Computational Modeling and Simulation to Quantify the Effects of Obstructions on the Performance of Ventricular Catheters Used in Hydrocephalus Treatment.

Pediatric hydrocephalus is a debilitating condition that affects an estimated 1-2 in 1000 newborns, and there is no cure. A traditional treatment is surgical insertion of a shunt system which was designed 50 years ago, and minimal ensuing progress has been made in improving the failure rate of these devices resulting in the need for multiple brain surgeries during an affected child's lifetime for shunt replacement. A first step toward decreasing the failure rate is to optimize the ventricular catheter component of the shunt to minimize its propensity for obstruction. Given the many geometric properties and patient specific in vivo conditions needed to characterize the fluid dynamics affecting ventricular catheter performance, validated computational simulation is an efficient method to rapidly explore and evaluate the effects of this large parameter space to inform improved design and to investigate patient specific shunt performance. This chapter provides the details on how to build a computational model of a ventricle and implanted catheter, analyze the fluid dynamics through an obstructed catheter, and postprocess the results to predict catheter performance for varying geometry and in vivo conditions.

Causes, Complications, and Costs Associated with External Ventricular Drainage Catheter Obstruction.

Ventricular catheter obstructions in patients treated with external ventricular drains (EVDs) have the potential to substantially impact the cost of patient care. There is a paucity of literature that directly addresses catheter obstruction over large numbers of patients with EVDs in multiple centers. Contemporary literature was reviewed to characterize causes, complications, and costs of EVD catheter obstruction. Data from published studies of EVD complications were compiled to estimate the rate of EVD catheter replacement and quantify the correlation between catheter replacement and infection. In these studies, the average number of catheters placed per patient with an EVD was 1.26, indicating a relatively high rate of replacement. Obstructions because of thrombosis and catheter malposition were identified as frequent causes of EVD replacement. Patients who underwent replacement had a 29% rate of ventriculostomy-related infection compared with 6% in those who had no replacement. The estimated diagnostic, procedural, and material cost of EVD replacement is in the range of approximately $1300-$3200 per replacement. The diagnosis and treatment of ventricular catheter obstruction, along with associated complications, creates a substantial cost burden. Further research should focus on strategies to reduce the incidence of ventricular catheter obstruction.

A Review on the Effectiveness of Surgical Intervention for Symptomatic Intracranial Arachnoid Cysts in Adults.

BACKGROUND: Intracranial arachnoid cysts are generally benign and can be asymptomatic or symptomatic. When symptoms are indicated, the effects of arachnoid cysts can be disabling to the patient. Quantitative assessment on the effectiveness of surgical intervention to relieve symptoms is inconsistently reported throughout the literature and is often contradictory. Due to this lack of direct evidence and disagreement among practitioners, nonsurgical treatment, such as pain management, is often prescribed. The objectives of this research were to evaluate the effectiveness of the 3 most common surgical treatments (craniotomy, endoscopic fenestration, and shunting) in relieving patient symptoms and to provide a resource of case study information for doctors and patients considering surgical intervention. METHODS: A worldwide literature review was performed using the PubMed database to collect reported data on case studies describing surgical intervention for intracranial arachnoid cysts. A meta-analytic review was performed on the viable data to investigate the overall surgical effectiveness for an adult population (aged 18 years or older). To increase the number of patient outcomes, some mixed data (case studies containing both adult and pediatric patients) were included in this study. RESULTS: The meta-analytic results show that, for the mixed adult and pediatric population, surgical treatment improves patient outcomes (r¯ = 0.828; P < 0.01), and the specific effects for craniotomy, shunting, and endoscopy are r¯ = 0.890, 0.738, and 0.892. For the adult-only population, the meta-analytic results show that surgical treatment also improves patient outcomes (r¯ = 0.667; P < 0.01), and the specific effects for craniotomy, shunting, and endoscopy are r¯= 0.638, 0.684, and 0.727. CONCLUSIONS: The results indicate that surgical intervention is an effective approach to reduce or eliminate symptoms caused by intracranial arachnoid cysts.

A computational fluid dynamics simulation framework for ventricular catheter design optimization.

In this research an optimization methodology and 3D computational fluid dynamics algorithm were coupled to reach an important design objective for ventricular catheters: uniform inlet flow distribution. The optimized catheter design presented significantly improves on previous designs explored in the literature and on standard catheter designs used clinically. The automated, iterative fluid simulation framework described in this work can be used to rapidly explore design parameter influence on other flow-related objectives in the future.

Ventricular catheter development: past, present, and future.

Cerebrospinal fluid diversion via ventricular shunting is the prevailing contemporary treatment for hydrocephalus. The CSF shunt appeared in its current form in the 1950s, and modern CSF shunts are the result of 6 decades of significant progress in neurosurgery and biomedical engineering. However, despite revolutionary advances in material science, computational design optimization, manufacturing, and sensors, the ventricular catheter (VC) component of CSF shunts today remains largely unchanged in its functionality and capabilities from its original design, even though VC obstruction remains a primary cause of shunt failure. The objective of this paper is to investigate the history of VCs, including successful and failed alterations in mechanical design and material composition, to better understand the challenges that hinder development of a more effective design.