Abstract

Hydrocephalic shunt dysfunction diagnosis is one of the most complicated and time consuming aspects of treating hydrocephalic infants and young children, since preverbal children cannot describe such critical symptoms as persistent headaches. One must instead rely on observable symptoms that often resemble those of common childhood illnesses.

As a result, suspected shunt dysfunction often requires emergency room admission and invasive diagnostic tests, yet it is estimated that the shunt is actually working properly two out of three visits. One could greatly improve outcomes and reduce patient/parental stress if doctors could non-invasively measure shunt tubing CSF flow to assess shunt patency and shunt under/overdrainage.

Transonic Systems, Phoenix Biomedical, and the Children's Hospital of Wisconsin will address this need by developing a transcutaneously-powered/measured flow probe module integrated with standard shunt tubing exterior to the skull. This module will measure dynamic shunt volumetric flow by sending transit-time ultrasonic pulses through the tubing wall. This extra-luminar design ensures that transducers never contact CSF, and that the module can be integrated with existing shunt systems.

Phase-I bench/in-vivo studies will validate the monitor's flow resolution and accuracy, leading to a Phase-II program to develop a fully implantable unit suitable for animal validation and initial clinical studies.

Overview

This project will develop and validate a device that can transcutaneously monitor flow in implanted pediatric hydrocephalic shunt systems.

The proposed device consists of a flow measurement module that is integrated with standard shunt tubing, and istranscutaneously powered and monitored (see Figure A-1 below). This module will measure dynamic shunt volumetric flow by sending transit-time ultrasonic pulses through the tubing wall. The extra-luminar design ensures that transducers never contact CSF, and that the module can be integrated with existing shunt systems.

Figure A-1: A concept diagram for the pediatric transcutaneous shunt flow monitor

Implantation location (top), Concept model for implanted hardware (bottom).

We expect that such a device will reduce the time, patient/parental stress, and costs involved in diagnosing suspected hydrocephalic shunt dysfunction in preverbal children. The device could also lead to better outcomes for pediatric patients, since the ability to make fast, non-invasive measurements would encourage parents and physicians to check for shunt blockage when suspicious symptoms first emerge, rather than waiting until symptoms are severe enough to warrant Emergency Room visits.

This device could improve patient health by giving neurosurgeons a device for non-invasively measuring flow through suspected under- or over-draining shunts. Longer term, this device may lead to major improvements in shunt designs, since researchers could non-invasively measure shunt flow dynamics during a patient's normal physical activities.

Vygon Neuro is a division of Vygon Corporation, which purchased the assets of Phoenix Biomedical Corp under the name Vygon US LLC in July 2003. Vygon US LLC has its roots in the development of the first hydrocephalus shunt. In 1956, John Holter designed what would soon become the first functional shunt. In 1993, Holter retired and his company Phoenix Bioengineering was merged with Theramedics, another shunt company, to create Phoenix Biomedical Corp (PBC).

Since this time, Phoenix Biomedical has introduced nearly twenty new products to the market, including four new hydrocephalus shunts. Vygon US LLC is certified to ISO 9001:1994, EN 46001:1994 and ISO 13485:1996 and complies with the requirements of 21 CFR, part 820. Vygon is a medical device manufacturing company with 40000 square feet of class 10,000 clean room space where Vygon manufactures, tests, and packages hydrocephalus valves and related products.

The Cornell University College of Veterinary Medicine is one of the top veterinary research schools in the United States. The college conducts extensive large- and small-animal research, and has fully equipped, standard operating theaters with anesthesia and patient monitoring apparatus. The facilities also include holding pens for large and small ruminants and a fully staffed veterinary hospital with a 24-hour emergency room.

Our collaborator Dr. Robin Gleed is a tenured faculty member who has collaborated with Transonic Systems for the last twelve years. Dr. Gleed has extensive experience in animal anesthesia, surgery, and post-operative care, and he regularly conducts studies that evaluate prototype Transonic flow measurement hardware implanted into sheep.

A.1.c Dr. Bruce Kaufman and The Children's Hospital of Wisconsin/Medical College of Wisconsin

Dr. Kaufman is Chief of Pediatric Neurosurgery at the Children's Hospital of Wisconsin, and Professor of Neurosurgery at the Medical College of Wisconsin, where he heads the Division of Pediatric Neurosurgery.

At the Children's Hospital (a 225-bed pediatric facility) his department handles over 500 pediatric neurosurgical cases per year. Approximately 40% are related to hydrocephalus, with the remainder divided among the typical neurosurgical procedures - including spinal dysraphism, tumors, malformations, and trauma.

In addition to his clinical practice, Dr. Kaufman is an active clinical researcher. He has published 56 papers in peer-reviewed journals on such areas as hydrocephalus outcomes and craniofacial surgery procedure outcomes. He serves as an ad hoc reviewer for the Journal of Neurosurgery, the Journal of Pediatric Hematology/Oncology, and Pediatric Neurosurgery.

Dr. Kaufman has been involved in multi-center trials of shunting devices. As an active member of several national pediatric neurosurgery organizations, he is in regular contact with pediatric neurosurgeons that have developed and completed a series of shunt related prospective, randomized trials (these involved testing different shunt valves, and different insertion techniques). Dr. Kaufman serves as a pediatric neurosurgery representative to the national neurosurgery outcomes committee, and is on the Medical Advisory Board for the Hydrocephalus Association (a patient advocacy organization).

Dr. Kaufman has achieved national recognition for his extensive clinical and research accomplishment - he was named "One of America's Best Doctors" in 1999, 2001, 2004, and 2007.