[Music] now going into their natural history and again this is how we decide whether or not to treat these aneurysms if you're deciding if anything in supervisors use am i going to treat it or not the first question asked is what is the natural history and i'm going to talk about two very important natural history studies so the first is isuia the international study of unruptured cranial aneurysms the study was almost 20 years old now this was a prospective evaluation of a cohort of aneurysms but it's important to emphasize that this was a selected cohort of aneurysms where they decided some of them were treated and excluded from the analysis and others were included so you already have some selection bias where uh perhaps high-risk aneurysms are treated now initially there's sort of a notoriously studied prior isuia study the retrospective study that was published in journal in 1998 that quoted an extremely low rupture risk for cerebral aneurysms that is really no longer accepted today just to briefly state they cited a 0.05 for your risk of aneurysms risk of rupture for aneurysms less than 10 millimeters which is which is just inaccurate i put this slide up almost for historical purposes so this is the prospective component that was published in lancet uh they looked at aneurysms over a seven year period although the majority were for the last two years of the collection period uh from over 53 centers uh and again this study did have patients that were treated you can see more patients were treated than were observed but about 1 692 patients did not have aneurysm repair and they were followed over a mean follow-up of 4.1 years uh stratified in group one whether there was subarachnoid hemorrhage from another aneurysm group two if they had several damage from another aneurysm and the patients were removed from follow if they were treated or if they passed away and so this is really sort of the money slide from isuia uh so basically 51 patients three percent ruptured um you can see the mortality from rupture was 65 uh and these are and so this chart is the five-year rupture rate so a lot of people annualize rupture rates so you have to actually divide these numbers by five um so patients without a subarachnoid hemorrhage actually if they had anti-circulation mca or ic aneurysm were quoted as having a quote zero percent risk of rupture of less than seven millimeters this is a highly biased cohort though where patients with perhaps irregularities or higher risk small aneurysms were probably treated um so the actual risk is not zero percent but in this study they quote zero percent if you had a poster circulation or poster communicating artery aneurysm that was less than seven millimeters your risk of rupture was zero point five percent per year or two point five percent over five years and everyone can sort of review or take a snapshot of this chart you can see they went up to seven to twelve millimeters and thirteen to twenty four millimeters and if you had a giant aneurysm in the posterior circulation or the p com the risk of rupture was fifty percent over five years or annualized that's ten percent and they found that basil apex location uh t-con location were higher risk factors for rupture and obviously cavernous aneurysms unless they're extremely large or extra durable and thus don't have a risk of rupture perhaps a more applicable study although it was exclusively done in japan as the natural course of unruptured struggle aneurysms in a japanese core study where ucas studied published in the indian journal about a decade ago this was a study of over 5 000 patients um you can see the selection here of the patients uh and they included sacular aneurysms that released three millimeters and they looked at a variety of risk factors associated with ruptured follow-up they found that an irregularity or daughter sac was a significant risk factor that always intuitively guides our treatment they found that size was a risk factor they found that acom location was a significant risk factor for rupture as was key calm location as well on the verge of lower risk for ica non-pecan aneurysms we'll talk about that in a little bit more detail they found however that another aneurysm of subarachnoid hemorrhage smoking family history and multiple aneurysms were not significant risk factors although these have borne out in other studies to be significant risk factors for hemorrhage so the overall annual rupture rate was about one percent this study that's just a a crude rough estimate that people generally quote for aneurysms if they say what's the risk factor risk of aneurysm rupture per year it's about one percent per year although admittedly it's a lot lower for small ica aneurysms uh and so the morbidity and mortality in this study from rupture was 29 and 35 respectively and this is a really useful table that i've exerted below you can see that acom aneurysms that were only three or four millimeters had almost a one percent risk of rupture per year that was really the highest risk of rupture per year but what's really also interesting is if you look at both the three to four and five to six millimeter cohort the acom location the p com location and this undesignated other cohort um were probably the highest risk locations and what's interesting is this other cohort was largely comprised and those distal aca aneurysms that i allude to are actually sneaky high risk they generally don't get very large they don't grow to seven to nine or ten millimeters because they generally rupture before they get to that point so there is some clandestine evidence from this study or suggestion from the study i should say that that pericolosal aneurysms in addition to acom and pecan aneurysms are higher risk aneurysm locations and you can see the risk of rupture bearing out i'm not going to say every single percent you can look at how malignant large p common acom aneurysms are uh in addition to the steep rise in risk of rupture for basilar tip or basilar sca aneurysms as well um and this was just a little a far less significant study of of my own that that i did when i was a resident that that stratified aneurysms locations by presentation and just even parsed out location and risk of rupture even more uh and so the lowest risk we found was superior hypothesial aneurysms and you can see supereposeals at the top and was really the lowest risk location uh lower risk locations included ica bifurcation ophthalmic aneurysms and then sort of getting up there were the pecan the acom and again here the colossal uh aneurysms as well so this is just again a detailed review of aneurysm location and risk of rupture as it relates to that so to answer our question to treat or not to treat what is the natural history right so ruptured aneurysms have an extremely high risk of redirection so we treat them across the board symptomatic aneurysms those that are large enough or regular enough to cause third nerve palsies or vision loss are treated across the board their thoughts have a very bad natural history but other factors so the patient is very elderly the relevance of of a one percent or less risk of rupture per year is is becomes a lot more a lot less significant rather than someone who is perhaps very young with perhaps a more innocuous looking aneurysm so i do factor in age when i decide whether to treat an unruptured aneurysm or not size is also a factor i generally treat most aneurysms more than seven millimeters they're less than five millimeters i look for other factors that would push me to treat such as an irregularity or something but otherwise i usually use that as a cut off towards conservative management as i've mentioned in detail location is very relevant so super apophysial aneurysms and ophthalmic artery aneurysms unfortunately they are definitely over treated i think in this day and age because people like to put flow diverters across them but they generally tend to be fairly low risk aneurysms for a lot of patients so unless they're irregular and so forth they can often be observed on the other hand even small a common prairie colossal aneurysms tend to be high risk and we should probably have a lower threshold to treat these aneurysms and certainly if the aneurysm harbors an irregularity that should be treated so this is an example of an ica terminus aneurysm in a patient they've been lost a follow-up that had been treated for contralateral injury hey everyone ryan rad here from neurosurgerytraining.org if you like that video subscribe and donate to keep our content available for medical students across the world