gms | German Medical Science

Objective: Patients with pharmacoresistant epilepsy caused by an epileptogenic focus in an eloquent brain area are difficult to treat. An operative resection or multiple subpial transsection may result in severe neurological deficits (hemiparesis, motoric- or sensomotoric aphasia). Therefore we have developed a novel experimental technique by implanting biodegradable gabapentin (GBP)-continaing polymer matrices onto the cortex of rats with tetanus toxin induced focal cortical epilepsy.

Methods: Tetanus toxin (50 µg) was injected stereotactically into the motor area 4 of Wistar rats. Epileptic activity was measured by video-electro-encephalography (video-EEG). In a second operation the scull was reopened and a biodegradable GBP-polymer matrix was implanted onto the cortex where the epilepsy was induced. In a second video-EEG monitoring the seizure time was compared with the pre-implantation video-EEG. As controls against tetanus toxin served injections with normal saline (0.9% NaCl). GBP-polymer matrices were controlled with saline containing polymer matrices.

Results: Ten rats were injected with tetanus toxin into the cortical motor area 4. As control 10 rats were injected with normal saline. In video-EEG-monitoring 8 of 10 animals with tetanus toxin injections developed epilepsy. None of the saline injected animals developed epilepsy. In a second operation 4 rats were reopened and 2 were implanted with GBP-polymer matrices cortically. One sham-animal received a GBP-polymer matrix subgaleal without opening the scull and one sham-animal received a saline polymer matrix which was implanted on the cortex surface. Effects of GBP-polymer implants on frequency and duration of epileptic discharges will be presented.

Conclusions: Application of local anticonvulsant therapy by polymer matrices in vivo is a new therapeutic concept which may offer an option for patients with pharmacoresistant epilepsy in eloquent brain areas.