Size, location, and multiplicity of ruptured intracranial aneurysms in the Hong Kong Chinese population with subarachnoid haemorrhage.

To review the pattern of ruptured intracranial aneurysms in terms of size, location, and the prevalence of multiple aneurysms in the Hong Kong Chinese population with subarachnoid haemorrhage.Retrospective study.Three public hospitals in Hong Kong.A total of 267 Chinese patients with subarachnoid haemorrhage from ruptured intracranial aneurysms between July 1998 and June 2002 were reviewed retrospectively.The patients had a mean age of 59 (range, 13-96) years, with a female-to-male ratio of 2:1. Concerning the age at presentation, males presented with ruptured intracranial aneurysms at a younger age (P=0.001) than females. Ruptured aneurysms were more commonly located in the anterior than posterior circulation (84% vs 16%). The posterior communicating artery (26%) and anterior communicating artery (22%) were the most common sites of rupture. As a whole, 64% of the aneurysms had a size of 5 mm or less. The anterior communicating artery had a higher proportion with a size of 5 mm or less compared to other locations (P<0.05). In this cohort, the prevalence of multiple aneurysms was 17%. There was no significant difference in the prevalence of multiple aneurysms between men and women (P=0.30). In patients with multiple aneurysms, the sizes of ruptured aneurysms were greater than those of the largest unruptured aneurysms (P<0.001). When compared with the group with single aneurysms, patients with multiple aneurysms had a smaller proportion of small aneurysms, sized 5 mm or less (P<0.05).The pattern of ruptured intracranial aneurysms in the Hong Kong Chinese population was different from western and Japanese populations. Although the distribution of locations for ruptured aneurysms was similar, Hong Kong Chinese had a larger proportion of small aneurysms sized 5 mm or less. The prevalence of multiple aneurysms in Hong Kong is comparable to that in the Japanese population, but lower than that in the western populations.