Histological examination of carotid artery tissue in cases of ligature strangulation and hanging

Violence against the neck can result in a range of macromorphological and micromorphological findings. However, the forensic relevance of the carotid sinus in cases of violence against the neck remains controversial. In this follow-up study of 22 cases of suicidal and accidental strangulations, carotid bifurcations were examined histologically for morphological changes implying direct trauma, including haemorrhage and immunohistochemical expression of heat-shock proteins 27, 60, and 70 and aquaporin-3. These cases were compared with a control group (82 cases) without neck compression or head trauma and with variable causes of death. No relevant histopathological findings implying direct trauma of the carotid bifurcation were found. No cases showed positive aquaporin-3 staining and only five cases showed positive heat-shock protein-27 staining, all of which were hangings. Without massive trauma of the carotid bifurcation, histological alterations cannot be expected. Without signs of rapid death, findings of acute circulatory failure, macromorphological and micromorphological findings of neck compression, and reliable markers indicating relevant impact on the carotid bifurcation the diagnosis of a lethal reflex cannot be verified.

Key points

• Among 22 cases of strangulation causing death, there were 16 cases of hanging and 6 cases of ligature strangulation
• Few cases showed small haemorrhages located predominantly in the surrounding fat and connective tissues; however, the haemorrhages did not have any effects on the tissues
• Neck compression had minimal effects on heat shock protein 27 expression in carotid artery tissue
• Aquaporin-3 staining suggested it is not a useful marker for relevant neck pressure, or that there had not been any relevant neck impact
• Our findings suggested no direct evidence for reflex cardiac death resulting from a brief force against the neck