Visceral pain

Previously, it was assumed that internal organs do not have pain sensitivity. The basis for such a judgment was the evidence of experimenters and, to some extent, surgeons that irritation of these organs does not cause a feeling of pain. However, medical practice shows that the most persistent and excruciating pain syndromes occur precisely in pathologies of internal organs - intestines, stomach, heart, etc. At present, these contradictions have been partially resolved, since it has become known that internal organs react not so much to mechanical stimuli as to disorders of their inherent functions: intestines and stomach - to stretching and compression, blood vessels - to their contraction, and the heart - in response to metabolic disorders. Predominantly sympathetic innervation of internal organs determines certain features of their pain perception (wide prevalence of pain, duration and pronounced emotional coloring).

Visceral pain has two fundamental differences from somatic pain: firstly, it has a different neurological mechanism, and secondly, visceral pain itself has at least 5 differences:

1. they are not caused by irritation of internal organs that do not have sensitive nerve endings (liver, kidneys, lung parenchyma);
2. they are not always associated with visceral injuries (for example, a cut in the intestine does not cause pain, while tension on the bladder or mesentery of the appendix is very painful);
3. visceral pain is diffuse and poorly localized;
4. they radiate;
5. they are associated with motor or autonomic pathological reflexes (nausea, vomiting, spasm of the back muscles during renal colic, etc.).

Visceral receptors with high threshold activity include sensitive nerve endings in the heart, veins, lungs, respiratory tract, esophagus, bile ducts, intestines, ureters, bladder and uterus. Modern diagnostics allow us to come closer to understanding the perception of visceral pain. In particular, microstimulation of the thalamus in an experiment reveals its integrative role in the process of "remembering" pain and makes it possible to create a "map" of active points of the brain that perceive visceral pain. So far, these studies have provided little for the development of treatment methods for such non-specific visceral pain syndromes as, for example, irritable bowel syndrome or functional intestinal dyspepsia. Such pains lasting 7 or more days, without a precise anatomical substrate, are determined in 13-40% of all urgent hospitalizations and, despite all the most modern and expensive examinations, almost a third of such patients are discharged without a diagnosis (there is even a special term for this - "an expensive secret"). Modern computer diagnostics has improved the recognition of pathology in such patients by about 20%, but the best method for recognizing the causes of such chronic abdominal pain syndromes is early laparoscopy. Laparoscopy is combined with abdominal lavage and sampling of peritoneal fluid to study neutrophils: if they are more than 50% of all cells, then there are indications for surgery. Thus, MEKIingesmi et al. (1996) found that in 66% of cases, the cause of unclear abdominal pain lasting more than 2 months was abdominal adhesions, which could not be diagnosed by any other methods. After laparoscopic adhesiolysis, pain disappeared or decreased significantly in most patients.

Treatment

The problem of visceral pain is especially relevant for cancer patients. More than half of cancer patients suffer from pain of varying intensity.

As for the treatment of pain syndrome in cancer patients, the main role, as many years ago, is given to pharmacotherapy - non-narcotic and narcotic analgesics, used according to a three-step scheme: