Purpose or Case Report: Within the last several years there have been updates and changes to the clinical terminology in epilepsy, as well as the histopathologic classification of hippocampal sclerosis and focal cortical dysplasia. The purpose of this exhibit is to review these changes and illustrate them with corresponding MR examples. Methods & Materials: This exhibit provides three updates:
1. Summary of recent changes to the terminology of epilepsy types that are commonly provided as an imaging indication. 2. An illustrated review of the new histopathology classification system for focal cortical dysplasia types I-III on pediatric MRI imaging. 3. An illustrated review of the new histopathology classification system for three hippocampal sclerosis subtypes using MRI imaging. Results: The new classification system of epilepsy eliminates neonatal seizures as a separate entity, simplifies abscence seizures, adds epileptic spasms, removes the distinction between focal seizures and adds myoclonic atonic seizures. The etiology of seizures is now classified as genetic, structural/metabolic and unknown etiology as opposed to idiopathic, symptomatic and cryptogenic. Other terminology that has changed includes the addition of self-limited, pharmacoresponsive, evolving to bilateral and focal seizures.
New to the focal cortical dysplasia classification is the addition of FCD type III which is subdivided into type type IIIa, IIIb, IIIc, and IIId as follows:
Type IIIa: FCD type II with hippocampal sclerosis. Type IIIb: FCD type II with a glial or glioneuronal tumor. Type IIIc: FCD type II with a vascular malformation. Type IIId: FCD type II with an acquired lesion.
Also new, are the subtypes of hippocampal sclerosis. Type 1 is the classic hippocampal sclerosis associated with diffuse segmental volume loss of the hippocampus. Type 2 is when cell loss is isolated to the CA1 segment. Type 3 is when the cell loss is isolated to the dentate gyrus and CA4 segment. Conclusions: At the end of the exhibit, the viewer will be familiar with the new histopathologic and clinical epilepsy classification system and will be able to classify brain MRI findings in pediatric epilepsy patients according to these classifications.