Our patient was a 7-year and 8-month-old boy (height: 122.1 cm, weight: 18.1 kg) with a complex congenital heart disease diagnosed as complete atrioventricular septal defect, pulmonary atresia, major aortopulmonary collateral artery, and total anomalous pulmonary venous connection with pulmonary vein stenosis. On September 8, 2020, the patient visited a general hospital (the First Hospital) due to fever and headaches. After establishing a diagnosis of multiple brain abscesses, treatment with meropenem (120 mg per kg/day), ceftriaxone (120 mg per kg/day), and vancomycin (60 mg per kg/day) was started (Fig. 1). Blood cultures were obtained. Streptococcus intermedius and Staphylococcus aureus were detected. Two weeks later, the patient showed improvement in symptoms, such as fever and headache.
However, on September 26, neurological symptoms, such as headache and numbness of the hands and feet, reappeared, for which the patient was transferred to the Second Hospital, to seek further examination and medical treatment due to exacerbation of his brain abscess and circumferential edema on magnetic resonance imaging (MRI). Meropenem (120 mg per kg/day), ceftriaxone (120 mg per kg/day), and vancomycin (60 mg per kg/day) were then started as continuation treatment (Fig. 1), followed by whole-body scanning for the identification of the fungus and source of the infection at the Second Hospital. Accordingly, MRI showed several nodular lesions in the right frontal lobe, right basal ganglia, right thalamus, and bilateral temporal lobes subcortically, with hyperintensity on the rings on T2-weighted images and hyperintensity and reduced apparent diffusion coefficient internally on diffusion-weighted images (Fig. 2). Based on MRI findings, we suspected a hematogenous infection due to multiple brain abscesses. Echocardiography showed no vegetation in the heart, whereas rereading of the positron emission tomography-computed tomography images taken at the previous hospital did not reveal any obvious source of infection in the systemic or otolaryngological areas. Blood culture were obtained and later found negative.
On September 29, the patient was referred to the Pediatric Dentistry of the Second Hospital for further examination of the source of infection in the oral region. Intraoral views showed unfavorable fillings in the maxillary right deciduous incisor remnant root, mandibular bilateral deciduous incisor late remnant, and maxillary and mandibular bilateral deciduous molars (Fig. 3A, B). Panoramic radiography showed periapical transmission and root resorption in both maxillary and mandibular deciduous molars (Fig. 3C). The causative organism of the hematogenous brain abscess was thought to have depended on the infection of the primary lesion. Examination for the causative factor at our hospital revealed no possible source other than dental infection. Therefore, apical periodontitis of deciduous teeth was considered the source of multiple brain abscesses in this case. All deciduous teeth, including those with infected lesions, were extracted under local anesthesia. The neurological symptoms and headache disappeared immediately after the extraction in late October. Although the administration of the antimicrobial agent was also completed by early November, the patient’s general condition improved considerably afterward. A head MRI performed 1 month after the extraction of the deciduous teeth showed that the brain abscess remained but was noticeably reduced (Fig. 4). The patient was discharged from the hospital on November 17, 2020, given the lack of residual disease activity and the curative course of the patient’s condition.