- PURPOSE: Normal gut muscular function depends on the coordinated activity of both the enteric nervous system (ENS) and the interstitial cells of Cajal (ICC). Hirschsprung's disease (HD) has long been considered a purely neuronal deficit but recent data point to abnormalities in ICC in the proximal ganglionated HD colon. We examined the labeling of ICC and neuronal cells in the proximal ganglionated colon in patients with HD to determine whether abnormalities of ICC and ENS might be associated with a poor clinical outcome. METHODS: Tissue from 11 patients with HD was studied using immunohistochemistry for ICC and neuronal identification in comparison to control tissue from patients without HD. Image data were evaluated quantitatively and interpreted relative to clinical outcome. RESULTS: Interstitial cells of Cajal in the ganglionated colon of the HD group did not differ from the control group, but nerve cells/fibers were decreased 40%. Paired decreases in both nerve fibers and ICC in individual patients were associated with normal bowel function. Poor postoperative outcome was observed in a patient with normal innervation but with a profound decrease in ICC in the ganglionated colon. CONCLUSIONS: Nerve fibers are decreased in the proximal ganglionated colon in patients with HD without associated gut dysmotility. Poor clinical outcome was noted only in a patient with normal innervation and markedly decreased ICC. Collection of data from a much larger number of patients with poor clinical outcome will be necessary to determine the significance of this imbalance of ICC and innervation.