Injuries of nerves and their consequences - Reflex Sympathetic ...

SENSORY LESIONS.
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lus to its activity, aud the very tiict of deficient feeling
subjects the part to rough aud unusual irritations. It
does not seem impossible that this may explain, in part
at least, the early disappearance of sensory paralysis in
cases where the function of sensation seems to be quite as
much aiiected at the outset as that of motility.
"In regard to voluntary movement, the case is quite
different. When muscles are paralyzed partially, an effort
of will, and a greater one than common, is demanded to
call them into action. The early inflammator}^ conditions
make motion painful. The effort is unusually wearisome,
and there is no inevitable and constant stimulus, such as
exists in regard to touch. Hence, perhaps,
it is that motility
is regained less easily than sensibility, although beyond
all this, there are also certain mechanical obstacles
in the way of a return of voluntary movement, which
vary greatly, and constitute every single case a special
object of study.
"We may sum up the matter in this briefer shape. The
skin is all the time stimulated, whether we will or not.
The muscles which volition has ceased to move with ease
have no such incidental stimulus. Accident and position
do for the skin what artificial agencies must do for the
muscles, if we desire to sustain their nutrition and restore
their power."
As the case advances there soon exists a new reason
for the non-return of motor function in the atrophic
changes which affect the muscles, and which, after a time,
place the gravest impediments in the way of movement,
even though the nerve itself should have become perfectl}'
restored. The receptive centre for sensation remains
always ready, and incessant stimuli play upon
its connected
sets of nerves. The muscles, on the other hand, the receivers
of motor impulses, become diseased and unimpressible
by volition even where at last this is enabled to reach them.