乳突天蓋部先天性骨欠損が原因で生じたAir in epidural hematomaの1例

The Presence of Air in epidural hematoma due to congenital bone defect in the mastoid tegmen : A case report

I．はじめに

　Air in epidural hematomaは，CTが普及する頃になってから認識されるようになり，比較的稀な所見として症例報告も散見されたが，その後の報告から，それほど稀な病態ではないと考えられるようになった．このような症例では骨折がair-containing structureに生じている例がほとんどであるが，空気の流入経路が不明な症例も存在しており，その原因は常に推測の域を脱し得なかった．今回われわれは，骨折がair-containing struc-tureに生じておらず，血腫により硬膜が骨より剥離されたことで乳突天蓋部の骨欠損部から空気が流入した症例を経験したので，この稀なる病態について，若干の文献的考察を加え報告する．

Presence of air in acute epidural hematomas has been described by several authors. Although the air trapped in the epidural space is thought to be derived from the air-containing structure, there are some cases in which there is an absence of any demonstrable fracture involving air-containing structure. We re-port a very rare case of air in an epidural hematoma which was not related to fracture involving air-con-taining structure. The patient was a 30-year-old man whose left temporal bone was struck during a fall. CT scan revealed acute epidural hematoma with a large amount of air in the epidural space. We found many congenital bone defects in the mastoid tegmen during the operation and suspected that the air had been derived from them. The differance between our case and other cases reported was the amount of the air in epidural space. We suspected that air bubbles were derived from the fracture involving air-containing struc-ture, while a large amount of air could be derived from congenital bone defects in the mastoid tegmen.