Abstracts

One third of epilepsy patients are refractory to pharmacologic treatment. Malformations of cortical development (MCD) are a well-recognized cause of refractory epilepsy that can often be cured by surgical resection. The presence of periventricular heterotopia (PVH) is associated with the development of epilepsy, although the role of these lesions in the generation of epileptogenicity and their cellular/molecular characteristics remain unclear., In this report, we present the histological and immunocytochemical (ICC) characteristics of a periventricular nodule that was resected from a 17 years old female with a history of pharmacoresistant epilepsy, a lateral temporal MCD and multiple PVH. Invasive video electrographic encephalography (VEEG) with subdural electrodes and a depth electrode targeted at the PVH did not confirm the PVH as the seizure onset zone. The patient underwent a temporal lobectomy that included the removal of a subcortical nodule. She remained seizure free on no antiepileptics for four years, then presented with a single generalized seizure., Histological and ICC examinations of the resected nodule showed dysmorphic neurons lacking any laminar or columnar organizations. These neurons were intermixed with GFAP positive glial cells, immature neurons (TUJ1 positive) and immature astrocytes (vimentin positive). Some subcortical neurons expressed doublecortin, a marker of migrating cells. The expression of GABA (Calbindin, parvalbumin) and NMDA (NR1, NR2A, NR2B) receptors were also examined., Our results suggest that PVH is constituted of a mixture of neuronal and glial cells at various levels of differentiation that failed to mature and migrate to their final position in the neocortex. It is unclear if these nodules are epileptogenic. Further studies of the role of PVH in epilepsy are needed in order to further characterize the electrophysiology and molecular biology of the constituent cells of these lesions and their overlying neocortical areas.,