Opiate-related death: morphometric study of neurons from the dorsal motor nucleus of the vagus nerve.

The aim of this work is to verify the presence of objectively observable morphological alterations caused by the direct action of opiates on brain structures controlling respiration in cases of drug-related deaths. A computer-assisted morphometric study was carried out on the Dorsal Motor Nucleus of the Vagus Nerve (DMNV) in seven subjects (four of whom died of drug overdose, and 3 controls). Serial sections 10-15 microns thick were stained according to Nissl. The sections were then examined under the optical microscope and 200 fields per subject were digitalized. The resulting images, regarding at least 700 neurons per subject were segmented using a semi-automatic procedure and analysed by the Optilab software. The data obtained were subjected to cluster analysis to identify the neuron classes in the DMNV. Each subject was characterized with a vector of percentages indicating the fraction of neurons falling in each of these classes. Discriminant analysis was then applied to verify to what extent the variables discriminated between the two populations. Results indicated that: the statistical methods adopted have a good power of discrimination; in subjects who died of opiate overdose, the neurons are distributed to a greater extent in classes composed of smaller neurons than in controls.