Arteriovenous malformations in the cerebellopontine angle: assessment of the "backdoor resection" technique and microsurgical results in 38 patients.

OBJECTIVE: Posterior fossa arteriovenous malformations (AVMs) represent 7% to 15% of all intracranial AVMs and are associated with an increased risk of hemorrhage, morbidity, and mortality compared with supratentorial AVMs, thus prompting urgent and definitive treatment. Cerebellopontine angle (CPA) AVMs are a unique group of posterior fossa AVMs incorporating characteristics of brainstem and cerebellar lesions, which are particularly amenable to microsurgical resection. This study reports the clinical, radiological, operative, and outcome features of patients with CPA AVMs in a large cohort. METHODS: The authors conducted a single-surgeon, 2-institution retrospective cohort study of all consecutive patients with CPA AVMs treated with microsurgical resection during a 25-year period. RESULTS: CPA AVMs represented 22% (38 of 176) of all infratentorial AVMs resected by the senior author. Overall, 38 patients (22 [58%] male and 16 [42%] female) met the study inclusion criteria and were analyzed. Most patients presented with hemorrhage (n = 29, 76%). The median age at surgery was 56 (range 6-82) years. Subtypes included 22 (58%) petrosal cerebellar AVMs, 11 (29%) lateral pontine AVMs, and 5 (13%) AVMs involving both the brainstem and cerebellum. Most AVM niduses were small (< 3 cm; n = 35, 92%) and compact (n = 31, 82%). Fourteen (37%) patients harbored flow-related aneurysms. Twenty (53%) patients underwent preoperative embolization. Complete angiographic obliteration was achieved with microsurgery in 35 (92%) patients. Five (13%) patients with poor neurological conditions at presentation died before hospital discharge. Of the 7 (18%) patients with new postoperative neurological deficits, 5 had transient deficits. The median (interquartile range) follow-up was 1.7 (0.5-3.2) years; 32 (84%) patients were alive at last follow-up, and 30 (79%) had achieved a favorable neurological outcome (modified Rankin Scale [mRS] score 0-2). The only independent predictor of unfavorable postoperative outcome (mRS score 3-6) was the preoperative mRS score (p = 0.002). CONCLUSIONS: CPA AVMs are unique posterior fossa lesions, including petrosal cerebellar and lateral pontine AVMs. The "backdoor resection" technique provides a safe and efficient strategy with high obliteration rates and a low risk of treatment-related morbidity. Microsurgical resection should be considered the frontline treatment for most CPA AVMs, except for those with a significant diffuse brainstem component.

Early Treatment of Ruptured Cerebral Arteriovenous Malformations: Analysis of Neurological Outcomes and Health Care Costs.

BACKGROUND: The timing of surgical resection is controversial when managing ruptured arteriovenous malformations (AVMs) and varies considerably among centers. OBJECTIVE: To retrospectively analyze clinical outcomes and hospital costs associated with delayed treatment in a ruptured cerebral AVM patient cohort. METHODS: Patients undergoing surgical treatment for a ruptured cerebral AVM (January 1, 2015-December 31, 2020) were retrospectively analyzed. Patients who underwent emergent treatment of a ruptured AVM because of acute herniation were excluded, as were those treated >180 days after rupture. Patients were stratified by the timing of surgical intervention relative to AVM rupture into early (postbleed days 1-20) and delayed (postbleed days 21-180) treatment cohorts. RESULTS: Eighty-seven patients were identified. The early treatment cohort comprised 75 (86%) patients. The mean (SD) length of time between AVM rupture and surgical resection was 5 (5) days in the early cohort and 73 (60) days in the delayed cohort ( P < .001). The cohorts did not differ with respect to patient demographics, AVM size, Spetzler-Martin grade, frequency of preoperative embolization, or severity of clinical presentation ( P ≥ .15). Follow-up neurological status was equivalent between the cohorts ( P = .65). The associated mean health care costs were higher in the delayed treatment cohort ($241 597 [$99 363]) than in the early treatment cohort ($133 989 [$110 947]) ( P = .02). After adjustment for length of stay, each day of delayed treatment increased cost by a mean of $2465 (95% CI = $967-$3964, P = .002). CONCLUSION: Early treatment of ruptured AVMs was associated with significantly lower health care costs than delayed treatment, but surgical and neurological outcomes were equivalent.

Cost-Effectiveness of Forgoing Postoperative Catheter Angiography After Microsurgical Occlusion of Spinal Dorsal Intradural Arteriovenous Fistulas.

OBJECTIVE: Spinal dorsal intradural arteriovenous fistulas (DI-AVFs) represent 70% of all spinal vascular lesions. Diagnostic tools include pre- and postoperative digital subtraction angiography (DSA) and intraoperative indocyanine green videoangiography (ICG-VA). ICG-VA has a high predictive value in DI-AVF occlusion, but postoperative DSA remains a core component of postoperative protocols. The aim of this study was to evaluate the potential cost reduction of forgoing postoperative DSA after microsurgical occlusion of DI-AVFs. METHODS: Cohort-based cost effectiveness study of all DI-AVFs within a prospective, single-center cerebrovascular registry from January 1, 2017, to December 31, 2021. RESULTS: Complete data including intraoperative ICG-VA and costs were available for 11 patients. Mean (SD) age was 61.5 (14.8) years. All DI-AVFs were treated with microsurgical clip ligation of the draining vein. ICG-VA showed complete obliteration in all patients. Postoperative DSA was performed for 6 patients and confirmed complete obliteration. Mean (SD) cost contributions for DSA and ICG-VA were $11,418 ($4,861) and $12 ($2), respectively. Mean (SD) total costs were $63,543 ($15,742) and $53,369 ($27,609) for patients who did and did not undergo postoperative DSA, respectively. Comorbidity status was identified as the main driver of total cost (P = 0.01 after adjusting for postoperative DSA status). CONCLUSIONS: ICG-VA is a powerful diagnostic tool in demonstrating microsurgical cure of DI-AVFs, with a negative predictive value of 100%. Eliminating postoperative DSA in patients with confirmed DI-AVF obliteration on ICG-VA may yield substantial cost savings, in addition to sparing patients the risk and inconvenience of a potentially unnecessary invasive procedure.

Procedural, workforce, and reimbursement trends in neuroendovascular procedures.

BACKGROUND: This study aims to define the proportion of Medicare neuroendovascular procedures performed by different specialists from 2013 to 2019, map the geographic distribution of these specialists, and trend reimbursement for these procedures. METHODS: The Medicare Provider Utilization Database was queried for recognized neuroendovascular procedures. Data on specialists and their geographic distribution were tabulated. Reimbursement data were gathered using the Physician Fee Schedule Look-Up Tool and adjusted for inflation using the United States Bureau of Labor Statistics' Consumer Price Index Inflation calculator. RESULTS: The neuroendovascular workforce in 2013 and 2019, respectively, was as follows: radiologists (46% vs 44%), neurosurgeons (45% vs 35%), and neurologists (9% vs 21%). Neurologists increased proportionally (p=0.03). Overall procedure numbers increased across each specialty: radiology (360%; p=0.02), neurosurgery (270%; p<0.01), and neurology (1070%; p=0.03). Neuroendovascular revascularization (CPT 61645) increased in all fields: radiology (170%; p<0.01), neurosurgery (280%; p<0.01), neurology (240%; p<0.01); central nervous system (CNS) permanent occlusion/embolization (CPT61624) in neurosurgery (67%; p=0.03); endovascular temporary balloon artery occlusion (CPT61623) in neurology (29%; p=0.04). In 2019, radiologists were the most common neuroendovascular specialists everywhere except in the Northeast where neurosurgeons predominated. Inflation adjusted reimbursement decreased for endovascular temporary balloon occlusion (CPT61623, -13%; p=0.01), CNS transcatheter permanent occlusion or embolization (CPT61624, -13%; p=0.02), non-CNS transcatheter permanent occlusion or embolization (CPT61626, -12%; p<0.01), and intracranial stent placement (CPT61635, -12%; p=0.05). CONCLUSIONS: The number of neuroendovascular procedures and specialists increased, with neurologists becoming more predominant. Reimbursement decreased. Coordination among neuroendovascular specialists in terms of training and practice location may maximize access to acute care.

Health Care Expenditures Associated with Delayed Cerebral Ischemia Following Subarachnoid Hemorrhage: A Propensity-Adjusted Analysis.

OBJECTIVE: The additional hospital costs associated with delayed cerebral ischemia (DCI) have not been well investigated in prior literature. In this study, the total hospital cost of DCI in aneurysmal subarachnoid hemmorhage (aSAH) patients treated at a single quaternary center was analyzed. METHODS: All patients in the Post-Barrow Ruptured Aneurysm Trial treated for an aSAH between January 1, 2014, and July 31, 2019, were retrospectively analyzed. DCI was defined as cerebral infarction identified on computed tomography, magnetic resonance imaging, or autopsy after exclusion of procedure-related infarctions. The primary outcome was the difference in total cost (including hospital, discharge facility, and all follow-up) using a propensity-adjusted analysis. Propensity score covariate-adjusted linear regression analysis included age, sex, open versus endovascular treatment, Hunt and Hess score, and Charlson Comorbidity Index score. RESULTS: Of the 391 patients included, 144 (37%) had DCI. Patients with DCI had a significantly greater cost compared to patients without DCI (mean standard deviation $112,081 [$54,022] vs. $86,159 [$38,817]; P < 0.001) and a significantly greater length of stay (21 days [11] vs. 18 days [8], P = 0.003, respectively). In propensity-adjusted linear regression analysis, both DCI (odds ratio, $13,871; 95% confidence interval, $7558-$20,185; P < 0.001) and length of stay (odds ratio, $3815 per day; 95% confidence interval, $3480-$4149 per day; P < 0.001) were found to significantly increase the cost. CONCLUSIONS: The significantly higher costs associated with DCI further support the evidence that adverse effects associated with DCI in aSAH pose a significant burden to the health care system.

Cost Comparison of Microsurgery vs Endovascular Treatment for Ruptured Intracranial Aneurysms: A Propensity-Adjusted Analysis.

BACKGROUND: In specialized neurosurgical centers, open microsurgery is routinely performed for aneurysmal subarachnoid hemorrhage (aSAH). OBJECTIVE: To compare the cost of endovascular vs microsurgical treatment for aSAH at a single quaternary center. METHODS: All patients undergoing aSAH treatment from July 1, 2014, to July 31, 2019, were retrospectively reviewed. Patients were grouped based on primary treatment (microsurgery vs endovascular treatment). The primary outcome was the difference in total cost (including hospital, discharge facility, and all follow-up) using a propensity-adjusted analysis. RESULTS: Of 384 patients treated for an aSAH, 234 (61%) were microsurgically treated and 150 (39%) were endovascularly treated. The mean cost of index hospitalization for these patients was marginally higher ($9504) for endovascularly treated patients ($103 980) than for microsurgically treated patients ($94 476) ( P = .047). For the subset of patients with follow-up data available, the mean total cost was $45 040 higher for endovascularly treated patients ($159 406, n = 59) than that for microsurgically treated patients ($114 366, n = 105) ( P < .001). After propensity scoring (adjusted for age, sex, comorbidities, Glasgow Coma Scale score, Hunt and Hess grade, Fisher grade, aneurysms, and type/size/location), linear regression analysis of patients with follow-up data available revealed that microsurgery was independently associated with healthcare costs that were $37 244 less than endovascular treatment costs ( P < .001). An itemized cost analysis suggested that this discrepancy was due to differences in the rates of aneurysm retreatment and long-term surveillance. CONCLUSION: Microsurgical treatment for aSAH is associated with lower total healthcare costs than endovascular therapy. Aneurysm surveillance after endovascular treatments, retreatment, and device costs warrants attention in future studies.

Comparative Anatomical Assessment of Full vs Limited Transcavernous Exposure of the Carotid-Oculomotor Window.

BACKGROUND: Although the full transcavernous approach affords extensive mobilization of the oculomotor nerve (OMN) for exposure of the basilar apex and interpeduncular cistern region, this time-consuming procedure requires substantial dural dissection along the anterior middle cranial fossa. OBJECTIVE: To quantify the extent to which limited middle fossa dural elevation affects the carotid-oculomotor window (C-OMW) surgical area during transcavernous exposure after OMN mobilization. METHODS: Four cadaveric specimens were dissected bilaterally to study the C-OMW area afforded by the transcavernous exposure. Each specimen underwent full and limited transcavernous exposure and anterior clinoidectomy (1 procedure per side; 8 procedures). Limited exposure was defined as a dural elevation confined to the cavernous sinus. Full exposure included dural elevation over the gasserian ganglion, extending to the middle meningeal artery and lateral middle cranial fossa. RESULTS: The C-OMW area achieved with the limited transcavernous exposure, compared with full transcavernous exposure, provided significantly less total area with OMN mobilization (22 ± 6 mm2 vs 52 ± 26 mm2, P = .03) and a smaller relative increase in area after OMN mobilization (11 ± 5 mm2 vs 36 ± 13 mm2, P = .03). The increase after OMN mobilization in the C-OMW area after OMN mobilization was 136% ± 119% with a limited exposure vs 334% ± 216% with a full exposure. CONCLUSION: In this anatomical study, the full transcavernous exposure significantly improved OMN mobilization and C-OMW area compared with a limited transcavernous exposure. If a transcavernous exposure is pursued, the difference in the carotid-oculomotor operative corridor area achieved with a limited vs full exposure should be considered.

Total 1-year hospital cost of middle meningeal artery embolization compared to surgery for chronic subdural hematomas: a propensity-adjusted analysis.

BACKGROUND: Middle meningeal artery (MMA) embolization results in fewer treatment failures than surgical evacuation for chronic subdural hematomas (cSDHs). We compared the total 1-year hospital cost for MMA embolization versus surgical evacuation for patients with cSDH. METHODS: Data for patients who presented with cSDHs from January 1, 2018, through May 31, 2020, were retrospectively reviewed. Patients were grouped by initial treatment (surgery vs MMA embolization), and total hospital cost was obtained. A propensity-adjusted analysis was performed. The primary outcome was difference in mean hospital cost between treatments. RESULTS: Of 170 patients, 48 (28%) underwent embolization and 122 (72%) underwent surgery. cSDHs were larger in the surgical (20.5 (6.7) mm) than in the embolization group (16.9 (4.6) mm; P<0.001); and index hospital length of stay was longer in the surgical group (9.8 (7.0) days) than in the embolization group (5.7 (2.4) days; P<0.001). More patients required additional hematoma treatment in the surgical cohort (16%) than in the embolization cohort (4%; P=0.03), and more required readmission in the surgical cohort (28%) than in the embolization cohort (13%; P=0.04). After propensity adjustment, MMA embolization was associated with a lower total hospital cost compared to surgery (mean difference -$32 776; 95% CI -$52 766 to -$12 787; P<0.001). A propensity-adjusted linear regression analysis found that unexpected additional treatment was the only significant contributor to total hospital cost (mean difference $96 357; 95% CI $73 886 to $118 827; P<0.001). CONCLUSIONS: MMA embolization is associated with decreased total hospital cost compared with surgery for cSDHs. This lower cost is directly related to the decreased need for additional treatment interventions.

Propensity-adjusted cost analysis of radial versus femoral access for neuroendovascular procedures.

BACKGROUND: Transradial artery (TRA) access for neuroendovascular procedures is associated with fewer complications than transfemoral artery (TFA) access. This study compares hospital costs associated with TRA access to those associated with TFA access for neurointerventions. METHODS: Elective neuroendovascular procedures at a single center were retrospectively analyzed from October 1, 2018 to May 31, 2019. Hospital costs for each procedure were obtained from the hospital financial department. The primary outcome was the difference in the mean hospital costs after propensity adjustment between patients who underwent TRA compared with TFA access. RESULTS: Of the 338 elective procedures included, 63 (19%) were performed through TRA versus 275 (81%) through TFA access. Diagnostic procedures were more common in the TRA cohort (51 of 63, 81%) compared with the TFA cohort (197 of 275, 72%), but the difference was not significant (p=0.48). The TRA cohort had a shorter length of hospital stay (mean (SD) 0.3 (0.5) days) compared with the TFA cohort (mean 0.7 (1.3) days; p=0.02) and lower hospital costs (mean $12 968 ($6518) compared with the TFA cohort (mean $17 150 ($10 946); p=0.004). After propensity adjustment for age, sex, symptoms, angiographic findings, procedure type, sheath size, and catheter size, TRA access was associated with a mean hospital cost of $2514 less than that for TFA access (95% CI -$4931 to -$97; p=0.04). CONCLUSION: Neuroendovascular procedures performed through TRA access are associated with lower hospital costs than TFA procedures. The lower cost is likely due to a decreased length of hospital stay for TRA.

Dural Substitutes Differentially Interfere with Imaging Quality of Sonolucent Transcranioplasty Ultrasound Assessment in Benchtop Model.

BACKGROUND: Sonolucent cranioplasty implants were recently introduced into clinical practice and tested for use with transcranioplasty ultrasound (TCUS). In situations where dural substitutes (DSs) are needed during closure, such as in extracranial-intracranial bypass, it is unclear if the DS influences the imaging quality of TCUS. The aim of this study was to assess the influence of DSs on imaging quality during TCUS assessment with sonolucent cranioplasty. METHODS: A tofu vascular brain model was constructed with a ClearFit implant in between 2 layers of tofu. Injection of saline solution through a 6-F Envoy DA XB endovascular catheter (6-F Envoy DA XB) inserted into the deeper tofu layer mimicked an intracranial vessel. TCUS image quality, including Doppler, with 4 different DSs (DuraGen, Durepair, DuraMatrix-Onlay, DuraMatrix Suturable) placed under the cranioplasty was compared against a control by 2 examiners. A literature search of MEDLINE and EMBASE was conducted to find previous reports of acoustic properties of DSs. RESULTS: TCUS assessment including Doppler was feasible with the model in longitudinal and axial planes, and the pulsatile particle injection was visualized in real time. DuraGen and Durepair showed Doppler quality and picture detail comparable to the control, while the DuraMatrix-Onlay and DuraMatrix Suturable were inferior to the control. The literature search yielded only 1 previous report on acoustic properties of DSs. CONCLUSIONS: DSs interfere differentially with imaging quality during TCUS assessment. However, these results are based on a benchtop model and need to be further assessed in the clinical setting.

Safety, Feasibility, and Patient-Rated Outcome of Sonolucent Cranioplasty in Extracranial-Intracranial Bypass Surgery to Allow for Transcranioplasty Ultrasound Assessment.

OBJECTIVE: We sought to analyze the safety and feasibility of elective sonolucent cranioplasty in the setting of extracranial-to-intracranial (EC-IC) bypass surgery to monitor bypass patency using ultrasound. METHODS: Patients who underwent direct EC-IC bypass surgery agreed to sonolucent cranioplasty at the time of surgery and received a sonolucent polymethyl methacrylate (PMMA) implant. Besides monitoring clinical outcome, all patients received transcranioplasty ultrasound (TCUS) on postoperative day 1 and at last follow-up. In addition, bypass patency was confirmed using catheter angiogram and fit of implant using computed tomography. Patient-rated outcome was assessed through phone questionnaire. RESULTS: EC-IC bypass surgery with PMMA cranioplasty was successful in all 7 patients with patent bypasses on postoperative angiogram. Direct TCUS was feasible in all patients, and bypass patency was monitored. There were no complications such as postoperative hemorrhagic/ischemic complications related to the bypass procedure in this patient population, as well as no complications related to the PMMA implant. Postoperative computed tomography showed favorable cosmetic results of the PMMA implant in both the pterional area for superficial temporal artery-middle cerebral artery bypasses and parietooccipital area for occipital artery-middle cerebral artery bypasses as confirmed by high-rated overall patient satisfaction with favorable cosmetic, pain, and sensory patient-rated outcomes. CONCLUSIONS: In this study we were able to show that this novel technique is safe, allows for patency assessment of the EC-IC bypass using bedside TCUS technique, and is cosmetically satisfying for patients.

Cognitive Sequelae of Unruptured and Ruptured Intracranial Aneurysms and their Treatment: Modalities for Neuropsychological Assessment.

BACKGROUND: Cognitive sequelae frequently follow subarachnoid hemorrhage (SAH) and include deficits across multiple domains of executive function. This factor affects overall functional outcomes negatively, especially in younger patients. Several clinical correlates predict development and severity of cognitive dysfunction after SAH. Hypothetical mechanisms of cognitive dysfunction in the absence of radiographic lesion include cerebral hypoperfusion and blood breakdown products, resulting in perturbed interneuronal communication and network synchrony, excitotoxicity, and altered microRNA expression. METHODS: The PubMed database was searched for articles discussing cognitive outcomes in patients with unruptured and ruptured intracranial aneurysmal disease, sequelae of treatment, and modalities for neuropsychologic testing. RESULTS: Treatment of unruptured intracranial aneurysms, although capable of preventing SAH, comes with its own set of complications and may also affect cognitive function. Neuropsychological tests such as the Montreal Cognitive Assessment, Mini-Mental Status Examination, and others have proved useful in evaluating cognitive decline. Studies using functional neurologic imaging modalities have identified regions with altered activation patterns during various cognitive tasks. The sum of research efforts in this field has provided useful insights and an initial understanding of cognitive dysfunction after aneurysm treatment and SAH that should prove useful in guiding and rendering future investigations more fruitful. CONCLUSIONS: Development of finer and more sensitive neuropsychological tests in evaluating the different domains of cognitive function after aneurysm treatment and SAH in general will be useful in accurately determining outcomes after ictus and comparing efficacy of different therapeutic strategies.

Prolapse of the Pipeline embolization device in aneurysms: incidence, management, and outcomes.

OBJECTIVE The Pipeline embolization device (PED) is frequently used in the treatment of anterior circulation aneurysms, especially around the carotid siphon, with generally excellent results. However, the PED has its own unique technical challenges, including the occurrence of device foreshortening or migration leading to prolapse into the aneurysm. The authors sought to determine the incidence of this phenomenon, the rescue strategies, and outcomes. METHODS Four institutional databases of neuroendovascular procedures were reviewed for cases of intracranial aneurysms treated with PEDs. Patient and aneurysm data as well as angiographic imaging were reviewed for all cases involving device prolapse into the aneurysm. RESULTS A total of 413 intracranial aneurysms were treated with PEDs during the study period, by 5 neurointerventionalists. Large and giant aneurysms (≥ 2 cm) accounted for 32 of these aneurysms. Among these 32 PEDs, prolapse into the aneurysm occurred in 3 patients, with 1 of these PEDs successfully rescued and the other 2 left in situ. No patients suffered any severe complications. The 2 patients in whom the PEDs were left in situ remained on antiplatelet therapy. CONCLUSIONS The PED may foreshorten or migrate during or after deployment, leading to prolapse into the aneurysm. This phenomenon appears to be associated with large and giant aneurysms, vessel tortuosity, short landing zones, and use of balloon angioplasty. Future study and follow-up is needed to further evaluate this phenomenon, but some of the observations and techniques described in this paper may help to prevent or salvage prolapsed devices.

Cerebrospinal fluid shunt placement in the pediatric population: a model of hospitalization cost.

UNLABELLED: OBJECT There have been no large-scale analyses on cost drivers in CSF shunt surgery for the treatment of pediatric hydrocephalus. The objective of this study was to develop a cost model for hospitalization costs in pediatric CSF shunt surgery and to examine risk factors for increased costs. METHODS: Data were extracted from the Kids' Inpatient Database (KID) of the Healthcare Cost and Utilization Project. Children with initial CSF shunt placement in the 2009 KID were examined. Patient charge was converted to cost using a cost-to-charge ratio. The factors associated with costs of CSF shunt hospitalizations were examined, including patient demographics, hospital characteristics, and clinical data. The natural log transformation of cost per inpatient day (CoPID) was analyzed. Three multivariate linear regression models were used to characterize the cost. Variance inflation factor was used to identify multicollinearity for each model. RESULTS: A total of 2519 patients met the inclusion criteria and were included in study. Average cost and length of stay (LOS) for initial shunt placement were $49,317 ± $74,483 (US) and 18.2 ± 28.5 days, respectively. Cost per inpatient day was $4249 ± $2837 (median $3397, range $80-$22,263). The average number of registered nurse (RN) full-time equivalents (FTEs) per 1000 adjusted inpatient days was 5.8 (range 1.6-10.8). The final model had the highest adjusted coefficient of determination (R(2) = 0.32) and was determined to be the best among 3 models. The final model showed that child age, hydrocephalus etiology, weekend admission, number of chronic diseases, hospital type, number of RN FTEs per 1000 adjusted inpatient days, number of procedures, race, insurance type, income level, and hospital regions were associated with CoPID. CONCLUSIONS: A patient's socioeconomic status, such as race, income level, and insurance, in addition to hospital-related factors such as number of hospital RN FTEs, hospital type, and US region, could affect the costs of initial CSF shunt placement, in addition to clinical factors such as hydrocephalus origin and LOS. To create a cost model of initial CSF shunt placement in the pediatric population, consideration of such nonclinical factors may be warranted.