Abstracts

LONG-TERM EFFECTS OF CHRONIC-INTERMITTEND DEEP BRAIN STIMULATION OF THE NCL. SUBTHALAMICUS (STN) ON SEIZURE ACTIVITY IN A RAT MODEL OF ABSENCE EPILEPSY

Abstract number : 1.176
Submission category :
Year : 2003
Submission ID : 1898
Source : www.aesnet.org
Presentation date : 12/6/2003 12:00:00 AM
Published date : Dec 1, 2003, 06:00 AM

Authors :
Brita Fritsch, Hristos Karakizlis, Hajo M. Hamer, Astrid Dempfle, Wolfgang H. Oertel, Felix Rosenow Epilepsy Center - Department of Neurology, Philipps-University Marburg, Marburg, Hessen, Germany; Institute of Biostatistics, Philipps-University Marburg,

An anticonvulsive effect by inhibiting the substantia nigra pars reticulata (SNpr), the major output nucleus of the basal ganglia, via consecutive disinhibition of the collicullus superior, has been reported.
Experimental data and case reports of patients suffering from epilepsy treated with STN stimulation (HFS) suggest an anticonvulsive effect, probably mediated by an inhibition of the STN which interferes with the excitatory subthalamico-nigral pathway.
In the present study the influence of a bilateral, chronic-intermittend HFS of the STN on seizure activity was investigated in rats of the WAG/Rij strain (n=12), suffering from well defined absence seizures.
Bipolar, concentric deep brain electrodes and screw-scull electrodes were implanted by stereotaxy. A stimulation-frequency of 130 Hz with an single-impulse duration of 60 [mu]s, applicated as train of 30 sec. every 5 min. for one hour, was used. The procedure was repeated after one week.
Effects were evaluated for both experimental days by cumulated seizure duration (CSD) and seizure frequency (SF) in EEG during a baseline period (B1 and B2 for 1h), stimulation (S1 and S2) and directly after stimulation (P1 and P2 for 1h). For statistical analysis the non-parametric Friedman-Test followed by Wilcoxon-Test was performed.
The chronic-intermittent bilateral HFS of the STN resulted after the first stimulation in a decrease of cumulated seizure duration (B1: 119 sec; S1: 61 sec.; P1: 38 sec.) and in further reduction even during baseline measurement at the second experimental day one week later (B2: 20 sec; S2: 13 sec.; P2: 3 sec.). This reduction in CSD and SF was statistical significant (CSD: B1 vs B2 p = 0,006, B1 vs. P1 p = 0,008; SF: B1 vs B2 p = 0,006, B1 vs. P1 p = 0,013).
This study provides evidence for anticonvulsive properties of chronic-intermittend, bilateral HFS of the STN in absence epilepsy. Ineffectiveness of chronic-tonic stimulation seen in previous studies suggest dependency of anticonvulsive effects on stimulation paradigms.
In addition a long-term anticonvulsive effect lasting at least for one week was assessed and was boosted by the second stimulation.
[Supported by: F. Rosenow was partially supported by the Urlan-Professorship for Neurology/Epileptology]