Abstract TP349: Incidence of Cerebral Ischemia Associated Seizures in Patients With Narrowing or Occlusion of the Ipsilateral Internal Carotid or Middle Cerebral Artery: The EC/IC Bypass Study

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Background: Cerebral ischemia associated seizures are well recognized in patients with internal carotid or middle cerebral artery stenosis or occlusion although the incidence is not well documented. Methods: We analyzed the data that was collected on 1377 patients with recent hemisphere strokes, retinal infarction, or transient ischemic attacks with atherosclerotic narrowing or occlusion of the ipsilateral internal carotid or middle cerebral artery who were enrolled in the EC/IC Bypass Study. The patients were followed for an average of 55.8 months and any seizures related to cerebral ischemia based on clinical and imaging criteria were ascertained. We calculated the relative risk in pre-defined patient subgroups: Age (<55 and ≥55 years), gender, presenting symptom (transient ischemic attack and ischemic stroke), allocated treatment (bypass surgery and medical treatment), site of stenosis/occlusion (internal carotid artery and middle cerebral artery), and presence or absence of hypertension and diabetes mellitus. Results: A total of 64 patients experience one or more cerebral ischemia associated seizures during follow up: first seizure was focal and generalized in 33 and 31 patients, respectively. The incidence of cerebral ischemia associated seizures was 1.7 per 100 person observation years. The relative risk of seizures was higher among patients aged <55 years (relative risk 1.36, 95% confidence interval [CI] 0.8-2.2), women (relative risk 1.1, 95% CI 0.6-2.1), with stroke as presenting symptom (RR 1.9, 95% CI 1.1-3.3), with medical group as allocated treatment (RR 1.2,95%CI 0.7-2.0), with middle cerebral artery as site of stenosis/occlusion(RR 1.13, 95% C.I 0.6-2.0), with diabetes mellitus (RR 1.7, 95% CI 0.96-3.0) or hypertension (RR 1.1, 95% CI 0.7-1.8). Conclusions: We provide the incidence of and factors affecting occurrence of cerebral ischemia associated seizures in patients with narrowing or occlusion of the ipsilateral internal carotid or middle cerebral artery