Hirschsprung's disease

Hirschsprung's disease



Hirschsprung's disease, or congenital aganglionic megacolon, involves an enlargement of the colon, caused by bowel obstruction resulting from an aganglionic section of bowel (the normal enteric nerves are absent) that starts at the anus and progresses upwards. The length of bowel that is affected varies but seldom stretches for more than a foot or so.

History and Description

This disease is named for Harald Hirschsprung, the Danish physician who first described the disease in 1886, describing two infants who had died with swollen bellies. "The autopsies showed identical pictures with a pronounced dilatation and hypertrophy of the colon as the dominant features" (Madsen 17:2).

Hirschsprung’s disease is a congenital disorder of the colon in which certain nerve cells, known as ganglion cells, are absent, causing chronic constipation [1]. A barium enema is the mainstay of diagnosis of Hirschsprung’s, though a rectal biopsy showing the lack of ganglion cells is the only certain method of diagnosis.

The usual treatment is "pull-through" surgery where the portion of the colon that does have nerve cells is pulled through and sewn over the part that lacks nerve cells (National Digestive Diseases Information Clearinghouse). For a long time, Hirschsprung’s was considered a multi-factorial disorder, where a combination of nature and nurture were considered to be the cause (Madsen 19). However, in August of 1993, two articles by independent groups in Nature Genetics said that Hirschsprung’s disease could be mapped to a stretch of chromosome 10 [2][3]. This research also suggested that a single gene was responsible for the disorder. However, the researchers were unable to isolate the single gene that they thought caused Hirschsprung’s.

History

* Approximately 10% of patients have a positive family history. This is more common in patients with longer segment disease.
* Hirschsprung disease should be considered in any newborn with delayed passage of meconium or in any child with a history of chronic constipation since birth. Other symptoms include bowel obstruction with bilious vomiting, abdominal distention, poor feeding, and failure to thrive.
* Prenatal ultrasound demonstrating bowel obstruction is rare except in cases of total colonic involvement (Belin, 1995).
* Older children with Hirschsprung disease have usually had chronic constipation since birth. They may also show evidence of poor weight gain.
* Older presentation is more common in breastfed infants who will typically develop constipation around the time of weaning.
* Despite significant constipation and abdominal distension, children with Hirschsprung disease rarely develop encopresis. In contrast, children with functional constipation or stool-withholding behaviors more commonly develop encopresis.
* About 10% of children may present with diarrhea caused by enterocolitis, which is thought to be related to stasis and bacterial overgrowth. This may progress to colonic perforation, causing life-threatening sepsis (Teitelbaum, 1989).

Physical

* Physical examination in the newborn period is usually not diagnostic, but it may reveal a distended abdomen and/or spasm of the anus.
* A low imperforate anus with a perineal opening may have a similar presentation to that of a patient with Hirschsprung disease. Careful physical examination differentiates the two.
* In older children, however, a distended abdomen resulting from an inability to release flatus is not uncommon.

Treatment

Treatment of Hirschsprung's disease consists of surgical removal of the abnormal section of the colon. There used to be two steps typically used to achieve this goal.

* The first stage used to be a colostomy. When a colostomy is performed, the large intestine is cut and an opening is made through the abdomen. This allows bowel contents to be discharged into a bag.
* Later, when the child’s weight, age, and condition is right, a pull-through procedure is performed.

Orvar Swenson, the same man who discovered the cause of Hirschsprung’s, first performed it in 1948 (Swenson 839). The pull-through procedure repairs the colon by connecting the functioning portion of the bowel to the anus. The pull through procedure is the typical method for treating Hirschsprung’s in younger patients. Swenson devised the original procedure, but the pull-through surgery has been modified many times. Sawin, an expert in pull-through surgery, notes that, "Although there are about five different pull-through procedures, they are all more or less equally effective in treating the disorder."

The Swenson, Soave, Duhamel, and Boley procedures all vary slightly from each other with equivalent results (Sawin).

* The Swenson procedure leaves a small portion of the diseased bowel.
* The Soave procedure leaves the outer wall of the colon unaltered.
* The Boley procedure is just a small modification of the Soave procedure.
* The Duhamel procedure uses a surgical stapler to connect the good and bad bowel. The front of the bowel will end up with no cells, but the back will be healthy (Sawin).

Sawin notes that “Pull-through procedures used to require a colostomy, but with increased awareness among doctors and parents about the symptoms of Hirschsprung’s and with early diagnosis, doctors can keep the colon clean and perform the pull-through procedure without a colostomy”. In general, “85 percent of patients that have the pull-through surgery live normal lives afterwards. The other 15 percent have to take a laxative for the rest of their lives”.

In rare cases, if the mother has Hirschsprung’s and passes it on to her child, the child is said to have “total Hirschsprung’s”, where there are no ganglion cells at all in the colon (Sawin). In this case, the Martin pull-through operation is conducted. The Martin operation is the most invasive of the operations, for it requires a colostomy no matter how early you diagnose total Hirschsprung’s.

Even rarer, notes Dr. Sawin, "there are times where the disease begins in the small intestine, making treatment even harder". When a child has total Hirschsprung's or small intestine Hirschsprung's, an ileostomy or jejunostomy is conducted along with the Martin operation, and the child is then treated for short bowel syndrome. On very rare occasions, pull-through surgery is not the preferred method when it comes to treating Hirschsprung’s disease.

If the affected portion of the lower intestine is restricted to the lower portion of the rectum, other surgical procedures, such as the posterior rectal myectomy, can be performed.