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Neuromodulation Today Vagus Nerve Stimulation Neural Network NeuromodulationNeuromodulation TodayToday VagusVagus NerveNerve StimulationStimulation NeuralNeural NetworkNetwork ModulationModulation Reese Terry, Founder, Cyberonics Ingela Danielsson, M.D. Ph.D, Medical Director, Cyberonics University of Minnesota – LifeScience Alley Breakthrough June 4, 2007 VNSVNS forfor EpilepsyEpilepsy VNSVNS toto interruptinterrupt seizuresseizures suggestedsuggested byby aa seventyseventy yearyear historyhistory ofof publishedpublished researchresearch DirectDirect brainbrain stimulationstimulation hadhad aa veryvery badbad stigmastigma inin thethe 19801980’’s.s. SeveralSeveral animalanimal modelsmodels demonstratedemonstrate VNSVNS interruptsinterrupts seizuresseizures ClinicalClinical studiesstudies startedstarted inin 19881988 withwith 3030 secondsseconds ON/5ON/5 minutesminutes OFFOFF withwith goalgoal ofof randomlyrandomly interruptinginterrupting seizures.seizures. StimulationStimulation couldcould alsoalso bebe triggeredtriggered byby anan externalexternal magnet.magnet. FDAFDA approvedapproved inin 1997.1997. VNSVNS forfor EpilepsyEpilepsy Significant mood elevation observed in patients treated for epilepsy. Seizure control improves over the first 3-6 months. Although triggered stimulation is effective for many seizures, the main effect seems to be a gradual increase in “seizure threshold”. Commercial experience reported in registry is that about 65% patients have at least a 50% reduction in seizures. VNS FDA approved for treatment resistant depression July 2005. Insurance coverage difficult - CMS and major private insurers have denied national coverage. VNSVNS ImplantImplant DiagramDiagram ModelModel 102102 PulsePulse GeneratorGenerator withwith ModelModel 302302 BipolarBipolar LeadLead Caudal Circumneural (cn) Bipolar Electrode Anchor Tether (+) Electrode (-) Electrode Rostral VNSVNS SystemSystem ModulationModulation No invasion of neural tissue. Reversible - Electrodes can be removed from the nerve. Patients receive therapy 24/7. Mitigates compliance and drug substitution issues. The vagus nerve can be thought of as a “Super highway” into brain Preferentially stimulate the >80,000 afferent fibers Enters NTS and branches bi-laterally to both sides of brain Projections via overlapping pathways into parts of brain associated with seizure and depression control Vagal Afferent Pathways in CNS Endocrine Limbic Pre-motor •Vagal afferents •Heart System System System NTS (hormonal) (behavioral) (autonomic) •Blood vessels •Airways & Lungs •GI tract Vagal Afferents Hippo INS PBN Thal LC Cing DRN NTS DMX BST Amyg AMB IML Hypothal VLM Courtesy of Thomas Cunningham, PhD, University of Texas Health Science Center at San Antonio TheThe VagusVagus NerveNerve ProjectsProjects toto KeyKey BrainBrain RegionsRegions orbitofrontal cortex hypothalamus amygdala parabrachial nucleus nucleus (PB) locus coeruleus George MS, et al. Biol Psychiatry. 2000;47(4):287-295. VagalVagal ProjectionsProjections toto thethe CNSCNS Vagal Afferents INS PBN Thal LC NTS ILC DRN DMX BST IML Amyg AMB Hypothal VLM INS = insular cortex; ILC = infralimbic cortex; PBN = parabrachial nucleus; LC = locus coeruleus; DRN = dorsal raphe; NTS = nucleus tractus solitarius; AMB = nucleus ambiguus; VLM = ventrolateral medulla; IML = intermediolateral cell column Courtesy of Thomas Cunningham, PhD, University of Texas Health Science Center at San Antonio. Effects of VNS on The Nucleus of the Solitary Tract 2 hr 3 wk Acute VNS (2 h) Chronic VNS (3 wk) 40 40 Fos ΔFosB * 30 30 * 20 * 20 * * 10 10 * Average Number of Positive Cells 0 0 Sham L Sham R VNS L VNS R Sham L Sham R VNS L VNS R * is significantly different from sham, P < 0.05 Courtesy of Thomas Cunningham, PhD, University of Texas Health Science Center at San Antonio VagalVagal ProjectionsProjections toto thethe CNSCNS Vagal Afferents INS PBN Thal LC NTS ILC DRN DMX BST IML Amyg AMB Hypothal VLM INS = insular cortex; ILC = infralimbic cortex; PBN = parabrachial nucleus; LC = locus coeruleus; DRN = dorsal raphe; NTS = nucleus tractus solitarius; AMB = nucleus ambiguus; VLM = ventrolateral medulla; IML = intermediolateral cell column Courtesy of Thomas Cunningham, PhD, University of Texas Health Science Center at San Antonio. SpontaneousSpontaneous firingfiring ratesrates ofof DRNDRN 55--HTHT neuronsneurons withwith VNSVNS Door and Debonnel, J Pharmacol Exp Ther. 2006 Aug;318(2):890-8 D1 Slide 12 D1 D610_XP_FEB2005, 5/23/2007 Effects of VNS on The Dorsal Raphe Acute VNS (2 h) Chronic VNS (3 wk) 20 20 Fos * ΔFosB 15 15 10 10 5 5 Average Number of Positive Cells 0 0 Sham VNS Sham VNS * is significantly different from sham, P < 0.05 Courtesy of Thomas Cunningham, PhD, University of Texas Health Science Center at San Antonio VagalVagal ProjectionsProjections toto thethe CNSCNS Vagal Afferents INS PBN Thal LC NTS ILC DRN DMX BST IML Amyg AMB Hypothal VLM INS = insular cortex; ILC = infralimbic cortex; PBN = parabrachial nucleus; LC = locus coeruleus; DRN = dorsal raphe; NTS = nucleus tractus solitarius; AMB = nucleus ambiguus; VLM = ventrolateral medulla; IML = intermediolateral cell column Courtesy of Thomas Cunningham, PhD, University of Texas Health Science Center at San Antonio. LCLC NENE NeuronNeuron firingfiring ratesrates withwith VNSVNS Door and Debonnel, J Pharmacol Exp Ther. 2006 Aug;318(2):890-8 Effects of VNS on The Locus Coeruleus Acute VNS (2 h) Chronic VNS (3 wk) 20 20 Fos * ΔFosB * * 15 15 * * Positive Cells * 10 10 5 5 Average Number of 0 0 Sham VNS Sham VNS * is significantly different from sham, P < 0.05 Courtesy of Thomas Cunningham, PhD, University of Texas Health Science Center at San Antonio SummarySummary andand QuestionsQuestions Neuromodulation of the vagus nerve provides an FDA Approved pathway for treating refractory epilepsy and depression. Is VNS the most effective neuromodulation pathway for seizure or depression control? Can the VNS signals be optimized for increased efficacy? Efficacy builds slowly for epilepsy and depression. Can the rate of response be increased? The durability of response is quite impressive for these disorders. Can the durability be further improved? Does automatic seizure detection and activation really help efficacy for the treatment of epilepsy? Can responders be identified prior to implant?.
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