Midazolam Administration Reduces Leptomeningeal Enhancement in Patients Treated with Flow Diverting Stents

Objective: Imaging findings of cerebrovascular dysfunction following endovascular therapy have been increasingly reported. Special attention has been given to leptomeningeal abnormalities seen on post-contrast FLAIR (pcFLAIR) imaging as its presence is associated with poorer prognosis following endovascular therapy. The aim of this study is to investigate the relationship of various clinical variables on the presence and extent of pcFLAIR abnormalities in patients undergoing elective flow diversion of intracranial aneurysms. Patients and Methods: In a single center retrospective cohort, 80 consecutive patients treated with flow diverting stents who subsequently underwent post-operative MR-imaging within 24 hours of the procedure between July 2012 and November 2017 were identified and included in the study. Patient, aneurysm, and imaging characteristics were collected for review. Analysis of clinical variables on the presence and extent of leptomeningeal abnormalities seen on pcFLAIR imaging was performed. Results: We identified 69 of 80 patients (86%) with leptomeningeal enhancement (LME) on pcFLAIR imaging. In all instances, the distribution of LME matched the ipsilateral side of endovascular intervention. Of the 20 patients who had both pre and pcFLAIR imaging, LME was absent on precontrast imaging and seen exclusively on pcFLAIR in all cases. Complete resolution of LME was seen in 31 of 35 (89%) patients with available followup imaging. No significant association was found between LME and the extent of DWI abnormalities, dose of intra-arterial contrast administration, anesthetic or opioid use, procedural time, time until post-operative MR imaging, renal function, age, or number of stents used during embolization. There is a significant inverse relationship between the presence and extent of LME and the dose of intra-operative midazolam administration used during anesthesia (p=0.018). Conclusion: The majority of patients undergoing flow diversion therapy will develop LME on pcFLAIR imaging. LME is absent on pre-contrast imaging and seen exclusively on pcFLAIR in all cases. LME appears to be a transient finding affecting the vascular territory of intervention but in some cases may take months to completely resolve. There is no direct relationship of LME with lesions on DWI or the timing of MR imaging but there is a statistically significant inverse association of midazolam administration and presence and extent of LME. This study provides new evidence suggesting that midazolam may reduce the presence and extent of LME following neuroendovascular surgery and could have neuroprotective effects.