10077-NI-4 POSTOPERATIVE DISAPPEARANCE OF LEPTOMENINGEAL ENHANCEMENT AROUND THE BRAINSTEM IN GLIOBLASTOMA

Abstract

Abstract BACKGROUND AND PURPOSE Leptomeningeal enhancement (LME) suggests leptomeningeal dissemination (LMD) of tumor cells, which is an end-stage glioblastoma complication associated with a poor prognosis. However, magnetic resonance imaging (MRI) occasionally indicates the disappearance of peri-brainstem LME after surgical resection of glioblastoma. Since preoperative LMD may affect treatment indication, we aimed to analyze the clinical significance of preoperative LME of the brainstem on glioblastoma, focusing on imaging examinations and patient outcomes. METHODS We retrospectively collected clinical and radiological data obtained from consecutive patients with glioblastoma and preoperative LME of the brainstem, who were treated at our hospital between 2017 and 2020. RESULTS AND CONCLUSIONS Among 112 patients with glioblastoma, nine (8%) showed preoperative LME of the brainstem. Tumors with LME were relatively large (median size, 59 cm; range, 47-83 cm) and frequently located in the temporal lobe (temporal lobe: n = 4, 44%; frontal lobe: n = 1; parietal lobe: n = 2; corpus callosum: n = 2). Notably, among six patients who underwent surgical resection for glioblastoma with peri-brainstem LME, four showed significant radiological disappearance of the LME on postoperative MRI. This suggests that the LME did not result from LMD in these cases. Moreover, these four patients lived longer than would be expected from the presence of LMD. This LME disappearance was not observed after biopsy or chemoradiotherapy. These findings suggest that preoperative LME does not necessarily indicate the presence of untreatable LMD; moreover, LME may disappear after surgical tumor resection. Thus, transient preoperative LME could be attributed to other mechanisms, including impaired venous flow due to intratumoral arteriovenous shunts, which can be resolved by reducing the tumor burden.