EEG Derived Brain Activity Reflects Treatment Response from Vagus Nerve Stimulation in Patients with Epilepsy

The mechanism of action of vagus nerve stimulation (VNS) is yet to be elucidated. To that end, the effects of VNS on the brain of epileptic patients were studied. Both when VNS was switched “On” and “Off”, the brain activity of responders (R, seizure frequency reduction of over 50%) was compared to the brain activity of nonresponders (NR, seizure frequency reduction of less than 50%). Using EEG recordings, a significant increase in P300 amplitude for R and a significant decrease in P300 amplitude for NR were found. We found biomarkers for checking the efficacy of VNS with accuracy up to 94%. The results show that P300 features recorded in nonmidline electrodes are better P300 biomarkers for VNS efficacy than P300 features recorded in midline electrodes. Using source localization and connectivity analyses, the activity of the limbic system, insula and orbitofrontal cortex was found to be dependent on VNS switched “On” versus “Off” or patient group (R versus NR). The results suggest an important role for these areas in the mechanism of action of VNS, although a larger patient study should be done to confirm the findings.

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Vagus nerve stimulation for drug-resistant epilepsy

Practical Neurology ◽

10.1136/practneurol-2019-002210 ◽

2019 ◽

Vol 20 (3) ◽

pp. 189-198 ◽

Cited By ~ 1

Author(s):

Laura Pérez-Carbonell ◽

Howard Faulkner ◽

Sean Higgins ◽

Michalis Koutroumanidis ◽

Guy Leschziner

Keyword(s):

Vagus Nerve ◽

Seizure Frequency ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Therapeutic Option ◽

Drug Resistant ◽

Drug Resistant Epilepsy ◽

Randomised Controlled

Vagus nerve stimulation (VNS) is a neuromodulatory therapeutic option for drug-resistant epilepsy. In randomised controlled trials, VNS implantation has resulted in over 50% reduction in seizure frequency in 26%–40% of patients within 1 year. Long-term uncontrolled studies suggest better responses to VNS over time; however, the assessment of other potential predictive factors has led to contradictory results. Although initially designed for managing focal seizures, its use has been extended to other forms of drug-resistant epilepsy. In this review, we discuss the evidence supporting the use of VNS, its impact on seizure frequency and quality of life, and common adverse effects of this therapy. We also include practical guidance for the approach to and the management of patients with VNS in situ.

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Vagus nerve stimulation for complex partial seizures: surgical technique, safety, and efficacy

Journal of Neurosurgery ◽

10.3171/jns.1993.78.1.0026 ◽

1993 ◽

Vol 78 (1) ◽

pp. 26-31 ◽

Cited By ~ 79

Author(s):

Howard J. Landy ◽

R. Eugene Ramsay ◽

Jeremy Slater ◽

Roy R. Casiano ◽

Robert Morgan

Keyword(s):

Vagus Nerve ◽

Vocal Cord ◽

Seizure Frequency ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Vocal Cord Dysfunction ◽

High Current ◽

Partial Seizures ◽

Complex Partial Seizures ◽

Stimulation Group

✓ Electrical stimulation of the vagus nerve has shown efficacy in controlling seizures in experimental models, and early clinical trials have suggested possible benefit in humans. Eleven patients with complex partial seizures were subjected to implantation of vagus nerve stimulators. Electrode contacts embedded in silicone rubber spirals were placed on the left vagus nerve in the low cervical area. A transcutaneously programmable stimulator module was placed in an infraclavicular subcutaneous pocket and connected to the electrode. One patient required replacement of the system due to electrode fracture. Another patient developed delayed ipsilateral vocal-cord paralysis; the technique was then modified to allow more tolerance for postoperative nerve edema. A third patient showed asymptomatic vocal-cord paresis on immediate postoperative laryngoscopy. Vagus nerve stimulation produces transient vocal-cord dysfunction while the current is on. Nine patients were randomly assigned to receive either high- or low-current stimulation, and seizure frequency was recorded. The high-current stimulation group showed a median reduction in seizure frequency of 27.7% compared to the preimplantation baseline, while the low-current stimulation group showed a median increase of 6.3%. This difference approached statistical significance. The entire population then received maximally tolerable stimulation. The high-current stimulation group showed a further 14.3% reduction, while the low-current stimulation group showed a 25.4% reduction compared to the blinded period. The efficacy of vagus nerve stimulation seemed to depend on stimulus parameters, and a cumulative effect was evident. These results are encouraging, and further study of this modality as an adjunct treatment for epilepsy is warranted.

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Novel insights in the mechanism of action of vagus nerve stimulation

Brain Stimulation ◽

10.1016/j.brs.2017.01.287 ◽

2017 ◽

Vol 10 (2) ◽

pp. 432-433 ◽

Cited By ~ 1

Author(s):

K. Vonck

Keyword(s):

Vagus Nerve ◽

Mechanism Of Action ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation

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Vagus nerve stimulation for partial and generalized epilepsy from infancy to adolescence

Journal of Neurosurgery Pediatrics ◽

10.3171/2012.5.peds11489 ◽

2012 ◽

Vol 10 (3) ◽

pp. 200-205 ◽

Cited By ~ 30

Author(s):

Eric M. Thompson ◽

Susan E. Wozniak ◽

Colin M. Roberts ◽

Amy Kao ◽

Valerie C. Anderson ◽

...

Keyword(s):

Vagus Nerve ◽

Seizure Frequency ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Pediatric Patients ◽

Medication Use ◽

Partial Epilepsy ◽

Seizure Duration ◽

Antiepileptic Medication ◽

Generalized Epilepsy

Object Vagus nerve stimulation (VNS) is approved by the FDA for the treatment of partial epilepsy in patients older than 12 years. Authors of the current study performed a large retrospective analysis and comparison of VNS outcomes in children with an age ≥ and < 12 years, including those with partial and generalized epilepsy. Methods A retrospective review of the records of pediatric patients (age < 18 years) who had undergone primary VNS system implantation between 2001 and 2010 by a single pediatric neurosurgeon was undertaken. Considered data included demographics, epilepsy type (partial vs generalized), seizure frequency, seizure duration, postictal period duration, and antiepileptic medication use. Results One hundred forty-six patients (49% female) were followed up for a mean of 41 months after VNS implantation. Thirty-two percent of patients had partial epilepsy and 68% had generalized epilepsy. After VNS system implantation, seizure frequency was reduced in 91% of patients, seizure duration in 50%, postictal period in 49%, and antiepileptic medication use in 75%. There was no significant difference in age, sex, or duration of follow-up according to epilepsy type. Neither was there any significant difference in seizure frequency reduction, seizure duration, postictal period, medication use, overall clinical improvement, or improvement in quality of life based on an age ≥ or < 12 years or epilepsy type. Conclusions Vagus nerve stimulation reduced both seizure frequency and antiepileptic medication use in the majority of pediatric patients regardless of sex, age cohort, or epilepsy type. Vagus nerve stimulation also reduced seizure duration and postictal period in approximately half of the pediatric patients. Contrary to expectation, children with partial epilepsy do not benefit from VNS at higher rates than those with generalized epilepsy.

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Robust Estimation of Respiratory Variability Uncovers Correlates of Limbic Brain Activity and Transcutaneous Cervical Vagus Nerve Stimulation in the Context of Traumatic Stress

IEEE Transactions on Biomedical Engineering ◽

10.1109/tbme.2021.3108135 ◽

2021 ◽

pp. 1-1

Author(s):

Asim H. Gazi ◽

Matthew T. Wittbrodt ◽

Anna B. Harrison ◽

Srirakshaa Sundararaj ◽

Nil Z. Gurel ◽

...

Keyword(s):

Vagus Nerve ◽

Robust Estimation ◽

Nerve Stimulation ◽

Traumatic Stress ◽

Vagus Nerve Stimulation ◽

Brain Activity ◽

Respiratory Variability

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Vagus nerve stimulation may be a sound therapeutic option in the treatment of refractory epilepsy

Arquivos de Neuro-Psiquiatria ◽

10.1590/s0004-282x2013000100006 ◽

2013 ◽

Vol 71 (1) ◽

pp. 25-30 ◽

Cited By ~ 4

Author(s):

Murilo S. Meneses ◽

Samanta F. B. Rocha ◽

Cristiane Simão ◽

Heraldo Nei Hardt Laroca dos Santos ◽

Cleudi Pereira ◽

...

Keyword(s):

Vagus Nerve ◽

Seizure Frequency ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Palliative Treatment ◽

Refractory Epilepsy ◽

Therapeutic Option ◽

Treatment Objective

INTRODUCTION: Refractory epilepsy accounts for 20 to 30% of epilepsy cases and remains a challenge for neurologists. Vagus nerve stimulation (VNS) is an option for palliative treatment. OBJECTIVE: It was to study the efficacy and tolerability of VNS in patients implanted with a stimulator at the Curitiba Institute of Neurology (INC). METHODS: A case study of six patients with refractory epilepsy submitted to a VNS procedure at the INC in the last four years was described and discussed. RESULTS: Mean age at time of implantation was 29 years. Mean follow-up was 26.6 months. Seizure frequency decreased in all patients (40-50% (n=2) and >80% (n=4)). Three patients no longer required frequent hospitalizations. Two patients previously restricted to wheelchairs started to walk, probably because of improved mood. CONCLUSION: In this population, VNS proved to be a sound therapeutic option for treating refractory epilepsy.

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Older Age and Longer Epilepsy Duration Do Not Predict Worse Seizure Reduction Outcome after Vagus Nerve Stimulation

Journal of Neurological Surgery Part A Central European Neurosurgery ◽

10.1055/s-0037-1607396 ◽

2017 ◽

Vol 79 (02) ◽

pp. 152-158 ◽

Cited By ~ 6

Author(s):

Jitka Kocvarova ◽

Zdenek Novak ◽

Irena Dolezalova ◽

Michal Svoboda ◽

Milan Brazdil ◽

...

Keyword(s):

Intellectual Disability ◽

Vagus Nerve ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Older Patients ◽

Age Groups ◽

Seizure Reduction ◽

Follow Up Care ◽

Patients With Epilepsy

Introduction We analyzed the results of vagus nerve stimulation (VNS) on older patients and patients with long-lasting epilepsy and included severely intellectually disabled patients. Patients and Methods A total of 103 adults with VNS implanted from 2005 to 2014 were studied. The responder rates, that is, the percentage of VNS patients who responded to VNS, classified as seizure reduction ≥ 50% (50R) and seizure reduction ≥ 90% (90R), were compared in defined age groups (< 40 and ≥ 40 years, and < 50 and ≥ 50 years) and epilepsy duration groups (< 20 and ≥ 20 years, < 30 and ≥ 30 years, and < 40 and ≥ 40 years) at the 1-year follow-up visit and the last follow-up visit (at least 2 years after surgery). The age distributions and responder rates were also studied in patients with an intellectual disability. Results The analysis did not confirm a significantly lower 50R or 90R rate in patients ≥ 40, ≥ 50, or ≥ 60 years when compared with their younger counterparts, but the 50R rate increase during follow-up care was the lowest in patients ≥ 50 and ≥ 60 years. The highest percentage of patients with an intellectual disability in the group < 40 years of age did not adversely affect the 50R rate. Longer epilepsy duration was not confirmed as a negative predictor of VNS outcome. There was a significantly higher 50R rate in patients with epilepsy duration ≥ 20 years (at the last follow-up visit) and a higher 90R rate in patients with epilepsy duration ≥ 30 years (at the 1-year follow-up visit). The increase in the 50R rate during follow-up care was lower in patients with epilepsy durations ≥ 30 and ≥ 40 years. Conclusions The study did not find worse VNS outcomes, as defined by the 50R or 90R rate, in older adult patients or in patients with a longer epilepsy duration. The increasing stimulation effect over time is less marked in older patients and in patients with longer epilepsy duration.

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