Yield of Brain Magnetic Resonance Imaging in Epilepsy Diagnosis from 1998 to 2020: A Large Retrospective Cohort Study.

ABSTRACT

BACKGROUND: We aimed to find the clinical significance of brain abnormalities on magnetic resonance imaging (MRI) in epilepsy and the lateralization of these findings with electroencephalogram (EEG). METHODS: We retrospectively analyzed the results of all EEGs and brain MRIs of 600 consecutive epilepsy patients from 1998 to 2020. RESULTS: Data were available for 563 cases (267 females). Ninety percent of the patients were 18 years old or younger. A total of 345 patients (61.3%) had focal epilepsy, 180 (32%), generalized, and 38 (6.7%), inconclusive. In 187 (33.2%), the first MRI was abnormal and in 81 (out of 108 repeated MRI), the second was pathological. The most frequent brain abnormalities were cortical dysplasia in 41 (18.1%), other structural abnormalities in 25 (11%), various phacomatoses in 23 (10.1%), and mesial temporal sclerosis in 17 (7.5%). Among 226 patients with abnormal MRI, 171 (75.6%) had focal epilepsy when compared with 36 (15.9%) with generalized epilepsy (p <0.001). In 121 patients (53.5%), the result of the abnormal MRI contributed significantly to the understanding of the epilepsy etiology. The side of abnormality was lateralized to the EEG focus in 120 cases (53%); in 10/15 cases with infantile spasms (66%), MRI was significantly abnormal. In 33, in whom the first MRI was normal, a second MRI revealed a significant abnormality. CONCLUSION: Brain MRI is an important tool in epilepsy diagnosis, mainly in focal seizures and infantile spasms. A repeat MRI is mandatory in intractable focal cases to improve the yield of this test.