Abdominal Pain-Visceral Abdominal Pain-Somatic Abdominal Pain-Referred Abdominal Pain-Lumbar Sympathectomy-

Abdominal Pain

We will talk about Abdominal pain because it is one of the most important problems facing the physician. This section provides an anatomic basis for the different forms of abdominal pain found in clinical practice. Three distinct forms of pain exist:

 visceral, somatic, and referred pain.

Visceral Abdominal Pain

Visceral abdominal pain means pain in abdominal organs, visceral peritoneum, and the mesenteries. The sensations that arise in viscera reach the central nervous system in afferent nerves that accompany the sympathetic nerves and enter the spinal cord through the posterior roots.

Visceral pain from the stomach is commonly referred to the epigastrium The causes of visceral pain include impaired blood supply (ischemia) to a viscus, stretching of a viscus or mesentery, distention of a hollow viscus, and chemical damage  to a viscus or its covering peritoneum. Pain arising from an abdominal viscus is dull and poorly localized. Visceral pain is referred to the midline, probably because the viscera develop embryologically as midline structures and receive a bilateral nerve supply; many viscera later move laterally as development proceeds, taking their nerve supply with them.

violent contraction of smooth muscle cause Colic  is a form of visceral pain; it is commonly caused by luminal obstruction as in intestinal obstruction, in the passage of a gallstone in the biliary ducts, or in the passage of a stone in the ureters.

Many visceral afferent fibers that enter the spinal cord participate in reflex activity. Reflex sweating, salivation, nausea, vomiting, and increased heart rate may accompany visceral pain.

Somatic Abdominal Pain

Somatic abdominal pain in the abdominal wall can arise from the skin, fascia, muscles, and parietal peritoneum. It can be severe and precisely localized. When the origin is on one side of the midline, the pain is also lateralized. The somatic pain impulses from the abdomen reach the central nervous system in the following segmental spinal nerves:

■■ Central part of the diaphragm: Phrenic nerve (C3, 4, and 5)

■■ Peripheral part of the diaphragm: Intercostal nerves(T7 to 11)

■■ Anterior abdominal wall: Thoracic nerves (T7 to 12) and the1st lumbar nerve

■■ Pelvic wall: Obturator nerve (L2, 3, and 4)

The inflamed parietal peritoneum is extremely sensitive, and because the full thickness of the abdominal wall is innervated by the same nerves, it is not surprising to find cutaneous hypersensitivity (hyperesthesia) and tenderness. Local reflexes involving the same nerves bring about a protective phenomenon in which the abdominal muscles increase in tone. This increased tone or rigidity, sometimes called guarding, is an attempt to rest and localize the inflammatory process. Rebound tenderness occurs when the parietal peritoneum is inflamed. Any movement of that inflamed peritoneum, even when that movement is elicited by removing the examining hand from a site distant from the inflamed peritoneum, brings about tenderness.

Examples of acute, severe, localized pain originating in the parietal peritoneum are seen in the later stages of appendicitis. Cutaneous hyperesthesia, tenderness, and muscular spasm or rigidity occur in the lower right quadrant of the anterior abdominal wall. A perforated peptic ulcer, in which the parietal peritoneum is chemically irritated, produces the same symptoms and signs but involves the right upper and lower quadrants.

Referred Abdominal Pain

Referred abdominal pain is the feeling of pain at a location other than the site of origin of the stimulus but in an area supplied by the same or adjacent segments of the spinal cord. Both somatic and visceral structures can produce referred pain. In the case of referred somatic pain, the possible explanation is that the nerve fibers from the diseased structure and the area where the pain is felt ascend in the central nervous system along a common pathway, and the cerebral cortex is incapable of distinguishing between the sites. Examples of referred somatic pain follow. Pleurisy involving the lower part of the costal parietal pleura can give rise to referred pain in the abdomen because the lower parietal pleura receives its sensory innervation from the lower five intercostal nerves, which also innervate the skin and muscles of the anterior abdominal wall.

 

Lumbar Sympathectomy

Lumbar sympathectomy is performed mainly to produce a vasodilatation of the arteries of the lower limb in patients with vasospastic disorders. The preganglionic sympathetic fibers that supply the vessels of the lower limb leave the spinal cord from segments T11 to L2. They synapse in the lumbar and sacral ganglia of the sympathetic trunks. The postganglionic fibers join the lumbar and sacral nerves and are distributed to the vessels of the limb as branches of these nerves. Additional postganglionic fibers pass directly from the lumbar ganglia to the common and external iliac arteries, but they follow the latter artery only down as far as the inguinal ligament. In the male, a bilateral lumbar sympathectomy may be followed by loss of ejaculatory power, but erection is not impaired.

Trauma to the Abdominal Aorta-Obliteration of the Abdominal Aorta and Iliac Arteries-Trauma to the Inferior Vena Cava- Compression of the Inferior Vena Cava-

Trauma to the Abdominal Aorta

Blunt trauma to the aorta is most commonly caused by headon automobile crashes. Rupture of the tunica intima and media occurs and is quickly followed by rupture of the turnica adventitia. The initial rupture of the intima and media is probably mainly caused by the sudden compression of the aorta against the vertebral column, while the delayed rupture of the adventitia is caused by the aortic blood pressure. Unless quickly diagnosed by MRI, and surgical treatment instituted, death follows.

 

Obliteration of the Abdominal Aorta and Iliac Arteries

Gradual occlusion of the bifurcation of the abdominal aorta, produced by atherosclerosis, results in the characteristic clinical symptoms of pain in the legs on walking (claudication) and impotence, the latter caused by lack of blood in the internal iliac arteries. In otherwise healthy individuals, surgical treatment by thromboendarterectomy or a bypass graft should be considered. Because the progress of the disease is slow, some collateral circulation is established, but it is physiologically inadequate. However, the collateral blood flow does prevent tissue death in both lower limbs, although skin ulcers may occur.

Trauma to the Inferior Vena Cava

Injuries to the inferior vena cava are commonly lethal, despite the fact that the contained blood is under low pressure. The anatomic inaccessibility of the vessel behind the liver, duodenum, and mesentery of the small intestine and the blocking presence of the right costal margin make a surgical approach difficult. Moreover, the thin wall of the vena cava makes it prone to extensive tears.

Because of the multiple anastomoses of the tributaries of the inferior vena cava, it is impossible in an emergency to ligate the vessel. Most patients have venous congestion of the lower limbs.

Compression of the Inferior Vena Cava

the enlarged uterus during the later stages of pregnancy is commonly compress The inferior vena cava. This produces edema of the ankles and feet and temporary varicose veins. Malignant retroperitoneal tumors can cause severe compression and eventual blockage of the inferior vena cava. This results in the dilatation of the extensive anastomoses of the tributaries. This alternative pathway for the blood to return to the right atrium of the heart is commonly referred to as the caval–caval shunt. The same pathway comes into effect in patients with a superior mediastinal tumor compressing the superior vena cava. Clinically, the enlarged subcutaneous anastomosis between the lateral thoracic vein, a tributary of the axillary vein; and the superficial epigastric vein, a tributary of the femoral vein, may be seen on the thoracoabdominal wall

Cushing’s Syndrome-Addison’s Disease-Pheochromocytoma-Surgical Significance of the Renal Fascia-Aortic Aneurysms-Embolic Blockage of the Abdominal Aorta-

Cushing’s Syndrome

Suprarenal cortical hyperplasia is the most common cause of Cushing’s syndrome, the clinical manifestations of which include moon-shaped face, truncal obesity, abnormal hairiness (hirsutism), and hypertension; if the syndrome occurs later in life, it may result from an adenoma or carcinoma of the cortex.

Addison’s Disease

Adrenocortical insufficiency (Addison’s disease), which is characterized clinically by increased pigmentation, muscular weakness, weight loss, and hypotension, may be caused by tuberculous destruction or bilateral atrophy of both cortices.

Pheochromocytoma

Pheochromocytoma, a tumor of the medulla, produces a paroxysmal or sustained hypertension. The symptoms and signs result from the production of a large amount of catecholamines, which are then poured into the bloodstream. Because of their position on the posterior abdominal wall, few tumors of the suprarenal glands can be palpated. CT scans can be used to visualize the glandular enlargement; however, when interpreting CT scans, remember the close relationship of the suprarenal glands to the crura of the diaphragm.

Surgical Significance of the Renal Fascia

The suprarenal glands, together with the kidneys, are enclosed within the renal fascia; the suprarenal glands, however, lie in a separate compartment, which allows the two organs to be separated easily at operation

Aortic Aneurysms

Localized or diffuse dilatations of the abdominal part of the aorta (aneurysms) usually occur below the origin of the renal arteries. Most result from atherosclerosis, which causes weakening of the arterial wall, and occur most commonly in elderly men. Large aneurysms should be treated by open surgical repair. Endovascular repair can also be used by the introduction of a stent graft through one of the iliac arteries with access through the femoral arteries in the groin.

Embolic Blockage of the Abdominal Aorta

The bifurcation of the abdominal aorta where the lumen suddenly narrows may be a lodging site for an embolus discharged from the heart. Severe ischemia of the lower limbs results

Ascites- Peritoneal Infection-Internal Abdominal Hernia-Peritoneal Dialysis

Ascites

Ascites an excessive accumulation of peritoneal fluid within the peritoneal cavity. it can occur as a result to hepatic cirrhosis (portal venous congestion), malignant disease (e.g., cancer of the testis), or congestive heart failure. In a thin patient, as much as 1500 mL has to accumulate before ascites can be recognized clinically. In obese individuals, a far greater amount has to collect before it can be detected.

Peritoneal Infection

Infection may gain entrance to the peritoneal cavity through several routes: from the interior of the gastrointestinal tract and gallbladder, through the anterior abdominal wall, via the uterine tubes in females (gonococcal peritonitis in adults and pneumococcal peritonitis in children occur through this route), and from the blood. Collection of infected peritoneal fluid in one of the subphrenic spaces is often accompanied by infection of the pleural cavity. It is common to find a localized empyema in a patient with a subphrenic abscess. It is believed that the infection spreads from the peritoneum to the pleura via the diaphragmatic lymph vessels. A patient with a subphrenic abscess may complain of pain over the shoulder. (This also holds true for collections of blood under the diaphragm, which irritate the parietal diaphragmatic peritoneum.) The skin of the shoulder is supplied by the supraclavicular nerves (C3 and 4), which have the same segmental origin as the phrenic nerve, which supplies the peritoneum in the center of the undersurface of the diaphragm. To avoid the accumulation of infected fluid in the subphrenic spaces and to delay the absorption of toxins from intraperitoneal infections, it is common nursing practice to sit a patient up in bed with the back at an angle of 45°. In this position, the infected peritoneal fluid tends to gravitate downward into the pelvic cavity, where the rate of toxin absorption is slow .

Internal Abdominal Hernia

When  a loop of intestine enters a peritoneal pouch or recess like the lesser sac or the duodenal recesses and becomes strangulated at the edges of the recess. Remember that important structures form the boundaries of the entrance into the lesser sac and that the inferior mesenteric vein often lies in the anterior wall of the paraduodenal recess.

Peritoneal Dialysis

Because the peritoneum is a semipermeable membrane, it allows rapid bidirectional transfer of substances across itself. Because the surface area of the peritoneum is enormous, this transfer property has been made use of in patients with acute renal insufficiency. The efficiency of this method is only a fraction of that achieved by hemodialysis.

A watery solution, the dialysate, is introduced through a catheter through a small midline incision through the anterior abdominal wall below the umbilicus. The technique is the same as peritoneal lavage. The products of metabolism, such as urea, diffuse through the peritoneal lining cells from the blood vessels into the dialysate and are removed from the patient.