Hirschsprung’s disease – Types, Pathophysiology, and Treatment

Definition

Hirschsprung’s disease is a rare birth defect that affects the large intestine (bowel). It is caused by missing some or all of the nerve cells in your intestine. Nerve cells are important because they tell your intestine to push stools through your bowel. This condition occurs while a baby is in the womb. Cells may be missing from a small part of the intestine near the bottom (anus). Or cells may be missing from a large part of the intestine. This causes stools to back up in the intestine. It causes severe constipation, blockage, and colon infections.

Epidemiology

Hirschsprung’s disease affects approximately 1:5000-8000 live births. In short segment disease, there is a significant predilection for males (M: F of 3.5:1), which reduces with the increasing length of involvement. Interestingly, it is almost never seen in premature infants.

Pathophysiology of Hirschsprung’s disease

Hirschsprung’s disease is where ganglionic cells of the myenteric and submucosal plexuses in the bowel aren’t present proximally from the anus to a variable-length along the large intestine. The enteric nervous system is derived from the vagal segment of neural crest cells which migrate along the vagus nerve to enter the foregut mesenchyme in a cranial to caudal direction. The most common accepted aetiology of this disease is due to the arrest of the neuroblast, derived from neural crest cell migration in fetal development between week 8 to 12. It is also accepted that sometimes normal cell migration occurs but the neuroblast fails to properly develop due to apoptosis, improper differentiation, or failure in proliferation.

The aganglionic segment remains in a tonic state leading to failure in peristalsis and bowel movements. Feces in the rectum fail to trigger relaxation of the internal anal sphincter, due to aganglionosis. The accumulation of feces in the rectosigmoid region is responsible for the functional obstruction, which is the cause of many of the symptoms. It can lead to proximal bowel dilatation which can present as abdominal distension. Increased intraluminal pressure can lead to decreased blood flow and deterioration in the mucosal layer. This stasis can lead to bacterial proliferation and the subsequent complication of Hirschsprung’s enterocolitis, which has a mortality rate of 25-30%. If not recognized early this can lead to sepsis and death.

Types of Hirschsprung’s disease

The two main types of Hirschsprung disease are:

Short-segment: This type is the most common. It affects 80% of people (mostly males) with the disease. Nerve cells don’t form in the last segment of the large intestine.

Long-segment: This type affects males and females equally. It occurs when nerve cells are missing from the large intestine.

Rarely, nerve cells don’t form in the large intestine and part of the small intestine. Healthcare providers call this condition total colonic aganglionosis. A very small number of children have no nerve cells in the intestines at all. This condition is known as total intestinal aganglionosis.

Hirschsprung’s disease causes

• Hirschsprung disease occurs when nerve cells in the intestines don’t develop normally before an infant is born. Experts are still studying factors that may cause problems with how these nerve cells grow.
• Certain genes increase the chance that a child will have Hirschsprung disease. Experts think that several different genes may play a role.

Risk factors

Factors that may increase the risk of Hirschsprung’s disease include:

Having a sibling who has Hirschsprung’s disease: Hirschsprung’s disease can be inherited. If you have one child who has the condition, future biological siblings could be at risk.

Being male: Hirschsprung’s disease is more common in males.

Having other inherited conditions: Hirschsprung’s disease is associated with certain inherited conditions, such as Down syndrome and other abnormalities present at birth, such as congenital heart disease.

Symptoms of Hirschsprung’s disease

An early symptom in some newborns is failure to have a first bowel movement within 48 hours after birth. Other symptoms may include

• Green or brown vomit
• Explosive stools after a doctor inserts a finger into the newborn’s rectum
• Swelling of the abdomen
• Diarrhea, often with blood
• Failure to pass their first bowel movement (meconium)
• Constipation
• Nausea and vomiting
• Abdominal pain or distension
• Diarrhea
• Aganglionic megacolon
• Intestinal obstruction
• Weight loss
• Adducted thumb
• Failure to thrive in infancy
• Sepsis
• Enterocolitis

Symptoms of Hirschsprung disease in toddlers and older children may include

• Not being able to pass stools without enemas or suppositories. An enema involves flushing liquid into the child’s anus using a special wash bottle. A suppository is a pill Placed into the child’s rectum.
• Swelling of the abdomen.
• Diarrhea, often with blood.
• Slow growth.
• Intellectual disability

Complications

In Hirschsprung disease a part of the large intestine lacks normal nerve cells. This means that digested food and stool can’t move forward through that part of the digestive tract. The large intestine becomes blocked with stool. Your baby will be constipated, or unable to have normal bowel movements.

The blockage creates pressure on the inside of the intestine. This causes part of the intestinal wall to wear thin. Over time, a bacterial infection called enterocolitis can develop in the digestive tract. This is very serious. Symptoms of enterocolitis include:

• Fever
• Swollen belly
• Vomiting
• Diarrhea
• Bleeding from the rectum
• Lack of energy

Call your child’s healthcare provider right away if your child has any signs of enterocolitis.

Diagnosis

A physician will examine your child and obtain a medical history. Other tests may be done to evaluate whether your child has Hirschsprung disease. These tests may include:

Rectal biopsy: This is the only definitive test for Hirschsprung disease. For this test, a very small piece (1-2 mm) of the rectal lining is obtained using a small instrument passed through the anal opening. Sometimes a full-thickness rectal biopsy under anesthesia is recommended, but at other times a rectal suction biopsy without anesthesia is appropriate. There is no sensation for cutting inside the colon so pain-relieving medicines are not needed for the biopsy.

Abdominal X-ray: An X-ray of the child’s abdomen allows physicians to determine if there is a lack of stool at the end of the large intestine near the anus and dilated segments of the large and small intestine. This test may aid in confirming a diagnosis of Hirschsprung disease.

Barium enema: For this test, a fluid called barium (a chalky liquid used to coat the inside of the bowel so that it will show up on an X-ray) is given into the rectum as an enema. An abdominal X-ray of children with Hirschsprung disease should show that the end of the bowel is narrower than areas of the bowel close to the mouth. This test may also show other problems including strictures (narrow areas). Barium enema may appear normal in about 10 percent of children with Hirschsprung disease and is less reliable in infants than in older children.

Anorectal manometry: This test measures nerve reflexes that are missing in Hirschsprung disease.

Treatment for Hirschsprung’s disease

Treatment for Hirschsprung disease depends on the severity of the disease and your child’s overall health. All children with the condition undergo procedures that help eliminate static stool, and ultimately, surgery to remove the portion of the intestine that is malfunctioning.

Most children who have treatment and surgery do very well and go on to have normal, healthy bowel function.

Irrigation to Flush the Intestines

As a first step, doctors will irritate the bowel to remove trapped waste and gas. The irrigation is done by inserting a tube through the anus to flush out the colon. In most cases, this successfully clears the intestines and provides immediate relief to the child. These irrigations are continued until surgery can be done.

Sodium Supplementation

Some patients, particularly those whose entire colon is affected by Hirschsprung disease, may need an ileostomy for many months and sometimes years.

The ileostomy can cause the body to lose sodium, something that your child needs in order to absorb nutrients from what they eat. For that reason, children with an ileostomy are often prescribed sodium supplements by their doctor. Doctors will also monitor your child’s growth carefully to make sure that they are getting the nutrients they need to develop normally.

Surgery

The goals of surgery are to remove the abnormal part of the intestine and to reconnect a healthy part of the intestine to the anus so that the body can pass waste normally. In most cases, the rectum and the sigmoid colon (the last parts of the large intestine) will need to be removed. A very key technical aspect is to preserve the anal canal and anal sphincters which comprise the continence mechanism.

Surgery is typically performed on a healthy infant that has responded well to bowel irrigations. The operation performed while your child is under anesthesia involves both laparoscopic and transanal surgery. This allows the surgeon to reach the bowel through three or four tiny (3-5 mm) incisions on the abdomen (stomach area). This approach is minimally invasive and helps reduce recovery time.

In rare cases, if a child is very ill from enterocolitis (intestinal infection), and irrigations are not working, an ileostomy or colostomy is performed. These ostomy procedures collect waste from the small or large intestines and channel it into a bag attached to the child’s side. This is a temporary measure (lasting from a few months to a few years) that allows the child’s intestines to heal until surgery can be performed.

Your doctor will give you detailed information about how to manage your child’s ostomy.

Prevention

Since the cause of Hirschsprung’s disease is unknown, you cannot prevent or avoid it. However, parents who have the disease can unknowingly pass it on to their children.