Ischemic events associated with unruptured intracranial aneurysms: Multicenter clinical study and review of the literature

OBJECTIVE: To determine the prevalence, clinical characteristics, and long- term outcomes in cases involving transient ischemic attacks (TIAs) or ische mic strokes secondary to embolization from unruptured intracranial aneurysm s. METHODS: We identified all available patients with intracranial aneurysms a nd ischemic strokes in three university-affiliate hospitals, using either I nternational Classification of Diseases-9th Revision codes or local registr ies. Patients with clinically or radiologically detected cerebral infarctio ns distal to intracranial aneurysms, in the absence of other causes for the infarctions, were included. An aneurysmal embolic source was considered hi ghly probable by the primary neurosurgeon/ neurologist in all cases. Follow -up data for the patients were acquired through reviews of clinical visits or telephone interviews. A review of the literature was performed to identi fy characteristics of previously reported patients. RESULTS: Ischemic strokes or TIAs attributable to embolization from the ane urysmal sac were observed for 9 of 269 patients (3.3%) with unruptured aneu rysms. Of these nine patients, five were women and four were men (mean age, 62 yr; age range, 45-72 yr). Symptomatic aneurysms were located in the mid dle cerebral artery (n = 4), internal carotid artery (n = 3), posterior cer ebral artery (n = 1), or vertebral artery (n = 1). The mean maximal diamete r was 12.5 mm (range, 5-45 mm). Six patients underwent surgical treatment, of whom two experienced postoperative cerebral infarctions referable to the distribution of the artery harboring the aneurysm. Two patients were treat ed with aspirin, and one patient received no treatment. The mean follow-up period was 38 months (range, 1-60 mo). None of the patients experienced add itional ischemic events during the follow-up period. Among the 41 previousl y reported patients, conservative treatment was used for 20 patients (mean follow-up period, 50.7 +/- 44.5 mo). Four of the 20 patients experienced re current TIAs, 1 patient experienced worsening of symptoms, and 1 patient di ed during the follow-up period. A total of 21 patients underwent surgical t reatment (mean follow-up period, 33.6 +/- 32.3 mo). Of these patients, only one experienced recurrent TIAs. Two patients experienced postoperative sei zures, and one patient died during the follow-up period. All recurrent symp toms with either surgical or conservative treatment were transient, and no patient experienced a major or disabling stroke during the follow-up period . CONCLUSION: Ischemic events can occur distal to both small and large unrupt ured intracranial aneurysms (predominantly in the anterior circulation). Th e long-term risk of recurrent ischemic events, particularly major or disabl ing strokes, seems to be low with either surgical or conservative treatment .