Abstract
The occurrence of intracranial aneurysm in Nagasaki Prefecture has been studied since 1979 when subarachnoid hemorrhage started to be diagnosed correctly by computed tomographic scan. The incidence of aneurysmal patient was 8 per 100 thousands habitants in the first three years when neurosurgical survices were avairable only in major hospital. The incidence dramatically increased following years when another 7 hospitals began to serve for neurosurgical clinic, which considered to be covered all over the prefecture. The incidence increased to 16.6 per 100 thousands habitants in the end of 1990.
The unruptured aneurysm which was not related to another ruptured aneurysm, arteriovenous malformation and Moyamoya disease increased to be detected in recent years. The incidence of unruptured aneurysm was about 10% of all intracranial aneurysm in the end of 1990, however, most of them were detected as to be symptomatic aneurysm. Since the operative result in the unruptured aneurysm has been better than that in the ruptured aneurysm, we need further effort to detect the asymptomatic unruptured aneurysm by using computerized angiotomography and/or magnetic resonance angiography.
