Aganglionosis
Aganglionosis is a developmental malformation of the gastrointestinal tract in which constipation is the main clinical manifestation and there is a lack of ganglion cells in the intestinal canal.
Although the name of congenital megacolon is widely used in domestic textbooks and articles. However, according to the international practice and pathological basis, it should be more correctly called Hirschsprung disease (HD) or absence of ganglion cells.
The incidence of Hirschsprung’s disease is 1 in 2000-5,000, and it is more common in males, with an average male to female ratio of 4:1. The disease has a tendency to occur familially, and in recent years, about 4% of familial megacolon has been reported abroad.
Clinical manifestations
Most cases of acute intestinal obstruction occur within 1 week after birth, the clinical manifestation is that 90% of the children have meconium constipation, no meconium discharge for 24-48 hours, or only a small amount, must be treated with enemas or other methods to have more meconium discharge.
Vomiting is also a common symptom, which may be infrequent and small, but can also be frequent and with bile; abdominal distension, most of which is moderate, in severe cases, the skin of the abdominal wall is shiny and the veins are angry, often seeing the intestinal pattern, sometimes significant intestinal peristalsis, and the presence of intestinal whine on auscultation; rectal palpation is quite helpful for diagnosis, the rectal jug abdomen is empty without feces, finger examination can also stimulate the defecation reflex, and after the finger is pulled out, more with After the finger is pulled out, there is a lot of feces or fecal discharge with a lot of gas, and the abdominal distension also improves.
In conclusion, anaplasia is an incomplete, low-level, acute or subacute intestinal obstruction in the late stages of life, which usually improves after enema, and the child may also have a small amount of automatic defecation, but most of them develop severe constipation again after a few days. In a few cases, after a few days of intestinal obstruction in the newborn, there may be a “remission” period of several weeks or even months, but this ends in recurrent obstructive constipation.
In infants and children, the history of megacolon is quite typical, with constipation, bloating and vomiting in the neonatal period or in infancy, and later in infants, constipation becomes more and more persistent with the need for enemas, anal suppositories or laxatives. The most prominent sign on physical examination is abdominal distention, abdominal bulge is most prominent in the upper abdomen, in most cases, the intestinal pattern is faintly visible, abdominal palpation sometimes in the left lower abdomen can be palpable fecal stone masses, auscultation bowel sounds are often hyperactive. Rectal finger examination reveals a hollow pot belly. The stool stays in the dilated colon. The pediatrician’s general condition, emaciation, pallor, and anemia.
Most of the various complications occur within the first two months and later are less common or less severe. Complications of ganglion cell-free disease can include intestinal obstruction, intestinal perforation, peritonitis, small bowel conjunctivitis and a decrease in systemic resistance to infection. In particular, small bowel colitis is a very serious complication, accounting for approximately 60% of deaths due to small bowel colitis. It can occur not only before surgery, but also after colostomy and even after radical resection of megacolon.
The clinical manifestations of small bowel colitis are abdominal distension, diarrhea, fecal juice with gas and odor, fever >38℃, and X-ray examination of the abdomen in the upright position, which indicates dilatation of the small intestine and colon, and may be accompanied by a fluid plane. If a barium enema is made, the mucosa of the colonic segment is seen to be rough, with jagged manifestations, and even ulcers are seen.
It is now recognized that the occurrence of small bowel colitis has little to do with gender, length of the segment without ganglion cells, etc. Distal obstruction (including loss of relaxation of the internal sphincter) and the resulting extreme dilatation of the colon and defective circulation of the intestinal wall are the basic causes. It has also been suggested that enterocolitis may be viral or bacterial in origin, with dilatation of the colon, accumulation of intestinal contents, and retention that induces bacterial infections, especially of anaerobic bacteria.
Teitelbaum (1988) suggested that agranulocytosis with severe malformations, especially trisomy 21, predisposes to the development of small bowel colitis and that the mechanism may be related to T-cell immunity. Agranulocytosis can be associated with a number of other malformations, the incidence of which is higher than in the normal population, with reports in the literature ranging from 5% to 20%. This is especially true in twin cases. Ganglioneuropathy can be combined with the following malformations: immature and very low weight infants, 3.5% to 10%; Down syndrome, 3% to 5%; urinary tract malformations, 3%; anorectal malformations, 2.5% to 3.4%; cardiovascular malformations, 1%.
Diagnosis
Recently, four kinds of auxiliary examinations are commonly used: radiological examination, anorectal manometry, histochemistry of rectal mucosa acetylcholinesterase and pathological biopsy. In clinical practice, several methods are often used in conjunction with each other to complement each other.
1, radiological examination It can be used not only as a diagnosis, but also to understand the length of the diseased intestinal segment and whether there are complications such as small bowel colitis. The diagnosis rate is currently reported to be 80%. The disadvantage of this examination is the potential damage to the child, and the difficulty in diagnosing ultra-short segment type and idiopathic megacolon in neonates without ganglion cell disease and children with colostomy.
An upright abdominal plain radiograph shows a dilated intestinal canal with gas and liquid stool above the diseased segment – a “gas-liquid plane” – and no gas in the diseased segment, and no gas shadow in the small pelvic area, which presents a typical upright radiographic sign of low bowel obstruction.
The barium enema has the following characteristics: there is a clear area of migration between the lesioned segment and the dilated segment, showing a “cone” shape; the lesioned segment is abnormally innervated, so irregular contractions are seen; the barium is retained and remains undischarged for more than 24 to 48 hours. In contrast, if there is small intestine colitis, the proximal dilated colon is thickened and edematous, and there is even a nodular feeling.
This method has been recognized as safe and simple, and the main content of the pressure measurement is the internal sphincter relaxation reflex and the pressure in the anal canal.
The internal sphincter relaxation reflex, also known as the recto-anal inhibition reflex, plays an important role in the control of the defecation mechanism. The external sphincter is a transverse muscle innervated by somatic nerves, whereas the internal sphincter consists of smooth muscle fibers thickened in the muscular layer of the lower rectal wall, which maintains 80% of the pressure in the anal canal during the resting phase. Under normal conditions the rectal wall is compressed and dilated by pressure receptors, and this stimulus causes relaxation of the internal sphincter via ganglion cells and their postganglionic fibers in the intermuscular plexus of the intestinal wall.
This low-level reflex consisting of rectal wall pressure receptors – intermural ganglion cells – internal sphincter has been shown experimentally and clinically to have little relationship with the central nervous system of the spinal cord. In the absence of ganglion cells, this reflex arc is disrupted and does not cause relaxation of the internal sphincter when the rectal wall fills and expands.
The diagnostic accuracy of anorectal manometry is more than 90% in the children’s group and about 60%-85% in the neonatal group.
3, rectal mucosal acetylcholinesterase histochemical method One of the most prominent features is the presence of unmyelinated nerve fibers in the muscular layer of the ungulate intestinal canal, these abnormal nerve fibers belong to cholinergic nerves, with more than normal, more concentrated, and can stretch to the submucosa and mucosal tissue.
The histochemical method can be detected by the Gomori staining method in 1952 or the Karnovsky-Roots method (1964), and the histochemical method of rectal mucosal acetylcholinesterase staining is a qualitative and semi-quantitative method. According to the literature, its correct rate is about 95%.
4, rectal biscuit histological examination reliable diagnosis, especially for some cases of diagnostic difficulties is still a very effective diagnostic method. The main observation is whether there are ganglion cells in the submucosa and intermuscular plexus and the degree of ganglion cell development. The absence of ganglion cells in the intestinal segment of ganglion cell-free lesions is the main criterion for pathologic histological diagnosis.
Differential diagnosis
Constipation has a dual meaning: difficulty in defecation or reduced frequency. In adults, the criteria are lower than those for adults if straining to defecate for more than 25% of the time and/or 2 or fewer bowel movements per week.
In newborns, the possibility of ganglion cell disease should be suspected if the meconium is expelled late and in small amounts after birth, or if the meconium is expelled only after finger examination or enema, and is accompanied by abdominal distention and vomiting. However, there are many diseases in the neonatal period resembling no ganglion cell disease, so it is necessary to distinguish.
1, simple fetal fecal constipation or called fetal fecal plug syndrome Symptoms similar to no ganglion cell disease, delayed fetal fecal excretion, constipation and abdominal distension, but after rectal finger examination, open plug stimulation or saline enema can be excreted a large amount of fetal feces, and from then on no longer occur constipation. The ganglion cells of the rectal wall of the child exist normally.
2, congenital intestinal atresia for typical low intestinal obstruction, rectal finger examination only a small amount of gray-green secretions, saline enema did not see a large amount of fetal feces discharge, barium enema colon is fetal type colon, but the presence of colonic pouch.
3, neonatal peritonitis neonates due to sepsis, umbilical cord infection or other causes of peritonitis, clinically can also have abdominal distension, vomiting, less stool or diarrhea; and neonatal megacolon serious complications of small bowel colitis similar. The differentiation requires attention to whether there is a delay in the discharge of meconium, in addition to the development of infection in the medical history, it is important to cooperate with some auxiliary diagnosis.
4, neonatal necrotizing small intestine colitis This disease is most often seen in premature infants with a history of postnatal asphyxia, hypoxia, shock, and blood in the stool, and air cysts in the intestinal wall on X-ray, which is rare in megacolon.
5, left hemicolectomy syndrome found after birth, bloating, constipation, barium enema to see the splenic flexure to descending colon spastic thinning, very similar to the long segment type without ganglion cell disease. However, histological examination of the rectal biscuit showed the normal presence of ganglion cells; if the children survived, the spastic and narrow colon thickened after 4 months and the constipation function was relieved, and it was found that these children had abnormal addition of hyperglycemia and their mothers were diabetic. Such cases are very rare in China.
6, hypothyroidism (low thyroid) for newborns with primary or secondary hypothyroidism caused by abdominal distension, constipation. These children are abnormally quiet, cry less, have delayed regression of physiological jaundice, and have abnormal blood biochemical indicators related to thyroxine, such as serum protein-bound iodine.
The diagnosis of anaplasia in children is much easier than in the neonatal period, but in the differential diagnosis it is important to distinguish it from idiopathic megacolon, secondary megacolon and megacolonoid origin disease. The key is the history and supporting diagnosis. Idiopathic megacolon has the same signs as short-segment megacolon on barium enema X-rays, but the internal sphincter relaxation reflex is normally present if rectal-anal manometry is performed.
Secondary megacolon occurs mainly after anal stenosis and is more common in children after trauma to the anus, especially after anorectal surgery. It is worth mentioning that anorectal malformations combined with anorectal gangliocytosis can also occur, but they are rare after all. Macrocolic-like disease is not a ganglion cell deficiency, but a qualitative and quantitative change, but constipation is also predominant in clinical practice, and the main point of differentiation is pathological examination. The main point of differentiation is pathological examination. Clinically, we often encounter central nervous system lesions, such as cerebral hypoplasia, cerebral atrophy, congenital stupidity and microcephaly, which are often associated with constipation and need to be differentiated.
Treatment]
The treatment of anaplastic ganglion cell syndrome should generally be based on radical surgery, except for a part of short segment type and ultra-short segment type. Recently, the age of radical surgery tends to be completed in the neonatal period, the surgery is not too difficult and can reduce the occurrence of complications, the key is to correctly handle the various changes in the perioperative period of the newborn.
In the absence of conditions to perform radical surgery or to prepare for radical surgery before the treatment are correcting the child’s general nutritional status, enema, anal dilatation, Chinese and Western medicine laxatives, open plug and other auxiliary applications. Among them, enema is a simple and economical effective measure. It can release the accumulated stool, reduce the occurrence of small intestine colitis, and can be used as intestinal preparation before radical surgery. The enema solution should be isotonic warm saline, repeatedly flush irrigation and suction until the effluent does not contain fecal juice, must be carried out daily or every other day, the enema needs to pay attention to warmth, the assistant should be pressed in the abdomen according to the anatomical path of the colon to help expand the intestinal segment in the fecal infusion out.
Thomas (1986) showed that about 30% of neonates with Clostridium difficile infection and its toxin effects are associated with Clostridium difficile, and recommended treatment with vancomycin during the acute phase. The purpose of dilation is to dilate the muscular layer of the intestinal wall in the short segment of the lesion, including the internal sphincter. In a few cases, partial rectal myotomy (Lynn procedure) can be performed.
In children with small bowel colitis or poor systemic condition or total colonic type, colostomy should be performed first. The colostomy should be made at the proximal end of the ganglion cell-free segment of the intestine. Generally, it is at the proximal end of the sigmoid colon or the right transverse colon, and a terminal ileostomy should be made for the total colon type. A pathologic biopsy of the entire intestinal canal at the proximal stoma should be taken at the time of the stoma. There must be normal ganglion cells present, otherwise some unnecessary troubles will arise after surgery. Surgical treatment of total colonic anaplasia is often recommended in two ways: the Martin procedure and total colectomy with rectal pouching.
The purpose of radical surgery is to target the segment of the intestine without ganglion cells, and four of the most used and more established surgical approaches are described.
1, Swenson surgery (drag-out rectal and sigmoid resection)
The surgical mortality rate has been reduced to 1.25% in the last 20 years. It is believed that the factors affecting the prognosis include the presence of Down syndrome malformation, age of surgery, anastomotic leak, infection, and postoperative intestinal obstruction.
2.Duhamel surgery (colectomy, post-rectal colectomy)
3.Soave surgery (rectal mucosal dissection, colonic drag-out resection in the rectal muscle sheath)
4.Rehbein surgery (colectomy, intrapelvic low rectal colonic anastomosis)
In the past 10 years, with the introduction of foreign advanced technology, laparoscopic radical surgery for ganglioneuropathy has been gradually carried out in China, which is less traumatic and has fewer complications such as intestinal adhesions, and the principle is similar to that of Soave’s surgery. 1998, L. De-la Torre-Mondragon, a Mexican pediatric surgeon, proposed the treatment of ganglioneuropathy using one-stage transanal drag-out surgery, which is more suitable in neonatal and infantile period.
The procedure is performed by placing the child in a cystotomy position, dissecting the submucosa 0.5 cm above the anal dentate line up to the peritoneal reflex of the bladder, then cutting the muscle pin and dragging out the colon through the anus, separating the mesenteric vessels of the colon segment one by one and cutting and dragging out the colon when the presence of normal ganglion cells is pathologically confirmed (usually reported in frozen sections), and anastomosing the proximal end with the proximal mucosa and muscle layer of the anal margin. The posterior junction of the myosynovial sheath is split or excised before the anastomosis to reduce the occurrence of stenosis at the anus exit.
A number of reports have also agreed that transanal one-stage drag-out surgery is associated with less intraoperative bleeding, shorter operative time, shorter hospitalization days, and lower hospitalization costs, and has significant advantages compared with transabdominal laparoscopic surgery and transabdominal classical surgery.