Perivascular clustering in temporal lobe epilepsy: oligodendroglial cells of unknown function.

Marked perivascular clustering (PC), i.e., groups and rows of small round cells along white matter vessels, is seen in temporal lobe epilepsy (TLE) specimens obtained by surgery. This study focuses on the constituting cell types and discusses clinical significance and pathogenesis of PC, which are so far unknown. Based on a series of 59 nonlesional TLE surgical specimens, we characterized PC by immunohistochemistry and correlated the amount of PC with clinical parameters. PC cells were variably positive for galactocerebroside, myelin basic protein and S-100 protein, while glial fibrillary acidic protein, vimentin, nestin and neuronal antigens were not expressed. There was no correlation between the amount of PC and any clinical feature, including age at surgery, age at epilepsy onset, duration of epilepsy, preoperative seizure frequency, childhood febrile convulsions, family history of epilepsy, and postsurgical outcome. Our findings suggest oligodendroglial differentiation of PC, while its primary (dysplastic) versus secondary (reactive) pathogenesis remains unresolved.