Association between temporal lobe P-glycoprotein expression and seizure recurrence after surgery for pharmacoresistant temporal lobe epilepsy.

Surgery is recommended for pharmacoresistant temporal lobe epilepsy (TLE), but seizures recur in approximately one third of patients postsurgery. P-glycoprotein is an efflux multidrug transporter that is overexpressed in a range of epileptogenic pathologies. We hypothesized that increased expression of P-glycoprotein in the epileptogenic temporal lobe might be a marker for recurrence of pharmacoresistant seizures postsurgery. We performed immunohistochemistry on temporal lobe tissues resected from 69 patients who underwent anterior temporal lobectomy for pharmacoresistant TLE with histopathological proven hippocampal sclerosis. P-glycoprotein expression was rated by three pathologists independently. Patients with seizure recurrence (n=22) had greater number of positively stained capillaries (p=0.001) and higher P-glycoprotein immunoreactive score in capillaries (p=0.002) in the white matter of resected temporal lobe. The differences remained significant in multivariate analysis (p=0.002 and 0.006, respectively). The results suggest that P-glycoprotein expression in temporal lobe may be associated with seizure recurrence after surgery for pharmacoresistant TLE.