Postoperative Chronic Subdural Hematoma Following Unruptured Intracranial Aneurysm Surgery: Prevention with Arachnoid Plasty and Conservative Management Using Gorei-san

The incidence of postoperative chronic subdural hematoma (CSH) after clipping surgery for unruptured intracranial aneurysm (UIA) is reported to be in the range of 1.8–13.3%. Recent reports revealed that an increase in subdural fluid collection (SFC) during the first postoperative week is a significant risk factor for CSH after UIA surgery. Accumulating evidence from various studies indicates the potential benefit of arachnoid plasty in the prevention of SFC/CSH after surgery for intracranial aneurysms. In addition, Gorei-san, a Kampo medicine that exerts a hydragogue effect through aquaporins, has been suggested as a useful option for conservative management of CSH in which symptoms are either absent or minimal. Here, we retrospectively analyze the effects of arachnoid plasty and Gorei-san on the prevention and management of postoperative CSH after clipping surgery for UIA. Between January 2008 and December 2012, 42 patients underwent clipping surgery for UIA in anterior circulation using front-temporal craniotomy. Arachnoid plasty was performed immediately after UIA clipping. Four patients (9.5%) developed CSH after the surgery. In one case, a head injury during the postoperative period caused CSH. By excluding this case, the true incidence of postoperative CSH in our study was 7.1%, which was consistent with data shown in previous reports of case series without arachnoid plasty. The previous reports, however, included symptomatic cases and cases requiring surgical intervention. In contrast, all CSH cases in the present study were asymptomatic and improved without surgical treatment. Among the four CSH cases, three received Gorei-san during the postoperative period. Preventive administration of Gorei-san was started in 10 patients who showed increasing SFC in the postoperative period (1–2 weeks). In nine of the 10 cases, SFC diminished in one to two months. The remaining case developed CSH, which was eventually cured with conservative management. Symptomatic cases of CSH after UIA surgery often require surgical evacuation. Data in the present study suggested that intraoperative arachnoid plasty in combination with Gorei-san administration in cases that show increasing postoperative SFC or evidence of asymptomatic CSH might help prevent such detrimental complications. Further studies are required to clarify the precise effects of this therapeutic approach.