The passage of electric currents through tissues : (with particular reference to the percutaneous stimulation of human nerve and muscle)
Abstract
The
physiologist enjoys a great advantage over
the
clinical
neurologist
in the electrical stimulation of muscle,
in that he
is
generally able
to kill
or anaesthetise
his
experimental animal
and
to
excise or expose
the tissues to be
stimulated.
The
electrical
impedance of
the
preparation
is
predominantly resistive,
and
the
question of
the
comfort and safety of
the
animal scarcely
arises.
The
stimulation of
human
muscle, on
the
other
hand, normally
has to be
carried out on ac cious subject, whose comfort and
safety must
be
considered,
by
means of electric currents applied
through electrodes placed
in
contact with
the
skin, which exhibits
very complex electrical properties.
Conflict
arises
between the
requirements of
technical accuracy and ease of
interpretation of
results on the one
hand,
and comfort and convenience on
the other.
This thesis represents an attempt
to
assemble as much as possible
of
the information required
for intelligent
solution of
the
problems encountered
in the
percutaneous stimulation of muscle.
Part I
of
the thesis reviews published
information on nerve,
muscle and
denervated
muscle,
the
electrical
impedance of
tissues,
and
diagnostic
and
therapeutic
stimulation of muscle.
Part II
describes the
author's personal research
into the
electrical
impedance
of the body, the interplay between body impedance, stimulator
impedance
and
the
electrical excitability characteristics of nerve and muscle,
and
the influence of these
various
factors
on stimulator performance.
In view of the variety of topics involved, the material
has been
arranged
in
separate more or
less
self-contained sections,
including
discussion
of
the implications
of the
results
in
each section.
Technical details
of
the
main electronic
devices
used are given
in
the Appendix, (Part III, together
with
details of the
various
mathematical analyses and calculations.
Part
of
the
work on which
this thesis is based
was carried out
during the tenure of a
temporary lectureship in Biophysics donated
by the late Sir David Russell, to
whom
the
author
is deeply indebted.
The author
is
also greatly
indebted to Professor A. E. Ritchie for
creating
the
circumstances which made
this
work possible,
for
permitting
the
author access
to
unpublished material, and
for his
patient encouragement and support of
this
protracted project;
to
Dr J. Crossland for
assistance
in the translation
of
German texts,
and
to Mr E. Carstairs for
advice and assistance
in devising the
photographic
techniques used
in
recording and reproducing
the
experimental results.
Type
Thesis, PhD Doctor of Philosophy
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