Subacute Electrical Stimulation of the Hippocampus Blocks Intractable Temporal Lobe Seizures and Paroxysmal EEG Activities

Abstract

Summary:Purpose: To investigate the clinical, electroencephalographic (EEG), and histopathologic effects of subacute electrical stimulation of the hippocampal formation or gyrus (SAHCS) on 10 patients with intractable temporal lobe seizures.Methods: Bilateral, depth, hippocampal or unilateral, subdural, basotemporal electrodes were implanted in all 10 patients for a topographic diagnosis of the site and extent of the epileptic focus before a temporal lobectomy. In all patients, antiepileptic drugs (AEDs) were discontinued from 48 to 72 h before a program of continuous SAHCS, which was performed for 2-3 weeks. Stimulation parameters were biphasic Lilly wave pulses, 1301s in frequency, 450 p. s in duration, and 200-400 p,A in amplitude. The stimuli were delivered 23 of every 24 h for the 2-3-week SAHCS period. The effects of SAHCS on the number of clinical seizures per day and the percentage of interictal EEG spikes per 10-second samples of maximal paroxysmal activity at the epileptic focus were determined daily during the 16 days of SAHCS. At the completion of this program, patients underwent an en bloc temporal lobectomy, and the histopathologic effects of SAHCS on the stimulated tissue were analyzed by means of light-microscopy studies.Results: In seven patients whose stimulation electrode contacts were placed within the hippocampal formation or gyrus and who experienced no interruption in the stimulation pro- creased the number of interictal EEG spikes at the focus after 5-6 days. The most evident and fast responses were found by stimulating either the anterior pes hippocampus close to the amygdala or the anterior parahippocampal gyrus close to the entorhinal cortex. Other surface, hippocampal, and basotemporal EEG signs predicted and accompanied this antiepileptic response. These included an electropositive DC shift and monomorphic delta activity at the medial hippocampal and parahippocampal regions, and a normalization of the background EEG activity and signs of slow-wave sleep in surface, depth, and subdural regions. In contrast, no evident antiepileptic responses or no responses at all were found in three patients when stimulation was either interrupted or when it was adniinistered outside the hippocampus.Light microscopy analysis of the stimulated hippocampal tissue showed histopathological abnormalities attributable to the depth-electrode penetration damage or to the pial surface reaction to the subdural, Silastic electrode plate. However, no evident histopathological differences were found between the stimulated and nonstimulated hippocampal tissue.Conclusions: SAHCS appears to be a safe procedure that can suppress temporal lobe epileptogenesis with no additional damage to the stimulated tissue.

Responsive Cortical Stimulation for the Treatment of Epilepsy

“…10 -12 More recent open-loop stimulation paradigms have also included stimulation into the epileptogenic region, such as the mesial temporal structures and primary motor cortex. [13][14][15] A review of openloop DBS for epilepsy is provided in this issue by Halpern et al 16 In contrast to open-loop stimulation, closed-loop or responsive stimulation aims to suppress epileptiform activity by delivering stimulation directly in response to the electrographic activity. Due to the technical complexity of developing an integrated system that provides realtime electrographic analysis and automatic delivery of responsive stimulation, few centers have specifically tested the efficacy of responsive stimulation.…”

Repetitive low-frequency stimulation reduces epileptiform synchronization in limbic neuronal networks

“…Over the last few years, several attempts have been made to use deep-brain electrical (Velasco et al, 2000a(Velasco et al, ,b, 2001Vonck et al, 2002;Yamamoto et al, 2002) or transcranial magnetic stimulation (Menkes and Gruenthal, 2000;Tergau et al, 1999) to abate seizures in patients presenting with epileptic disorders resistant to antiepileptic drugs, including mesial temporal lobe epilepsy (MTLE). These stimulating procedures have been often proved to be effective in reducing and/or abolishing both interictal and ictal discharges.…”

Invazív neuromoduláció a gyógyszerrezisztens epilepsziák kezelésében

“…Az 1. táblázat azokat a célpontokat foglalja össze, amelyek antiepilepsziás célzattal stimulációra kerültek [11,12,13,14,15,16,17,18,19,20].…”