Hirschsprung's Disease Aswad H. Al.Obeidy FICMS, FICMS GE&Hep Kirkuk General Hospital

Hirschsprung's Disease A congenital absence of ganglion cells in both the submucosal (Meissner's) and myenteric (Auerbach's) plexuses Extends continuously for a variable distance proximal to the internal anal sphincter It may extend up to the splenic flexure or even more proximally, involving the entire colon, as well as portions of the small intestine (long-segment Hirschsprung's disease) It may be restricted to the rectum and sigmoid (short- segment Hirschsprung's disease) It may involve only a few centimeters proximal to the dentate line (ultra-short-segment Hirschsprung's disease)

Hirschsprung's Disease Incidence of 1 in 5000 live births Approximately 700 new cases of Hirschsprung's disease occur each year in the United State Familial occurrence has been reported in about 7% of cases, particularly in those with long aganglionic segments Is seen most commonly in full-term infants In the short-segment type, a 4:1 male preponderance is observed, and in the long-segment type, the ratio is reduced to about 2:1 Short-segment Hirschsprung's disease accounts for nearly 90% of cases in childhood It is rare that ultra-short-segment Hirschsprung's disease manifests in the pediatric population, but it does explain certain cases of chronic constipation that come to attention in adulthood

Hirschsprung's Disease Twelve percent of children with Hirschsprung's disease have chromosomal abnormalities, 2% to 8% of which are trisomy 21 (Down syndrome) Congenital Anomalies Genitourinary (5.6%) Cardiac (4.5%) Central nervous system (3.9%) Gastrointestinal (3.9%) Syndromes Shah-Waardenburg (regional hyperpigmentation, white forelock, bicolored irides, sensorineural deafness) Movat-Wilson (characteristic facies, microcephaly, mental retardation) Smith-Lemli-Opitz (anteverted nostrils, ptosis of eyelids, syndactyly of 2nd and 3rd toes, hypospadias and cryptorchidism) Congenital central hypoventilation Syndromes with limb abnormalities (metaphyseal dysplasia, McKusick-type—mild bowing of legs, irregular metaphyses, fine sparse hair) MEN II (medullary thyroid cancer, pheochromocytoma, parathyroid hyperplasia) Piebaldism (hypopigmentation of skin and hair)

Pathogenesis Two pathogenetic mechanisms have been proposed for Hirschsprung's disease (1) failure of migration (2) alteration of the colonic microenvironment Genetic, vascular, and infectious factors are invoked to explain these alterations

Clinical Features Should be diagnosed in the newborn nursery Any full-term infant who does not pass meconium within the first 48 hours of life should be suspected of having the disorder Frequently, such infants will have abdominal distention and feeding difficulties They also may have bilious emesis from partial bowel obstruction Hirschsprung's disease–associated enterocolitis occurs more frequently in the first 3 months of life, in patients with delayed diagnosis, in trisomy 21, and with long-segment involvement; females and patients with a positive familial history Mortality rates of up to 30% have been reported for enterocolitis, which remains the major cause of death Colonic perforation, most frequently involving the cecum and rarely the appendix, may occur even in utero Continue to have variable but significant constipation, punctuated by recurrent obstructive crises or impaction, often with failure to thrive Anemia and hypoalbuminemia are common Fecal soiling occasionally may occur

Diagnosis The diagnosis may be made by one or a combination of the following tests: barium enema, rectal biopsy, and anal manometry. Flexible sigmoidoscopy reveals a normal but empty rectum. The dilated proximal bowel, if within reach of the scope, is traversed easily, except for abundant feces in the lumen; occasionally stercoral ulcers may be seen Anal manometry is the most reliable method by which the gastroenterologist can make the diagnosis of ultra-short-segment Hirschsprung's disease. A normal physiologic response to distention of the rectum is relaxation of the smooth muscle internal sphincter pressure. In Hirschsprung's disease, not only does rectal distention fail to induce internal sphincter relaxation, but a paradoxical rise in external sphincter pressure often is seen A suction biopsy of the rectal mucosa is the most reliable method of diagnosis, except in patients with ultra-short-segment Hirschsprung's disease. The biopsy capsule should be placed at least 2 cm above the mucocutaneous junction in infants and 3 cm above the junction in older children to avoid the physiologic hypoganglionic zone A full-thickness biopsy of the anorectal wall performed by a surgeon is diagnostic of ultra-short-segment Hirschsprung's disease, in contrast with the suction biopsy, which is not as reliable

Management Definitive treatment of Hirschsprung's disease is surgical All full-term babies with meconium plug in the newborn nursery should be evaluated for this disorder before discharge because approximately 15% of children with Hirschsprung's disease have a history of meconium plug Discharge of any newborn with undiagnosed Hirschsprung's disease with consequent delay in operative intervention may result in a greater frequency of entercolitis The specific method of surgery is operator dependent. In general, long-term results are good, but 10% to 20% of children have residual problems, usually with fecal soiling Long-term prognosis varies and may depend on the length of the aganglionic segment. It is usual to see older children continue to have defecatory issues with fecal retention and encopresis The exact reasons for these continuing problems remain unclear, but the mechanism may involve an intrinsic abnormality in what is described as normal colon or in the pacemaker system of the colon