ABDOMINAL PAIN

Michael M Kline MD Division of Gastroenterology

Keck School of Medicine

AIMS

1. Pain Receptors 2. Pain Pathways 3. Physiological Mechanisms 4. Referred Pain 5. Acute Abdomen

PAIN RECEPTORS

Mechanical a. stretch b. torsion c. contraction d. distention Chemical and other a. products of inflammation b. pH changes c. temperature

PAIN PATHWAYS 1ST Order neurons

Travel with sympathetic nerves from the viscera to the spinal cord

2nd Order neurons Located in the dorsal horn a. travel with the spinothalamic and spinorecticular

tract to the brain stem Pain inhibition occurs at this site b. inhibitory local neurons (Gate theory) c. descending inhibitory fibers from the CN 3rd Order neurons Carry information to higher centers

NEURONAL PATHWAYS

PAIN PATHWAYS 2nd Order neurons

Located in the dorsal horn a.travel contra lateral with the spinothalamic and

spinorecticular tract to the brain stem b.travel ipsilateral with post synaptic dorsal

column Pain inhibition/modulation occurs at this site c. inhibitory local neurons (Gate theory) d. descending inhibitory fibers from the CN 3rd Order neurons Carry information to higher centers

NEURONAL PATHWAYS

PAIN PATHWAYS

2nd Order neurons Pain inhibition/modulation occurs at this site b. inhibitory local neurons (Gate theory) c. descending inhibitory fibers from the CN

GATE CONTROL THEORY

PAIN PATHWAYS

3rd Order neurons Carry information to higher centers

NEURONAL PATHWAYS

PATHOPHYSIOLOGICAL MECHANISMS

1. Visceral organ obstruction ie: small bowel obstruction due to adhesions, large bowel obstruction 2ndary to intra-luminal Ca.

2. Abnormal motility ie: small and /or large bowel pseudobstruction, Hirschsprungs disease.

3. Mucosal irritation ie: gastric and duodenal ulcer. Ulcerative colitis.

4. Vascular insufficiency ie: mesenteric angina, ischemic colitis

5. Peritoneal irritation ie: appendicitis, cholycystitis, pancreatitis, perforated viscus.

6. Metabolic aberrations ie. Porphyria, heavy metal poisoning.

7. Psycho pathology ie: irritable colon syndrome, non ulcer dyspepsia, chronic abdominal pain syndrome.

8. Referred pain ie: pain from a visceral source usually felt on the skin at site somewhat distant from the viscera involved.

REFERRED PAIN

Visceral pain felt at a site distant from the involved viscera ie: acute appendicitis felt initially in the upper abdomen.

REFERRED PAIN

REFERRED PAIN PATTERNS

ACUTE ABDOMEN

SUDDEN, UNEXPECTED PAIN DEVELOPING OVER A PERIOD OF 24 HOURS OR LESS.

ABDOMINAL PAIN ONSET

1. Sudden (seconds) a Perforation or rupture of viscus, abscess,

hematoma,peptic ulcer, abdominal aortic aneurysm, esophagus, ectopic pregnancy, pneumothorax

b. Infarction of gut, heart, lung

ABDOMINAL PAIN ONSET

Rapid (minutes) a. Colic: biliary, ureteral, small bowel obstruction b. Inflammatory: pancreatitis , diverticulitis,

peptic ulcer, appendicitis, cholecystitis, pneumonitis

c. Ischemia: Strangulation of obstructed intestine, mesenteric ischemia, torsion, volvulus

ABDOMINAL PAIN ONSET

Gradual (hours) a. Inflammation: appendicitis, cholecystitis,

pancreatitis, gastritis, IBD, diverticulitis, salpingitis, cystitis, intra abdominal abscess

b. Obstruction: of small bowel or colon, urinary retention, incarerated hernia, ectopic pregnancy.

c. Neoplastic: Perforating or penetrating tumors

DIAGNOSTIC STUDIES

1. Fecal leukocytes 2. Stool culture 3. Stool guaiac (OB) 4. Stool fat 5. Hepatitis serology for A,B,C,D and E 6. Liver enzymes 7. Amylase/Lipase 8. Paracentesis

DIAGNOSTIC STUDIES

9. EGD (endoscopy) 10. Flexible sigmoidscopy 11. Colonoscopy 12. Barium studies 13. Abdominal ultrasound, CAT and MRI 14. M to A capsule

ABDOMINAL PAINAIMSPAIN RECEPTORSPAIN PATHWAYSNEURONAL PATHWAYSPAIN PATHWAYSNEURONAL PATHWAYSPAIN PATHWAYSGATE CONTROL THEORYPAIN PATHWAYSNEURONAL PATHWAYSPATHOPHYSIOLOGICAL MECHANISMSSlide Number 13REFERRED PAINREFERRED PAINREFERRED PAIN PATTERNSACUTE ABDOMENABDOMINAL PAIN ONSETABDOMINAL PAIN ONSETABDOMINAL PAIN ONSETDIAGNOSTIC STUDIESDIAGNOSTIC STUDIES