ORIGINAL ARTICLE Retrospective application of risk scores to ruptured intracranial aneurysms: would they have predicted the risk of bleeding? Carmelo Lucio Sturiale 1 & Vittorio Stumpo 2 & Luca Ricciardi 2 & Gianluca Trevisi 3 & Iacopo Valente 4 & Sonia D’Arrigo 5 & Kristy Latour 2 & Paolo Barbone 3 & Alessio Albanese 1,2 Received: 8 April 2020 /Revised: 25 June 2020 /Accepted: 14 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract As the incidental diagnosis of unruptured intracranial aneurysms has been increasing, several scores were developed to predict risk of rupture and growth to guide the management choice. We retrospectively applied these scores to a multicenter series of patients with subarachnoid hemorrhage to test whether they would have predicted the risk of bleeding in the event of aneurysm discovery previous to its rupture. Demographical, clinical, and radiological information of 245 adults were retrieved from two neurovascular centers’ database. Data were pooled and PHASES, UCAS, and ELAPSS scores were retrospectively calculated for the whole population and their performances in identifying aneurysms at risk of rupture were compared. Mean PHASES, UCAS, and ELAPSS scores were 5.12 ± 3.08, 5.09 ± 2.62, and 15.88 ± 8.07, respectively. Around half (46%) of patients would have been assigned to the low- or very low-risk class (5-year rupture risk < 1%) in PHASES. Around 28% of patients would have been in a low-risk class, with a probability of 3-year rupture risk < 1% according to UCAS. Finally, ELAPSS score application showed a wider distribution among the risk classes, but a significant proportion of patients (45.5%) lie in the low- or intermediate-risk class for aneurysm growth. A high percentage of patients with ruptured aneurysms in this multicenter cohort would have been assigned to the lower risk categories for aneurysm growth and rupture with all the tested scores if they had been discovered before the rupture. Based on these observations, physicians should be careful about drawing therapeutic conclusions solely based on application of these scores. Keywords Subarachnoid hemorrhage . Intracranial aneurysm . ELAPSS score . PHASES score . UCAS study Introduction The incidence of unruptured intracranial aneurysms (uIAs) has progressively increased over the past decades, but this observation might be only due to an increasing availability of diagnostic imaging. At the same time, neurosurgeons around the world daily cope with two apparent paradoxes regarding IAs: firstly, the prevalence of uIAs appears higher than the incidence of sub- arachnoid hemorrhage (SAH) [10]; secondly, most of rup- tured intracranial aneurysms (rIAs) are smaller than 5 mm [5], although the ISAT trial set a risk of rupture cutoff at 7 mm [13]. Possible explanations can be that rIAs and uIAs have dif- ferent characteristics; small IAs are probably much more nu- merous than large IAs in general; not all IAs tend to grow over time; some IAs present weak points in their wall; etc. However, none of these theories provided strong enough criteria to decide whether to treat a patient or not. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10143-020-01352-w) contains supplementary material, which is available to authorized users. * Vittorio Stumpo vittorio.stumpo@yahoo.it 1 Department of Neurosurgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy 2 Institute of Neurosurgery, Università Cattolica del Sacro Cuore, Rome, Italy 3 Department of Neurosurgery, Santo Spirito Hospital, Università degli Studi di Chieti-Pescara, Chieti, Italy 4 Department of Bioimaging, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy 5 Department of Anesthesiology and Intensive Care, Fodazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy Neurosurgical Review https://doi.org/10.1007/s10143-020-01352-w