Association between postoperative pneumocephalus and chronic subdural hematoma recurrence: A single-center population-based study in Puerto Rico

Background: Chronic subdural hematomas (CSDHs) are common conditions in neurosurgery, and their recurrence rate after initial surgery is high. Many studies have attempted to use radiographic features to predict recurrence, including postoperative pneumocephalus. However, to our knowledge, no study has directly measured the volume of pneumocephalus and its association with CSDH recurrence at the population-based level. Methods: A single-center Puerto Rican population-based retrospective review was performed on patients surgically treated for CSDH from July 2017 to December 2019. The volume of postoperative pneumocephalus was measured using open-source imaging software. Univariate and multivariate analyses were used to compare recurrence and nonrecurrence groups. Results: A total of 108 patients were included in the study: 42 patients (39%) with recurrence and 66 patients (61%) without recurrence. The median postoperative pneumocephalus volume was 7.0 cm(3) (Q(1)-Q(3): 2.3-23.6). After the univariate analysis, sex, size of subdural space, postoperative midline shift, and volume of postoperative pneumocephalus differed significantly between recurrence and nonrecurrence groups (p & LE; 0.04). Multivariate logistic regression analysis showed that the volume of postoperative pneumocephalus was the only independent variable associated with CSDH recurrence (p = 0.01). Conclusions: Postoperative pneumocephalus is common after the evacuation of a CSDH. In our sample population, postoperative pneumocephalus volume was the only independent variable that differed between recurrence and nonrecurrence patients. Our results indicate that for every cubic centimeter of air introduced into the cranial cavity after burr-hole drainage, the risk of CSDH recurrence increases by 4%.