An uncommon case of congenital thoracic venous anomaly and extracardiac sinus venosus defect in an asymptomatic adult first presenting with brain abscesses: a case report

BACKGROUND: Congenital thoracic venous anomalies (CTVAs) with right-to-left shunt constitute an uncommon source of paradoxical embolization in adults. We present a case of a healthy and physically fit individual with a rare asymptomatic anomaly first presenting with brain abscesses after a visit to the dental office; persistent left superior vena cavae (PLSVC) without bridging vein, over-riding right-sided superior vena cavae (RSVC) connected to the left atrium (LA), and an extracardiac sinus venosus defect. CASE SUMMARY: A 29-year-old male presented to the neurosurgical unit due to intracranial abscesses requiring intervention following a visit to his dentist. The abscess cultures isolated bacteria commonly found in the normal oral flora. Transthoracic echocardiography revealed an enlarged coronary sinus consistent with PLSVC. An agitated saline study was performed and raised suspicion of simultaneous extra- and intracardiac shunting. Magnetic resonance angiography confirmed the presence of a PLSVC and revealed an RSVC connected to the LA; however, no intracardiac shunt was evident. Electrocardiogram-gated computed tomography was therefore conducted and discovered the rudimentary remains of the physiologic RSVC forming a connection to the right atrium, explaining the bilateral contrast loading seen on the agitated saline study and diagnosing an extracardiac sinus venosus defect (SVD). The patient recovered and has been referred for surgery. DISCUSSION: This case illustrates a CTVA and a forme fruste type SVD resulting in a severe complication in a healthy adult. We highlight the diagnostic challenges posed, suggest early usage of agitated saline studies, and discuss the rationale for surgical correction of this patient.