Common Findings
In muscular rheumatism, neuralgia, neuritis, or in case of a local
boil or abscess indicating local disturbance of the trophic influence of
nerves, clear and definite tracings are common. Muscular spasm,
such as wry-neck, usually has a very tender nerve associated.
Localized painful disease of any kind is likely to be associated with a
very definite nerve tenderness, as is the case frequently with
appendicitis, ovaritis, hepatic colic, etc.
The painless disorders, or various disorders of spleen,
diaphragm, heart, lungs, etc., though they be of a very serious
nature, seldom are discoverable by nerve-tracing unless their serous
membranes are involved. Tracings may be made from D 2 or 3 to
anterior thoracic walls in heart or lung disease but are not common.
Any spinal nerve may be traceable at times through at least a
part of its course.
Sources of Error
Several of these have been mentioned, such as the natural
suggestibility of both examiner and patient. Among others are:
failure in the back, thigh, or leg to reach the really tender nerve
because of the interposition of several muscle layers between it and
the finger, ignorance of nerve-paths, failure to apply equal pressure
to all parts of a nerve, application of such heavy pressure that
muscle tissue is bruised and hurt, and failure of full co-operation on
the part of the patient. Let us consider these in turn.
If several muscle layers interpose themselves between the
searching finger and the nerve, it is proper to push aside the
intervening layers, using a twisting and rolling movement until the
finger feels underneath the muscles. This done, and a tender nerve
found underneath several muscle layers, the same amount of
overlying tissue must be pushed aside each time the finger searches
for the nerve. Only exhaustive study of the anatomy of the typical
nervous system will enable the examiner to know exactly at what