12 years old male with chronic constipation.
Hirschsprung disease is the most common cause of neonatal colonic obstruction. It accounts for ~ 15 - 20% of all intestinal obstructions in the neonate 9.
Hirschsprung disease affects approximately 1 : 5000 - 8000 live births. In short segment disease there is a significant predilection for males (M : F of ~ 3 - 4:1), which reduces with increasing length of involvement 4,6. Interestingly it is almost never seen in premature infants.
The condition typically presents in term neonates with failure to pass meconium in the first 1 - 2 days after birth, although later presentation is also common. Overall approximately 75% of cases present within 6 weeks of birth 4, and over 90% of cases present within the first 5 years of life. A very small number may present in the adult population 1.
In cases of delayed presentation with constipation anorectal manometry may be useful in distinguishing short / ultrashort segment Hirschsprung disease from other causes 5.
A definitive diagnosis requires a full thickness rectal biopsy.
Hirschsprung disease is characterised by aganglionosis (absence of ganglion cells) in the distal colon and rectum and is thought to either occur from a failure of neuroblasts in neural crest cells to migrate into bowel segments or degeneration of already migrated neuroblasts. It affects cells both in the myenteric and submucosal plexuses 4. Hence, functional obstruction develops as a result of spasm in the denervated colon.
It can be anatomically divided into 4 types according to the length of the aganglionic segment:
• short segment disease : ~ 75% *
o rectal and distal sigmoid colonic involvement only
• long segment : ~ 15%
o typically extends to splenic flexure / transverse colon
• total colonic aganglionosis : 2 - 13%
o also known as Zuezler-Wilson syndrome
o occasional extension of aganglionosis into small bowel
• ultrashort segment disease
o 3 - 4 cm of internal anal sphincter only
o controversial entity
* see notes on percentages
It is postulated that hypoganglionosis (reduced number of ganglion cells) is responsible for intestinal pseudo-obstruction 4.
Although Hirschsprung is an isolated abnormality in 70% of cases, there are a number of well documented associations, including 4,6:
• Down syndrome : in ~ 10% of Hirschsprung cases
• neurocristopathy syndromes
o Waardenburg-Shah syndrome
o Haddad syndrome
o MEN IIa
• other non-neurocristopathy syndromes
o Aarskog syndrome
o Bardet-Biedl syndrome
o Fryns syndrome
o Pallister-Hall syndrome
o Smith-Lemli-Opitz syndrome
Findings are primarily those of a bowel obstruction. The affected bowel is of smaller calibre, and thus depending on the length of segment affected variable amounts of colonic distension are present.
In protracted cases marked dilatation can develop, and even progress to enterocolitis and perforation.
Fluoroscopy - contrast enema
A carefully performed contrast enema is indispensable in both the diagnosis of Hirschsprung disease but also in assessing the length of involvement. It should be noted however that the depicted transition zone on the contrast enema is not accurate at determining the transition between absent and present ganglion cells.
The affected segment is of small calibre with proximal dilatation. Fasciculation / saw-tooth irregularity of the agangliotic segment is frequently seen.
Views of particular importance include :
• early filling views that include rectum and sigmoid colon allowing for rectosigmoid ratio to be determined.
• transition zone
• in certain cases there may be evidence of fetal colonic dilatation
Treatment and prognosis
Surgical treatment is by removal of the affected portion of colon. Where this is successful, prognosis is good. However, in 3 - 4% of cases colonic perforation complicates the presentation 2 and this and its sequalae significantly increase both mortality and morbidity. Mortality rates can be as high as 30% due to enterocolitis.
It was first described by Harald Hirschsprung (1830 - 1916) : paediatrician, Denmark, in 1888 6-8.
General differential considerations include:
• functional megarectum
• necrotising enterocolitis
• microcolon : appears similar to long segment / whole colon Hirschsprung disease
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