Analgesia. Loss of Sensation.
This is a loss of sensation caused by disease of the nerves of sensation, and may therefore occur in any part of the body[1]. Most commonly anaesthesia of the skin is met with — one half the surface, laterally, may be involved, or the upper or lower part of the body may be affected, or the whole surface. Anæsthesia may be confined to the sense of touch or the sense of pain. In testing for anæsthesia the patient should be blindfolded and various portions of the surface touched with the fingers, pencils, or heated keys or particles of ice. It will often be noticed that only some regions have lost feeling, and thus the exact nerves affected may be traced.[1] Anaesthesia and analgesia are currently used when discussing 'artificial' or medically induced states, with 'hypoesthesia' and 'hypoalgesia', indicating reduced sensation, now used to describe these somatosensory disorders.
Analgesia is the term used to denote absence of power to realize pain. It may exist even when there is sensitiveness to touch, though usually loss of power to experience touch accompanies it. Blindfolding the patient and then running points of pins in him, or pinching him unawares, will give proof of analgesia. The cause of the difficulty must be ascertained and removed. When due to ''lethargy" of the skin or local causes, baths and friction and stimulating liniments are advisable. Electric baths[2] are especially beneficial, and the electric brush attached to a battery and used freely over the skin will often accomplish permanent cure. For artificial anaesthesia see section on Remedies and Applications.
[2] I suspect the author is referring to what we now call galvanic baths, as opposed to early tanning beds.