Epidemiology of Aneurysmal Subarachnoid Hemorrhage in Shiga Prefecture, Japan: A Population-Based Study from the Shiga Stroke and Heart Attack Registry.

INTRODUCTION: Population-based data describing aneurysm location and treatment patterns in aneurysmal subarachnoid hemorrhage (SAH) remain limited in Japan. We aimed to describe the epidemiological characteristics of aneurysmal SAH using a large population-based stroke registry. METHODS: We conducted a descriptive epidemiological study using the Shiga Stroke and Heart Attack Registry, an ongoing population-based registry covering approximately 1.4 million residents of Shiga Prefecture, Japan. Among 1,056 patients with first-ever SAH identified between 2011 and 2015, 819 patients with aneurysmal SAH were included after excluding patients with multiple aneurysms in whom the ruptured lesion could not be identified and those with insufficient imaging information. Patient characteristics, aneurysm locations, treatment patterns, and discharge outcomes were summarized descriptively. RESULTS: The most common aneurysm locations were the middle cerebral artery (MCA) (26.0%), posterior communicating artery (PComA) (23.4%), and anterior communicating artery (AcomA) (22.8%). Overall, 426 patients underwent surgical clipping, 279 underwent endovascular treatment, and treatment selection differed according to aneurysm location. Surgical clipping predominated for MCA aneurysms, whereas endovascular treatment was more frequently performed for vertebrobasilar aneurysms. CONCLUSIONS: This population-based registry demonstrated a predominance of MCA, PComA, and AComA aneurysms, distinct treatment patterns according to aneurysm location, and a marked female predominance among patients with aneurysmal SAH in Shiga Prefecture, Japan. These findings provide population-based reference data for understanding the epidemiology and clinical management of aneurysmal SAH in Japan.