Principles: The risk of seizures increases in patients with brain tumours (BT) and brain vascular malformations (BVM), but not all risk factors are known. We aimed to identify factors that increase the risk of a first seizure in patients with BT or BVM.
Methods: Multicentre case-control study; 102 cases with a first seizure as a presenting symptom of BT or BVM; 121 hospital controls with BT or BVM, but without seizures, matched by centre, gender and age.
Results: In the univariate analysis, the risk of first seizure (Odds Ratio, 95% Confidence Limits) was 6.4 (2.3-17.6) for supratentorial lesions, 4.7 (2.4-9.3) for cortical involvement, 2.5 (1.0-7.7) for family history of seizures, and 2.1 (1.2-4.1) for frontal location. The types of lesion with higher risk were low grade glioma (4.7; 1.7-13.9) and cavernous malformations (13.2; 2.1-58.0). After multivariate analysis, including all the imaging characteristics and family history, the strongest independent predictors of first seizure were cortical involvement (OR 4.0; 2.0-8.1) and type of lesion (low grade glioma: 4.0; 1.3-12.8; cavernous malformations: 12.6 (1.5-103.5).
Conclusions: Cortical involvement and type of lesion are the independent risk factors for a first-ever seizure as a presenting symptom of BT or BVM.