Focal cortical dysplasia (FCD), characterized by abnormal cortical architecture, are the most common cause of refractory focal epilepsy in the pediatric population. Only surgery can remove FCD lesions to cure focal epilepsy, but surgical success depends on the ability to resect the lesion completely while minimizing damage to perilesional normal tissues. Therefore, it remains extremely challenging to remove FCD lesions completely. Thus, better methods of delineating FCD lesions and their borders are needed to improve post-surgical seizure outcomes. Raman spectroscopy induces vibrations in the molecules of a sample and the scattered radiation is used to characterize it. The goal of this in vitro prospective study is to use Raman spectroscopy to discriminate between normal brain tissue and dysplastic tissue using specimens of focal cortical dysplasia patients.Methods: Stained sections of biopsy specimens from 20 patients with focal epilepsy were acquired and assessed by a pediatric neuropathologist. Raman map points were recorded from targeted abnormal regions with structures characterizing FCD: dysmorphic neurons, balloon cells and cortical dyslamination.
Significant spectral differences were observed between the dysplastic tissues and normal tissues in the cortex. Indeed, FCD tissues exhibit increased spectral at 1032 cm-¹ and 1660 cm-¹ peaks, indicating a higher intensity of protein components and abnormal stretching mode of protein, lower quantity of lipids and most interestingly, a higher intensity of glycogen in the dysplastic tissues, respectively. In addition, the fingerprint region between FCDIIa and FCDIIb differs in intensity in specific biomolecules as well.
These findings suggest the potential spectral fingerprint of Raman spectroscopy to not only to delineate between normal tissue and dysplastic tissues, but also to distinguish the presence of specific structures like the balloon cells in FCDIIb. Future in vivo, intra-operative applications could potentially allow the differentiation of the histopathogical borders of FCD from adjacent normal, functional brain.