Role of Magnetic Resonance Imaging in Evaluation of Epilepsy

Introduction: Seizures have been classified in several ways, according to their etiology, i.e., idiopathic (primary) or symptomatic (secondary); their site of origin; their clinical form (generalized or focal); their frequency (isolated, cyclic, or repetitive, or the closely spaced sequence of status epilepticus); or their electrophysiologic correlates. Epileptic seizures are brief episodes of abnormal excessive or synchronous neuronal brain activity, characterized by typical ictal neurophysiological patterns and postictal and/or interictal abnormalities. Computed tomography introduced in 1973, with its widespread availability at emergent care facilities, rapid scan time, high sensitivity in detecting major abnormalities is widely used for screening patients with new-onset seizures. The present study is to evaluate the magnetic resonance imaging characteristics of epileptogenic substrates to identify the epileptogenic substrates based on imaging features, to assess the distribution of epileptogenic substrates, the diagnostic yield of magnetic resonance imaging and evaluate the role of magnetic resonance imaging in the pre-operative evaluation of patients with intractable epilepsy. Material and methods: The present study was a prospective observational study, conducted in the Department of Radiodiagnosis and Imaging, GMC Srinagar J&K, MRI centre, Sheerin Bagh. Imaging was done with Magnetom Skyra, 3 Tesla Magnetic Resonance Imaging equipment from Siemens. All patients with magnetic resonance imaging reference for seizures at SMHS and Associated Hospitals between April 2017 to April 2018, irrespective of age and sex were included in the study. This was a type of purposive sampling. Results: Majority of the patients were in the first two decades, the percentage of patients in the first decade being 29% and those in the second decade being 27%. Mesial temporal sclerosis was the most common abnormality identified in 29% of the study group. MRI was normal in 60 patients while abnormalities were identified in 90 patients of the study group. Among patients with partial seizures, 68 patients had lesions detected in magnetic resonance imaging. The diagnostic yield in the partial seizure group was 68%. Conclusion: Magnetic resonance imaging should be considered in the initial evaluation of patients presenting with seizures, particularly with intractable partial seizures because of its high sensitivity for epileptogenic substrates, superior soft tissue contrast, multiplanar capability, lack of beam hardening artifact and lack of ionizing radiation.