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

SENSORY LESIONS. 193
nerve, is felt as pain, and into this sad language the nerve
finally translates all save the mildest impressions made
elsewhere than upon its peripheral expansions.
In many eases, the nervi nervorum enahle us to localize
the point at which the nerve is injured, as when a
blow falls on the ulnar nerve at the elbow. We feel intensely
the referred pain, but have also a clear sense of
local hurt to the nerve at the point struck. This is, however,
by no means usual as to causes which act slowly
and steadily. So that when in disease we feel pain, it is
often impossible to say at what point of the nerve track
the pain-making cause is busy, nor how remote it is from
the region where the pain seems to be.
Any mechanical or other irritation of a nerve of common
sensation is usually referred to its region of peripheral
distribution, so that the pain appears to exist in that
part.
Nerve injuries may also cause pain which, owing to
inexplicable reflex transfers in the centres, may be felt in
remote tissues outside of the region which is tributary to
the wounded nerve.
When the later pathological changes of an irritative
nature Avhich follow nerve injuries begin to occur, new
causes of pain arise, the reflex references become wider,
and when in certain cases the nutrition of the skin sufiers,
novel forms of suffering spring up, which are due to
alterations of the peripheral nerve ends or their protective
tissues.
Pain is, perhaps, the most constant sequence of nerve
injuries, but it exhibits the utmost variety as to the time
of its
coming and the character of the torment. I have
the first
alread}' discussed the question of pain as regards
moments of nerve wounds. In cases of contusion, the
first pain having passed, only tingling may remain, unless
secondary changes in the nerve result in the production