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• Journal of Neurosurgery: Pediatrics
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## Using an artificial neural network to predict traumatic brain injury

### OBJECTIVE

Pediatric traumatic brain injury (TBI) is common, but not all injuries require hospitalization. A computational tool for ruling in patients who will have a clinically relevant TBI (CRTBI) would be valuable, providing an evidence-based way to safely discharge children who are at low risk for a CRTBI. The authors hypothesized that an artificial neural network (ANN) trained on clinical and radiologist-interpreted imaging metrics could provide a tool for identifying patients likely to suffer from a CRTBI.

### METHODS

The authors used the prospectively collected, publicly available, multicenter Pediatric Emergency Care Applied Research Network (PECARN) TBI data set. All patients under the age of 18 years with TBI and admission head CT imaging data were included. The authors constructed an ANN using clinical and radiologist-interpreted imaging metrics in order to predict a CRTBI, as previously defined by PECARN: 1) neurosurgical procedure, 2) intubation > 24 hours as direct result of the head trauma, 3) hospitalization ≥ 48 hours and evidence of TBI on a CT scan, or 4) death due to TBI.

### RESULTS

Among 12,902 patients included in this study, 480 were diagnosed with CRTBI. The authors’ ANN had a sensitivity of 99.73% with precision of 98.19%, accuracy of 97.98%, negative predictive value of 91.23%, false-negative rate of 0.0027%, and specificity for CRTBI of 60.47%. The area under the receiver operating characteristic curve was 0.9907.

### CONCLUSIONS

The authors are the first to utilize artificial intelligence to predict a CRTBI in a clinically meaningful manner, using radiologist-interpreted CT information, in order to identify pediatric patients likely to suffer from a CRTBI. This proof-of-concept study lays the groundwork for future studies incorporating iterations of this algorithm directly into the electronic medical record for real-time, data-driven predictive assistance to physicians.

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## The cost of hydrocephalus: a cost-effectiveness model for evaluating surgical techniques

### OBJECTIVE

Many studies have aimed to determine the most clinically effective surgical intervention for hydrocephalus. However, the costs associated with each treatment option are poorly understood. In this study, the authors conducted a cost-effectiveness analysis, calculating the incremental cost-effectiveness ratio (ICER) of ventriculoperitoneal shunting (VPS), endoscopic third ventriculostomy (ETV), and ETV with choroid plexus cauterization (ETV/CPC) in an effort to better understand the clinical effectiveness and costs associated with treating hydrocephalus.

### METHODS

The study cohort includes patients under the age of 18 who were initially treated for hydrocephalus between January 2012 and January 2015 at the authors’ institution. Overall treatment costs were calculated using patient-level hospitalization costs and professional fees reimbursable to the hospital and directly related to the initial and follow-up (postoperative day 1 to 12 months) treatment of hydrocephalus. TreeAge Pro was used to conduct the cost-effectiveness analyses.

### RESULTS

A total of 147 patients were identified. Based on the initial intervention for hydrocephalus, their cases were classified as follows: 113 VPS, 14 ETV, and 20 ETV/CPC. During the initial intervention, VPS patients required a longer length of stay at 5.6 days, compared to ETV/CPC (3.35 days) and ETV (2.36 days) patients. Failure rates for all treatment options ranged from 29% to 45%, leading to recurrent hydrocephalus and additional surgical intervention between postoperative day 1 and 12 months. Cost-effectiveness analyses found ETV to be less costly and more clinically effective, with an ICER of $94,797 compared to VPS ($130,839) and ETV/CPC ($126,394). However, when stratified by etiology, VPS was found to be more clinically effective and cost-effective in both the myelomeningocele and posthemorrhagic hydrocephalus patient groups with an incremental cost per clinical unit of effectiveness (success or failure of intervention) of$76,620 compared to ETV and ETV/CPC. However, when assessing cases categorized as “other etiologies,” ETV was found to be more cost-effective per clinical unit, with an ICER of $60,061 compared to ETV/CPC ($93,350) and VPS (\$142,135).

### CONCLUSIONS

This study is one of the first attempts at quantifying the patient-level hospitalization costs associated with surgical management of hydrocephalus in pediatric patients treated in the United States. The results indicate that the conversation regarding CSF diversion techniques must be patient-specific and consider etiology as well as any previous surgical intervention. Again, these findings are short-run observations, and a long-term follow-up study should be conducted to assess the cost of treating hydrocephalus over the lifetime of a patient.

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## Oral presentation to publication: publication rates of abstract presentations across two pediatric neurosurgical meetings

### OBJECTIVE

Both the American Association of Neurological Surgeons/Congress of Neurological Surgeons Joint Section on Pediatric Neurological Surgery (AANS/CNS Pediatric Section) and the International Society for Pediatric Neurosurgery (ISPN) annual meetings provide a platform for pediatric neurosurgeons to present, discuss, and disseminate current academic research. An ultimate goal of these meetings is to publish presented results in peer-reviewed journals. The purpose of the present study was to investigate the publication rates of oral presentations from the 2009, 2010, and 2011 AANS/CNS Pediatric Section and ISPN annual meetings in peer-reviewed journals.

### METHODS

All oral presentations from the 2009, 2010, and 2011 AANS/CNS Pediatric Section and ISPN annual meetings were reviewed. Abstracts were obtained from the AANS/CNS Pediatric Section and ISPN conference proceedings, which are available online. Author and title information were used to search PubMed to identify those abstracts that had progressed to publication in peer-reviewed journals. The title of the journal, year of the publication, and authors’ country of origin were also recorded.

### RESULTS

Overall, 60.6% of the presented oral abstracts from the AANS/CNS Pediatric Section meetings progressed to publication in peer-reviewed journals, as compared with 40.6% of the ISPN presented abstracts (p = 0.0001). The journals in which the AANS/CNS Pediatric Section abstract-based publications most commonly appeared were Journal of Neurosurgery: Pediatrics (52%), Child’s Nervous System (11%), and Journal of Neurosurgery (8%). The ISPN abstracts most often appeared in the journals Child’s Nervous System (29%), Journal of Neurosurgery: Pediatrics (14%), and Neurosurgery (9%). Overall, more than 90% of the abstract-based articles were published within 4 years after presentation of the abstracts on which they were based.

### CONCLUSIONS

Oral abstract presentations at two annual pediatric neurosurgery meetings have publication rates in peer-reviewed journal comparable to those for oral abstracts at other national and international neurosurgery meetings. The vast majority of abstract-based papers are published within 4 years of the meeting at which the abstract was presented; however, the AANS/CNS Pediatric Section abstracts are published at a significantly higher rate than ISPN abstracts, which could indicate the different meeting sizes, research goals, and resources of US authors compared with those of authors from other countries.

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## Ventricular catheter entry site and not catheter tip location predicts shunt survival: a secondary analysis of 3 large pediatric hydrocephalus studies

### OBJECTIVE

Accurate placement of ventricular catheters may result in prolonged shunt survival, but the best target for the hole-bearing segment of the catheter has not been rigorously defined. The goal of the study was to define a target within the ventricle with the lowest risk of shunt failure.

### METHODS

Five catheter placement variables (ventricular catheter tip location, ventricular catheter tip environment, relationship to choroid plexus, catheter tip holes within ventricle, and crosses midline) were defined, assessed for interobserver agreement, and evaluated for their effect on shunt survival in univariate and multivariate analyses. De-identified subjects from the Shunt Design Trial, the Endoscopic Shunt Insertion Trial, and a Hydrocephalus Clinical Research Network study on ultrasound-guided catheter placement were combined (n = 858 subjects, all first-time shunt insertions, all patients < 18 years old). The first postoperative brain imaging study was used to determine ventricular catheter placement for each of the catheter placement variables.

### RESULTS

Ventricular catheter tip location, environment, catheter tip holes within the ventricle, and crosses midline all achieved sufficient interobserver agreement (κ > 0.60). In the univariate survival analysis, however, only ventricular catheter tip location was useful in distinguishing a target within the ventricle with a survival advantage (frontal horn; log-rank, p = 0.0015). None of the other catheter placement variables yielded a significant survival advantage unless they were compared with catheter tips completely not in the ventricle. Cox regression analysis was performed, examining ventricular catheter tip location with age, etiology, surgeon, decade of surgery, and catheter entry site (anterior vs posterior). Only age (p < 0.001) and entry site (p = 0.005) were associated with shunt survival; ventricular catheter tip location was not (p = 0.37). Anterior entry site lowered the risk of shunt failure compared with posterior entry site by approximately one-third (HR 0.65, 95% CI 0.51–0.83).

### CONCLUSIONS

This analysis failed to identify an ideal target within the ventricle for the ventricular catheter tip. Unexpectedly, the choice of an anterior versus posterior catheter entry site was more important in determining shunt survival than the location of the ventricular catheter tip within the ventricle. Entry site may represent a modifiable risk factor for shunt failure, but, due to inherent limitations in study design and previous clinical research on entry site, a randomized controlled trial is necessary before treatment recommendations can be made.

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## Endoscopic third ventriculostomy with choroid plexus cauterization outcome: distinguishing success from failure

### OBJECTIVE

Endoscopic third ventriculostomy with choroid plexus cauterization (ETV/CPC) offers an alternative to shunt treatment for infantile hydrocephalus. Diagnosing treatment failure is dependent on infantile hydrocephalus metrics, including head circumference, fontanel quality, and ventricle size. However, it is not clear to what degree these metrics should be expected to change after ETV/CPC. Using these clinical metrics, the authors present and analyze the decision making in cases of ETV/CPC failure.

### METHODS

Infantile hydrocephalus metrics, including bulging fontanel, head circumference z-score, and frontal and occipital horn ratio (FOHR), were compared between ETV/CPC failures and successes. Treatment outcome predictive values of metrics individually and in combination were calculated.

### RESULTS

Forty-four patients (57% males, median age 1.2 months) underwent ETV/CPC for hydrocephalus; of these patients, 25 (57%) experienced failure at a median time of 51 days postoperatively. Patients experiencing failure were younger than those experiencing successful treatment (0.8 vs 3.9 months, p = 0.01). During outpatient follow-up, bulging anterior fontanel, progressive macrocephaly, and enlarging ventricles each demonstrated a positive predictive value (PPV) of no less than 71%, but a bulging anterior fontanel remained the most predictive indicator of ETV/CPC failure, with a PPV of 100%, negative predictive value of 73%, and sensitivity of 72%. The highest PPVs and specificities existed when the clinical metrics were present in combination, although sensitivities decreased expectedly. Only 48% of failures were diagnosed on the basis all 3 hydrocephalus metrics, while only 37% of successes were negative for all 3 metrics. In the remaining 57% of patients, a diagnosis of success or failure was made in the presence of discordant data.

### CONCLUSIONS

Successful ETV/CPC for infantile hydrocephalus was evaluated in relation to fontanel status, head growth, and change in ventricular size. In most patients, a designation of failure or success was made in the setting of discordant data.

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## Surgeon interrater reliability in the endoscopic assessment of cistern scarring and aqueduct patency

### OBJECTIVE

The success of endoscopic third ventriculostomy with choroid plexus cauterization may have associations with age, etiology of hydrocephalus, previous shunting, cisternal scarring, and possibly aqueduct patency. This study aimed to measure interrater reliability among surgeons in identifying cisternal scarring and aqueduct patency.

### METHODS

Using published definitions of cistern scarring and aqueduct patency, 7 neuroendoscopists with training from Dr. Warf in Uganda and 7 neuroendoscopists who were not trained by Dr. Warf rated cistern status from 30 operative videos and aqueduct patency from 26 operative videos. Interrater agreement was calculated using Fleiss' kappa coefficient (κ). Fisher's 2-tailed exact test was used to identify differences in the rates of agreement between the Warf-trained and nontrained groups compared with Dr. Warf's reference answer.

### RESULTS

Aqueduct status, among all raters, showed substantial agreement with κ = 0.663 (confidence interval [CI] 0.626–0.701); within the trained group and nontrained groups, there was substantial agreement with κ = 0.677 (CI 0.593–0.761) and κ = 0.631 (CI 0.547–0.715), respectively. The identification of cistern scarring was less reliable, with moderate agreement among all raters with κ = 0.536 (CI 0.501–0.571); within the trained group and nontrained groups, there was moderate agreement with κ = 0.555 (CI 0.477–0.633) and κ = 0.542 (CI 0.464–0.620), respectively. There was no statistically significant difference in the amount of agreement between groups compared with Dr. Warf's reference.

### CONCLUSIONS

Regardless of training with Dr. Warf, all neuroendoscopists could identify scarred cisterns and aqueduct patency with similar reliability, emphasizing the strength of the published definitions. This makes the identification of this risk factor for failure generalizable for surgical decision making and research studies.

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## Chiari malformation Type I surgery in pediatric patients. Part 1: validation of an ICD-9-CM code search algorithm

### OBJECTIVE

Administrative billing data may facilitate large-scale assessments of treatment outcomes for pediatric Chiari malformation Type I (CM-I). Validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code algorithms for identifying CM-I surgery are critical prerequisites for such studies but are currently only available for adults. The objective of this study was to validate two ICD-9-CM code algorithms using hospital billing data to identify pediatric patients undergoing CM-I decompression surgery.

### METHODS

The authors retrospectively analyzed the validity of two ICD-9-CM code algorithms for identifying pediatric CM-I decompression surgery performed at 3 academic medical centers between 2001 and 2013. Algorithm 1 included any discharge diagnosis code of 348.4 (CM-I), as well as a procedure code of 01.24 (cranial decompression) or 03.09 (spinal decompression or laminectomy). Algorithm 2 restricted this group to the subset of patients with a primary discharge diagnosis of 348.4. The positive predictive value (PPV) and sensitivity of each algorithm were calculated.

### RESULTS

Among 625 first-time admissions identified by Algorithm 1, the overall PPV for CM-I decompression was 92%. Among the 581 admissions identified by Algorithm 2, the PPV was 97%. The PPV for Algorithm 1 was lower in one center (84%) compared with the other centers (93%–94%), whereas the PPV of Algorithm 2 remained high (96%–98%) across all subgroups. The sensitivity of Algorithms 1 (91%) and 2 (89%) was very good and remained so across subgroups (82%–97%).

### CONCLUSIONS

An ICD-9-CM algorithm requiring a primary diagnosis of CM-I has excellent PPV and very good sensitivity for identifying CM-I decompression surgery in pediatric patients. These results establish a basis for utilizing administrative billing data to assess pediatric CM-I treatment outcomes.

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## Chiari malformation Type I surgery in pediatric patients. Part 2: complications and the influence of comorbid disease in California, Florida, and New York

### OBJECTIVE

Chiari malformation Type I (CM-I) is a common and often debilitating pediatric neurological disease. However, efforts to guide preoperative counseling and improve outcomes research are impeded by reliance on small, single-center studies. Consequently, the objective of this study was to investigate CM-I surgical outcomes using population-level administrative billing data.

### METHODS

The authors used Healthcare Cost and Utilization Project State Inpatient Databases (SID) to study pediatric patients undergoing surgical decompression for CM-I from 2004 to 2010 in California, Florida, and New York. They assessed the prevalence and influence of preoperative complex chronic conditions (CCC) among included patients. Outcomes included medical and surgical complications within 90 days of treatment. Multivariate logistic regression was used to identify risk factors for surgical complications.

### RESULTS

A total of 936 pediatric CM-I surgeries were identified for the study period. Overall, 29.2% of patients were diagnosed with syringomyelia and 13.7% were diagnosed with scoliosis. Aside from syringomyelia and scoliosis, 30.3% of patients had at least 1 CCC, most commonly neuromuscular (15.2%) or congenital or genetic (8.4%) disease. Medical complications were uncommon, occurring in 2.6% of patients. By comparison, surgical complications were diagnosed in 12.7% of patients and typically included shunt-related complications (4.0%), meningitis (3.7%), and other neurosurgery-specific complications (7.4%). Major complications (e.g., stroke or myocardial infarction) occurred in 1.4% of patients. Among children with CCCs, only comorbid hydrocephalus was associated with a significantly increased risk of surgical complications (OR 4.5, 95% CI 2.5–8.1).

### CONCLUSIONS

Approximately 1 in 8 pediatric CM-I patients experienced a surgical complication, whereas medical complications were rare. Although CCCs were common in pediatric CM-I patients, only hydrocephalus was independently associated with increased risk of surgical events. These results may inform patient counseling and guide future research efforts.

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## 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.

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## Risk factors for shunt malfunction in pediatric hydrocephalus: a multicenter prospective cohort study

### OBJECT

The rate of CSF shunt failure remains unacceptably high. The Hydrocephalus Clinical Research Network (HCRN) conducted a comprehensive prospective observational study of hydrocephalus management, the aim of which was to isolate specific risk factors for shunt failure.

### METHODS

The study followed all first-time shunt insertions in children younger than 19 years at 6 HCRN centers. The HCRN Investigator Committee selected, a priori, 21 variables to be examined, including clinical, radiographic, and shunt design variables. Shunt failure was defined as shunt revision, subsequent endoscopic third ventriculostomy, or shunt infection. Important a priori–defined risk factors as well as those significant in univariate analyses were then tested for independence using multivariate Cox proportional hazard modeling.

### RESULTS

A total of 1036 children underwent initial CSF shunt placement between April 2008 and December 2011. Of these, 344 patients experienced shunt failure, including 265 malfunctions and 79 infections. The mean and median length of follow-up for the entire cohort was 400 days and 264 days, respectively. The Cox model found that age younger than 6 months at first shunt placement (HR 1.6 [95% CI 1.1–2.1]), a cardiac comorbidity (HR 1.4 [95% CI 1.0–2.1]), and endoscopic placement (HR 1.9 [95% CI 1.2–2.9]) were independently associated with reduced shunt survival. The following had no independent associations with shunt survival: etiology, payer, center, valve design, valve programmability, the use of ultrasound or stereotactic guidance, and surgeon experience and volume.

### CONCLUSIONS

This is the largest prospective study reported on children with CSF shunts for hydrocephalus. It confirms that a young age and the use of the endoscope are risk factors for first shunt failure and that valve type has no impact. A new risk factor—an existing cardiac comorbidity—was also associated with shunt failure.