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

182 INJURIES OF NERVES.
loss of tactile sensibilit}' to the most entire absence of
as to these losses can
that sense, as well as of the feeling of pain and of temperature.
Accurate knowledge
only be had through careful examination of the skin
with the aid of certain instruments.
When examining a patient as to loss of any
of the
sensory functions of the skin, it is, of course, necessary
to cover his eyes, and, if possible, it is best not to acquaint
him with the methods about to be employed. "We desire
to learn what change has taken place as to his power to
discriminate tactile impressions, those of pain, and those
of temperature.
As regards touch, we need practically
in
only three tests. For
nerve wounds
rough examination, the touch of a
pencil-point on the surface, or, in dubious cases, the tip
of a feather, suffices to reveal whether the patient feels
the touch, as he should do; but incessant questioning
and repeated examinations are sometimes needed, when
the loss of tactile discrimination is slight. Perhaps the
most delicate test of all is to touch the tips of single hairs.
The very slight movement which this produces in the skin
about the bulb is plainly enough felt during health, but
a very small diminution in the acuteness of touch will
cause the motion to be unfelt. By these means we map
out on the skin the region of affected or lost touch, and I
have found it
convenient, in the hand especially, to record
these results on previously-prepared drawings of the two
faces of this part,
— a plan which, with slight memoranda
added, enables me to avoid tedious note-taking. Absolute
annihilation of touch is noted on the diagram by a
zero within the affected space.
Having thus made out the region attacked, we wish to
learn accurately the amount of sensation still left. This
is far more difficult in local nerve lesions than in central
anaesthesia, because of the frequent causalgia, hyperas-