Brain abscess commonly occurs secondary to an adjacent infection (mostly in the middle ear or paranasal sinuses) or due to hematogenous spread from a distant infection or trauma. Pulmonary arteriovenous fistulas (AVFs) are abnormal direct communications between the pulmonary artery and vein. We present two cases of brain abscess associated with asymptomatic pulmonary AVF. A 65-year-old woman was admitted with a headache and cognitive impairment that aggravated 10 days prior. An magnetic resonance (MR) imaging revealed a brain abscess with severe edema in the right frontal lobe. We performed a craniotomy and abscess removal. Bacteriological culture proved negative. Her chest computed tomography (CT) showed multiple AVFs. Therapeutic embolization of multiple pulmonary AVFs was performed and antibiotics were administered for 8 weeks. A 45-year-old woman presented with a 7-day history of progressive left hemiparesis. She had no remarkable past medical history or family history. On admission, blood examination showed a white blood cell count of 6290 cells/uL and a high sensitive C-reactive protein of 2.62 mg/L. CT and MR imaging with MR spectroscopy revealed an enhancing lesion involving the right motor and sensory cortex with marked perilesional edema that suggested a brain abscess. A chest CT revealed a pulmonary AVF in the right upper lung. The pulmonary AVF was obliterated with embolization. There needs to consider pulmonary AVF as an etiology of cerebral abscess when routine investigations fail to detect a source.
The cerebral abscess is a common central nervous system infection that can result from trauma, hematogenous spread, or spread from an adjacent infection such as otitis media or sinusitis. Despite exhaustive searches, 15 to 30% of abscesses are termed cryptogenic when no source of infection is identified
A 65-year-old woman was admitted with a 1-month history of headache and cognitive impairment that had become aggravated 10 days prior. She showed impairment in orientation and judgment, but there were no lateralization signs of motor paralysis or cranial nerve deficits. Her past medical history was unremarkable except for intermittent medication for hypercholesterolemia. There was no history of diabetes mellitus, hypertension, lung disease or heart disease. There was no sinusitis or ear infection. Her blood pressure was 110/70 mmHg, pulse rate was 74/min, body temperature was 36.5°C, and her respiration rate was 20 breaths/min. Hb/Hct was 14.5 g/dL/41.6%. Erythrocyte sedimentation rate was 54 mm/h and C-reactive protein (CRP) was 0.22 mg/L. Arterial blood gas analysis revealed a pH of 7.425, pCO2 of 42.5 mmHg, pO2 of 90.4 mmHg, and an HCO3 of 22.2 mmoL/L on room air. Total cholesterol was 249 mg/dL and LDL-cholesterol was 172 mg/dL. Blood glucose was 117 mg/dL. Thyroid hormone and pulmonary function tests were all within normal range. Echocardiography showed normal global left ventricular systolic function. Brain computed tomography (CT) showed a mass with perilesional edema on the right frontal lobe. Brain magnetic resonance (MR) imaging revealed a 4×3-cm ring enhanced mass in the right frontal lobe, which was associated with severe edema and midline shifting to the left side (
A 45-year-old woman presented with a 7-day history of a progressive left hemiparesis. She had no remarkable past medical history or family history. On admission, blood tests showed a Hb of 13.4 g/dL, an Hct of 39.6%, a white blood cell (WBC) count of 6290 cells/μL, and a CRP elevated to 2.62 mg/L. Liver function tests were within normal range. Blood glucose was 101 mg/dL. There were no systemic or focal infection signs. Diffusion MR imaging showed a diffusion-restricted ovoid mass on the right motor and sensory cortex measuring 1.5×0.9 cm that was surrounded by diffuse vasogenic perilesional edema (
Cryptogenic brain abscesses can occur due to rare diseases that are not addressed in routine clinical practice. Congenital cyanotic heart disease
The incidence of idiopathic pulmonary AVF-related CNS complications is between 19 and 59 %
The most likely mechanism for these neurological events is a paradoxical embolism across the pulmonary AVF or across a coexisting cerebral arteriovenous malformation in patients with HHT
The fundamental defect that we found was a right-to-left shunt from the pulmonary artery to the pulmonary vein, and the degree of shunting determines the clinical effects. If shunting is minimal, cyanotic symptoms are usually absent. If the right-to-left shunt is greater than 20% of the systemic cardiac output, or if there is reduction of hemoglobin by more than 50 g/L, the patient will have obvious cyanosis, clubbing, and polycythemia
A literature review (
The organisms in the brain abscess were not consistent but most frequently isolated ones were streptococci genus. 6 cases out of 13 did not reveal an organism at all.
If young adults without a premorbid history present with a brain abscess, pulmonary problems must be evaluated.
This report highlights the need to consider pulmonary AVF as an etiology of cerebral abscess when routine investigations fail to detect a source. Diagnosis can be confirmed through thoracic CT or pulmonary angiography.
Brain magnetic resonance imaging of case 1. A 4×3-cm ring-enhanced mass in the right frontal lobe, which was associated with severe edema and midline shifting to the left side (A). Diffusion restriction of the enhancing area suggests that the lesion is an abscess (B).
Chest computed tomography (A) and angiography (B) of case 1. Fistulous vascular abnormality on the left lower lung field (A). A catheter is used to perform embolization (white arrow). Another lesion on the left upper lung field was already embolized with coils (black arrow; B).
A 45-year-old woman (case 2) presented with a 7-day history of a progressive left hemiparesis. Enhanced brain magnetic resonance (MR) imaging shows a well-enhancing ovoid mass on the right motor and sensory cortex measuring 1.5×0.9 cm (A). Diffusion weighted MR reveals restriction of the mass (B).
Chest computed tomography (A) and angiography (B) of case 2. Fistulous dilatation of the pulmonary vasculature on the right upper lung field (A). The lesion is approached with a catheter to perform embolization. It was a single lesion (B).
Brain abscess cases caused by idiopathic pulmonary arteriovenous fistulas
Authors and year | Age | Sex | Symptoms of pulmonary AVF | Multiplicity of AVF | Multiplicity of brain abscess | Organisms | Comments |
---|---|---|---|---|---|---|---|
Arivazhagan et al. (2009) |
20 | M | Asymptomatic polycythemia | Single | Multiple when the 3rd recurrence | Anaerobic growth of |
Three recurrences of brain abscess |
40 | M | Finger clubbing | Single | Single | No growth | Three recurrences of brain abscess | |
45 | M | Polycythemia, hypoxemia, finger clubbing | Single | Single | No growth | NC | |
Kawano et al. (2009) |
52 | M | Asymptomatic | Single | Single | ||
Kakar et al. (2003) |
18 | M | Cyanosis, clubbing, polycythemia | Multiple | Multiple | No growth | |
Kaido et al. (2011) |
69 | F | Asymptomatic | Single | Single | No growth | Recurrent brain abscess |
Caroli et al. (1992) |
35 | M | Asymptomatic | Single | Single | Eikenella/Fusobacterium | Recurrent brain abscess |
Momma et al. (1990) |
50 | M | Asymptomatic | Single | Single | Anaerobic G+ streptococci | |
Ratcliffe and Earl (1982) |
49 | F | Asymptomatic | Multiple | Single | Mixed growth of bacteroides, haemophilus and anaerobic streptococci | Recurrent brain abscess |
Watanabe et al. (1995) |
45 | F | Asymptomatic | Single | Single | Gram-positive cocci and Gram-negative rods | |
Preston and Shapiro (2001) |
23 | F | Asymptomatic | Single | Single | Gram-positive cocci |
|
Present study | 65 | F | Asymptomatic | Multiple | Single | No growth | |
45 | F | Asymptomatic | Single | Single | No growth |
AVF : arteriovenous fistula