Position-Dependent Right-to-Left Shunt Causing a Brain Abscess

A 50-year-old man suffering from generalized convulsions and right quadrantic hemianopia was admitted to the hospital. Contrast-enhanced magnetic resonance imaging showed an enhanced ring in the left parieto-occipital lobe, suggesting a brain abscess (Figure 1). The patient underwent an immediate craniotomy and drainage. Culture of pus yielded α-hemolytic streptococci. Brain abscesses are often caused by hematogenous spread of bacteria from a primary source. Although much effort was expended seeking the primary infection, the origin of the brain abscess in this patient remained unclear. After almost complete relief of his neurological symptoms, the patient was referred for further diagnostic workup in our hospital. Chest contrast-enhanced computed tomography in the arterial phase revealed an anomalous vessel bridging from …