pediatrics
Hirschsprung Disease
Introduction
Hirschsprung disease is a congenital anomaly consisting of a failure of neuronal colonization (and thus a failure of innervation) of the lower intestine, usually limited to the colon, resulting in partial or total functional obstruction. Symptoms are obstipation and distention. The diagnosis may be suggested by evaluation with a barium enema; definitive diagnosis requires a rectal biopsy (suction biopsy or surgical biopsy). Anal manometry can help in the evaluation and reveals lack of relaxation of the internal anal sphincter upon rectal balloon distention. Treatment is surgical. (Also see Overview of Congenital Gastrointestinal Anomalies .) Hirschsprung disease is caused by congenital absence of the Meissner and Auerbach autonomic plexus (aganglionosis) in the intestinal wall. The estimated incidence is 1 in 5000 live births ( General references ). Disease is usually limited to the distal colon (75% of cases) but can involve the entire colon (3 to 10% of cases) or even the entire large and small bowels; the denervated area is always contiguous ( The etiology of the aganglionosis is thought to be the failure of migration of neural progenitors from the neural crest. There is a significant genetic component to this disorder, and at least 12 different genetic mutations are associated with Hirschsprung. The likelihood of disease among family members increases with increasing length of the involved gut—3 to 8% for disease of the distal colon and up to 20% for disease involving the entire colon. Twenty to 25% of patients with Hirschsprung disease have another congenital anomaly, and 15% have a genetic abnormality ( Down Syndrome (Trisomy 21) is the most common). Approximately 20% of patients with congenital central hypoventilation syndrome also have Hirschsprung disease; the combination is referred to as Haddad syndrome. Other disorders associated with Hirschsprung disease include Waardenburg syndrome, Bardet-Biedl syndrome, Goldberg-Shprintzen syndrome, and cartilage-hair hypoplasia. Approximately 20 to 25% of patients with Hirschsprung disease have another congenital anomaly. Peristalsis in the involved segment is absent or abnormal, resulting in continuous smooth muscle spasm and partial or complete obstruction with accumulation of intestinal contents and massive dilation of the more proximal, normally innervated intestine. Skip lesions almost never occur. 