受傷翌日に消失し，その後再発するという稀な経過を辿った急性硬膜外血腫の1例

An Unusual Case of Acute Epidural Hematoma Showing Rapid Spontaneous Resolution with Delayed Recurrence

Ⅰ．はじめに

　急性硬膜外血腫は生命の危険を伴うため，神経症状などがある場合は速やかに血腫除去術を行うことが推奨されている．一方で，血腫の大きさや神経症状から，保存的に経過をみることも可能である¹⁴⁾．通常であれば血腫は数週間の期間をかけて徐々に吸収され，消失していく¹⁷⁾．しかし，稀ではあるが，急速に血腫が自然消退する例も報告されている．血腫が消退したのちは，基本的に良好な経過を辿っている．過去に1例だけ，血液凝固能の異常を伴う症例で血腫消退後の再発例が報告されている¹⁵⁾．

　今回われわれは，血液凝固能に異常所見がなく，急速に自然消退したのちに再発するという稀な経過を辿った急性硬膜外血腫の1例を経験したため，文献的考察を加えて報告する．

　A 16-year-old boy collided with a passenger car while riding a motorcycle. He was thrown to a distance and experienced a head injury on impact. When brought to our medical facility, he was alert, had no neurological abnormalities, and did not complain of headache. A head computed tomography（CT）scan indicated a left cranial fracture and an acute epidural hematoma（15mm thick）directly under the fracture. Follow-up head CT performed 3 hours after the injury indicated no change in the size of the hematoma. The head CT performed on the following day indicated that most of the hematoma had disappeared. As the patient had neither headache nor neurological symptoms, he was placed under observation. However, a head CT performed 7 days after the injury indicated the formation of an epidural hematoma approximately the same size as the initial hematoma and located at the same site. We performed craniotomy to evacuate the hematoma, identify the source of the bleeding, and restore hemostasis. Although cases in which an acute epidural hematoma rapidly and spontaneously resolves have been reported, these are extremely rare. Recurrence of an epidural hematoma despite normal blood coagulation function after its initial rapid resolution has not been reported yet. We report on this rare case of acute epidural hematoma with reference to relevant literatures.