OBJECTIVE: The size of unruptured intracranial aneurysms (UIA) remains the most crucial risk factor for treatment decisions. On the other side, there is a non-negligible portion of small ruptured IA and large stable UIA. This study aimed to identify the patients' characteristics related to IA size in the context of IA rupture status.

METHODS: A total of 2152 patients, with 1002 being hospitalized for an acute aneurysmal subarachnoid hemorrhage (SAH), were included from our institutional IA database. Different demographic and clinical characteristics of patients and IA were collected. IA size was the study endpoint, assessed as continuous variable in univariate and multivariable linear regression analysis, separately for ruptured (R) IA and UIA.

RESULTS: The mean IA size was 8.3 and 7.3 mm in the UIA and RIA subpopulations, respectively. Higher age (p = 0.003) and baseline blood urea level (p < 0.001) were independently associated with increasing UIA size. In contrast, location at the posterior circulation (p < 0.001), familiar intracranial aneurysms (p < 0.001), serum potassium (p = 0.006), and total serum protein (p = 0.019) were related to smaller UIA size in the multivariate analysis. For RIA, a statistically significant and independent association was detected for location (p = 0.019), history of gastrointestinal diseases (p = 0.042), and levothyroxine intake (p = 0.002).

CONCLUSIONS: Identification of clinical characteristics related to the size of ruptured and unruptured IA allows a more differentiated view on the genesis of RIA and UIA and the value of sack size as a basis for therapeutic decision-making. More research is needed to verify the identified risk factors.