Association between persisting peritumoral brain edema and seizures as well as worse functional outcome after meningioma surgery: a retrospective study of 218 patients.

OBJECTIVE

Peritumoral brain edema (PTBE) of intracranial meningioma (IM) often persists after gross-total resection (GTR) and likely represents reactive gliosis. The authors investigated whether persisting PTBE (i.e., FLAIR hyperintensity) is associated with postoperative seizures and functional outcomes, hypothesizing that it is associated with a higher likelihood of seizures and worse outcomes.

METHODS

The authors retrospectively reviewed all patients (age ≥ 18 years) with IM who underwent GTR at their institution between 2000 and 2020. Included patients had a preoperative MRI study showing PTBE and at least a 2-year MRI follow-up. Univariable and multivariable analyses identified factors associating with seizures and functional outcome (Karnofsky Performance Status [KPS]). Postoperative electroencephalography (EEG), when available, was reviewed to locate epileptogenic foci.

RESULTS

Among 218 adult IM patients with preoperative PTBE, preoperative seizures occurred in 94 (43.1%). Seizures persisted in 27 (28.7%) patients after surgery (mean time to first postoperative seizure 8.4 months). Of the 124 patients without preoperative seizures, 18 (14.5%) developed new-onset postoperative seizures (mean time to first seizure 7.6 months). Persisting PTBE volume in the highest tertile (median 12.8 cm3, range 6.7-54.0 cm3) was associated (p = 0.03, OR 4.7) with new-onset seizures in comparison with the lowest tertile (median 0.5 cm3, range 0.0-1.6 cm3). An increase in postoperative PTBE volume was also associated with new-onset seizures (p = 0.008, OR 6.7) and persisting seizures (p = 0.004, OR 4.4). Postoperative EEG was available for 23 patients, of whom 10 (43.5%) had an epileptogenic focus at the site of persisting PTBE. Larger persisting PTBE volumes were associated with worse postoperative KPS (p = 0.04, OR 1.03 per cm3 increase).

CONCLUSIONS

Persisting PTBE is associated with worse functional outcome and with persisting and new-onset seizures. Based on EEG findings, persisting PTBE (i.e., gliosis) may be the epileptogenic focus in some patients. Future studies are needed to assess whether these gliotic sites could even be therapeutic targets for seizure control.