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University of Groningen
Hydrocephalus shunts Metzemaekers, Joannes Dionysius Maria
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Publication date: 1998
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Citation for published version (APA): Metzemaekers, J. D. M. (1998). Hydrocephalus shunts: a clinical and laboratory study. Groningen: s.n.
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A clinical and laboratory study
This study was financially supported by grants from: Het Van Leersumfonds, Biomedic, Codman, Cordis and Promedics.
Hydrocephalus shunts. A clinical and laboratory study. Jan D.M. Metzemaekers, Groningen Thesis University Groningen
ISBN 90-367-0975-x NUGI 743
© Copyright 1998 by Jan D.M. Metzemaekers, Groningen All rights reserved. No part of this book may be reproduced in any form or by any electronic or mechanical means, including information storage and retrieval systems, without permission in writ- ing from the publisher.
Typesetting : COMPUTEKST grafische tekstverwerking, Groningen Phototypesetting : PEACH belichtingsstudio bv, Groningen Printing : Dijkhuizen Van Zanten bv, Groningen
A CLINICAL AND LABORATORY STUDY
ter verkrijging van het doctoraat in de Medische Wetenschappen
aan de Rijksuniversiteit Groningen op gezag van de Rector Magnificus Dr. D.F.J. Bosscher
in het openbaar te verdedigen op woensdag 30 september 1998
om 14 .45 uur
Joannes Dionysius Maria Metzemaekers
geboren op 14 november 1957 te Breda
Promotores Prof. dr. J.J.A. Mooij Prof. dr. J.W.F. Beks Prof. dr. K.G. Go
Referent Dr. Ir. H.L. Journée
Promotiecommissie Prof. dr. D.A. Bosch Prof. dr. J.H.A. De Keyser Prof. dr. R.P. Zwierstra
Paranimfen Monique Metzemaekers & Maarten Coppes
Chapter 1 General introduction page 1.1 Introduction 1 1.2 History of the surgical treatment for hydrocephalus 2
Chapter 2 Clinical study on hydrocephalus shunts 4 2.1 General data 4 2.1.1 Patients and data collection 4 2.1.2 Etiology of hydrocephalus and most prevalent pre-operative symptoms 4 2.1.3 Surgical procedure 4 22.214.171.124 Surgeon 4 126.96.36.199 Duration of operative procedure 5 188.8.131.52 Drainage route 6 184.108.40.206 Peri-operative antibiotics 6 2.1.4 Shunt systems 6 220.127.116.11 Valves 6 18.104.22.168 Shunt components 6 2.1.5 Pre-operative external ventricular drainage 6 2.1.6 Cerebrospinal fluid analysis 6 2.1.7 Statistical analysis 8
2.2 Results 8 2.2.1 Number of revisions and interval until revision 8 2.2.2 Causes of shunt dysfunction 8 22.214.171.124 Proximal dysfunction 8 126.96.36.199 Valve dysfunction 9 188.8.131.52 Distal dysfunction 9 184.108.40.206 Infection 9 220.127.116.11.1 Definition of infection 9 18.104.22.168.2 Epidemiology of infection 10 22.214.171.124.3 Treatment of infection 11 126.96.36.199.4 Peri-operative antibiotics and infection 11 2.2.3 Revisions and etiology of hydrocephalus 11 2.2.4 Surgical procedure and revision rate 12 188.8.131.52 Surgeon 12 184.108.40.206 Duration of operative procedure 12 220.127.116.11 Drainage route 12 2.2.5 Shunt system and first revision 12 18.104.22.168 Valves 12 22.214.171.124 Shunt components 14 2.2.6 CSF composition and revision 15 2.2.7 Morbidity 16 2.2.8 Mortality 16
2.3 Discussion 18 2.3.1 Shunt revision rate per patient 19 2.3.2 Causes of shunt dysfunction 19 126.96.36.199 Proximal dysfunction 19 188.8.131.52 Valve dysfunction 20 184.108.40.206 Distal dysfunction 20 220.127.116.11 Infection 20 18.104.22.168.1 Infection and epidemiology 20 22.214.171.124.2 Treatment of infection 21 126.96.36.199.3 Prevention of infection 22 2.3.3 Revisions in various age groups 23 2.3.4 Revisions related to underlying etiology of hydrocephalus 23 2.3.5 Operative procedure and incidence of shunt revisions 24 188.8.131.52 Surgeon 24 184.108.40.206 Duration of the surgical procedure 24 220.127.116.11 Drainage route 24 2.3.6 Shunt system versus revision 24 18.104.22.168 Valves 24 22.214.171.124 Shunt components 26 2.3.7 Cerebrospinal fluid composition versus revision operations 27 2.3.8 Morbidity 27 2.3.9 Mortality 28
2.4 Conclusions 29 2.4.1 Summary of previous conclusions 29
2.5 Future directions 30
Chapter 3 Cerebrospinal fluid dynamics and hydrocephalus shunts 31 3.1 Cerebrospinal fluid dynamics 31 3.1.1 CSF flow and production 31 3.1.2 CSF absorption 32 3.1.3 CSF composition 32 3.1.4 Pressure in CSF and other compartments 33
3.2 Pressure, resistance and flow in a shunt system 34 3.2.1 Pressure 34 3.2.2 Flow 35 3.2.3 Resistance 35 3.2.3 Viscosity 35 3.2.4 Siphoning 36 3.2.5 Measuring flow in shunt systems 36
3.3 Shunt materials 37
3.4 Valve mechanics and valve types 38 3.4.1 Valve mechanics 38 3.4.2 Valve types most commonly used in our clinical study 40
3.5 Protein concentration and shunt functioning 41
3.6 Blood and shunt functioning 43
Chapter 4 Laboratory study on hydrocephalus shunt valves 44 4.1 Valve testing in a laboratory setting 44 4.1.1 Methods and materials 44 126.96.36.199 Tested valves 44 188.8.131.52 Pump-driven versus pressure-driven test rigs 46 184.108.40.206 Conditions for in vitro testing of shunt valves 46 220.127.116.11 Test rig set-up 47 18.104.22.168 Flow generator 48 22.214.171.124 Pressure modulation unit 48 126.96.36.199 Pressure measurements 50 188.8.131.52 Flow resistance devices 50 184.108.40.206 Prevention of air bubbles 51 220.127.116.11 Composition of test solutions 51 18.104.22.168 Recording protocol 51 22.214.171.124 Data-processing 53 4.1.2 Results 54 126.96.36.199 Valves 54 188.8.131.52 Pressure diagrams per valve type 54 184.108.40.206 Results per valve 55 220.127.116.11 Dynamical properties 57
4.2 Discussion 62 4.2.1 Summary of test results 62 4.2.2 Performance (saline) compared to the manufacturer’s specifications 64 4.2.3 Effect of protein on valve performance 65 4.2.4 Effect of red blood cells on valve functioning 65 4.2.5 Opening characteristics 66 4.2.6 Closing characteristics 66 4.2.7 Effect of modulation 67 4.2.8 Concluding remarks 68
4.3 Conclusions 69
Chapter 5 General discussion 70 5.1 Comparison between clinical and laboratory results 70
5.2 Future recommendations 71
Appendix A Pressure diagrams per valve 75
Appendix B Dynamical characteristics 83
Curriculum Vitae 107
Chapter 1 General introduction
In the Netherlands, about 650 cerebrospinal fluid (CSF) shunt insertions for hydrocepha- lus and about 500 shunt revisions take place each year127. Therefore, the treatment of hydrocephalus consitutes an important part of the neurosurgical practice. At the begin- ning of this study there was a meeting of Dutch Neurosurgeons, where it became clear that there was hardly any communication between surgeons about the treatment of hydro- cephalus. There was no clear overview of the shunt systems that were used and the com- plications that occurred. The choice for a certain system was based on remarks such as: ‘this system is easy to work with’ and ‘I hardly see any complications of this system in practice’. Furthermore, there was no consensus on the surgical technique and the implica- tions of raised protein and erythrocyte concentrations in the CSF. The need for a multi- centre clinical study on the functioning of CSF shunts was obvious.
From December 1989 until January 1992 data were collected on 400 patients undergo- ing primary shunt insertions for hydrocephalus. These patients were recruted from eight neurosurgical centres. The follow-up period of these patients was at least two and a half years. Next to this clinical study, a laboratory study was conducted in which the eight most frequently inserted hydrocephalus valves from the clinical study were tested in several ways.
The aim of the study is: * to give an overview of shunt systems used in Dutch neurosurgery and their concomi-
tant complications * to show if increased protein or erythrocyte concentrations in a laboratory setting
impair valve performance compared to the performance during perfusion with saline, and, to compare the results of saline perfusion with the manufacturer’s specifications.
* to find a correlation between the properties of the valve as found in the laboratory and the behavior of the valves in clinical practice.