Volume 2

The science and practice of medicine / by William Aitken.

  • Aitken, William, 1825-1892.
Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: The science and practice of medicine / by William Aitken. Source: Wellcome Collection.

    191/1258 (page 135)
    ates the sense of pain. The impairment, diminution, or loss of the first has been distinguished by the term ancesihesia ; of the latter by the term ■analgesia. The skin may also lose the sense of pain and still retain the power of touch. The finger may then be felt Avhen rubbed over the skin, but the skin is insensible to pricking or pinching. In extreme cases the skin and subjacent parts may be cut, burnt, or otherwise injured without the patient's knowledge; but when common tactile sensibility is lost, the sense of pain is also lost, except in some instances of centric reflex paralysis, and likewise the appreciation of heat and cold (Beau). Anaesthesia most commonly occurs as an immediate antecedent of motor palsy, or coincident with it, and also exists in various parts of the body, independent of paralysis of motion. It varies in extent from a tingling, pricking formication, or mere numbness of the parts, to a complete loss of sensation. The patient feels as if the alTected part were protected or •covered by some thick soft texture. The hands feel as if clothed with gloves, or the feet experience the sensation as if walking on felt, cotton, wool, or other yielding soft substance. The cutaneous nerves are those most frequently affected, and from this cause the disease most usually advances to the integuments of a portion of the trunk, or of an arm, or a leg, or some portion of the extremities, and also the whole face or parts of the face. The pathology of anaesthesia may be comprehended from the following •considerations:—The function of sensation depends upon the concurrence of three sets of organs, anatomically continuous, yet to a certain extent physiologically distinct—(1.) The nerve-extremities, which receive an impression; (2.) the aff'erent nerve-fibres, which carry the impression to the centre; (3.) the centres, which receive the impression and trans- form it into a sensation. Thus the three factors of sensation are, the sensitive nervous extremities, the sensory conducting filaments, and the sentient portions of the nervous centres. If the integrity of any one of these is affected, there must result diminution or loss of sensation. If perception in the sensorium is destroyed, the nerves may transmit the impression to the sentient centres, but there is no sensation. This cause of anesthesia occurs in cerebral hemorrhage, softening, and tumors; or the function of the organ may be temporarily in abeyance, from the effect of certain agents, as chloroform or narcotics. Anaesthesia is also produced by interruption of the continuity of the nerve-trunk, by section, or compression, or atrophy, or tissue-degeneration. A third mode is, whilst both the nerve-centres and the nerve-trunks are sound, the sentient nerve-extremities have undergone some morbid change, and the impression is not received, as in insensibility of the skin from the application of intense cold, blindness from disease of the retina, loss of the sense of smell during coryza, and certain cutaneous eruptions. It sometimes happens as the result of reflex action in visceral disorders, and after mechanical injuries (Brown-Sequard, S. W. Mitchell). This pathogeny of anaesthesia being admitted, can we determine clinically the seat of the morbid condition, and refer it to a given lesion of the brain or medulla, or of the nerves themselves? Is the anaesthesia central or peripheral—(1.) Anaesthesia resulting from cerebral disease is usually of large extent, and may involve the whole body, as in the general paralytic condition which is associated