Atony

ATONY (from Greek atonia - weakness), weakness, flaccidity, loss of tone (see). The concept of tone, according to the old classical definition, refers to the muscular system, where muscle tone is understood as a state of constant or prolonged weak tension of a muscle, without fatigue and with almost no expenditure of energy, in contrast to ordinary muscle contraction. Later, this understanding began to be lost among new meanings, and people began to speak not only of muscle tone, but also of the tone of the nervous system, and of "tonic nerve discharges," and even of the "biotone of living matter." The causes and origin of atony are quite varied. In view of the fact that the tone of both striated and smooth muscles is under the powerful influence of the autonomic nervous system, atony in a number of cases may depend on changes in the centers of the hypothalamus and, in the end (perhaps), the corpus striatum, where, among other things, the glands of internal secretion, which are in intimate relation to the autonomic nervous system, cannot but have significant importance. Some hormones, such as the pituitary, can, however, act directly on muscle tissue, apart from the nervous system (cf. the effect of pituitrin on an excised uterus). Incidentally, creatine metabolism, which plays such an important role precisely in determining muscle tone, but not in the ordinary work of muscles (Pekelharing, Riesser), is regulated by the endocrine system and, primarily, by the pituitary gland. The well-known fact of the development of tetany as a result of parathyroid gland insufficiency, the tonic influence of the testicular hormone on neuromuscular apparatuses, as well as adrenaline on smooth musculature, e.g., of blood vessels, can serve as a further illustration of the essential significance of the endocrine system in this regard. But atony of any organ can also be of autochthonous origin, depending both on the constitutional weakness of the muscular apparatus in a given part of the body, and on the basis of chronic inflammations relaxing the organ, as well as abnormal conditions of its work, both in the sense of prolonged or repeated overstrain, and in the sense of insufficient activity (atrophy from disuse). An example of atony of the first kind can be atony of the stomach in an asthenic constitution, where, along with nervous factors, the participation of an autochthonous moment is also admitted (Strümpell), and an example of atony of the second kind is such cases as atony of the stomach as a result of inflammatory changes in its wall, as well as excessive burdening of the stomach with ingested food; further, atony of the intestines depending on the same causes, where the consumption of food that produces little waste often proves to be a contributing factor; atony of the abdominal walls in multiparous women. Atony of an organ is accompanied by a decrease in its activity, which can sometimes have serious consequences. Thus, an atonic state of the uterus during childbirth leads to weakness of labor pains and difficult delivery, and in the postpartum period—due to insufficient muscle contraction and, in connection with this, the gaping of uterine vessels—to the possibility of profuse blood loss. Atony of the stomach results in serious digestive disorders, atony of the intestines—constipation. Atony of blood vessels can be the basis for persistent bleeding after injuries and operations. (For atony of individual organs, see the corresponding organs.)