Standardization of cerebrospinal fluid shunt valves in pediatric hydrocephalus: an analysis of cost, operative time, length of stay, and shunt failure.

OBJECTIVE: CSF shunts are the most common procedures performed in the pediatric neurosurgical population. Despite attempts in multiple studies, a superior shunt valve has never been shown. Because of this, the authors aim was to examine the impact of shunt valve standardization at their institution to determine if there is a difference in surgical cost, operative time, or short-term postoperative shunt failure. METHODS: A retrospective analysis at the authors' institution was performed for all new CSF diversion shunts, as well as shunt revisions requiring a new valve, or a new valve and at least a new proximal or distal catheter over a 1-year period (January 1, 2016, to December 31, 2016). After a period of transition, neurosurgeons were encouraged to use only one type of fixed-differential-pressure valve and one type of programmable valve when performing shunt surgeries. These patients who underwent "standardized" shunt surgery over a 1-year period (January 1, 2018, to December 31, 2018) were then compared to patients in the prestandardization epoch. All patients were followed for a 12-month period after surgery. Demographic information, surgical cost, operative time, and postoperative shunt failure data were collected in all patients in the study. RESULTS: The authors analyzed 87 shunt surgeries in patients prior to standardization and 94 shunt surgeries in patients after standardization. The rate of violation of the standardized shunt valve policy after implementation was 5.3% (5 of 94 procedures). When comparing the prestandardization group to those who received the standardized valve, operative costs were less ($1821.04 vs $1333.75, p = 0.0034). There was no difference in operative times between groups (78 minutes vs 81 minutes, p = 0.5501). There was no difference in total number of shunt failures between the two groups at 12 months after surgery (p = 0.0859). The rate of postoperative infection was consistent with the literature at 8%. CONCLUSIONS: In accordance with quality improvement principles, the reduction of unexplained clinical variance invariably leads to a decrease in cost and, more importantly, increased value. In this study, the implementation of a standardized shunt valve decreased operative cost. There were no differences in postoperative shunt failures at 12 months after surgery and no differences in length of surgery. Standardizing shunt valves in the treatment of pediatric hydrocephalus seems to be cost-effective and safe.

A Comparison of Ventriculoperitoneal and Ventriculoatrial Shunts in a Population of 544 Consecutive Pediatric Patients.

BACKGROUND: Although ventriculoperitoneal shunts (VPS) remain the first-line option in most instances of pediatric hydrocephalus, the long-term efficacy of ventriculoatrial shunts (VAS) remains unknown. OBJECTIVE: To characterize the long-term outcomes and adverse occurrences associated with both VPS and VAS at our institution. METHODS: The authors retrospectively analyzed all cerebrospinal fluid (CSF) shunting procedures performed over a 13-yr period at a single institution. A total of 544 pediatric shunt patients were followed for at least 90 d (VPS: 5.9 yr; VAS: 5.3 yr). RESULTS: A total of 54% of VPS and 60% of VAS required at least 1 revision. VPS demonstrated superior survival overall; however, if electively scheduled VAS lengthening procedures are not considered true "failures," no statistical difference is noted in overall survival (P = .08). VPS demonstrated significantly greater survival in patients less than 7 yr of age (P = .001), but showed no difference in older children (P = .4). VAS had a significantly lower rate of infection (P < .05) and proximal failure (P < .001). CONCLUSION: VAS can be a useful alternative to VPS when the abdomen is unsuitable, particularly in older children. Although VPS demonstrates superior overall survival, it should be understood that elective VAS lengthening procedures are often necessary, especially in younger patients. If elective lengthening procedures are not considered true failures, then the devices show similar survival.

Application of the Preventable Shunt Revision Rate to an Adult Population.

BACKGROUND: The preventable shunt revision rate (PSRR) was recently introduced in pediatric hydrocephalus as a quality metric for shunt surgery. We evaluated the PSRR in an adult hydrocephalus population. METHODS: All ventricular shunt operations (January 1, 2013 to March 31, 2018) performed at a university-based teaching hospital were included. For any index surgery (de novo or revision) resulting in reoperation within 90 days, the index surgery details were collected, and a consensus decision was reached regarding whether the failure had been potentially avoidable. Preventable failure was defined as failure due to infection, malposition, disconnection, migration, or kinking. The 90-day shunt failure rate and PSRR were calculated. Bivariate analyses were performed to evaluate the individual effects of each independent variable on preventable shunt failure. RESULTS: A total of 318 shunt operations had been performed in 245 patients. Most patients were women (62%), with a median age of 48.2 years (interquartile range, 31.2-63.2 years). Most had had ventriculoperitoneal shunts placed (86.5%), and just more than one half were new shunts (51.6%). A total of 53 cases (16.7%) in 42 patients experienced shunt failure within 90 days of the index operation. Of these, 27 failures (8.5% of the total cases; 51% of the failures) were considered potentially preventable. The most common reasons were infection (37%; n = 10) and malposition of the proximal and distal catheters (both 25.9%; n = 7). Age was the only statistically significant difference between the 2 groups, with the patients experiencing preventable shunt failure older than those without preventable shunt failure (51.4 vs. 37.1 years; P = 0.017). CONCLUSIONS: The 90-day PSRR can be applied to an adult population and serve as a quality metric.

Evidence-Based Management of External Ventricular Drains.

PURPOSE OF REVIEW: The optimal management of external ventricular drains (EVD) in the setting of acute brain injury remains controversial. Therefore, we sought to determine whether there are optimal management approaches based on the current evidence. RECENT FINDINGS: We identified 2 recent retrospective studies on the management of EVDs after subarachnoid hemorrhage (SAH) which showed conflicting results. A multicenter survey revealed discordance between existing evidence from randomized trials and actual practice. A prospective study in a post-traumatic brain injury (TBI) population demonstrated the benefit of EVDs but did not determine the optimal management of the EVD itself. The recent CLEAR trials have suggested that specific positioning of the EVD in the setting of intracerebral hemorrhage with intraventricular hemorrhage may be a promising approach to improve blood clearance. Evidence on the optimal management of EVDs remains limited. Additional multicenter prospective studies are critically needed to guide approaches to the management of the EVD.

Durability of antimicrobial activity of antibiotic-impregnated external ventricular drains: a prospective study.

BACKGROUND: Antibiotic-impregnated external ventricular drains (AI-EVDs) have a debated efficacy in clinical studies. OBJECTIVES: Our aim was to assess the durability of antimicrobial activity of AI-EVDs used in clinical settings. METHODS: From April 2017 to January 2018, all consecutive AI-EVDs (Bactiseal™) inserted in adult patients were prospectively included. After removal, each AI-EVD was cultured and assessed for antimicrobial activity on both internal and external sides of AI-EVDs. Catheters were each challenged with a single Staphylococcus strain [MSSA, MRSA or methicillin-resistant Staphylococcus epidermidis (MRSE)]. MS was used to measure residual concentrations of rifampicin and clindamycin. RESULTS: Sixty-five AI-EVDs were included (56 patients). Among these, 21 were challenged with MSSA, 23 with MRSA and 21 with MRSE. Five ventriculostomy-related colonizations (9%) and two ventriculostomy-related infections (4%) occurred. Staphylococcus was the main bacterium responsible for colonization (4/5). AI-EVD inhibition decreased significantly against MRSA and MRSE according to duration of catheterization (for external and internal sides, P < 0.02) and overall volume of CSF drained (P < 0.005 for both sides against MRSE, P < 0.005 for external side against MRSA), but not against MSSA. Clindamycin concentration was not correlated with duration of catheterization or CSF volume drained, but <20% of initial concentration was recovered even after 5 days of AI-EVD dwelling. Conversely, rifampicin concentration showed a rapid and significant decline correlated to duration and CSF volume (P < 0.001 and P = 0.03, respectively). CONCLUSIONS: Antimicrobial activity of AI-EVDs dropped quickly in vivo. Antimicrobial impregnation did not prevent AI-EVD colonization by susceptible strains in 9% of the cases.

Lumboperitoneal and Ventriculoperitoneal Shunt Surgery for Posthemorrhagic Communicating Hydrocephalus: A Comparison.

OBJECTIVE: This study aimed to compare the efficacy and complications of lumboperitoneal (LP) and ventriculoperitoneal (VP) shunt surgeries in patients with posthemorrhagic communicating hydrocephalus. METHODS: Retrospective analysis of the records of patients who were admitted to the Shanghai Tenth People's Hospital Affiliated to Tongji University between February 2012 and January 2018 was performed. The efficacy of the LP and VP shunt surgeries and their associated complications were compared. The evaluation of the efficacy of these surgeries involved both clinical and radiologic aspects. The evaluated complications included hemorrhage, infection, excessive drainage, seizure disorder, shunt obstruction, and migration. Revision and mortality were regarded as the consequence of complications and were collected. RESULTS: One-hundred and fifty-eight (115 males and 43 females) patients were treated with VP or LP shunt (102 vs. 56, respectively) for posthemorrhagic communicating hydrocephalus. The percentage of patients with a Glasgow Coma Scale (GCS) score between 3.00 and 12.00 was 79.11%. There was no significant difference in the observed clinical (P = 0.097) or radiologic (P = 0.360) improvements between the LP and VP shunt groups. The total rate of complications (P = 0.009) and hemorrhage (P = 0.03) were lower in the LP shunt group than in the VP shunt group. CONCLUSIONS: In the treatment of moderate and severe coma patients with posthemorrhagic communicating hydrocephalus, LP shunt surgery is equally as effective as the VP shunt surgery and is associated with fewer complications.

Effect of introduction of a standardised peri-operative protocol on CSF shunt infection rate: a single-centre cohort study of 809 procedures.

PURPOSE: Shunt infection is a major problem in paediatric neurosurgery. Our institution introduced a mandatory shunt protocol with the aim of reducing infection rate. METHODS: A retrospective cohort study including consecutive patients undergoing permanent shunt operations (primary insertion and revision) across two study periods: 3 years immediately prior (2009-2012) and 3 years immediately after (2012-2015) protocol introduction. Absolute and relative risk reductions (ARR/RRR) and Chi-square statistical analysis was used alongside logistic regression, where any single factor with p ≤ 0.20 included in the multivariate model, producing an odds ratio (OR). RESULTS: Eight hundred nine operations in 504 children were identified (442 pre-protocol, 367 post). Overall infection rate decreased from 5.43% (24/442) pre-protocol to 3.27% (12/367) post-protocol (ARR = 2.16%, RRR = 39.8%, NNT = 46.3, p = 0.138), which did not reach statistical significance. For primary shunt insertions, infection rate reduced from 3.63 to 2.55% (ARR = 1.08%, RRR = 29.8%, NNT = 92.6, p = 0.565), whilst for revisions, it reduced from 6.83 to 3.81% (ARR = 3.02%, RRR 44.2%, NNT = 33.1, p = 0.156). Multivariate logistic regression showed that surgeon experience was a statistically significant predictor of infection, whilst responsible pathogens and latency were similar across the pre- and post-protocol groups. CONCLUSION: The protocol reduced overall infection rate in primary and revision shunt operations and we recommend paediatric units consider introducing a similar protocol for these procedures.

Survey of Techniques Utilized to Access Ventricular Shunts and Reservoirs.

AIMS: This study assessed variations in pediatric neurosurgical technique when accessing shunts and ventricular access devices (VADs). METHODS: A 12-question survey was developed and sent to members of the American Association of Neurological Surgeons (AANS) whose self-identified subspecialty was pediatric neurosurgery. RESULTS: Four hundred and twenty surveys were sent out, and 149 responses were received (35.5% response rate); 95.3% of respondents always use sterile gloves, 55.0% never use a sterile gown, and 69.8% always have a member of the neurosurgery team perform the procedure. The majority of respondents answered "sometimes" for use of a facemask (38.3%), sterile drapes (39.6%), site shaving (45.6%), having an attending present (68.5%), and having an assistant hold the patient's head (78.5%). The majority reported using a 23- or 25-gauge butterfly needle for site entry (96.6%), and betadine or ChloraPrep™ as the preferred antiseptic solution (64.4%). The frequency in which CSF is sent for analysis is not standardized in 31.5% of respondents, and wait time for the antiseptic solution to dry is not standardized in 62.4%. CONCLUSIONS: There is great variation in the technique for accessing shunts and VADs. Future studies are needed to assess whether these discrepancies affect infection rates.

Comparison of ventricular drain location and infusion test in hydrocephalus.

OBJECTIVES: Suspected cerebrospinal fluid shunt (CSF) dysfunction in hydrocephalic patients poses a diagnostic uncertainty. The clinical picture can be non-specific and CT imaging alone is not always pathognomonic. Infusion tests are an increasingly used investigation for real-time hydrodynamic assessment of shunt patency. We report the correlation between infusion test results with the quality of ventricular drain placement on CT scans in a large retrospective group of hydrocephalic patients. MATERIALS & METHODS: Three hundred and six infusion test results performed in 200 patients were correlated with 306 corresponding CT head scans. Nominal logistic regression was used to correlate shunt catheter position on CT imaging to patency of ventricular drain as determined by infusion tests. RESULTS: Infusion test results of shunt patency are statistically congruent with the analysis of shunt catheter position on CT head scans. Catheter tips completely surrounded by either parenchyma or CSF on CT imaging are strongly associated with evidence of occlusion or patency from infusion tests, respectively (χ² = 51.68, P < 0.0001, n = 306 and χ² = 31.04, P < 0.0001, n = 306). CONCLUSIONS: The most important anatomical factor for shunt patency is the catheter tip being completely surrounded by CSF. Infusion tests provide functional and reliable assessment of shunt patency in vivo and are strongly correlated with the position of the ventricular catheter on CT imaging.

Disease duration: the key to accurate CSF tap test in iNPH.

OBJECTIVES: The cerebrospinal fluid tap test for idiopathic normal pressure hydrocephalus (iNPH) is one of the good predictors of the shunt treatment, although this test has a low sensitivity. We aimed to identify key parameters that could be used to improve this sensitivity. MATERIALS & METHODS: During 2010-2011, we recruited and then followed 93 patients with possible iNPH for 12 months after shunt. Among them, 82 patients were finally enrolled in this study. The modified Rankin Scale, iNPH grading scale, and several quantitative measurements were evaluated at entry, after the tap test, before and after shunt. Area under the receiver-operating characteristic curves (AUCs), sensitivities, and specificities of the tap test for predicting shunt effectiveness were calculated for each measurement. They were additionally assessed after stratification by disease duration since the initial presentation of iNPH symptoms. RESULTS: The gait disturbance on the iNPH grading scale had the highest accurate scale at the tap test for predicting effectiveness 12 months after shunt: AUC 0.74, sensitivity 56.5%, specificity 91.7%. This AUC increased to 0.76, 0.91 and 0.94 in the subgroup of disease duration <24, <12, and <6 months, respectively. The sensitivity and specificity of the gait disturbance on the iNPH grading scale in the subgroup of <12 months' duration were 92.3% and 90.0%. CONCLUSIONS: The shorter period of clinical symptoms, for example, <12 months, made the tap test sufficiently accurate examination for predicting improvement 12 months after shunt surgery. The findings imply that the tap test should be applied to patients being considered for shunt surgery as soon as possible.

Comparison of the accuracy and proximal shunt failure rate of freehand placement versus intraoperative guidance in parietooccipital ventricular catheter placement.

OBJECTIVE The aim of this paper is to compare the accuracy of the freehand technique versus the use of intraoperative guidance (either ultrasound guidance or frameless stereotaxy) for placement of parietooccipital ventricular catheters and to determine factors associated with reduced proximal shunt failure. METHODS This retrospective cohort study included all patients from 2 institutions who underwent a ventricular cerebrospinal fluid (CSF) shunting procedure in which a new parietooccipital ventricular catheter was placed between January 2005 and December 2013. Data abstracted for each patient included age, sex, method of ventricular catheter placement, side of ventricular catheter placement, Evans ratio, and bifrontal ventricular span. Postoperative radiographic studies were reviewed for accuracy of ventricular catheter placement. Medical records were also reviewed for evidence of shunt failure requiring revision. Standard statistical methods were used for analysis. RESULTS A total of 257 patients were included in the study: 134 from the University of Michigan and 123 from Washington University in St. Louis. Accurate ventricular catheter placement was achieved in 81.2% of cases in which intraoperative guidance was used versus 67.3% when the freehand technique was used. Increasing age reduced the likelihood of accurate catheter placement (OR 0.983, 95% CI 0.971-0.995; p = 0.005), while the use of intraoperative guidance significantly increased the likelihood (OR 2.809, 95% CI 1.406-5.618; p = 0.016). During the study period, 108 patients (42.0%) experienced shunt failure, 79 patients (30.7%) had failure involving the proximal catheter, and 53 patients (20.6%) had distal failure (valve or distal catheter). Increasing age reduced the likelihood of being free from proximal shunt failure (OR 0.983, 95% CI 0.970-0.995; p = 0.008), while both the use of intraoperative guidance (OR 2.385, 95% CI 1.227-5.032; p = 0.011), and accurate ventricular catheter placement (OR 3.424, 95% CI 1.796-6.524; p = 0.009) increased the likelihood. CONCLUSIONS The use of intraoperative guidance during parietooccipital ventricular catheter placement as part of a CSF shunt system significantly increases the likelihood of accurate catheter placement and subsequently reduces the rate of proximal shunt failure.

The role of diffusion tensor imaging and fractional anisotropy in the evaluation of patients with idiopathic normal pressure hydrocephalus: a literature review.

OBJECTIVE Diffusion tensor imaging (DTI) for the assessment of fractional anisotropy (FA) and involving measurements of mean diffusivity (MD) and apparent diffusion coefficient (ADC) represents a novel, MRI-based, noninvasive technique that may delineate microstructural changes in cerebral white matter (WM). For example, DTI may be used for the diagnosis and differentiation of idiopathic normal pressure hydrocephalus (iNPH) from other neurodegenerative diseases with similar imaging findings and clinical symptoms and signs. The goal of the current study was to identify and analyze recently published series on the use of DTI as a diagnostic tool. Moreover, the authors also explored the utility of DTI in identifying patients with iNPH who could be managed by surgical intervention. METHODS The authors performed a literature search of the PubMed database by using any possible combinations of the following terms: "Alzheimer's disease," "brain," "cerebrospinal fluid," "CSF," "diffusion tensor imaging," "DTI," "hydrocephalus," "idiopathic," "magnetic resonance imaging," "normal pressure," "Parkinson's disease," and "shunting." Moreover, all reference lists from the retrieved articles were reviewed to identify any additional pertinent articles. RESULTS The literature search retrieved 19 studies in which DTI was used for the identification and differentiation of iNPH from other neurodegenerative diseases. The DTI protocols involved different approaches, such as region of interest (ROI) methods, tract-based spatial statistics, voxel-based analysis, and delta-ADC analysis. The most studied anatomical regions were the periventricular WM areas, such as the internal capsule (IC), the corticospinal tract (CST), and the corpus callosum (CC). Patients with iNPH had significantly higher MD in the periventricular WM areas of the CST and the CC than had healthy controls. In addition, FA and ADCs were significantly higher in the CST of iNPH patients than in any other patients with other neurodegenerative diseases. Gait abnormalities of iNPH patients were statistically significantly and negatively correlated with FA in the CST and the minor forceps. Fractional anisotropy had a sensitivity of 94% and a specificity of 80% for diagnosing iNPH. Furthermore, FA and MD values in the CST, the IC, the anterior thalamic region, the fornix, and the hippocampus regions could help differentiate iNPH from Alzheimer or Parkinson disease. Interestingly, CSF drainage or ventriculoperitoneal shunting significantly modified FA and ADCs in iNPH patients whose condition clinically responded to these maneuvers. CONCLUSIONS Measurements of FA and MD significantly contribute to the detection of axonal loss and gliosis in the periventricular WM areas in patients with iNPH. Diffusion tensor imaging may also represent a valuable noninvasive method for differentiating iNPH from other neurodegenerative diseases. Moreover, DTI can detect dynamic changes in the WM tracts after lumbar drainage or shunting procedures and could help identify iNPH patients who may benefit from surgical intervention.

In vitro performance of the fixed and adjustable gravity-assisted unit with and without motion-evidence of motion-induced flow.

BACKGROUND: Anti-siphon devices and gravitational-assisted valves have been introduced to counteract the effects of overdrainage after implantation of a shunt system. The study examined the flow performance of two gravitational-assisted valves (shunt assistant - SA and programmable shunt assistant - proSA, Miethke & Co. KG, Potsdam, Germany) in an in vitro shunt laboratory with and without motion. METHODS: An in vitro laboratory setup was used to model the cerebrospinal fluid (CSF) drainage conditions similar to a ventriculo-peritoneal shunt and to test the SA (resistance of +20 cmH2O in 90°) and proSA (adjustable resistance of 0 to +40 cmH2O in 90°). The differential pressure (DP) through the simulated shunt and tested valve was adjusted between 0 and 60 cmH2O by combinations of different inflow pressures (40, 30, 20, 10, and 0 cmH2O) and the hydrostatic negative outflow pressure (0, -20, and -40 cmH2O) in several differing device positions (0°, 30°, 60°, and 90°). In addition, the two devices were tested under vertical motion with movement frequencies of 2, 3, and 4 Hz. RESULTS: Both gravity-assisted units effectively counteract the hydrostatic effect in relation to the chosen differential pressure. The setting the proSA resulted in flow reductions in the 90° position according to the chosen resistance of the device. Angulation-related flow changes were similar in the two devices in 30-90° position, however, in the 0-30° position, a higher flow is seen in the proSA. Repeated vertical movement significantly increased flow through both devices. While with the proSA a 2-Hz motion was not able to induce additional flow (0.006 ± 0.05 ml/min), 3- and 4-Hz motion significantly induced higher flow values (3 Hz: +0.56 ± 0.12 ml/min, 4 Hz: +0.54 ± 0.04 ml/min). The flow through the SA was not induced by vertical movements at a low DP of 10 cmH2O at all frequencies, but at DPs of 30 cmH2O and higher, all frequencies significantly induced higher flow values (2 Hz: +0.36 ± 0.14 ml/min, 3 Hz: +0.32 ± 0.08 ml/min, 4 Hz: +0.28 ± 0.09 ml/min). CONCLUSIONS: In a static setup, both tested valves effectively counteracted the hydrostatic effect according to their adjusted or predefined resistance in vertical position. Motion-induced increased flow was demonstrated for both devices with different patterns of flow depending on applied DP and setting of the respective valve. The documented increased drainage should be considered when selecting appropriate valves and settings in very active patients.

Integrating Cerebrospinal Fluid Shunt Quality Checks into the World Health Organization's Safe Surgery Checklist: A Pilot Study.

BACKGROUND: Despite efforts for improvement, cerebrospinal fluid (CSF) shunt failure rates remain high. Recent studies have shown promising reductions in failure rates and infection rates with the routine use of perioperative checklists. This study was conducted to pilot test the feasibility and efficacy of integrating specific CSF shunt surgery quality checks into the World Health Organization (WHO) Surgical Safety Checklist. METHODS: We designed CSF shunt checklist quality items according to a previously established methodology, including solicitation of best practices by a national multidisciplinary expert panel. We examined adherence to key processes before and after implementation as a measure of the efficacy of the integrated checklist. We then surveyed users regarding perceived checklist utility. RESULTS: Overall adherence to shunt-specific key processes increased from 8.6 (95% confidence interval [CI], 7.9-9.2) to 9.9 (95% CI, 9.3-10.4; P = 0.0070) per 12 items, driven by the infection control items (4.7 [95% CI, 4.1-5.3] to 6.0 [95% CI, 5.4-6.4] per 8 items; P = 0.0056). All of the survey respondents indicated that the checklist was easy to use. The majority stated that it helped them feel better prepared to perform the procedure consistently according to evidence-based practice, and that if they were to adhere to the checklist consistently, their rate of shunt failure would be expected to decrease. CONCLUSIONS: The integration of specialty-specific checks into the WHO Safe Surgery Checklist improved adherence to quality processes and generally was well accepted in our pilot study. A larger clinical trial is needed to assess whether this approach could improve shunt outcomes.

The Preventable Shunt Revision Rate: a potential quality metric for pediatric shunt surgery.

OBJECTIVE Shunt surgery consumes a large amount of pediatric neurosurgical health care resources. Although many studies have sought to identify risk factors for shunt failure, there is no consensus within the literature on variables that are predictive or protective. In this era of "quality outcome measures," some authors have proposed various metrics to assess quality outcomes for shunt surgery. In this paper, the Preventable Shunt Revision Rate (PSRR) is proposed as a novel quality metric. METHODS An institutional shunt database was queried to identify all shunt surgeries performed from January 1, 2010, to December 31, 2014, at Le Bonheur Children's Hospital. Patients' records were reviewed for 90 days following each "index" shunt surgery to identify those patients who required a return to the operating room. Clinical, demographic, and radiological factors were reviewed for each index operation, and each failure was analyzed for potentially preventable causes. RESULTS During the study period, there were 927 de novo or revision shunt operations in 525 patients. A return to the operating room occurred 202 times within 90 days of shunt surgery in 927 index surgeries (21.8%). In 67 cases (33% of failures), the revision surgery was due to potentially preventable causes, defined as inaccurate proximal or distal catheter placement, infection, or inadequately secured or assembled shunt apparatus. Comparing cases in which failure was due to preventable causes and those in which it was due to nonpreventable causes showed that in cases in which failure was due to preventable causes, the patients were significantly younger (median 3.1 vs 6.7 years, p = 0.01) and the failure was more likely to occur within 30 days of the index surgery (80.6% vs 64.4% of cases, p = 0.02). The most common causes of preventable shunt failure were inaccurate proximal catheter placement (33 [49.3%] of 67 cases) and infection (28 [41.8%] of 67 cases). No variables were found to be predictive of preventable shunt failure with multivariate logistic regression. CONCLUSIONS With economic and governmental pressures to identify and implement "quality measures" for shunt surgery, pediatric neurosurgeons and hospital administrators must be careful to avoid linking all shunt revisions with "poor" or less-than-optimal quality care. To date, many of the purported risk factors for shunt failure and causes of shunt revision surgery are beyond the influence and control of the surgeon. We propose the PSRR as a specific, meaningful, measurable, and-hopefully-modifiable quality metric for shunt surgery in children.

A new Hydrocephalus Clinical Research Network protocol to reduce cerebrospinal fluid shunt infection.

OBJECT In a previous report by the same research group (Kestle et al., 2011), compliance with an 11-step protocol was shown to reduce CSF shunt infection at Hydrocephalus Clinical Research Network (HCRN) centers (from 8.7% to 5.7%). Antibiotic-impregnated catheters (AICs) were not part of the protocol but were used off protocol by some surgeons. The authors therefore began using a new protocol that included AICs in an effort to reduce the infection rate further. METHODS The new protocol was implemented at HCRN centers on January 1, 2012, for all shunt procedures (excluding external ventricular drains [EVDs], ventricular reservoirs, and subgaleal shunts). Procedures performed up to September 30, 2013, were included (21 months). Compliance with the protocol and outcome events up to March 30, 2014, were recorded. The definition of infection was unchanged from the authors' previous report. RESULTS A total of 1935 procedures were performed on 1670 patients at 8 HCRN centers. The overall infection rate was 6.0% (95% CI 5.1%-7.2%). Procedure-specific infection rates varied (insertion 5.0%, revision 5.4%, insertion after EVD 8.3%, and insertion after treatment of infection 12.6%). Full compliance with the protocol occurred in 77% of procedures. The infection rate was 5.0% after compliant procedures and 8.7% after noncompliant procedures (p = 0.005). The infection rate when using this new protocol (6.0%, 95% CI 5.1%-7.2%) was similar to the infection rate observed using the authors' old protocol (5.7%, 95% CI 4.6%-7.0%). CONCLUSIONS CSF shunt procedures performed in compliance with a new infection prevention protocol at HCRN centers had a lower infection rate than noncompliant procedures. Implementation of the new protocol (including AICs) was associated with a 6.0% infection rate, similar to the infection rate of 5.7% from the authors' previously reported protocol. Based on the current data, the role of AICs compared with other infection prevention measures is unclear.

Validation of a noninvasive test routinely used in otology for the diagnosis of cerebrospinal fluid shunt malfunction in patients with normal pressure hydrocephalus.

OBJECTIVE: Ventriculoperitoneal shunting is the first-line treatment for normal pressure hydrocephalus. Noninvasive auditory tests based on recorded otoacoustic emissions were assessed, as currently used for universal neonatal hearing screenings, for the diagnosis of cerebrospinal fluid shunt malfunction. The test was designed based on previous works, which demonstrated that an intracranial pressure change induces a proportional, characteristic, otoacoustic-emission phase shift. METHODS: Forty-four patients with normal pressure hydrocephalus (23 idiopathic and 21 secondary cases) were included in this prospective observational study. The male:female sex ratio was 1.44, the age range was 21-87 years (mean age 64.3 years), and the range of the follow-up period was 1-3 years (mean 20 months). Patients were implanted with a Sophy SU8 adjustable-pressure valve as the ventriculoperitoneal shunt. The phase shifts of otoacoustic emissions in response to body tilt were measured preoperatively, immediately postoperatively, and at 3-6 months, 7-15 months, 16-24 months, and more than 24 months postoperatively. Three groups were enrolled: Group 1, 19 patients who required no valve opening-pressure adjustment; Group 2, 18 patients who required valve opening-pressure adjustments; and Group 3, 7 patients who required valve replacement. RESULTS: In Group 1, phase shift, which was positive before surgery, became steadily negative after surgery and during the follow-up. In Group 2, phase shift, which was positive before surgery, became negative immediately after surgery and increasingly negative after a decrease in the valve-opening pressure. In Group 3, phase shift was positive in 6 cases and slightly negative in 1 case before revision, but after revision phase shift became significantly negative in all cases. CONCLUSIONS: Otoacoustic emissions noninvasively reflect cerebrospinal fluid shunt function and are impacted by valve-opening pressure adjustments. Otoacoustic emissions consistently diagnosed shunt malfunction and predicted the need for surgical revision. The authors' diagnostic test, which can be repeated without risk or discomfort by an unskilled operator, may address the crucial need of detecting valve dysfunction in patients with poor clinical outcome after shunt surgery.

Practice guideline: Idiopathic normal pressure hydrocephalus: Response to shunting and predictors of response: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology.

OBJECTIVE: We evaluated evidence for utility of shunting in idiopathic normal pressure hydrocephalus (iNPH) and for predictors of shunting effectiveness. METHODS: We identified and classified relevant published studies according to 2004 and 2011 American Academy of Neurology methodology. RESULTS: Of 21 articles, we identified 3 Class I articles. CONCLUSIONS: Shunting is possibly effective in iNPH (96% chance subjective improvement, 83% chance improvement on timed walk test at 6 months) (3 Class III). Serious adverse event risk was 11% (1 Class III). Predictors of success included elevated Ro (1 Class I, multiple Class II), impaired cerebral blood flow reactivity to acetazolamide (by SPECT) (1 Class I), and positive response to either external lumbar drainage (1 Class III) or repeated lumbar punctures. Age may not be a prognostic factor (1 Class II). Data are insufficient to judge efficacy of radionuclide cisternography or aqueductal flow measurement by MRI. RECOMMENDATIONS: Clinicians may choose to offer shunting for subjective iNPH symptoms and gait (Level C). Because of significant adverse event risk, risks and benefits should be carefully weighed (Level B). Clinicians should inform patients with iNPH with elevated Ro and their families that they have an increased chance of responding to shunting compared with those without such elevation (Level B). Clinicians may counsel patients with iNPH and their families that (1) positive response to external lumbar drainage or to repeated lumbar punctures increases the chance of response to shunting, and (2) increasing age does not decrease the chance of shunting being successful (both Level C).

Thirty-day outcomes of cerebrospinal fluid shunt surgery: data from the National Surgical Quality Improvement Program-Pediatrics.

OBJECT: Cerebrospinal fluid shunts are the mainstay of the treatment of hydrocephalus. In past studies, outcomes of shunt surgery have been analyzed based on follow-up of 1 year or longer. The goal of the current study is to characterize 30-day shunt outcomes, to identify clinical risk factors for shunt infection and failure, and to develop statistical models that might be used for risk stratification. METHODS: Data for 2012 were obtained from the National Surgical Quality Improvement Program-Pediatrics (NSQIP-P) of the American College of Surgeons. Files with index surgical procedures for insertion or revision of a CSF shunt composed the study set. Returns to the operating room within 30 days for shunt infection and for shunt failure without infection were the study end points. Associations with a large number of potential clinical risk factors were analyzed on a univariate basis. Logistic regression was used for multivariate analysis. RESULTS: There were 1790 index surgical procedures analyzed. The overall rates of shunt infection and shunt failure without infection were 2.0% and 11.5%, respectively. Male sex, steroid use in the preceding 30 days, and nutritional support at the time of surgery were risk factors for shunt infection. Cardiac disease was a risk factor for shunt failure without infection, and initial shunt insertion, admission during the second quarter, and neuromuscular disease appeared to be protective. There was a weak association of increasing age with shunt failure without infection. Models based on these factors accounted for no more than 6% of observed variance. Construction of stable statistical models with internal validity for risk adjustment proved impossible. CONCLUSIONS: The precision of the NSQIP-P dataset has allowed identification of risk factors for shunt infection and for shunt failure without infection that have not been documented previously. Thirty-day shunt outcomes may be useful quality metrics, possibly even without risk adjustment. Whether important variation in 30-day outcomes exists among institutions or among neurosurgeons is yet unknown.

Quality measurement in the shunt treatment of hydrocephalus: analysis and risk adjustment of the Revision Quotient.

UNLABELLED: OBJECT.: The Revision Quotient (RQ) has been defined as the ratio of the number of CSF shunt revisions to the number of new shunt insertions for a particular neurosurgical practice in a unit of time. The RQ has been proposed as a quality measure in the treatment of childhood hydrocephalus. The authors examined the construct validity of the RQ and explored the feasibility of risk stratification under this metric. METHODS: The Kids' Inpatient Database for 1997, 2000, 2003, 2006, and 2009 was queried for admissions with diagnostic codes for hydrocephalus and procedural codes for CSF shunt insertion or revision. Revision quotients were calculated for hospitals that performed 12 or more shunt insertions annually. The univariate associations of hospital RQs with a variety of institutional descriptors were analyzed, and a generalized linear model of the RQ was constructed. RESULTS: There were 12,244 admissions (34%) during which new shunts were inserted, and there were 23,349 admissions (66%) for shunt revision. Three hundred thirty-four annual RQs were calculated for 152 different hospitals. Analysis of variance in hospital RQs over the 5 years of study data supports the construct validity of the metric. The following factors were incorporated into a generalized linear model that accounted for 41% of the variance of the measured RQs: degree of pediatric specialization, proportion of initial case mix in the infant age group, and proportion with neoplastic hydrocephalus. CONCLUSIONS: The RQ has construct validity. Risk adjustment is feasible, but the risk factors that were identified relate predominantly to patterns of patient flow through the health care system. Possible advantages of an alternative metric, the Surgical Activity Ratio, are discussed.