In vivo P-Glycoprotein Function Before and After Epilepsy Surgery

In the September 3, 2014, Neurology articles published ahead of print, Doctors Bauer and colleagues, representing a group of European researchers, present a provocative study that used PET scans before and after temporal lobe epilepsy surgery to look at the activity of the protein transporter P-glycoprotein (Pgp). This protein is located at the blood-brain barrier and moves multiple drugs out of cells (a process known as efflux). The study assessed whether post-operative changes and seizure frequency are associated with changes in this transporter protein.

How was the study conducted?

• During the study, 7 people with drug resistant temporal lobe epilepsy underwent PET scans before and after surgery. 
• Study participants were followed for a median of six years, a range of four to seven years after surgery, looking at the Pgp immunoreactivity in the surgically resected specimens.

What did the study find?

The investigators found that people who had achieved seizure freedom and withdrawal of antiepileptic drugs were associated with

• higher temporal lobe Pgp function before surgery,
• higher Pgp positive standing in surgically resected hippocampal specimens, and
• reduction in the global Pgp function postoperatively compared with non-optimal surgery outcome. 

The investigators conclude that the data from this pilot study suggests that Pgp overactivity in epilepsy is dynamic and complete seizure control and elimination of antiepileptic medication is associated with reversal of overactivity, although a larger study is needed to prove if this is the case.