Abstracts

Rationale: Deep brain stimulation of the anterior thalamus is a well studied treatment modality for difficult-to-treat pharmacoresistant epilepsies in European countries (Fisher et al., Epilepsia 2011). In view of a higher rate of depressive and cognitive symptoms changes as reported by patients, further potential targets for intractable partial epilepsy are warranted. Clinical data is summarized of patients with Ncl. accumbens (NAC) stimulation in patients with intractable partial epilepsy. Methods: Seizure frequency and severity as well as neurocognitive and psychiatric parameters were assessed in nine patients, either during a blinded 3-month on-period (4 patients) or a non-blinded 6-month period (5 patients). Antiepileptic drug medication remained unchanged. Results: Five out of nine patients had more than 50% reduction in seizure frequency with NAC-stimulation. Patient-reported outcomes (Beck-test, Mini-International-Neuropsychiatric-Interview, Beck-Depression-Inventory IA and Liverpool-Seizure-Severity-Score) and neuropsychological remained unchanged. Two patients experienced worsening of seizure frequency, which was reversed by reduction of stimulation voltage. Responders had a temporal (2 patients, both are non-responders after resective surgery), frontal (1 patient), fronto-temporal (1 patient), multifocal (1 patient) seizure onset. Non-responders had either bilateral temporal (2 patients), frontal (1 patient) or frontotemporal (1 patient) epilepsy. Conclusions: The site of seizure onset zone seems not be a positive predictive factor for efficacy of NAC-stimualtion. Possible candidates for NAC-stimulation are also patients after unsuccessfull resective surgery. The NAC may be a suitable target for electrical stimulation in intractable epilepsy - a result to be confirmed in an adequately powered study.