Risk factors for preoperative seizures in meningiomas - base versus non-bases of supratentorial
Authors: Nassar Abdalrahman , Smolanka Volodymyr , Studeniak Taras , Smolanka Andriy , Chaulagain Dipak , Pryima Mariana , Yuryk Marina 
Published: September 2023

Background: Meningiomas are the most frequent benign intracranial lesions. The literature review reported that 19-63% of the patients with meningioma suffer from preoperative seizures, and 35% experience epileptic seizures as the initial symptom. The present study attempted to establish the risk factors for seizures before surgery of supratentorial meningiomas.
Objective: To compare predictive factors for preoperative seizures for skull base meningiomas (SBMs), with non-skull base meningiomas (NSBMs).
Materials and methods: The clinical data of 244 patients with supratentorial meningiomas treated microsurgically between 2007 and 2018 were analyzed retrospectively. There were two groups; Group “A” with (NSBMs) and Group “B” with (SBMs). Demographic, clinical, imaging, histopathological, and electroencephalographic data were assessed. Univariate statistical analyses were performed among factors that might correlate with preoperative seizures.
Results: A total of 244 patients with a diagnosis of intracranial meningioma were retrospectively evaluated. The mean age was 54.34 years (range 16- 84), females 165, meals 79. Of these 154 patients for the non-skull base, seizures in 65 (42.2%), whereas, 90 patients for skull base, with 32 (35.5%) patients with seizures. The groups had similar preoperative seizure occurrence in relation to age (p=0.154, p=0.819), gender (p=0.396, p=0.445) tumor size (p=0.318,p=0.244), tumor side(p0.836, p=0.702)  for Group A and B respectively. The pre-op seizure was the third presentation in both groups after non-focal symptoms and (FND) respectively. For Group “A” seizure as the initial symptom was in 49.2% of patients versus 50.8% for others, while in Group “B” was in 37.5% vs 62.5%.                                         
The both groups had statistically significance between PTBE and pre op seizure, for Group “A”,PTBE was in 93(60.4%) patients,(seizure in 51patients 78.5%) vs (42 patients 47.2% for non-seizure), (?2=,15.356, p=0.000). For Group “B”, PTBE was in 43(47.8%) patients,(seizure in 25 patients 78.1%) vs(18 patients 31% for non-seizure),(?2=,18.328, p=0.000).
The most frequently seizure for Group “B” was in OGM (seizure 25% vs 13.8 without seizure) and SWM  (seizure 71.8% vs 65.5% non-seizure), while lesser overall in planum/tuberculum (seizure3.2% vs 20.7% non-seizure). There was a statistically significant relationship between tumour location and preoperative seizure for (SBM), (?2=5.985, p=0.050) while absent in Group “A”. (?2=1.373, p=0.503). There were no differences between the two groups with WHO grade and pre-op seizure. The unexpected finding in this study is that the presence of preoperative neurologic deficits has been less frequently associated with preoperative seizures in both groups. Careful analysis and further investigation are needed.
Conclusion: We identified that the major risk factor for pre-op seizure in both group studies is PTBE, and location for skull base meningiomas, where the planum/tuberculum lesser overall risk for pre-op seizure. While other radiological and histopathological factors are statistically non-significant. Interestingly, the factors associated with preoperative seizures were the absence of preoperative neurologic deficits for both groups.