Non-traumatic rupture of the intracranial vertebral artery of a man found dead in a severe car accident – Histopathological differentiation by step-serial sections

Abstract A 58-year-old male with untreated hypertension was found dead in his car after a traffic accident on his way to the office. Emergency head CT showed diffuse subarachnoid hemorrhage at cerebral base. On autopsy examination, traumatic injuries were seen on his face and lower extremities. The skull was not fractured and there were no brain contusions except subscalp bleeding at the frontal head. The brain weighed 1510g and showed diffuse subarachnoid hemorrhage due to a rupture of the left vertebral artery (VA). Histopathological examination using serial step sections of every 0.1mm of the whole VA revealed multiple arterial dissections (AD) with fresh and old states at bilateral VA. Previous dissections at the basilar artery and internal carotid artery were also observed. The symptoms that he reported a week before the accident, left sided headache and shoulder pains, could have come from previous dissections. We concluded that the AD occurred while driving and was the cause of death, with the car accident then being caused by the stroke. Other specific histopathological findings were medial degeneration and serrate changes of the internal elastic lamina which resembled lesion of the segmental arterial mediolysis. These would suggest a pathogenesis of intracranial AD. Differential diagnosis of subarachnoid hemorrhage from the ruptured VA, distinguishing between idiopathic AD and traumatic trilaminar rupture, is still a difficult matter in forensic autopsy. However, this serial step sections procedure could be useful for the morphological differentiation.