Focal XXXX : neuropathological subtypes, EEG, neuroimaging and surgical outcome.

@entity1 @entity131 @entity410 @entity75 @entity6795 @entity509 @entity854 @entity302 @entity10067 @entity528 @entity1141
Since the original description by Taylor, the term focal @entity6795 has been used to refer to a wide range of alterations of the cortical mantle. More recently, these conditions have been described from neuroimaging, neuropathological and genetic standpoints, generating several classifications. It is widely recognized that these classifications are unsatisfactory. We propose a simplified classification of focal @entity6795 based on easily recognized neuropathological characteristics. We retrospectively re-examined histological sections of cortex from 52 of 224 (23%) @entity1 operated on for drug-resistant partial @entity302 in which @entity6795 was present but not associated with other @entity75 except @entity131 . Three subgroups were identified: (i) @entity1141 (31 @entity1 ) characterized by abnormal cortical lamination and ectopic neurones in white matter; (ii) @entity1141 (six @entity1 ) characterized by giant neurofilament-enriched neurones in addition to altered cortical lamination; and (iii) @entity10067 (15 @entity1 ) with @entity528 and balloon cells (all but two @entity1 ) associated with @entity75 . The @entity1 with @entity1141 had lower @entity410 frequency than those with cytoarchitectural and @entity10067 , and the epileptogenic zone was mainly in the temporal lobe. In @entity1 with @entity10067 , the epileptogenic zone was mainly extratemporal, and interictal stereo-EEG was distinctive. MRI was unrevealing in 34% of @entity1 , but distinctive signal alterations characterized most @entity1 with @entity10067 , while focal @entity509 with @entity854 was found in @entity1141 . @entity1 with @entity10067 had the best outcome, with 75% @entity410 -free (Engel class Ia) after at least a year of follow-up compared with 50% of @entity1141 and 43% of @entity1141 @entity1 @entity410 -free. This three-category classification is based on easily recognized histopathological characteristics and avoids complicated terminology, while the distinctive ensemble of other characteristics defines clinically homogeneous groups.
