Magnetic resonance spectroscopy and histopathological findings in temporallobe epilepsy

Purpose: in some patients with temporal lobe epilepsy, histopathological ev aluation of resected brain tissue after surgical treatment may reveal sever al features indicative of discrete cortical malformations, We sought to det ermine whether these histopathological features were accompanied by hippoca mpal changes detectable preoperatively by proton magnetic resonance (MR) sp ectroscopy and to evaluate their relationship with postoperative outcome. Methods: In 25 consecutive temporal lobe epilepsy patients who were schedul ed for surgical treatment, MR spectroscopy was performed, and resected brai n tissue was analyzed histopathologically fur the presence of discrete cort ical malformations (e.g., microdysgenesis). Outcome was assessed in all pat ients with an average postoperative period of 26 months. Results: In 13 patients, we found subtle, histopathologically detectable si gns of cortical malformation: 6 of them with concomitant hippocampal sclero sis (dual pathology) and 7 without. The latter subgroup had a worse surgica l outcome and showed enhanced bilateral and/or contralateral pathological c hanges in the hippocampal formation when investigated by MR spectroscopy. Conclusions: These data suggest that by showing contralaterally or bilatera lly abnormal spectra, MR spectroscopy might be able to indicate pathologica l changes in subtle developmental disorders that an possibly more widesprea d over the brain. This observation may improve noninvasive diagnosis in pre surgical evaluation and the neurobiological understanding of cortical malfo rmations in pharmacoresistant temporal lobe epilepsy.