Thar she blows!
Not a whale, an intracranial aneurysm. This was a systematic review that found 26 low quality studies of unruptured intracranial aneurysm (UIA) growth and rupture risk. We have to take these results with a grain of salt because of the low quality of included studies and heterogeneity. With that in mind, they found that the growth rate for </= 3mm, 5mm, and 7mm was about 3% per year for all size categories. Rupture rates combining all studies were 0%, 0.5%, and 1% per year for the three sizes, respectively.
As CTA use increases, so does detection of small UIAs. Most are unlikely to grow, and rupture rates are low but may be up to 1% per year in larger, 7mm aneurysms.
Growth and Rupture Risk of Small Unruptured Intracranial Aneurysms: A Systematic Review. Ann Intern Med. 2017 Jun 6. doi: 10.7326/M17-0246. [Epub ahead of print]
Peer reviewed by Thomas Davis.