Biomaterials and the Central Nervous System: Neurosurgical Applications of Materials Science - Biomaterials Science: An Integrated Clinical and Engineering Approach - page 135

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Biomaterials and the Central
Nervous System: Neurosurgical
Application s of Materials Science
Urvashi M. Upadhyay
CONTENTS
Introduction ......................................................................................................... 135
Cerebrospinal Fluid Shunt Systems ................................................................. 136
Drug Delivery Systems ...................................................................................... 139
Tissue Scaffolds ............................................................................................... 141
Microelectrode Systems ................................................................................. 142
Conclusions .......................................................................................................... 144
References ............................................................................................................. 144
Introduction
A variety of biomaterials have been used in the treatment of various disor-
ders of the central nervous system (CNS). Materials that have historically
been used include both biodegradable and non-biodegradable materials,
such as silicone, natural and synthetic polymers, and lipids. The desired
biodegradability of these materials is in large part determined by their
intended application. That is, those materials that should remain func-
tional for long periods of time, such as deep brain stimulating electrodes,
do not employ biodegradable materials, whereas devices implanted for the
short-term purposes of tissue scaffolding or drug-delivery are made with
degradable materials [1].
Regardless of a material's stability over time, it must be deemed biocompati-
ble before it may be implanted intracranially. Biocompatibility with tissue out-
side the central nervous system does not always predict biocompatibility with
brain and spinal cord tissue, nor does short-term biocompatibility predict long-
term tolerance to implantation. For example, degradable poly(methylidene)
malonate (PMM)-based microspheres have been implanted into rat striatum
and acutely show no evidence of inflammation; however, several months post-
implantation, inflammation, necrosis, and animal death occurred, presumably
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