Neocortical epilepsy is a chronic condition characterized by focal or generalized seizures starting within the cortex of any lobe of the brain. In this chapter, some of the most common epileptogenic lesions will be discussed, including malformations of cortical development (MCDs) comprising focal cortical dysplasia (FCD), polymicrogyria (PMG), heterotopia (HTP), hemimegalencephaly (HME), and acquired lesions after vascular and traumatic injuries that can develop to post-stroke epilepsy (PSE) or post-traumatic epilepsy (PTE). Some other lesions like cortical tubers of tuberous sclerosis complex and cavernous angioma, which can be associated to neocortical epilepsy, are treated in other chapters of this book. Clinical neuroradiology plays a pivotal role to establish the diagnosis and to select patient candidate to surgery. The radiological technique fundamental for neocortical epilepsies is brain magnetic resonance imaging (MRI). It is mandatory in patients with drug-resistant focal epilepsy (DRFE) aimed to detect the suspected associated anatomical lesion and to define its location, extension, and relationship with the eloquent brain areas.
An epilepsy-specific protocol is needed to identify even very subtle lesions, particularly tiny FCDs. Knowledge of the electro-clinical presentation is key for planning a correct MRI examination to use the proper sequence angulation. The MRI study should cover the whole brain including different weighted sequences in three planes. Interpretation should be performed by experienced readers and particularly focused on the brain area suspected as the epileptogenic zone (EZ). In non-lesional MRI patients, re-evaluation of MRI could be helpful after all ancillary tests are completed, including nuclear medicine and invasive electrophysiological investigation, such as stereo-electroencephalography (SEEG), to search retrospectively for subtle structural lesions.
Neocortical epilepsy Malformation of cortical development Focal cortical dysplasia Post-stroke epilepsy Post-traumatic epilepsy