Patent foramen ovale as a possible risk factor for cryptogenic brain abscess: report of two cases.
OBJECTIVE
Patent foramen ovale (PFO) has been suggested as a potential source of paradoxical embolism. A higher prevalence of PFO in ischemic stroke of unexplained cause has been recognized. Brain abscesses are commonly associated with a contiguous focus of infection, hematogenous spread from a distant focus, or cranial trauma. However, no predisposing factors, including a distant focus with unknown cause, are identified in approximately 15 to 30% of reported cases.


METHODS
We encountered two patients with brain abscess presumably caused by dental infections. Both patients displayed PFO, through which right-to-left atrial contrast shunting was revealed by transesophageal echocardiography. Although the radiological location of the abscesses suggested hematogenous spread as a cause, the patients had no arteriovenous shunting other than the PFO, despite exhaustive investigations for a potential infectious route. The patients displayed no definite focal orofacial inflammatory signs during the postoperative course despite diagnosis of pyorrhea alveolaris or periodontitis.


METHODS
In Patient 1, the abscess was aspirated stereotactically, and in Patient 2, the abscess disappeared radiologically after high-dose antibiotic treatment.


CONCLUSIONS
The mechanism of brain abscess formation putatively related to PFO should be different from that related to common dental sepsis. Analysis of these cases suggested that infectious embolism from a latent or even identifiable focus through the PFO may be an underrecognized cause of brain abscess, in contrast to simple seeding of the brain via transit of the infecting bacteria through the valveless emissary veins.
Kawamata
T
T
Department of Neurosurgery, Tokyo Women's Medical University, Japan. tkawamata@nij.twmu.ac.jp
Takeshita
M
M
Ishizuka
N
N
Hori
T
T
D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001922:Brain Abscess / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology* / Q000382:microbiology / Q000601:surgery; D004322:Drainage / Q000379:methods; D017548:Echocardiography, Transesophageal; D006344:Heart Septal Defects, Atrial / Q000150:complications* / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013238:Stereotaxic Techniques; D013290:Streptococcal Infections / Q000188:drug therapy; D013492:Suppuration / Q000378:metabolism; D014057:Tomography, X-Ray Computed
D000900:Anti-Bacterial Agents