Background and Purpose Knowledge about different etiologies of non-traumatic intracerebral hemorrhage (ICH) and their outcomes is scarce.Methods We assessed prevalence of pre-specified ICH etiologies and their association with outcomes in consecutive ICH patients enrolled in the prospective Swiss Stroke Registry (2014 to 2019). Results We included 2,650 patients (mean±standard deviation age 72±14 years, 46.5% female, median National Institutes of Health Stroke Scale 8 [interquartile range, 3 to 15]). Etiology was as follows: hypertension, 1,238 (46.7%); unknown, 566 (21.4%); antithrombotic therapy, 227 (8.6%); cerebral amyloid angiopathy (CAA), 217 (8.2%); macrovascular cause, 128 (4.8%); other determined etiology, 274 patients (10.3%). At 3 months, 880 patients (33.2%) were functionally independent and 664 had died (25.1%). ICH due to hypertension had a higher odds of functional independence (adjusted odds ratio [aOR], 1.33; 95% confidence interval [CI], 1.00 to 1.77; P=0.05) and lower mortality (aOR, 0.64; 95% CI, 0.47 to 0.86; P=0.003). ICH due to antithrombotic therapy had higher mortality (aOR, 1.62; 95% CI, 1.01 to 2.61; P=0.045). Within 3 months, 4.2% of patients had cerebrovascular events. The rate of ischemic stroke was higher than that of recurrent ICH in all etiologies but CAA and unknown etiology. CAA had high odds of recurrent ICH (aOR, 3.38; 95% CI, 1.48 to 7.69; P=0.004) while the odds was lower in ICH due to hypertension (aOR, 0.42; 95% CI, 0.19 to 0.93; P=0.031).Conclusions Although hypertension is the leading etiology of ICH, other etiologies are frequent. One-third of ICH patients are functionally independent at 3 months. Except for patients with presumed CAA, the risk of ischemic stroke within 3 months of ICH was higher than the risk of recurrent hemorrhage.

Background and purposeRisk factors for IS in young adults differ between genders and evolve with age, but data on the age‐ and gender‐specific differences by stroke etiology are scare. These features were compared based on individual patient data from 15 European stroke centers.MethodsStroke etiology was reported in detail for 3331 patients aged 15–49 years with first‐ever IS according to Trial of Org in Acute Stroke Treatment (TOAST) criteria: large‐artery atherosclerosis (LAA), cardioembolism (CE), small‐vessel occlusion (SVO), other determined etiology, or undetermined etiology. CE was categorized into low‐ and high‐risk sources. Other determined group was divided into dissection and other non‐dissection causes. Comparisons were done using logistic regression, adjusting for age, gender, and center heterogeneity.ResultsEtiology remained undetermined in 39.6%. Other determined etiology was found in 21.6%, CE in 17.3%, SVO in 12.2%, and LAA in 9.3%. Other determined etiology was more common in females and younger patients, with cervical artery dissection being the single most common etiology (12.8%). CE was more common in younger patients. Within CE, the most frequent high‐risk sources were atrial fibrillation/flutter (15.1%) and cardiomyopathy (11.5%). LAA, high‐risk sources of CE, and SVO were more common in males. LAA and SVO showed an increasing frequency with age. No significant etiologic distribution differences were found amongst southern, central, or northern Europe.ConclusionsThe etiology of IS in young adults has clear gender‐specific patterns that change with age. A notable portion of these patients remains without an evident stroke mechanism according to TOAST criteria.