A new rapid acetylcholinesterase histochemical method for the intraoperative diagnosis of Hirschsprung's disease and intestinal neuronal dysplasia.

Abstract

The most commonly used acetylcholinesterase (AChE) method for the diagnosis of Hirschsprung's disease (HD) and intestinal neuronal dysplasia (IND) was first introduced in 1964 by Morris Karnovsky and Logan Roots. This technique requires about 80 - 120 minutes incubation time and cannot be used for the intraoperative diagnosis of HD and IND. To avoid these limitations, in 1994 Kobayashi et al first proposed an accelerated modified method in two different versions, the first using diaminobenzydine (DAB) reagent, the second using 4-chloro-1-naphthol as final reagent. In the present study, we propose a new rapid variation of AChE staining which avoids the use of DAB and naphthol, notably toxic reagents, but follows the same acceleration principle of Kobayashi's technique. Our modified rapid AChE requires a total incubation time of only 8 minutes, which is compatible with intraoperative histochemical examination purposes. Intraoperative seromuscular or full-thickness intestinal biopsies were obtained from 92 children affected by intestinal dysganglionoses. The biopsies were frozen and cut in 15 microm cryostatic sections. Rapid AChE was performed with a special incubation medium using 3-amino-9 ethylcarbazole (AEC) as chromogenic substance. The two complementary histochemical techniques alpha-naphthylesterase (ANE) and lactate-dehydrogenase (LDH) were also used intraoperatively for the staining of ganglion cells. The diagnosis was confirmed postoperatively with conventional AChE Karnovsky technique, comparing the extensions of hyperganglionic, hypoganglionic and aganglionic segments in each studied case. The new rapid AChE modified method can identify ganglion cells and fibers using a dark brown precipitate. In all the cases studied, the intestinal innervation pattern identified with this modified technique was similar to that obtained with Karnovsky AchE. Seventy-eight HD, 8 isolated IND and 6 HD associated with an evident IND segment were diagnosed. This new rapid AChE histochemical technique avoids the use of DAB and naphthol, and can thus be considered safe for operators. Rapid AChE is a valid tool for both the evaluation of aganglionosis extension and for the identification of IND pattern during surgery. We recommend this very reliable method for the intraoperative diagnosis of HD and IND, in association with other enzymatic markers of ganglion cells (ANE or LDH). We propose the following diagnostic protocols: a) for preoperative histochemical study: conventional AChE plus LDH and NADPH-diaphorase; b) for intraoperative study: rapid AChE plus ANE.