Postoperative air in the ventricle or cistern predicts early leptomeningeal disease of brain metastasis: a retrospective study

Abstract Purpose: This study investigated whether the presence of air in cisterns or ventricles on postoperative computed tomography (CT), reflecting an extensive opening of the cerebrospinal fluid spaces during surgery, is a predictor of nodular leptomeningeal disease (nLMD) or classical leptomeningeal disease (cLMD) after brain metastasis resection. Methods: We retrospectively analyzed the data of 73 patients who underwent gross total resection of brain metastases between 2012 and 2020. Patients with air in cisterns or ventricles on postoperative day-1 CT were categorized into the air-positive (Air(+)) group, whereas other patients were categorized into the air-negative (Air(–)) group. The primary outcome was the occurrence of nLMD or cLMD, and was assessed using survival analyses. Results: There were 15 (21%) patients in the Air(+) group and 58 (79%) in the Air(–) group. The Air(+) group exhibited significantly more cerebellar and ventricular contact lesions than the Air(–) group. The 4-year nLMD or cLMD rate was significantly higher in the Air(+) group than in the Air(–) group (67% vs. 33%, P < 0.001). Multivariate analysis revealed the presence of air in ventricles or cisterns on postoperative CT as the only significant predictor of nLMD or cLMD (P<0.001). Conclusions: The presence of postoperative air in ventricles or cisterns can predict early nLMD or cLMD.