急性後頭蓋窩硬膜外血腫—椎骨動脈写の診断的価値

ACUTE POSTERIOR FOSSA EXTRADURAL HEMATOMAS: THE DIAGNOSTIC VALUE OF VERTEBRAL ANGIOGRAPHY

Ｉ．はじめに

　後頭蓋窩硬膜外血腫はまれな疾患であり，専門病院へ送られて来る重症頭部外傷患者の中で占める頻度は0.3％^2）4）6），全硬膜外血腫中の頻度は5.4％^19）であるという。McKissockら^13）14）によると後頭蓋窩血腫中で，硬膜外血腫は硬膜下血腫の約10倍の頻度で発生するという。現在までに文献上100余例の報告があり，本邦では記載の明らかなものは，松村ら^11），佐藤ら^19），上野ら^21）および平井ら^6）の計4例がある。4例中，手術によって救命されたものは平井らの1例のみである。

　頸動脈写の普及に伴って天幕上血腫の診断は比較的容易に行なわれるようになったが，後頭蓋窩血腫に関しては，術前診断は依然として困難なのが現状である。当初著明な神経症状を伴わず，突如として急激な経過をとり，延髄圧迫症状を呈して死亡することがあるので，その存在には十分な注意を払わねばならない。事実文献例においては，生前に診断がつかず，剖検によって初めて発見されたものが多く，正しい診断の第一歩は鑑別することよりも，まずこの疾患が存在することを知ることであるとも言われている^2）。ただし，剖検においてすら，実際に存在する後頭蓋窩血腫が剖検によるartifactと誤認され，見逃がされている場合も多いという^20）。

Extradural hematoma of the posterior fossa is a rare clinical entity. As a rule this lesion has been overlooked because of the paucity of neurologic signs and symptoms or diagnosed so late that opera-tion was of no avail. It is also very possible that it might be missed entirely unless one is not alert to the possibility. To date we have found a little more than one hunderd cases in the literature. In Japan four cases have been reported among which only one was successfully treated surgically.

We are reporting two cases of acute posterior fossa extradural hematoma whose lesions were de-monstrated by direct percutaneous vertebral angio-graphy. The one was operatively treated with success and the other died after the operation.

Obviously, when the clinical signs and symptoms of a posterior fossa traumatic hematoma are pro-gressing very rapidly, there may not be time for vertebral angiography. However, we feel that when angiography is feasible, it is the procedure of choice when one is faced with the possibility of a lesion in this location. Our cases demonstrate that pos-terior fossa hematoma can be readily visualized by vertebral angiography. The knowledge of a precise localization of the lesion can be of great assistance to the surgeon in planning his surgical attack.

We believe that our technique of direct percu-taneous vertebral angiography is particularly useful in emergency cases because the technique is simple and the instruments can be the same as those of carotid angiography.

Once the diagnosis is established, the patient should be operated upon as early as possible. Success of surgery exclusively depends on how to repair dural sinus laceration.