A Risk Score for Neurological Complications following Endovascular Treatment of Unruptured Intracranial Aneurysms

The prevalence of unruptured intracranial aneurysms (UIAs) is estimated at 1% to 7%. Acute UIA rupture is associated with 30% to 67% mortality and 15% to 30% morbidity. Endovascular coiling and surgical clipping are the primary treatments for UIAs. The proportion of UIAs treated endovascularly has increased substantially in recent decades because detachable coils were introduced and the International Subarachnoid Aneurysm Trial (ISAT) results were published. However, endovascular treatment of UIAs has the potential to cause life-threatening neurological complications. In the Analysis of Treatment by Endovascular Approach of Nonruptured Aneurysms (ATENA) series, the incidence of neurological complications, including transient or permanent neurological deficits or death, was 5.4%. Several studies have proposed scales to evaluate the risk of neurological complications for UIA management, such as the Massachusetts General Hospital grade and the UIA treatment score. These scales are easy to apply but are primarily derived from surgical treatment of UIAs or indirectly from published data. Furthermore, definitions of neurological complications in these scales do not include transient neurological deficits, such as transient ischemic attack, or epilepsy, which may influence decision-making on UIA management. Clinical parameters, including age, aneurysm size, location, history of ischemic stroke, and stentor balloon-assisted coiling, have been shown to be associated with neurological complications after UIA management. However, currently no reliable scoring system is available to predict the risk of neurological Background and Purpose—Procedure-related neurological complications are common after endovascular treatment of unruptured intracranial aneurysms. We aimed to develop a score to quantify individual patient risk. Methods—We retrospectively analyzed consecutive patients who underwent endovascular treatment for unruptured intracranial aneurysms between January 2012 and September 2015. After excluding those who lost to followup and those with fusiform unruptured intracranial aneurysms, included patients were randomly divided into a derivation group (60%) and a validation group (40%). A neurological complication was defined as any transient or permanent increase in the modified Rankin Scale score after aneurysm embolization. A risk score for neurological complications was derived from multivariable logistic regression analyses in the derivation group and validated in the validation group. Results—Overall, 1060 patients were included (636 in the derivation group and 424 in the validation group). The incidence of neurological complications was 5.5% (95% confidence interval, 3.8%–7.4%). A 3-point risk score (S-C-C) was derived to predict neurological complications (size [≥10 mm=1], core areas [yes=1], and cerebral ischemic comorbidity [yes=1]). The incidence of neurological complications varied from 2.2% in 0-point patients to 25.0% in 3-point patients. The score demonstrated significant discrimination (C-statistic, 0.714; 95% confidence interval, 0.624–0.804) and calibration (McFadden R, 0.102) in the derivation group. Excellent prediction, discrimination, and calibration properties were reproduced in the validation group. Conclusions—One in 20 patients will develop neurological complications after endovascular treatment of unruptured intracranial aneurysms. The S-C-C score may be useful for predicting these adverse outcomes based on variables in daily practice. (Stroke. 2016;47:971-978. DOI: 10.1161/STROKEAHA.115.012097.)