The relationship between the intramuscular bleeding of the tongue and cause of death.

Intramuscular bleeding of the tongue (ImBT) is occasionally found during post mortem examination. Despite its frequent reports, its cause has not yet been clarified. In this study, forensic autopsy data of 799 cadavers were examined and the relationship between ImBT and cause of death was investigated. A total of 74 cases showed ImBT (16 of 66 cases of fire fatality, 17 of 108 cases of drowning, 23 of 74 cases of asphyxiation, and 18 of 551 cases of other causes of death). The frequency of bleeding was significantly greater in cases with causes of death including fire fatality, drowning, and asphyxiation compared to those with other causes of death (p < 0.01). Among asphyxiation cases, ImBT was confirmed in two of five cases of typical hanging, three of 16 cases of atypical hanging, six of six cases of ligature strangulation, two of two cases of manual strangulation, eight of 38 cases of airway obstruction, and two of seven cases of oxygen deficiency. Among fire fatalities, the carboxyhemoglobin (CO-Hb) concentration of cases with ImBT was significantly lower than that in cases without ImBT (p < 0.01). In addition, the frequency of bleeding was significantly higher (p < 0.05) in cases where the blood cyanide concentration was 0.05 ppm or less. These observations suggested that ImBT during fire fatality occurs in a manner similar to that of ligature or manual strangulation, in which the flames cause the contraction and decrease in elasticity of the skin. Past reports indicated that bleeding frequency in cases of drowning did not significantly differ from that in cases with other causes of death. However, our cases showed a statistically higher incidence of bleeding compared to that in the other causes of death (p < 0.01). These results suggested that ImBT is a characteristic finding in cases of asphyxia and is an important evaluation for the diagnosis of death. When the relationship between ImBT and petechial hemorrhage was examined in three of the causes of death, no significant difference was observed between fire fatality and asphyxiation, but drowning was significantly different (p < 0.05). In cases without ImBT, the secretion of noradrenaline and adrenaline was significantly higher (p < 0.01). This finding suggests that it is unlikely that excessive secretion of catecholamine causes ImBT.