1
|
Szaflarski JP, Allendorfer JB, Begnaud J, Ranuzzi G, Shamshiri E, Verner R. Optimized microburst VNS elicits fMRI responses beyond thalamic-specific response from standard VNS. Ann Clin Transl Neurol 2024. [PMID: 38532258 DOI: 10.1002/acn3.52029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 12/21/2023] [Accepted: 02/14/2024] [Indexed: 03/28/2024] Open
Abstract
OBJECTIVE In parallel to standard vagus nerve stimulation (VNS), microburst stimulation delivery has been developed. We evaluated the fMRI-related signal changes associated with standard and optimized microburst stimulation in a proof-of-concept study (NCT03446664). METHODS Twenty-nine drug-resistant epilepsy patients were prospectively implanted with VNS. Three 3T fMRI scans were collected 2 weeks postimplantation. The maximum tolerated VNS intensity was determined prior to each scan starting at 0.125 mA with 0.125 mA increments. FMRI scans were block-design with alternating 30 sec stimulation [ON] and 30 sec no stimulation [OFF]: Scan 1 utilized standard VNS and Scan 3 optimized microburst parameters to determine target settings. Semi-automated on-site fMRI data processing utilized ON-OFF block modeling to determine VNS-related fMRI activation per stimulation setting. Anatomical thalamic mask was used to derive highest mean thalamic t-value for determination of microburst stimulation parameters. Paired t-tests corrected at P < 0.05 examined differences in fMRI responses to each stimulation type. RESULTS Standard and microburst stimulation intensities at Scans 1 and 3 were similar (P = 0.16). Thalamic fMRI responses were obtained in 28 participants (19 with focal; 9 with generalized seizures). Group activation maps showed standard VNS elicited thalamic activation while optimized microburst VNS showed widespread activation patterns including thalamus. Comparison of stimulation types revealed significantly greater cerebellar, midbrain, and parietal fMRI signal changes in microburst compared to standard VNS. These differences were not associated with seizure responses. INTERPRETATION While standard and optimized microburst VNS elicited thalamic activation, microburst also engaged other brain regions. Relationship between these fMRI activation patterns and clinical response warrants further investigation. CLINICAL TRIAL REGISTRATION The study was registered with clinicaltrials.gov (NCT03446664).
Collapse
Affiliation(s)
- Jerzy P Szaflarski
- Department of Neurology and the UAB Epilepsy Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jane B Allendorfer
- Department of Neurology and the UAB Epilepsy Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | | | | | | | |
Collapse
|
2
|
Drees C, Afra P, Verner R, Kaye L, Keith A, Jiang M, Szaflarski JP, Nichol K. Feasibility study of microburst VNS therapy in drug-resistant focal and generalized epilepsy. Brain Stimul 2024; 17:382-391. [PMID: 38499287 DOI: 10.1016/j.brs.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 01/31/2024] [Accepted: 03/12/2024] [Indexed: 03/20/2024] Open
Abstract
BACKGROUND Vagus nerve stimulation (VNS) at low frequencies (≤30 Hz) has been an established treatment for drug-resistant epilepsy (DRE) for over 25 years. OBJECTIVE To examine the initial safety and efficacy performance of an investigational, high-frequency (≥250 Hz) VNS paradigm herein called "Microburst VNS" (μVNS). μVNS consists of short, high-frequency bursts of electrical pulses believed to preferentially modulate certain brain regions. METHODS Thirty-three (33) participants were enrolled into an exploratory feasibility study, 21 with focal-onset seizures and 12 with generalized-onset seizures. Participants were titrated to a personalized target dose of μVNS using an investigational fMRI protocol. Participants were then followed for up to 12 months, with visits every 3 months, and monitored for side-effects at all time points. This study was registered as NCT03446664 on February 27th, 2018. RESULTS The device was well-tolerated. Reported adverse events were consistent with typical low frequency VNS outcomes and tended to diminish in severity over time, including dysphonia, cough, dyspnea, and implant site pain. After 12 months of μVNS, the mean seizure frequency reduction for all seizures was 61.3% (median reduction: 70.4%; 90% CI of median: 48.9%-83.3%). The 12-month responder rate (≥50% reduction) was 63.3% (90% CI: 46.7%-77.9%) and the super-responder rate (≥80% reduction) was 40% (90% CI: 25.0%-56.6%). Participants with focal-onset seizures appeared to benefit similarly to participants with generalized-onset seizures (mean reduction in seizures at 12 months: 62.6% focal [n = 19], versus 59.0% generalized [n = 11]). CONCLUSION Overall, μVNS appears to be safe and potentially a promising therapeutic alternative to traditional VNS. It merits further investigation in randomized controlled trials which will help determine the impact of investigational variables and which patients are most suitable for this novel therapy.
Collapse
Affiliation(s)
- Cornelia Drees
- Mayo Clinic Arizona, Department of Neurology, Phoenix, AZ, USA; University of Colorado School of Medicine, Department of Neurology, Aurora, CO, USA
| | - Pegah Afra
- University of Utah School of Medicine, Department of Neurology, Salt Lake City, UT, USA; Weill-Cornell Medicine, Department of Neurology, New York, NY, USA; University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Ryan Verner
- LivaNova PLC (or a Subsidiary), Department of Clinical and Medical Affairs, London, UK
| | - Lesley Kaye
- University of Colorado School of Medicine, Department of Neurology, Aurora, CO, USA
| | - Amy Keith
- LivaNova PLC (or a Subsidiary), Department of Clinical and Medical Affairs, London, UK
| | - Mei Jiang
- LivaNova PLC (or a Subsidiary), Department Statistics and Data Science, London, UK
| | - Jerzy P Szaflarski
- University of Alabama at Birmingham School of Medicine, Department of Neurology, Birmingham, AL, USA
| | - Kathryn Nichol
- LivaNova PLC (or a Subsidiary), Department of Clinical and Medical Affairs, London, UK.
| |
Collapse
|
3
|
Nichol K, Verner R, Gordon C, Urry D. Assumptions and statistical inference. Epilepsia 2024; 65:242-243. [PMID: 38009669 DOI: 10.1111/epi.17821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 09/19/2023] [Accepted: 09/29/2023] [Indexed: 11/29/2023]
Affiliation(s)
- Kathryn Nichol
- Clinical and Medical Affairs, Epilepsy, LivaNova USA, Houston, Texas, USA
| | - Ryan Verner
- Clinical and Medical Affairs, Epilepsy, LivaNova USA, Houston, Texas, USA
| | - Charles Gordon
- Statistics and Data Science, LivaNova USA, Houston, Texas, USA
| | - Danielle Urry
- Clinical and Medical Affairs, Epilepsy, LivaNova USA, Houston, Texas, USA
| |
Collapse
|
4
|
Bagić AI, Verner R, Afra P, Benbadis S. ASCEND: A randomized controlled trial of titration strategies for vagus nerve stimulation in drug-resistant epilepsy. Epilepsy Behav 2023; 145:109333. [PMID: 37429122 DOI: 10.1016/j.yebeh.2023.109333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/12/2023] [Accepted: 06/15/2023] [Indexed: 07/12/2023]
Abstract
Vagus Nerve Stimulation (VNS) therapy is widely understood to provide clinically meaningful improvements in seizure control to patients with drug-resistant epilepsy, and has been a staple in the clinical armamentaria available to epileptologists for over 25 years. Despite the long history of evidence-based reviews by neurology professional societies, there is still evidence of a practice gap in VNS titration and dosing that aims to maximize clinical benefit. Recent retrospective analyses have strongly argued for a more consistent application of a population-wide target dose of VNS, and further argued the importance of quickly achieving this target dose to hasten the onset of clinical benefits; however, these analyses failed to provide evidence for practical implementation. Herein, we describe a randomized controlled trial assessing the impact of titrating VNS according to three different protocols to achieve the target dose of 1.5 mA at 500µsec, for a 20-Hz signal frequency. The study was registered as NCT02385526 on March 11, 2015. Sixty-two patients were randomized into treatment groups that followed different titration protocols. One protocol (Group A) was designed to align with currently accepted professional guidance for VNS titration and the manufacturer's labeling for VNS in epilepsy (Heck et al., 2002), while the other two protocols were derived from VNS applications in other therapeutic areas. Group A participants were most likely to achieve the target dose parameters in 12 weeks or less (81.8%), with a median time-until-achievement of the target dose of 8.1 weeks, while less than 60% of patients in other groups were able to achieve the same endpoint. Participants in all groups experienced low levels of transient tolerability concerns and adverse events, suggesting titration to the target dose in 12 weeks or less following the Group A protocol is generally acceptable to most patients. These findings indicate that patients receiving VNS for epilepsy can achieve the manufacturer-recommended dose range in 12 weeks or less. A wider implementation of the approach will likely improve the clinical impact of VNS on seizure control and prevent undertreatment.
Collapse
Affiliation(s)
- Anto I Bagić
- University of Pittsburgh Comprehensive Epilepsy Center (UPCEC), Department of Neurology, Pittsburgh, PA, USA.
| | - Ryan Verner
- LivaNova PLC (or a Subsidiary), Medical and Clinical Affairs, Houston, TX, USA.
| | - Pegah Afra
- University of Massachusetts Chan Medical School, Department of Neurology, Boston, MA, USA; University of Utah School of Medicine, Department of Neurology, Salt Lake City, UT, USA.
| | - Selim Benbadis
- University of South Florida, Department of Neurology, Tampa, USA.
| |
Collapse
|
5
|
Verner R, Szaflarski JP, Allendorfer JB, Vonck K, Giannicola G. Modulation of the thalamus by microburst vagus nerve stimulation: a feasibility study protocol. Front Neurol 2023; 14:1169161. [PMID: 37384278 PMCID: PMC10299807 DOI: 10.3389/fneur.2023.1169161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 05/04/2023] [Indexed: 06/30/2023] Open
Abstract
Vagus nerve stimulation (VNS) was the first device-based therapy for epilepsy, having launched in 1994 in Europe and 1997 in the United States. Since then, significant advances in the understanding of the mechanism of action of VNS and the central neurocircuitry that VNS modulates have impacted how the therapy is practically implemented. However, there has been little change to VNS stimulation parameters since the late 1990s. Short bursts of high frequency stimulation have been of increasing interest to other neuromodulation targets e.g., the spine, and these high frequency bursts elicit unique effects in the central nervous system, especially when applied to the vagus nerve. In the current study, we describe a protocol design that is aimed to assess the impact of high frequency bursts of stimulation, called "Microburst VNS", in subjects with refractory focal and generalized epilepsies treated with this novel stimulation pattern in addition to standard anti-seizure medications. This protocol also employed an investigational, fMRI-guided titration protocol that permits personalized dosing of Microburst VNS among the treated population depending on the thalamic blood-oxygen-level-dependent signal. The study was registered on clinicaltrials.gov (NCT03446664). The first subject was enrolled in 2018 and the final results are expected in 2023.
Collapse
Affiliation(s)
- Ryan Verner
- Clinical and Medical Affairs, LivaNova PLC (or a subsidiary), London, United Kingdom
| | - Jerzy P. Szaflarski
- Department of Neurology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, United States
| | - Jane B. Allendorfer
- Department of Neurology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, United States
| | - Kristl Vonck
- Department of Neurology, 4Brain, Ghent University Hospital, Ghent, Belgium
| | - Gaia Giannicola
- Clinical and Medical Affairs, LivaNova PLC (or a subsidiary), London, United Kingdom
| | | |
Collapse
|
6
|
Farrand A, Jacquemet V, Verner R, Owens M, Beaumont E. Vagus nerve stimulation parameters evoke differential neuronal responses in the locus coeruleus. Physiol Rep 2023; 11:e15633. [PMID: 36905173 PMCID: PMC10006695 DOI: 10.14814/phy2.15633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/13/2023] [Accepted: 02/15/2023] [Indexed: 03/12/2023] Open
Abstract
Vagus nerve stimulation (VNS) is used to treat drug-resistant epilepsy and depression, with additional applications under investigation. The noradrenergic center locus coeruleus (LC) is vital for VNS effects; however, the impact of varying stimulation parameters on LC activation is poorly understood. This study characterized LC activation across VNS parameters. Extracellular activity was recorded in rats' left LC while 11 VNS paradigms, utilizing variable frequencies and bursting characteristics, were pseudorandomly delivered to the left cervical vagus for five cycles. Neurons' change from baseline firing rate and timing response profiles were assessed. The proportion of neurons categorized as responders over 5 VNS cycles doubled in comparison to the first VNS cycle (p < 0.001) for all VNS paradigms, demonstrating an amplification effect. The percentage of positively consistent/positive responders increased for standard VNS paradigms with frequencies ≥10 Hz and for bursting paradigms with shorter interburst intervals and more pulses per burst. The synchrony between pairs of LC neurons increased during bursting VNS but not standard paradigms. Also, the probability of evoking a direct response during bursting VNS was higher with longer interburst intervals and a higher number of pulses per burst. Standard paradigms between 10-30 Hz best positively activates LC with consistency to VNS while the best bursting paradigm to increase activity was 300 Hz, seven pulses per burst separated by 1 s. Bursting VNS was effective in increasing synchrony between pairs of neurons, suggesting a common network recruitment originating from vagal afferents. These results indicate differential activation of LC neurons depending on the VNS parameters delivered.
Collapse
Affiliation(s)
- Ariana Farrand
- Department of Biomedical SciencesQuillen College of Medicine, East Tennessee State UniversityJohnson CityTennesseeUSA
| | - Vincent Jacquemet
- Department of Pharmacology and PhysiologyInstitute of Biomedical Engineering, University of MontrealMontrealQuebecCanada
- Research CenterSacred Heart Hospital of MontrealMontrealQuebecCanada
| | - Ryan Verner
- Neuromodulation DivisionLivaNova PLCHoustonTexasUSA
| | - Misty Owens
- Department of Biomedical SciencesQuillen College of Medicine, East Tennessee State UniversityJohnson CityTennesseeUSA
| | - Eric Beaumont
- Department of Biomedical SciencesQuillen College of Medicine, East Tennessee State UniversityJohnson CityTennesseeUSA
| |
Collapse
|
7
|
Tzadok M, Verner R, Kann L, Tungala D, Gordon C, El Tahry R, Fahoum F. Rapid titration of VNS therapy reduces time-to-response in epilepsy. Epilepsy Behav 2022; 134:108861. [PMID: 35963047 DOI: 10.1016/j.yebeh.2022.108861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 05/31/2022] [Accepted: 07/18/2022] [Indexed: 11/03/2022]
Abstract
BACKGROUND Common titration strategies for vagus nerve stimulation (VNS) prioritize monitoring of tolerability during small increases in stimulation intensity over several months. Prioritization of tolerability is partially based on how quickly side effects can be perceived and reported by patients, and the delayed onset of clinical benefits from VNS. However, many practices assess the clinical benefit of VNS at one year after implantation, and excessive caution during the titration phase can significantly delay target dosing or prevent a patient from reaching a therapeutic dose entirely. OBJECTIVE This study aimed to characterize the relationship between titration speed and the onset of clinical response to VNS. METHODS To assess differences between more aggressive titration strategies and more conservative ones, we analyzed the relationship between time-to-dose and time-to-response using a weighted Cox regression. The target dose was empirically defined as 1.625 mA output current delivered at 250 microsecond pulse widths at 20 Hz. Patient-level outcomes and dosing data were segregated into fast (<3 months), medium (3-6 months), and slow (>6 months) cohorts based on their titration speed. RESULTS The statistical model revealed a significant relationship between titration speed and onset of clinical response, defined as a 50% reduction from baseline in seizure frequency. Frequency of adverse events reported between each cohort trended toward higher rates of adverse events in adults who were titrated quickly; however, the pediatric population appeared to be more tolerant of titration at any speed. CONCLUSIONS This analysis indicates that faster titration yields faster onset of clinical benefit and is especially practical in the pediatric population, though attempts to accelerate adult titration may still be warranted.
Collapse
Affiliation(s)
- Michal Tzadok
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Pediatric Neurology Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Israel.
| | - Ryan Verner
- LivaNova PLC (or a subsidiary), London, Great Britain, United Kingdom
| | - Lennart Kann
- LivaNova PLC (or a subsidiary), London, Great Britain, United Kingdom
| | - Deepika Tungala
- LivaNova PLC (or a subsidiary), London, Great Britain, United Kingdom
| | - Charles Gordon
- LivaNova PLC (or a subsidiary), London, Great Britain, United Kingdom
| | - Riëm El Tahry
- Institute of Neuroscience, Université Catholique de Louvain (UCLouvain), Brussels, Belgium; Centre for Refractory Epilepsy, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Firas Fahoum
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| |
Collapse
|
8
|
Sen A, Verner R, Valeriano JP, Lee R, Zafar M, Thomas R, Kotulska K, Jespers E, Dibué M, Kwan P. Vagus nerve stimulation therapy in people with drug-resistant epilepsy (CORE-VNS): rationale and design of a real-world post-market comprehensive outcomes registry. BMJ Neurol Open 2022; 3:e000218. [PMID: 35018342 PMCID: PMC8705076 DOI: 10.1136/bmjno-2021-000218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/21/2021] [Indexed: 11/17/2022] Open
Abstract
Introduction The Vagus Nerve Stimulation Therapy System (VNS Therapy) is an adjunctive neuromodulatory therapy that can be efficacious in reducing the frequency and severity of seizures in people with drug-resistant epilepsy (DRE). CORE-VNS aims to examine the long-term safety and clinical outcomes of VNS in people with DRE. Methods and analysis The CORE-VNS study is an international, multicentre, prospective, observational, all-comers, post-market registry. People with DRE receiving VNS Therapy for the first time as well as people being reimplanted with VNS Therapy are eligible. Participants have a baseline visit (prior to device implant). They will be followed for a minimum of 36 months and a maximum of 60 months after implant. Analysis endpoints include seizure frequency (average number of events per month), seizure severity (individual-rated categorical outcome including very mild, mild, moderate, severe or very severe) as well as non-seizure outcomes such as adverse events, use of antiseizure medications, use of other non-pharmacological therapies, quality of life, validated measures of quality of sleep (Pittsburgh Sleep Quality Index or Children’s Sleep Habit Questionnaire) and healthcare resource utilisation. While the CORE-VNS registry was not expressly designed to test hypotheses, subgroup analyses and exploratory analysis that require hypothesis testing will be conducted across propensity score matched treatment groups, where possible based on sampling. Ethics and dissemination The CORE-VNS registry has already enrolled 823 participants from 61 centres across 15 countries. Once complete, CORE-VNS will represent one of the largest real-world clinical data sets to allow a more comprehensive understanding of the management of DRE with adjunctive VNS. Manuscripts derived from this database will shed important new light on the characteristics of people receiving VNS Therapy; the practical use of VNS across different countries, and factors influencing long-term response. Trail registration number NCT03529045.
Collapse
Affiliation(s)
- Arjune Sen
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, Oxfordshire, UK
| | - Ryan Verner
- Clinical and Medical Affairs, LivaNova Plc, London, UK
| | | | - Ricky Lee
- Department of Neurology, Ascension Medical Group, Wichita, Kansas, USA
| | - Muhammad Zafar
- Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, USA
| | - Rhys Thomas
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK.,Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Katarzyna Kotulska
- Department of Neurology and Epileptology, Children's Memorial Health Institute, Warszawa, Poland
| | - Ellen Jespers
- Clinical and Medical Affairs, LivaNova Plc, London, UK
| | - Maxine Dibué
- Clinical and Medical Affairs, LivaNova Plc, London, UK.,Department of Neurosurgery, Friedrich Schiller University Jena, Jena, Thüringen, Germany
| | - Patrick Kwan
- Department of Neuroscience, Central Clinical School, Monash University, Clayton, Victoria, Australia.,Epilepsy Unit, Brain Program, Alfred Hospital, Melbourne, Victoria, Australia.,Departments of Medicine and Neurology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | | |
Collapse
|
9
|
Kulju T, Haapasalo J, Verner R, Dibué-Adjei M, Lehtimäki K, Rainesalo S, Peltola J. Frequency of Automatic Stimulations in Responsive Vagal Nerve Stimulation in Patients With Refractory Epilepsy. Neuromodulation 2021; 23:852-858. [PMID: 32840019 DOI: 10.1111/ner.13238] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/02/2020] [Accepted: 06/15/2020] [Indexed: 01/05/2023]
Abstract
BACKGROUND In vagal nerve stimulation (VNS) therapy, the release of VNS model 106 (AspireSR) allowed for responsive VNS (rVNS). rVNS utilizes a cardiac-based seizure detection algorithm to detect seizure-induced tachycardia to trigger additional stimulation. There are some studies suggesting clinical benefits of rVNS over traditional VNS, but the performance and significance of autostimulation mode in clinical practice are poorly understood. OBJECTIVES To assess the effect of initiation of rVNS therapy and altered stimulation settings on the number of daily stimulations and energy consumption in VNS therapy and to compare autostimulation performance in different epilepsy types. MATERIALS AND METHODS Retrospective follow-up of 30 patients with drug-resistant epilepsy treated with rVNS including 17 new implantations and 13 battery replaces at a single center in Finland. Our data consist of 208 different stimulation periods, that is, episodes with defined stimulation settings and both autostimulation and total stimulation performance-related data along with clinical follow-up. RESULTS The variation in autostimulation frequency was highly dependent on the duration of the OFF-time and autostimulation threshold (p < 0.05). There was a large additional effect of autostimulation mode on therapy time and energy consumption with longer OFF-times, but a minor effect with shorter OFF-times. Significantly more autostimulations were triggered in the temporal lobe and multifocal epilepsies than in extratemporal lobe epilepsies. CONCLUSIONS The initiation of autostimulation mode in VNS therapy increased the total number of stimulations. Shortening the OFF-time leads to a decreased number and share of automatic activations. Epilepsy type may affect autostimulation activity.
Collapse
Affiliation(s)
- Toni Kulju
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, Tampere, Finland.,Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Joonas Haapasalo
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, Tampere, Finland.,The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
| | - Ryan Verner
- LivaNova USA, Neuromodulation Unit, Houston, TX, USA
| | - Maxine Dibué-Adjei
- Neuromodulation Medical Affairs, LivaNova PLC, London, UK.,Department of Neurosurgery, Heinrich Heine University Düsseldorf, Germany
| | - Kai Lehtimäki
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, Tampere, Finland
| | - Sirpa Rainesalo
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, Tampere, Finland
| | - Jukka Peltola
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, Tampere, Finland.,Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| |
Collapse
|
10
|
Kulju T, Verner R, Dibué-Adjei M, Eronen A, Rainesalo S, Lehtimäki K, Haapasalo J, Peltola J. Circadian distribution of autostimulations in rVNS therapy in patients with refractory focal epilepsy. Epilepsy Behav 2020; 110:107144. [PMID: 32473521 DOI: 10.1016/j.yebeh.2020.107144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/17/2020] [Accepted: 04/24/2020] [Indexed: 12/31/2022]
Abstract
BACKGROUND Responsive vagus nerve stimulation (rVNS) utilizes an electrocardiograph (ECG)-based algorithm to detect rapid sympathetic activations associated with the onset of a seizure. Abrupt sympathetic activation may also be associated with nocturnal arousals between sleep cycles or transitioning from sleep to wakefulness, a period in which many patients with epilepsy experience seizures. Because of circadian changes in autonomic function, we hypothesized that the autostimulation feature might also behave in a circadian fashion. OBJECTIVE The aim of this study was to assess the circadian rhythmicity of autostimulations in rVNS treatment in patients with drug-resistant epilepsy (DRE). MATERIALS AND METHODS We performed a retrospective follow-up study of 30 patients with DRE treated with rVNS including 17 new implantations and 13 battery replacements at a single center in Finland. After initiation of autostimulation mode, the exact rVNS stimulation parameters and the timestamps of all individual autostimulations delivered were registered. A clustered autostimulation was defined as any autostimulation that occurred within the duration of the therapeutic cycle during the therapy "OFF" time compared with both the previous autostimulation and the following autostimulation. RESULTS Autostimulations and especially autostimulation clusters show a higher probability of occurring in the morning and less at night. This trend appeared to follow the circadian rhythm of cortisol concentration. CONCLUSIONS Early morning peaks of autostimulations at low thresholds may reflect awakening-induced activation of the cardiovascular system, which is associated with a shift towards the dominance of the sympathetic branch of the autonomic nervous system. Cortisol release occurs in parallel driven by wakening-induced activation of the hypothalamic-pituitary-adrenal axis, which is fine-tuned by direct sympathetic input to the adrenal gland. This is of interest considering the known sympathetic hyperactivity in patients with epilepsy.
Collapse
Affiliation(s)
- Toni Kulju
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, P.O. Box 2000, Tampere FI-33521, Finland; Tampere University, Faculty of Medicine and Health Technology, FI-33014 Tampere, Finland.
| | - Ryan Verner
- LivaNova USA, Neuromodulation Unit, 100 Cyberonics Blvd, Houston, TX 77058, USA
| | - Maxine Dibué-Adjei
- Neuromodulation Medical Affairs, LivaNova PLC,London, United Kingdom; Department of Neurosurgery, Heinrich Heine University Düsseldorf, Germany
| | - Atte Eronen
- Tampere University, Faculty of Medicine and Health Technology, FI-33014 Tampere, Finland
| | - Sirpa Rainesalo
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, P.O. Box 2000, Tampere FI-33521, Finland
| | - Kai Lehtimäki
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, P.O. Box 2000, Tampere FI-33521, Finland
| | - Joonas Haapasalo
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, P.O. Box 2000, Tampere FI-33521, Finland; The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Jukka Peltola
- Department of Neurosciences and Rehabilitation, Tampere University Hospital, P.O. Box 2000, Tampere FI-33521, Finland; Tampere University, Faculty of Medicine and Health Technology, FI-33014 Tampere, Finland
| |
Collapse
|
11
|
Kelsey M, Politte D, Verner R, Zempel JM, Nolan T, Babajani-Feremi A, Prior F, Larson-Prior LJ. Determination of neural state classification metrics from the power spectrum of human ECoG. Annu Int Conf IEEE Eng Med Biol Soc 2013; 2012:4336-40. [PMID: 23366887 DOI: 10.1109/embc.2012.6346926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Brain electrical activity exhibits scale-free dynamics that follow power law scaling. Previous works have shown that broadband spectral power exhibits state-dependent scaling with a log frequency exponent that systematically varies with neural state. However, the frequency ranges which best characterize biological state are not consistent across brain location or subject. An adaptive piecewise linear fitting solution was developed to extract features for classification of brain state. Performance was evaluated by comparison to an a posteriori based feature search method. This analysis, using the 1/ƒ characteristics of the human ECoG signal, demonstrates utility in advancing the ability to perform automated brain state discrimination.
Collapse
Affiliation(s)
- Matthew Kelsey
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Zempel JM, Politte DG, Kelsey M, Verner R, Nolan TS, Babajani-Feremi A, Prior F, Larson-Prior LJ. Characterization of scale-free properties of human electrocorticography in awake and slow wave sleep States. Front Neurol 2012; 3:76. [PMID: 22701446 PMCID: PMC3373008 DOI: 10.3389/fneur.2012.00076] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 04/18/2012] [Indexed: 12/11/2022] Open
Abstract
Like many complex dynamic systems, the brain exhibits scale-free dynamics that follow power-law scaling. Broadband power spectral density (PSD) of brain electrical activity exhibits state-dependent power-law scaling with a log frequency exponent that varies across frequency ranges. Widely divergent naturally occurring neural states, awake and slow wave sleep (SWS), were used to evaluate the nature of changes in scale-free indices of brain electrical activity. We demonstrate two analytic approaches to characterizing electrocorticographic (ECoG) data obtained during awake and SWS states. A data-driven approach was used, characterizing all available frequency ranges. Using an equal error state discriminator (EESD), a single frequency range did not best characterize state across data from all six subjects, though the ability to distinguish awake and SWS ECoG data in individual subjects was excellent. Multi-segment piecewise linear fits were used to characterize scale-free slopes across the entire frequency range (0.2–200 Hz). These scale-free slopes differed between awake and SWS states across subjects, particularly at frequencies below 10 Hz and showed little difference at frequencies above 70 Hz. A multivariate maximum likelihood analysis (MMLA) method using the multi-segment slope indices successfully categorized ECoG data in most subjects, though individual variation was seen. In exploring the differences between awake and SWS ECoG data, these analytic techniques show that no change in a single frequency range best characterizes differences between these two divergent biological states. With increasing computational tractability, the use of scale-free slope values to characterize ECoG and EEG data will have practical value in clinical and research studies.
Collapse
Affiliation(s)
- John M Zempel
- Department of Neurology, Washington University School of Medicine, St. Louis MO, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Hirt M, Verner R. [Accompanying document to autopsy at forensic medicine department]. Cas Lek Cesk 2008; 147:578-579. [PMID: 19097363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- M Hirt
- Ustav soudního lékarství LF MU a FN U sv. Anny v Brne.
| | | |
Collapse
|