Abstract 63: Basilar Artery Occlusion due to Vertebral or Basilar Dissection in the Basilar Artery International Cooperation Study (BASICS)

Abstract

Introduction: Since there are few reports of patients with stroke secondary to basilar artery occlusion (BAO) due to dissection, there are scarce data on its risk factors, clinical presentation, prognosis and best treatment options. Methods: The Basilar Artery International Cooperation Study (BASICS) was a large prospective, observational registry of consecutive patients who presented with an acute symptomatic BAO. We assessed clinical, radiological and therapeutical data of patients with BAO secondary to radiologically confirmed vertebral or basilar artery dissection. Stroke severity at time of treatment was dichotomized as severe (coma, locked-in state, or tetraplegia) or mild to moderate (any deficit that was less than severe). Outcome was assessed at 1 month. Poor outcome was defined as a modified Rankin scale score of 4 or 5, or death. Patients were divided into three groups according to the treatment they received: antithrombotic treatment only (AT), which comprised antiplatelet drugs or systemic anticoagulation; primary intravenous thrombolysis (IVT), including subsequent intra-arterial thrombolysis; or intra-arterial therapy (IAT), which comprised thrombolysis, mechanical thrombectomy, stenting, or a combination of these approaches. Results: In 32 (5.4%) of 592 patients with BAO, the stroke etiology was dissection. Twenty patients were men, mean age was 45.2 (± 12.7 SD) years. Fourteen patients had no vascular risk factors. Seven patients were current smokers; history of hypertension was present in 4, of dyslipidemia in 4 and other risk factors in 6 patients. Prodromal symptoms (e.g. headache, neck pain, vomiting) were present in 24 patients. History of TIA prior to BAO was recorded in 5 patients and minor stroke in 9. Twenty one patients had a progressive stroke, in 6 symptoms fluctuated and 4 presented with a maximum deficit from onset. Deficits at time of treatment were severe in 22 patients and mild to moderate in 10. Initial CT scan was normal in 9 patients, 13 had a dense basilar sign and 13 presented with early ischemic changes. In most (20) patients the BAO was in the proximal third, in 8 it was located in the distal third and in 4 in the middle third. Eleven patients were treated with only AT (3 antiplatelets, 8 anticoagulation), 9 with IVT and 12 with IA. Three patients- all treated with IA - had symptomatic hemorrhage. Overall, 18 (56%) patients had a poor outcome (AT 9 of 11, IVT 2 of 9, IA 7 of 12, p=0.03, Fisher’s exact test). Conclusions: Dissection is a rare cause of BAO that affects mainly younger patients, with few or no vascular risk factors. Patients often present with prodromal symptoms, and a progressive stroke. Initial CT changes are common and the proximal third of the basilar artery is the main localization of occlusion. As in other causes of BAO, prognosis is poor and in this registry patients treated with IVT had a lower rate of poor outcome.