Important Types of Pain Abdomen and Its Pathophysiology Are;

Chronic Pain Abdomen (Students handout)

Important types of pain abdomen and its Pathophysiology are;

A: Intra abdominal pain

1. Parietal Peritoneal pain. Pain receptors in parietal peritoneum transmit pain to central nervous system via somatic nerves. Pain is usually well localized. Visceral pain of solid organs presents same way. The parenchyma is not painful in itself but the stretch of the overlying parietal peritoneum causes pain. The segmental supply is the same as that of abdominal wall. Localized. Hepatomegaly – Right upper quadrant pain, Kidney flank pain, chronic pancreatitis dull epigastric pain radiating to back etc.

2. Visceral pain of hollow organs. Pain impulses relayed through sympathetic nerves e.g. in obstruction to hollow viscera (except ureter).Pain is usually constant, diffuse and felt in the mid abdomen. Colonic pain is usually spasmodic and diffuse but sometime localized to lower abdomen (IBS), Gastric pain gnawing and localized to epigastrium / upper abdomen (Peptic ulcer), small intestinal diffuse mid abdomen, (TB intestine –young and middle age with typical doughy feel on palpation, Ischemic old age, chron’s disease and ulcerative colitis (sometimes) – young and middle) and poorly localized. Sometimes tumors may arise from these viscera and may cause dull localized pain like a solid organ pain.

3. Referred pain. The sympathetic nerve fibers and somatic nerve fibers share the neuronal pathway coming from the same spinal segment. Thus visceral pain is referred to superficial area of body.

B: Extra abdominal pain Sometime pain may be referred from other areas and felt in the abdomen. The important causes to remember are,

Upper abdominal (epigastric pain) from cardiac ischemia – Epigastrium is non tender. Pleuritic pain and diaphragmatic radiating to upper abdomen – relates to respiration and radiation to shoulder. Musculoskeletal pain from spine and paraspinal muscles – mid abdomen. Rarely pain may precede days / weeks before the appearance rash in Herpes Zoster.

C: Important causes of chronic pain abdomen in our population are; Chronic constipation, IBS (relieves with defecation and absent in sleep), Peptic ulcer, round worms in young adults / children, abdominal tuberculosis (alternating diarrhea / constipation and wt loss), Ischemic pain of gut/cardiac origin in old age. Chronic amebic and bacillary dysentery are also important causes. In postoperative patients recurrent pain may also be due to adhesions formation. Chronic cholecysytitis and chronic pancreatitis may also be sometimes present.

D: Important medical disease which usually present with acute recurrent abdominal pain are, chronic pancreatitis, diabetes (ketoacidosis), hemolytic crisis, ischemic in elderly (mid abdomen), cardiac angina (upper abdominal) and Acute intermittent porphyria .