Cortical dysplasia: Electroclinical, imaging, and neuropathologic study of13 patients

Purpose: The aim of this study was to correlate the electroclinical and rad iologic data with the neuropathologic findings and surgical outcome in epil eptic patients with epilepsy and Taylor's focal conical dysplasia (TFCD) an d to characterize further the abnormal intermediate filaments expression in the balloon cell present in the peculiar dysplasia. Methods: We retrospectively selected 13 TFCD patients who underwent surgery for intractable epilepsy with the aim of removing the magnetic resonance ( MR)-detectable lesion and/or the epileptogenic zone defined by stereoelectr oencephalographic recordings. The surgical specimens were analyzed by means of routine neuropathologic and immunocytochemical studies. Antisera agains t different intermediate filaments also were used in serial adjacent sectio ns to evaluate their coexpression in balloon cells. Results: Histopathologic abnormalities typical of TFCD were found not only within the MR-visible lesions but also in most of the epileptogenic zones w ith no MR signal alterations. Furthermore, the MR-visible lesions contained a high proportion of cells with an abnormal expression of intermediate fil ament proteins. After a long follow-up, 10 of the patients are now seizure free. Conclusions: Our Findings indicate that highly epileptogenic zones may corr espond to tissue alterations not revealed by neuroimaging. Furthermore, the immunocytochemical data show that the dysplastic tissue detected by MR con tained high concentrations of cells Filled with abnormal intermediate filam ents. The detected colocalization of neuronal and glial markers in balloon cells indicates a failure of cellular commitment during development.