A theoretical analysis of spinal cord stimulation with particular reference to myelinated fibres

Abstract

This thesis describes extensive development, and validation by experiment, of theoretical methods for the bioengineering analysis of electrical stimulation of spinal cord. Two-dimensional finite element methods are used to survey certain crucial geometrical and tissue property aspects, but the stimulus field analyses are centred on full three-dimensional representations. The three-dimensional models are validated by comparing results with published data from the monkey, and original work with both patients and cadaver material. A definitive finite element model is presented. An existing computer simulation of the myelinated nerve fibre, especially suitable for use with finite element field solutions, is tested experimentally using an in-vitro preparation from the chick. Further developments for branched and bending fibres, and stimulus field interaction with normal ongoing nerve impulses are examined theoretically. The two essential aspects, field analysis and neural modelling, are shown to be sufficiently well-developed to allow confident application in spinal cord stimulation studies.