Postoperative air in the cisterns or ventricles predicts early leptomeningeal disease of brain metastases: a retrospective study

Purpose: We investigated whether air in the cisterns or ventricles on postoperative computed tomography (reflecting the opening of the cerebrospinal fluid spaces during surgery) is a predictor of classical or nodular leptomeningeal disease after resection of brain metastases.

Methods: We retrospectively analyzed 73 patients who underwent gross total resection of brain metastases between 2012 and 2020. Patients with air in the cisterns or ventricles on postoperative day 1 computed tomography were categorized into the air-positive group, whereas those without air in the cisterns or ventricles on postoperative day 1 computed tomography were categorized into the air-negative group. The primary outcome was the occurrence of classical or nodular leptomeningeal disease, which was assessed using survival analysis.

Results: There were 15 (21%) patients in the air-positive group and 58 (79%) in the air-negative group. The air-positive group exhibited significantly more cerebellar and ventricular contact lesions than the air-negative group. The 4-year rate of classical or nodular leptomeningeal disease was significantly higher in the air-positive group than in the air-negative group (67% vs. 33%, P < 0.001). Multivariate analysis identified air in the cisterns or ventricles on postoperative computed tomography as the only significant predictor of classical or nodular leptomeningeal disease (P < 0.001).

Conclusions: Postoperative air in the cisterns or ventricles can predict early classical or nodular leptomeningeal disease.