Seizure Blockage with Automated [dsquote]Closed-Loop[dsquote] Electrical Stimulation: A Pilot Study
Abstract number :
2.336
Submission category :
Year :
2001
Submission ID :
2132
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
I. Osorio, KUMC and Flint Hills Scientific, L.L.C. (FHS); M.G. Frei, FHS; S.B. Wilkinson, KUMC and FHS; S. Sunderam, FHS; N.C. Bhavaraju, FHS; N. Graves, Medtronic, Inc. (MDT); S.F. Schaffner, MDT; T. Peters, FHS; A.M. Johnson, FHS; C.A. DiTeresi, FHS; J.
RATIONALE: The anti-seizure efficacy of periodic electrical stimulation (ES) of the brain is limited, due to a wide variety of factors, including but not limited to timing of stimulation. Anecdotal evidence from clinical literature and more rigorous observations in animals suggest that stimulation close to the onset of seizures has an arresting effect. An algorithm (Osorio et. al. Epilepsia 1998; 39:615) which reliably detects seizures and quantifies their intensity and duration allows automatic control of timing of stimulation. The purpose of this HSC and FDA approved study is to assess efficacy and safety of ES delivered [dsquote]around[dsquote] seizure onset (closed-loop; CL), in response to automated algorithm detections (Ad).
METHODS: After completing invasive surgery evaluation (control study with continuous algorithm monitoring), 7 subjects were enrolled in this study. Grass S-12 stimulators were automatically triggered to deliver ES to contacts in/near the epileptogenic zone (local closed-loop; ), or to anterior thalamic nuclei (remote closed-loop; ), in response to every other Ad. Stimulation frequency, intensity and duration varied inter-individually. Ad[scquote]s were verified visually. Clinical seizure index (CSI) was computed for control vs. CL. Within CL, number of seizures, their intensity and duration were compared with stimulation [italic]on[/italic] vs. [italic]off[/italic].
RESULTS: In 3 of 4 subjects, (mean duration: 52h) reduced mean CSI (control) from 1.19 to 0/day; in 1 subject, seizures were blocked at site of stimulation but not elsewhere.
In 3 of 3 subjects, (mean duration: 171h) reduced mean CSI from 1.06 to 0.65/day. Thirty second (but not 2.5s) stimulation was efficacious. Only 4 of 13 clinical seizures occurred with stimulation [italic]on[/italic], and the majority when stimulation was 2.5s. Subclinical seizure duration and intensity were significantly (p[lt]0.05) reduced in and compared to control and in with stimulation [italic]on[/italic] compared to stimulation [italic]off[/italic]. There were no adverse effects.
CONCLUSIONS: Closed-Loop ES appears efficacious and safe. These results suggest that timing of stimulation may be critically important for seizure blockage and, if confirmed in a larger scale study, bode well for the future of this therapeutic modality.
Support: This research was supported in part by a grant from Medtronic, Inc.
Disclosure: Grant - KUMC from Medtronic. Consulting - FHS from Medtronic. Ownership - FHS. Materials - Medtronic to KUMC and FHS. Other - FHS detection algorithm licensed by FHS from KUMC and sublicensed by Medtronic from FHS.