Patients with spontaneous cervicocranial dissection (SCCD) may experience new or recurrent ischemic events despite antiplatelet or anticoagulant therapy. Treatment with stent placement is an available option; however, the literature on patient selection is limited. Thus, identifying patients at high risk for neurologic deterioration after SCCD is of critical importance. The present study examined the rate of neurologic deterioration in medically treated patients with SCCD and evaluated demographic, clinical, and radiologic factors affecting this deterioration. We retrospectively identified consecutive patients with SCCD over a 7-year period from 3 medical institutions, and evaluated the relationships between demographic data, clinical characteristics, and angiographical findings and subsequent neurologic outcomes. Neurologic deterioration was defined as transient ischemic attack (TIA), ischemic stroke, or death occurring during hospitalization or within 1 year of diagnosis. Kaplan-Meier curves were used to determine neurologic event-free survival up to 12 months. A total of 69 patients (mean age, 47.8 +/- 14 years; 45 males) with SCCD were included in the study. Eleven patients (16%) experienced in-hospital neurologic deterioration (TIA in 9, ischemic stroke in 1) or death (1 patient). An additional 8 patients developed neurologic deterioration within 1 year after discharge (TIA in 5, ischemic stroke in 2, and death in 1). The overall 1-year event-free survival rate was 72%. Women (P = .046), patients with involvement of both vertebral arteries (P = .02), and those with intracranial arterial involvement (P = .018) had significantly higher rates of neurologic deterioration. Our findings indicate that neurologic deterioration is relatively common after SCCD despite medical treatment in women, patients with bilateral vertebral artery involvement, and those with intracranial vessel involvement.