Fatal Intracranial Aneurysms and Dissections Causing Subarachnoid Hemorrhage: An Epidemiological and Pathological Analysis of 607 Legal Autopsy Cases.

Background: There are no detailed reports, in terms of epidemiology and pathology, on intracranial aneurysms and on dissections that were found in unexpected fatal subarachnoid hemorrhage (SAH) cases. In this report we analyzed, based on large-sized medicolegal autopsy cases, the detailed epidemiology and pathological aspects of both lesions.

Methods: We analyzed 607 autopsy cases of unexpected fatal SAHs including 496 aneurysms and 111 dissections.

Results: The following results were obtained: (1) Patients who died of dissections were younger than those who died of aneurysms; (2) symptom prevalence rates of aneurysms were 31.9%, appearing to be lower than those in previous studies; (3) a significantly higher prevalence of clinical symptoms was found in patients with dissections (60.5%) than patients with aneurysms; (4) hypertensive cardiomegaly was indicated in more than 80%, while no obvious difference in incidence in hypertensive cardiomegaly was noted between aneurysms and dissections; (5) aneurysms were found to occur much more frequently in the anterior communicating artery (31.9%) and vertebral arteries (7.5%), while dissections were found much more commonly in vertebral arteries (93.7%); and (6) the size of aneurysms was much smaller in general than that previously regarded as a risk factor of rupturing.

Conclusions: These data might help in the prompt intervention in SAH and also in the prevention of lethal SAH in clinical settings.