拡散強調画像が診断および治療効果判定に有用であった感染性硬膜下血腫の1例

A Case of Infected Subdural Hematoma Diagnosed by Diffusion-Weighted Imaging

はじめに

　硬膜下膿瘍は急性な経過で予後不良となることが少なくなく，迅速かつ適切な治療が不可欠な神経救急疾患であるが^1），近年では拡散強調画像（diffusion-weighted imaging：DWI）での早期診断が可能になってきている^2－5）。一方，慢性硬膜下血腫に感染が波及して生じる感染性硬膜下血腫（infected subdural hematoma：ISH）は非常に稀であり^6－11），DWIの所見に関する報告についてはわれわれが渉猟し得た限りではいまだ2例しかない^9，10）。今回われわれは，脾臓摘出後の患者において尿路感染症に起因するISHの1例を経験したが，その診断および治療効果判定にDWIが非常に有用であったので文献的考察を含め報告する。

Abstract

　An 80-year-old man who had undergone total gastrectomy and splenectomy for gastric cancer 13 years ago presented with headache, drowsiness, and high fever 1 month after a traffic accident.　Brain CT scans revealed bilateral subdural fluid collections.　Diffusion-weighted imaging (DWI) showed mixed high and low signal intensities in the left subdural fluid, and contrast-enhanced MR imaging revealed capsule enhancement of the left subdural fluid collection.　The patient was diagnosed with left subdural empyema, and 2 burr-holes were drilled for drainage and irrigation.　Operative findings revealed a neomembrane underneath the dura mater.　Old hematoma and yellowish-white purulent fluid were present within the neomembrane.　This confirmed the diagnosis of infected subdural hematoma (ISH).　Abscess culture results were positive for Escherichia coli.　The patient's symptoms resolved postoperatively with subsequent antibiotic therapy.　However, 4 months after the operation, he suddenly died of severe sepsis and disseminated intravascular coagulation following cholecystitis, which was possibly associated with splenectomy.　The clinical presentation, diagnosis, and treatment of an unusual case of ISH have been discussed.　We emphasize that DWI and enhanced MR imaging may be useful for diagnosing ISH, and serial DWI evaluations may help in monitoring the therapeutic response in ISH.

（Received: June 30,2008,Accepted: October 17,2008)