I. Mechanism of abdominal pain
1.Anatomical concept. The nerves in the abdomen are divided into spinal nerves and vegetative nerves. The former division of the abdominal wall movement and sensation; the latter manages the movement and sensation of the viscera, and the nociceptive fibers are conducted to the center with the sympathetic nerves.
2. Types of abdominal pain. From the neural mechanism abdominal pain can be divided into three basic types.
Simple visceral pain. The afferent pathway is purely sympathetic pathway, and the spinal nerves are basically not involved or less involved. For example, certain sensations during gastrointestinal contractions and pulls.
Characteristics of pain.
(i) a deep dull or burning pain.
(ii) Ambiguous location of pain, usually more widespread or close to the abdominal midline.
(iii) no local muscle tension and skin sensory sensitization.
④Often accompanied by vagal excitation symptoms such as nausea, vomiting and sweating.
Involvement pain. Sympathetic nerves and spinal nerves are jointly involved in the mechanism of pain. It is further divided into involved somatic pain and involved visceral pain. The former is actually a somatic nerve mechanism, for example, when the central part of the diaphragm is stimulated, it can radiate to the shoulder, due to the phrenic nerve distributed in the middle of the diaphragm entering the level of the cervical dimension 3-5 spinal cord, which is distributed along the brachial plexus in the shoulder. The latter is the one we will mainly discuss.
The characteristics of its pain are.
① mostly sharp pains with a more intense degree.
(ii) Clearly located, on one side.
③There may be local muscle tension or skin sensory hypersensitivity.
This type of pain is more clinically significant and usually reflects inflammation or organic lesions of the organ rather than functionality.
Peritoneal skin reflex pain. Only somatic or spinal nerves and no visceral nerves are involved in the pain mechanism. The sensory fibers of the spinal nerves are distributed in the peritoneal wall layer, the mesenteric root and the retroperitoneum. When the lesion invades a site close to the above nerve endings, pain is reflected to the cutaneous area innervated by that spinal nerve.
The pain is characterized by.
(i) characterized by segmental nerve distribution of the spinal cord.
(ii) Intense and persistent in degree.
(iii) accompanied by localized abdominal muscle tonicity, pressure pain and rebound pain, which generally represents the presence of peritoneal invasion.
In our clinical work, the abdominal pain we are exposed to is actually often mixed, and more than one pain mechanism may be involved. Sometimes, the type of abdominal pain can change over time. For example, in the early stage of appendicitis, the lumen of the appendix is violently contracted in an attempt to eliminate fecal stones, which is manifested as pure visceral pain around the umbilicus and may be accompanied by nausea and vomiting; when inflammation appears, the nociceptive threshold decreases and excitability increases, affecting the somatic nerve in the dorsal root of the spinal cord in the conduction pathway, so that involvement pain occurs and the site of pain shifts to the right lower abdomen; finally, the development of inflammation spreads to the adjacent peritoneal wall layer, and Finally, the development of inflammation spreads to the adjacent peritoneal wall layer, and peritoneal skin reflex pain appears, and the degree of pain is more intense and accompanied by local pressure pain, rebound pain and muscle tension of the abdominal wall.
Second, the etiology of abdominal pain
(A) abdominal lesions
1, peritoneal irritation or inflammation, including lesions caused by bacterial infection or chemical irritation (such as gastric, intestinal, bile, pancreatic fluid leakage due to perforation and bleeding from ruptured internal organs).
2.Obstruction of cavity organs including diaphragmatic hernia, cardia, stomach and duodenum, small intestine, colon, bile duct, pancreatic duct, etc.; can be caused by inflammation, ulcer, roundworm, stone, tumor, etc.
3.Blood supply malfunction
①embolism and thrombosis.
② torsional or compressive obstruction, including strangulated hernia, intestinal torsion, cystic tip torsion, etc.
4, tension and pulling of supporting tissues such as dramatic increase in tension of liver envelope, pulling of mesentery or greater omentum, etc.
5, injury or inflammation of the abdominal wall muscles.