Neuron count reevaluation in the myenteric plexus of chagasic megacolon after morphometric neuron analysis

This study was made with the objective of reevaluating the colon denervatio n in chronic Chagas' disease. The diameters of neuron perikaryons of the my enteric plexus were measured on paraffin sections in a ring from the sigmoi d in Chagas' disease patients, 17 with and 10 without megacolon and in 10 n on-chagasic controls. All neurons were counted in ten en-echelon sections. Neuron hypertrophy only occurred in the group with megacolon, and the avera ge increase in diameter was 69.3%. This could generate an error factor in t he neuron count by increasing the probability of neurons being seen in a gr eater number of histological sections. The original result of the neuron co unt gave medians of 1264, 1961, and 2665 in the groups of chagasic patients with megacolon, without megacolon, and in the control, respectively. The d enervation was greater than 55% in only seven megacolon cases (41.2%). Afte r applying a correction factor, the median in the group with megacolon was 746, and the denervation was greater than 55% in 13 cases (76.5%). This occ urrence demonstrates the need to apply a correction factor when the neuron count in chagasic megacolon is being evaluated and in the other pathologies where neuron hypertrophy may be found.