Developmental Disorder

Hirschsprung Disease

Congenital aganglionic MegacolonBy Dr Mohammad Manzoor Mashwani

Hirschsprung disease• Hirschsprung disease is a developmental disorder

of the enteric nervous system and involves an enlargement of the colon, caused by bowel obstruction resulting from an aganglionic section of bowel that starts at the anus & progresses upwards.

Harald Hirschsprung, Danish Physician 1886

Congenital Aganglionic Megacolon

Pathogenesis• Two pathogenetic mechanisms have been

proposed for Hirschsprung's disease• (1) failure of migration of neuroblasts to the distal

intestine ( rectum).• (2) alteration of the colonic microenvironment• Genetic, vascular, and infectious factors are

invoked to explain these alterations . Normal migration may occur with a failure of neuroblasts to survive, proliferate or differentiate in the distal aganglionic segment.

Epidemiology• Rate of occurrence 1 case per 5000 live births.• Race - no racial predilection.• Sex – M: F = 4:1. Long S.D F• Age: Full term baby, uncommon in premature baby,Can occur in adult life.

Hirschprung’s Disease, diagrammatic representation of the pathologic changes

Morphology

Gross specimen of Hirschprung’s Disease. The proximally dilated segment of bowel has been resected.

• Depending on the extent and location of the aganglionic segment, several forms of the disease have been recognized:

• 1 Classic form. The aganglionic segment begins in the distal colorectum and extends for a considerable distance in the adjoining proximal dilated bowel. 2 Short-segment form. The aganglionic segment involves the rectum and rectosigmoid for a distance of only a few centimeters. 3 Ultra-short segment form. In this variant, the aganglionic segment is so short that the diagnosis can be missed if the biopsy is taken too high. 4 Long-segment form (total colonic aganglionosis). Here the abnormality is more extensive, involving most or all of the large bowel, and occasionally extending even to the small bowel. These patients present with symptoms of intestinal obstruction without megacolon. 5 Zonal colonic aganglionosis. Only a short segment of bowel is involved. In contrast to all other forms, ganglion cells are present not only above but also below the aganglionic segment.

Morphology• Microscopically, the hallmark of the disease is the absence of ganglion cells (aganglionosis) in both plexuses of a segment of bowel.

Colonic mucosa stained for acetylcholinesterase from a patient with Hirschsprung disease. There is a

marked increase in the number of nerve fibers in the lamina propria.

Clinical features 1) Delayed passage of meconium 2) Abdominal distension 3) Constipation

Diagnosis

Suspect Hirschsprung's in a baby who has not passed meconium within 48 hours of delivery.

Recall that 90% of babies pass their first meconium within 24 hours, and the next 9% within 48 hours. Definitive diagnosis is made by biopsy of the distally narrowed segment.

1. Full thickness biopsy2. Suction biopsy

Abdominal x-ray ( Plain)Barium Enema (Contrast x-ray)Anorectal manometry

TreatmentSurgical

removal (resection) of the abnormal section of the colon, followed by reanastomosis.

Initial therapy should include intravenous hydration, withholding of enteral intake, and intestinal and gastric decompression. Decompression can be accomplished through placement of a nasogastric tube and either digital rectal examination or normal saline rectal irrigations 3-4 times daily. Administer broad-spectrum antibiotics to patients with enterocolitis.

“Your practice of medicine will be as good

as your understanding of pathology”

Sir William Osler.