POSTERIOR CIRCULATION INFARCTS SIMULATING ANTERIOR CIRCULATION STROKE- PERSPECTIVE OF THE ACUTE-PHASE

Background and Purpose Ischemic stroke patients whose initial clinical presentation suggests an involvement of the anterior circulation (AC) are sometimes found to have a posterior circulation (PC) infarct, a f act that may generate erroneous decisions in clinical management. We i nvestigated the prevalence of this misdiagnosis in the first few hours after stroke onset. Methods We performed a cohort study of 158 patien ts hospitalized within 5 hours of onset of a presumed AC ischemic stro ke, as diagnosed on clinical grounds.Results Final CT or pathology dia gnosis was AC infarct in 128 patients (81%), a repeatedly negative CT in 14 (9%), PC infarct (5 pens, 1 midbrain and cerebellum, 6 supratent orial territory of the posterior cerebral artery) in 12 (8%), and othe r or undiagnosed lesions in 4 (3%). AC and PC stroke patients did not differ in terms of age, vascular risk factors, and initial severity, b ut the latter were more frequently men (83% versus 53%; P=.04), were h ospitalized later (mean +/- SD, 168 +/- 86 versus 109 +/- 55 minutes; P=.001), and presented a pure motor hemiparesis or a sensorimotor stro ke (50% versus 33%) more often than their counterparts. At baseline CT , PC stroke patients never exhibited an early parenchymal hypodensity in the carotid territory or a hyperdense middle cerebral artery, which were instead found in 59% (P=.0003) and 31% (P=.02) of AC stroke pati ents, respectively. Early neurological deterioration, 1 month case-fat ality rate, and disablement in survivors were comparable in the two gr oups. Conclusions Shortly after onset the clinical discrimination betw een AC and nontypical PC infarcts is not reliable, which explains the frequent occurrence of this misdiagnosis. Emergency CT scan helps in t he differential diagnosis only when it demonstrates an early focal hyp odensity within the carotid territory.