Preventive effect of postoperative Goreisan administration on symptomatic recurrence of chronic subdural hematoma: a systematic review and meta-analysis

Goreisan is a Japanese herbal medicine composed of five active ingredients and is believed to exert its effects by inhibiting various aquaporins. This systematic review and meta-analysis aim to evaluate the effectiveness of Goreisan in the postoperative management of chronic subdural hematoma (CSDH). This review was conducted in accordance with PRISMA guidelines and included studies evaluating Goreisan for the postoperative management of CSDH. PubMed, Cochrane Library, Embase, and Google Scholar were queried to identify studies that met our criteria from their inception to December 2024. Symptomatic recurrence was the primary outcome; heterogeneity was not assessed beyond this endpoint. Eleven studies (five randomized controlled trials and six retrospective studies) with 9443 patients (4809 received Goreisan and 4634 did not receive Goreisan postoperatively) were included in the analyses. The symptomatic recurrence rate was significantly lower in the Goreisan group compared to the control group (276 of 4,809 patients [5.7%] vs. 345 of 4,634 [7.4%]; odds ratio, 0.69 [95% confidence interval, 0.55 to 0.86]) with I2 = 13%. AEs were reported in seven studies: five studies reported no AEs related to Goreisan, while two studies reported pollakiuria (1%) and unspecified AEs (1%). An exploratory cost comparison also indicated that the cost of postoperative Goreisan ($15-18) was substantially lower than that of burr hole drainage ($694) or middle meningeal artery embolization ($1,304). Our study demonstrated that Goreisan is effective in preventing symptomatic recurrence in postoperative CSDH cases. (PROSPERO number CRD42025645208.).