Abstracts

Rationale: Neuromodulation has proved an alternative for patients with intractable epilepsy who otherwise are not candidates to ablative procedures. Several targets have been tried for patients with generalized seizures such as vagus nerve (1), centromedian (2) or VA (3) thalamic, cerebellar (4) stimulation. For mesial temporal lobe seizures stimulation of the epileptic foci in hippocampus has been proven to be effective (5). Epileptic foci localized within the motor cortex often prove to be intractable and the ablative procedures when the foci are located in eloquent areas carry a high risk of motor function loss. Based on the positive effect of neuromodulation in epilepsy we evaluated the possible anticonvulsive effect of stimulating the epileptic foci located in the motor area in two patients with non lesional intractable epilepsy, one of them in the supplementary motor area and the other in the primary motor area. .Methods: Two patients were studied following the Epilepsy Surgery Protocol of the General Hospital of Mexico (1). As such they had a complete workup including clinical history; AEDs blood levels, MRI, EEGs, neuropsychological battery. Both had severe seizures despite multiple AEDs. Both were candidates to having intracranial grids for foci detection. Patient and family signed the informed consent. Patient I was a 17 year old male. He started seizing at 14 years old. The seizures were characteristic supplementary motor ones, that is, brief, with abrupt posturing of left arm and sudden version of the head to the left, occasionally secondary tonic clonic seizures. Consciousness was preserved. Conduct abnormalities with perseverance and verbal aggressiveness were present. EEG showed frontal parasagittal epileptic activity. MRI was normal. Bilateral 20 contact grids were implanted in right and left SMA. Daily depth recording was performed without AEDs and ictal EEG activity showed a mesial focus located in the right SMA. Patients reinitiated AEDs. Grids were explanted and replaced by a 4 contact electrode for chronic stimulation (Resume, Medtronic Inc.) connected to a DBS system. Stimulation was started with the following parameters: bipolar continuous stimulation of 130Hz, 3.0 V (350μA).Results: Patient’s I follow up showed progressive decrease in seizure occurrence to become seizure free in month number five, he has been seizure free for 28 months. Patient II had showed a faster seizure decrease in 1 week, she stopped seizing after 2 weeks of chronic stimulation and has been seizure free for 6 months now, No adverse effects in either patient have been reported up to now. Neuropsychological testing and QOL scales showed improvement.Conclusions: Long term stimulation of the seizure foci located in the motor cortex provides a non lesional alternative method when compared to conventional ablative surgery that could improve seizure outcome without deterioration of motor function in patients with intractable motor seizures.