384: ACTINOMYCES BRAIN ABSCESS AS SEQUELAE FROM PULMONARY ARTERIOVENOUS MALFORMATION: A CASE REPORT

Abstract

Introduction: Most bacterial brain abscesses are a result of direct spread of bacteria, only a third are through hematogenous dissemination. A less common cause of hematogenous spread is via paradoxical embolism in the presence of a pulmonary arteriovenous malformation (PAVM). Currently PAVMs are not routinely screened for. Description: A 51-year-old male with past medical history of obstructive sleep apnea, and transient ischemic attack presented with left sided weakness. Initial CT head was concerning for subacute stroke. Patient’s physical exam was significant for 2/5 strength in left upper extremity, oral mucosa and skin findings were negative for telangiectasias. No significant family history reported. Initial white count negative. Worsening left sided numbness led to a repeat CT head which showed a 1.5 cm right posterior frontal/anterior mass lesion with surrounding edema. Patient underwent biopsy and drainage of brain abscess on hospital day 4, intraoperative pus was encountered. Patient was treated with ceftriaxone, metronidazole, and vancomycin. Cultures grew Actinomyces meyeri. On hospital day 8 a CT angiogram showed a PAVM in the medial middle lobe. Patient underwent right pulmonary artery angiogram on hospital day 12 which showed that the PAVM was fed by a branch of the right middle lobe pulmonary artery. After embolization follow-up angiogram showed cessation of flow through the PAVM. An MRI showed significantly less brain swelling around the cavity, based off the patient’s clinical and laboratory improvements patient was deemed stable for discharge to rehab facility on IV antibiotics. Discussion: A PAVM typically consists of afferent flow from a branch of the pulmonary artery to a branch of the pulmonary vein. Serious outcomes including strokes, seizures, and brain abscesses can arise from the right-to-left shunting of blood and paradoxical emboli. Most PAVMs are congenital associated with hereditary hemorrhagic telangiectasia, however, sporadic ones occur. Infections caused by Actinomyces are thought to induce hyperplastic changes in bronchial arteries which might lead to PAVMs. A PAVM should be considered in patients with a bacterial brain abscess and no identifiable site of infection. Treatment for PAVM include endovascular embolization vs thoracic surgery for removal.