Detection of unruptured cerebral aneurysms in healthy population and its significance for prevention of subarachnoid hemorrhage

Recent studies have shown that the true incidence of the SAH reaches approximately population/year, in the case that the elderly population of over 50 years of age is counted. Likewise, a higher incidence of the unruptured cerebral aneurysms (UCA) should be anticipated within the adult population. We performed screening studies using the MRA for UCA in healthy adult populations and confirmed the high incidence of UCA. The 3D-CTA was used for confirmation. In our study of 840 individuals we found an incidence of the UCA of 5.8%. It was 7.4% in females and 5.0% in males. The incidence increased with age, but there was a peak in the 40s, suggesting a dual nature of UCA formation. Sixty percent of UCA were less than 5 mm in diameter. The family history of SAH was the sole significant risk factor with a risk of 12%. The operation for UCA outnumbered ruptured aneurysms since this health check has been commenced. The morbidity was less than 2% with no mortality. A study in Kushiro City showed a decrease of the SAH in the recent 3 years of oral along with a rapid increase of operations for UCA since 1992. Current status of the finding of an UCA in the healthy individual in Japan and its significance for the preventing of a SAH will be discussed.