Poster H15 - Understanding Shunt System Failures through Cerebrospinal Fluid Dynamics Analysis

Saturday, October 26, 2024

10:00 AM – 11:00 AM EST

Location: Exhibit Hall E, F & G

Co-Author(s)

Bryan C. Good, PhD

Assistant Professor
University of Tennessee
Knoxville, Tennessee, United States

Presenting Author(s)

Dylan Fuentala (he/him/his)

College Student
University of Tennessee - Knoxville
Memphis, Tennessee, United States

Primary Investigator(s)

Bryan C. Good, PhD

Assistant Professor
University of Tennessee
Knoxville, Tennessee, United States

Introduction: Hydrocephalus affects more than 1 million Americans and can be life threatening if left untreated. It can happen at any age but occurs most often among infants and adults over 60. This disease is a result of excessive buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The overproduction of CSF enlarges the ventricles leading to an increase in intracranial pressure (Fig. 1). Symptoms of hydrocephalus include vision changes, impaired cognitive function, and disorientation. Treatment involves surgical intervention to implant a shunt system that drains excess CSF. However, shunt systems have one of the highest failure rates of any medical device on the market, with an estimated 50% of shunts in the pediatric population failing within two years of placement.

Materials and

Methods: Our study aimed to evaluate shunt system performance under varying intracranial pressures (ICPs) and shunt valve settings, focusing on a new Strata II (Medtronic) and an ex-vivo Strata II shunt system (failed device removed from a hydrocephalus patient). Using a standardized experimental setup consisting of a fluid reservoir, wooden stand, beaker, and a digital scale, water heights in the reservoir were adjusted to mimic varying ICPs and CSF outflow through the catheter and valve system analyzed. Data on fluid weight over time were collected in real-time using the digital scale and exported to Excel. Average volumetric flow rates were then calculated by dividing by the fluid density and graphed against manufacturer specifications for comparison.

Results, Conclusions, and Discussions: The study evaluated the performance of the new Strata II valve and a failed ex-vivo valve under varying intracranial pressure (ICP) conditions. For the Strata II valve, flow rates ranged from 20 to 45 mL/hr as pressures increased from 35 to 55 mm H2O. The relationship between pressure and flow rate was nearly linear, indicating effective performance comparable to the manufacturer's Performance Level 1.0 standards.
Conversely, the failed ex-vivo valve exhibited a broader range of flow rates, increasing from 0 to 148 mL/hr across pressures from 20 to 160 mm H2O. Notably, at pressures between 40 and 100 mm H2O, the flow rate demonstrated a linear relationship, but showed fluctuations at higher pressures. Comparison with manufacturer standards indicated intersection with Performance Levels 1.0 and 1.5, suggesting potential underdrainage at higher pressures, which could lead to reduced cerebrospinal fluid (CSF) drainage in clinical settings.
Future research plans include disassembling the Strata II valves to analyze internal components and construct CAD models in SolidWorks. These models will be crucial for identifying structural irregularities and design flaws. Additionally, the study aims to use medical imaging and 3D printing to develop accurate models of shunt valve assemblies, replicating in vivo device failures such as blockages. These combined approaches aim to enhance understanding and improve the reliability and effectiveness of shunt systems in treating hydrocephalus.

Acknowledgements (Optional):