Paradoxical brain embolism may not be uncommon-Prospective study in acute ischemic stroke

Abstract Background Proving that right-to-left shunt (RLS) represents the precise causative mechanism in ischemic stroke patients with RLS is difficult. The aim of this study was to examine the frequency and clarify the clinical characteristics of paradoxical brain embolism (PBE). Methods We prospectively enrolled consecutive acute ischemic stroke patients, who underwent transcranial Doppler and/or transesophageal echocardiography. For patients with RLS, diagnostic criteria for PBE were established as follows: 1) brain images suggesting embolic strokes; 2) presence of deep venous thrombus or pulmonary embolism; and 3) absence of any embolic sources. Patients were divided into 4 groups: patients meeting all 3 criteria (Definite); fulfilling 2 criteria (Probable); fulfilling 1 or 0 criteria (Possible); and patients without RLS (Non-RLS). Results A total of 240 subjects were analyzed for this study. The Definite group comprised 5% of patients, and displayed significantly more females (p = 0.038), and infarcts involving both anterior and posterior circulations (p < 0.001). Patients having neither hypertension nor diabetes mellitus also predominantly belonged to the Definite group (p < 0.001). Conclusions Clinical characteristics of PBE are a female preponderance, infarcts affecting both anterior and posterior circulations, and an absence of risk factors.