Nodular heterotopia: A neuropathological study of 24 patients undergoing surgery for drug-resistant epilepsy
Article first published online: 14 JUL 2008
Wiley Periodicals, Inc. © 2008 International League Against Epilepsy
Volume 50, Issue 1, pages 116–124, January 2009
How to Cite
Meroni, A., Galli, C., Bramerio, M., Tassi, L., Colombo, N., Cossu, M., Lo Russo, G., Garbelli, R. and Spreafico, R. (2009), Nodular heterotopia: A neuropathological study of 24 patients undergoing surgery for drug-resistant epilepsy. Epilepsia, 50: 116–124. doi: 10.1111/j.1528-1167.2008.01717.x
- Issue published online: 5 JAN 2009
- Article first published online: 14 JUL 2008
- Accepted May 18, 2008; Early View publication July 14, 2008.
- Neuropathology of epilepsy;
- Nodular heterotopia;
- Dual pathology
Purpose: Despite the availability of detailed electroclinical and imaging data, only a few neuropathological studies of nodular heterotopia have been published. The aim of this study was to describe the neuropathological features of various types of nodular heterotopia obtained from patients undergoing surgery for intractable epilepsy.
Methods: Specimens of heterotopic nodules taken from 24 patients were neuropathologically investigated using routine and immunocytochemical procedures, and the data were compared with magnetic resonance imaging (MRI), electroclinical findings, and surgical outcomes.
Results: The neuropathological data distinguished two groups. Group 1 (14 patients, 78% in Engel class 1) had similar characteristics regardless of the size, number, or location of the nodules, with both projecting and local circuit neurons in the nodules intermingled with glial cells. Thirteen patients had focal cortical dysplasia. The nodules were identified by MRI in all cases. In group 2 (10 patients, 90% in Engel class 1), all of the nodules were within the temporal lobe and associated with hippocampal sclerosis or gangliogliomas. They were very small (undetected by MRI) and mainly formed by projecting neurons with no evidence of glial cells. All of the patients had cortical dysplasia.
Discussion: The distinctive neuropathological features of the nodules in the two groups suggest different etiopathogenetic mechanisms. In group 2, the presence of nodular formations in association with cortical dysplasia and either hippocampal sclerosis or ganglioglioma raises a question concerning so-called dual pathology in the temporal lobe.