Peritumoral T2/FLAIR hyperintense MRI findings of meningiomas are not necessarily edema and may persist permanently: a systematic review

The current knowledge regarding the prevalence and persistence of edematous changes postmeningioma surgery is limited. Our hypothesis was that peritumoral edema is frequently irreversible gliosis, potentially influencing long-term postoperative epilepsy. We conducted a systematic literature search in PubMed, Cochrane Library, and Scopus databases. We included studies with adult patients undergoing first supratentorial meningioma surgery, which reported pre- and postoperative peritumoral brain edema (T2WI and FLAIR hyperintensity on MRI). Risk of bias was assessed based on detailed reporting of five domains: (1) meningioma characteristics, (2) extent of resection, (3) postoperative radiation therapy, (4) neurological outcome, and (5) used MRI sequence. Our loose search strategy yielded 1714 articles, of which 164 were reviewed and seven met inclusion criteria. Persistent edema rates ranged from 39% to 83% with final follow-up occurring between 0, 14, and 157 months. Among patient cohorts exhibiting persistent edema, a smaller portion achieved seizure resolution compared to a cohort without persistent edema. Relatively reliable assessment of persistent T2/FLAIR hyperintensity changes can be made earliest at one year following surgery. All studies were classified as low quality of evidence, and therefore, quantitative analyses were not conducted. Persistent T2/FLAIR hyperintensity changes are frequently observed in MRI imaging following meningioma surgery. The term “edema,” which is reversible, does not fully capture pre- and postoperative T2WI and FLAIR hyperintensity changes. Future studies focusing on peritumoral meningioma-related edema, its etiology, its persistence, and its impact on postoperative epilepsy are needed.