Intraoperative Arachnoid Plasty Has Possibility to Prevent Chronic Subdural Hematoma after Surgery for Unruptured Cerebral Aneurysms.

Some patients develop chronic subdural hematomas (CSDHs) after the clipping/coating of unruptured aneurysms. The risk factors are not well understood and while no preventive methods are currently available, arachnoid plasty (ARP) may intercept the development of postoperative CSDH. We investigated the risk factors for CSDH and the usefulness of ARP to prevent postoperative CSDH. Between January 2009 and June 2013, 393 patients underwent 416 aneurysm surgeries via the pterional approach at Kushiro Kojinkai Memorial Hospital. Of these, 394 aneurysms (371 patients) were included in this study. Using multivariate analysis we evaluated the relationship between the patient demographics and clinical characteristics, and the development of postoperative symptomatic CSDH. We also studied the effect of ARP performed during aneurysm surgery. We found that symptomatic CSDH developed after 20 (5.1%) of the 394 operations; it was addressed by burr hole surgery and evacuation/irrigation. Male gender, advanced age, and oral anticoagulant therapy were significant risk factors for CSDH. Additive ARP, performed in the course of 132 surgeries (33.5%) was found to be a significant negative risk factor. The incidence of CSDH was significantly lower in patients who had undergone ARP than in patients who had not undergone it (0.8% vs. 7.3%, p < 0.01). We first report that ARP is useful for the prevention of CSDH in patients treated by aneurysm surgery.