Taylor's cortical dysplasia: A confocal and ultrastructural immunohistochemical study

In the present report we describe the neuropathological characteristics of tissue surgically resected from three patients affected by intractable epil epsy secondary to cortical dysplasia, Common features, suggestive of a foca l cortical dysplasia of Taylor, were observed in all specimens, Immunocytoc hemical procedures were performed using neuronal and glial markers and the sections were observed at light traditional and confocal microscopes. This part of the investigation pointed out: 1, cortical laminar disruption; 2. v ery large neurons displaying a pyramidal or round shape; 3. ballooned cells ; 4. decrease of calcium binding proteins immunoreactivity; 5. abnormal net s of parvalbumin- and glutamic acid decarboxylase-positive puncta around gi ant neurons but not around ballooned cells, Ultrastructural investigation o n the same material provided evidence of a high concentration of neurofilam ents in giant neurons and of glial intermediate filaments in ballooned cell s. In addition, immunolabeled GABAergic terminals clustered around giant ne urons were not found to establish synapses on their cell bodies. The present data, derived from a limited sample of patients but showing ver y consistent features, suggest that in Taylor's type of cortical dysplasia a disturbance of migratory events could be paralleled by a disruption of ce ll differentiation and maturation and by an impairment of synaptogenesis. T his latter mechanism seemed to affect especially the inhibitory elements, a nd could account for the hyperexcitability of this tissue and thus for the high epileptogenicity of Taylor's dysplasia.