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

SENSORY LESIONS. 181
a certain stage of the cliilling of the uhiar- trunk at the
elbow, the whole nerve below this point becomes so irritable
that the least prcssnre upon it causes not only pain,
but sudden motion of every muscle which it supplies.
In cases of nerve wounds this condition is reached, owing
to inflammatory states of the nerve; but Avhether the eft'ect
be not in every such case merely to heighten the central
receptive impressibility, we can hardly say. The analogy
to excited motor states is
be allowed
curious, and, if I may
the use of such a phrase, I might describe the general
hj-pereesthesia which follows a nerve injury as sensory
tetanus.
In cases of causalgia and glossy skin, the hypersesthesia
is due, I think, to nutritive conditions affecting the
skin surfaces and the nerves beneath them, so as to make
the latter over-sensitive. The tendency
is towards atrophy,
and the thinned and shining skin, constantly fretted
with tiny ulcers, seems at last to fail to shelter sufficiently
its included nerve ends. Finally, the centres become
over-sensitive, and radiate their state of sensitive wakefulness
far and wide, just as in tetanus the motor excitability
floods, at length, the nearer and more distant ganglia.
Muscular liypera^sthesia.
— This condition is common in
gunshot wounds of nerves, and in blows on the back, injuring
the outgoing nerves. It was often the sole symptom
of spinal concussions, and was, in many of them, strictly
limited to certain muscles. The muscle may be oversensitive
when the skin above it is not, and the degree to
which it is alive to pain where pain should not exist, is
measured by pressure only. We pinch the skin slightly,
without giving annoyance, but deep pressure on the muscles
causes soreness, and motion of these
always productive of more or less pain.
parts is nearly
anassthcsia. — Defects of feeling may
Defects of sensation;
exist to any degree after nerve wounds, from the slightest