亜急性期の血腫増大により手術を要した軽症急性硬膜下血腫の特徴

Factors Contributing to Surgical Intervention for Subacute Subdural Hematoma Enlargement in Patients with Mild Head Injuries

Ⅰ．はじめに

　軽症頭部外傷例では，頭蓋内出血を伴っていても多くは外科治療を必要とせず，良好な予後が期待できるが，約4%の症例でdelayed neurological deterioration（DND）を来すことが知られており，その発症時期のほとんどは24時間以内であると報告されている^2,6)．しかし，当初手術介入を要さなかった急性硬膜下血腫症例において，DNDが発症する急性期ではなく遅発性に血腫が増大し，血腫除去術を要した症例を当院にて稀ならず経験する．そこで本研究では，当初内科的治療が行われた軽症頭部外傷の急性硬膜下血腫症例において，遅発性血腫増大に伴って手術介入を要した症例群と，内科的治療のみで悪化なく治療し得た症例群について，臨床像と放射線画像所見を比較検討した．加えて，軽症頭部外傷による急性硬膜下血腫症例において，遅発性血腫増大に伴って手術介入を要する危険因子について検討した．

　Delayed neurological deterioration following mild head injury（MHI）usually occurs within 24 hours. However, some cases require delayed surgical evacuation of an acute subdural hematoma（ASDH), owing to subacute progressive hematoma enlargement. This study aimed to determine radiological or clinical parameters associated with surgical intervention in ASDH cases in which surgery was not initially considered necessary. From 2010 to 2015, 64 patients were non-surgically treated for ASDH following MHI. We evaluated the various outcomes of eventual surgical ASDH evacuation after the first 48 hours following injury, due to hematoma enlargement and clinical deterioration. Univariate and multivariate analyses were applied to both the demographic and initial radiographic features to identify risk factors for ASDH progression and surgery. Overall, at the time of their last follow-up computed tomography, 57 patients（89%）demonstrated minimal ASDH or spontaneous hematoma resolution with conservative non-surgical management. The remaining 7 patients（11%）received delayed surgical ASDH evacuation a median of 5.1 days after the head trauma. There were no significant differences between the two groups for baseline characteristics, including age, prior history of anticoagulants, the presence of cerebral contusions, or subarachnoid hemorrhages. On multivariate analysis, use of antiplatelet drugs（p＝0.013, OR＝28, 95%CI＝1.82-24）was independently associated with delayed hematoma evacuation. These data indicate that as much as 11% of patients with minimal ASDHs after MHI can deteriorate over the course of a week and then require surgical intervention, and that patients on concurrent antiplatelet medication require especially careful monitoring of hematoma progression.