Subdural Air Increases Postoperative Recurrence of Chronic Subdural Hematoma After Initial Burr-hole Surgery Only in the Very Elderly: A Pilot Study

OBJECTIVE: Numerous randomized controlled trials have identified risk factors increasing the postoperative recurrence of chronic subdural hematoma (CSDH). Postoperative subdural air is frequently seen on computed tomography imaging. The aim of this study was to test the hypothesis that the presence of significant subdural air postoperatively is related to recurrence of CSDH after burr-hole surgery. METHODS: A single-center, retrospective pilot study analyzed patients 20 years and older who underwent initial burr-hole surgery for CSDH. Data from 452 consecutive patients were included. Significant subdural air was considered to be present when the subdural air area was >4 cm(2) in 1 axial CT slice. Correlation of the recurrence and the number of slices that included significant subdural air at postoperative day (POD) 1 was evaluated. Other classic predictive factors were also investigated. RESULTS: The recurrence rate was 13.0% in these 452 cases. After univariate analyses of all the variables, multivariate analysis for age, sex, cerebral infarction, number of slices containing significant subdural air, and maximum depth of the subdural space confirmed that older age and male sex were independent risk factors for recurrence (P = 0.032 and 0.047, respectively). After subdividing cases into older (>= 75 years of age)/younger and male/female subgroups, the presence of significant subdural air at POD 1 was identified as an independent risk factor for recurrence in older adults (P = 0.025, OR = 1.12). CONCLUSIONS: Although this is a pilot study, it is suggested that significant postoperative subdural air increases recurrence after initial burr-hole surgery for CSDH in adults >= 75 years of age.