analysis. Of the 112 normal flow studies, operative intervention was not undertaken in 102 (91%). The 10 (9%) remaining normal studies were performed in patients who underwent operative intervention, in which 8 patients had a proximal obstruction, 1 had a distal obstruction, and 1 patient had no obstruction. Of the 30 patients with abnormal flow studies, symptoms of shunt malfunction subsided in 9 (30%) patients and these patients did not undergo operative intervention. Of the 21 (70%) operated patients, obstruction was proximal in 9 patients and distal in 5, and for 7 patients the shunt tubing was either fractured or disconnected. Regression analysis indicated a significant association between the flow study interpretation and the odds for shunt revision (OR 27, 95% CI 10-75, p < 0.0001). No other clinical variables were significant. The sensitivity of a shunt flow study alone for detection of shunt malfunction in cases with stable ventricular size was the same as a shunt flow study plus an MRI or CT (70% vs 70%), but performing a shunt flow in addition to MRI or CT did increase the specificity from 92% to 100% and the accuracy from 87% to 94%.

CONCLUSIONS

RP shunt flow studies were of definite value in deciding whether to operatively intervene in patients with symptoms of shunt malfunction in whom no change in ventricular size was detected on current MRI or CT scans compared to scans obtained when the patients were asymptomatic.

Shunt infusion studies: impact on patient outcome, including health economics

Objectives

The diagnosis of shunt malfunction is often not straightforward. We have explored, in symptomatic shunted patients with hydrocephalus or pseudotumour cerebri syndrome (PTCS), the accuracy of CSF infusion tests in differentiating a functioning shunt from one with possible problems, and the health economic consequences.

Methods

Participants: hydrocephalus/PTCS patients with infusion tests performed from January 2013 until December 2015. We followed patients up after 6 and 12 months from the test to determine whether they had improved, had persisting symptoms or had required urgent revision. We calculated the total cost savings of revision versus infusion tests and standard protocol of revision and ICP monitoring versus infusion tests.

Results

Three hundred sixty-five shunt infusion tests had been performed where a shunt prechamber/reservoir was present. For hydrocephalus patients, more than half of the tests (~ 55%, 155 out of 280) showed no shunt malfunction versus 125 with possible malfunction (ages 4 months to 90 years old). For PTCS patients aged 10 to 77 years old, 47 had possible problems and 38 no indication for shunt malfunction. Overall, > 290 unnecessary revisions were avoided over 3 years’ time. Two hundred fifty-eight (> 85%) of those non-surgically managed, remained well, did not deteriorate and did not require surgery. No infections were associated with infusion studies. For Cambridge, the overall savings from avoiding revisions was £945,415 annually.

Conclusions

Our results provide evidence of the importance of shunt testing in vivo to confirm shunt malfunction. Avoiding unnecessary shunt revisions carries a strong health benefit for patients that also translates to a significant financial benefit for the National Health Service and potentially for other healthcare systems worldwide.

Electronic supplementary material

The online version of this article (10.1007/s00701-020-04212-0) contains supplementary material, which is available to authorized users.

Ventriculoperitoneal Shunts in the Emergency Department: A Review

In this paper, we review the indications, complications, and pitfalls associated with ventriculoperitoneal (VP) shunts. As most VP shunt problems initially present to the emergency department, it is important for emergency physicians to be well-versed in managing them. In the article, the possible reasons for shunt failure are explored and summarized using an infographic. We also examine potential clinical presentations of VP shunt failure.

Risk factors for cerebrospinal fluid shunt infections during an outbreak: a case-control study

BACKGROUND

There are few published reports of cerebrospinal fluid (CSF) shunt infection outbreaks. In 2017-2018, British Columbia Children's Hospital (BCCH) experienced an increase in CSF shunt infections co-incident with a move to new operating rooms and a change in shunt catheters used.

AIMS

To describe how an outbreak was detected, investigations were undertaken to determine the cause, risk factors associated with CSF shunt infection during the outbreak, and changes implemented to attempt to control the outbreak.

METHODS

Retrospective case-control study. Population included patients who underwent new shunt insertion or revision. Univariate logistic regression models were fitted for each of the variables. Associations with P-values <0.2 were considered of potential interest for further investigation.

FINDINGS

There were six cases of CSF shunt infection and 19 controls. The causative organism was different in each case. The only risk factors that met the criteria for further investigation were being a neonate at the time of surgery [odds ratio (OR) 9.0, 95% confidence interval (CI) 0.7-125.3, P=0.10] and the presence of gastrointestinal disease (OR 3.8, 95% CI 0.5-26.2, P=0.18). No association was found with the operating room used or the surgical staff. In response to the outbreak, human traffic through the operating rooms was limited, rigid adherence to the wearing of surgical masks was enforced, and return to the previous CSF shunt catheters used was implemented.

CONCLUSION

No modifiable risk factors were associated with CSF shunt infection. After implementation of surgical protocol changes, no further cases of CSF shunt infection linked to the outbreak were identified.

Surgical management of hydrocephalus secondary to intraventricular hemorrhage in the preterm infant

OBJECT Posthemorrhagic hydrocephalus (PHH) in the preterm infant remains a major neurological complication of prematurity. The authors first described insertion of a specially designed low-profile subcutaneous ventricular catheter reservoir for temporary management of hydrocephalus in 1983. This report presents the follow-up experience with the surgical management of PHH in this population and describes outcomes both in infants who were stable for permanent shunt insertion and those initially temporized with a ventricular reservoir (VR) prior to permanent ventriculoperitoneal (VP)/ventriculoatrial (VA) shunt placement. METHODS A retrospective review was undertaken of the medical records of all premature infants surgically treated for posthemorrhagic hydrocephalus (PHH) between 1997 and 2012 at Children's Hospital Los Angeles. RESULTS Over 14 years, 91 preterm infants with PHH were identified. Fifty neonates received temporizing measures via a VR that was serially tapped for varying time periods. For the remaining 41 premature infants, VP/VA shunt placement was the first procedure. Patients with a temporizing measure as their initial procedure had undergone CSF diversion significantly earlier in life than those who had permanent shunting as the initial procedure (29 vs 56 days after birth, p < 0.01). Of the infants with a VR as their initial procedure, 5/50 (10%) did not undergo subsequent VP/VA shunt placement. The number of shunt revisions and the rates of loculated hydrocephalus and shunt infection did not statistically differ between the 2 groups. CONCLUSIONS Patients with initial VR insertion as a temporizing measure received a CSF diversion procedure significantly earlier than those who received a permanent shunt as their initial procedure. Otherwise, the outcomes with regard to shunt revisions, loculated hydrocephalus, and shunt infection were not different for the 2 groups.

Comparison of the use of ventricular access devices and ventriculosubgaleal shunts in posthaemorrhagic hydrocephalus: systematic review and meta-analysis

INTRODUCTION

Ventricular access devices (VAD) and ventriculosubgaleal shunts (VSGS) are currently both used as temporising devices to affect CSF drainage in neonatal posthaemorrhagic hydrocephalus (PHH), without clear evidence of superiority of either procedure. In this systematic review and meta-analysis, we compared the VSGS and VAD regarding complication rates, ventriculoperitoneal shunt conversion and infection rates, and mortality and long-term disability.

METHODS

The review was registered with the PROSPERO international prospective register of systematic reviews (registration number CRD42015019750) and was conducted in accordance with PRISMA guidelines.

RESULTS AND CONCLUSIONS

The literature search of five databases identified 338 publications, of which 5 met the inclusion criteria. All were retrospective cohort studies (evidence class 3b and 4). A significantly lower proportion of patients with a VSGS required CSF tapping compared to patients with a VAD (log OR -4.43, 95% CI -6.14 to -2.72). No other significant differences between the VAD and VSGS were identified in their rates of infection (log OR 0.03, 95% CI -0.77 to 0.84), obstruction (log OR 1.25, 95% CI -0.21 to 2.71), ventriculoperitoneal shunt dependence (log OR -0.06, 95% CI -0.93 to 0.82), subsequent shunt infection (log OR 0.23, 95% CI -0.61 to 1.06), mortality (log OR 0.37, 95% CI -0.95 to 1.70) or long-term disability (p = 0.9). In all studies, there was a lack of standardised criteria, variations between surgeons in heterogeneous cohorts of limited sample size and a lack of neurodevelopmental follow-up. This affirms the importance of an ongoing multicentre, prospective pilot study comparing these two temporising procedures to enable a more robust comparison.

Quantitative contrast-enhanced ultrasound measurement of cerebrospinal fluid flow for the diagnosis of ventricular shunt malfunction

OBJECT

Cerebral shunt malfunction is common but often difficult to effectively diagnose. Current methods are invasive, involve ionizing radiation, and can be costly. The authors of this study investigated the feasibility of quantitatively measuring CSF flow in a shunt catheter using contrast-enhanced ultrasound.

METHODS

A syringe pump was used to push a solution of gas-filled microbubbles at specific flow rates through a shunt catheter while a high-frequency ultrasound imaging system was used to collect ultrasound images for offline processing. Displacement maps and velocity profiles were generated using a speckle-tracking method based on a cross-correlation algorithm. An additional correction factor, to account for a predictable underestimation and to adjust the measured flow rates, was calculated based on the geometry of the ultrasound imaging plane and assuming a simple model of laminar flow.

RESULTS

The developed method was able to differentiate between physiologically relevant flow rates, including no flow and 0.006 to 0.09 ml/min, with reasonable certainty. The quantitative measurement of flow rates through the catheter using this method was determined to be in good agreement with the expected flow rate.

CONCLUSIONS

This study demonstrated that contrast-enhanced ultrasound has the potential to be used as a minimally invasive and cost-effective alternative method for outpatient shunt malfunction diagnosis.