In children with Hirschsprung's disease (HD), bowel dysfunction may not resolve with surgical treatment of the colonic disorder. The persistence of symptoms is reportedly associated with the presence of submucosal hyperganglionosis in a segment proximal to the transitional hypoganglionic zone, but controversy remains regarding the importance of such submucosal hyperganglionosis. The aims of our study were to determine the concentration of myenteric plexus neurons in the most proximal region of resected colon from patients with HD and establish whether any correlation existed between myenteric hyperganglionosis and clinical outcome.
A mean ±SD follow-up of 16.8 ±6.9 months after surgery was available in 28 children (mean age ± SD: 34.5 ±27.4 months; 24 males) with HD. Twelve of 28 patients underwent surgical treatment in the neonatal period. The Coran procedure was performed in 12 neonates and in 8 children, the Duhamel in 6 children, and the Soave in 2. The concentration of myenteric neurons in the proximal margin of the resected bowel specimens (interpreted as normal at time of surgery) was reevaluated using conventional H&E staining, according to Smith's procedure (Ped Path 1993). The diagnosis of hyperganglionosis was based on the presence of at least 9 neurons/mm of myenteric plexus. A structured questionnaire that detailed bowel habits, soiling episodes, enterocolitis, abdominal distention, abdominal pain and any use of laxatives was completed using an interview at the time of follow-up.
Seven of 28 (25%) patients showed hyperganglionosis (mean ±SD: 11.7±2.6 myenteric neurons/mm) in the proximal resected specimen. In the remaining 21 patients, the mean ±SD of neuronal concentration was 5.1±1.66. The mean ±SD age of the 7 patients with hyperganglionosis at time of surgery was 14.3 ±20.0 months. On follow up, 8 of 28 (28.5%) patients continued to have GI symptoms. In particular, 4 had constipation (<3 evacuations per week, or hard stools, or use of laxatives), 4 had soiling (4 to 40 episodes per week), 2 had enterocolitis (both a single episode), 3 abdominal distention (mild to moderate). By Pearson's test the increasing number of myenteric neurons did not relate to persistence of symptoms (p=0.3). Of the 7 patients with myenteric hyperganglionosis, only one (14.2%) at follow-up was still symptomatic.
In conclusion, myenteric hyperganglionosis at the proximal margin of resected colon is found in 25% of children with HD. The concentration of myenteric neurons, however, has no significant relationship to the persistence of symptoms following surgery. Our study suggests that myenteric hyperganglionosis proximal to the aganglionic segment may be conceptually relevant when considering the pathogenesis of HD, but it seems to have no clinical importance in predicting symptomatic outcome.