Postmortem histochemical and electron microscopic changes in skeletal muscle fibers of fatal hypothermia: an experimental study

Hypothermia-related death is one of the areas that the determination of the definitive diagnosis is difficult. In this study, we aimed to evaluate the post-mortem histopathological changes in rat skeletal muscles of fatal hypothermia. The rats were divided into three groups. The first was the control group without any procedures while the second was the sham group where in hypothermia was applied after death. In the third group (fatal hypothermia), the rats were left in the hypothermia cabinet until their body temperatures decreased to 7-10 degrees C. Samples taken from the masseter, intercostal, pectoralis minor, iliopsoas, and anterior tibial muscles of the rats were examined under light and electron microscope. Based on the stereological analysis, the density of the Type I fibres of the masseter and intercostal muscles was found significantly lower in the fatal hypothermia group compared to the other two groups. There were intensive degeneration and the occurrence of ragged-red fibres, especially in the masseter and intercostal muscles of fatal hypothermia exposed rats. Ultrastructurally, impaired muscle fibre arrangement, Z-line irregularities, nuclear shrinkage, and mitochondrial enlargement and degeneration were observed in the hypothermia group. The changes may have diagnostic value to make the post-mortem diagnosis of fatal hypothermia-related deaths.