Intracranial aneurysm size responsible for spontaneous subarachnoid haemorrhage

It has been theorised that the relationship between smaller body size and smaller ruptured intracranial aneurysms in Asians indirectly supports the treatment of small, unruptured intracranial aneurysms. There has also been uncertainty regarding whether the progress that has been made in neuroimaging allows for better detection of smaller ruptured intracranial saccular aneurysms. Therefore, we conducted this systemic review of ruptured intracranial saccular aneurysm sizes according to region and time.

Computerised MEDLINE and PubMed searches of the literature for population-based studies of ruptured intracranial saccular aneurysms were carried out from 1 January 1980 to 1 March 2011. Statistical analyses were generated using SPSS for Windows, Version 15.0 (SPSS Inc., Chicago, IL) and Comprehensive MetaAnalysis 2.0 for Windows (Biostat, Englewood, NJ). The results of the meta-analyses are presented with 95% confidence intervals (CIs).

Six eligible population- or hospital-based studies were analysed. The percentage of ruptured intracranial aneurysms measuring less than 5 mm was 28.4% (95% CI: 18.1% to 41.6%, I(2) = 98%). The percentage of ruptured intracranial aneurysms measuring less than 10 mm was 76.7% (95% CI: 69.2% to 82.9%, I2 = 89%). A higher proportion of patients with ruptured intracranial aneurysms of less than 5 mm was found in Asia compared to other regions. Similarly, a higher proportion of patients with ruptured intracranial aneurysms of less than 10 mm was found in Asia compared to other regions.

The present findings suggest that ruptured intracranial aneurysms are smaller in Asians and should be confirmed in future prospective international multi-centre registries to assess ethnicity. Whether these findings support treating smaller unruptured intracranial aneurysms in Asians should be investigated.