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Warnock J, Ashcroft C, Sabado RJ, Keithler A, Perdikis S. Complete Heart Block and Ventricular Asystole Caused by Vagus Nerve Stimulation Therapy. Cureus 2024; 16:e53314. [PMID: 38435952 PMCID: PMC10906750 DOI: 10.7759/cureus.53314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2024] [Indexed: 03/05/2024] Open
Abstract
Left vagus nerve stimulation (VNS) is an advanced therapeutic option for refractory, drug-resistant epilepsy. A 45-year-old woman with a history of refractory catamenial focal epilepsy since age 16, treated with a five-drug antiepileptic regimen and VNS (implanted eight and one-half years prior), presented with dyspnea, chest discomfort, and lightheadedness. During observation, symptoms recurred and were associated with bradycardia (<20 bpm) and a complete atrioventricular node (AVN) block. Following admission, she continued to experience recurrent symptomatic AVN block and transient ventricular asystole, temporally correlated with her baseline seizure activity and resultant activation of her VNS. Deactivation of VNS resolved her bradyarrhythmia, and she experienced no recurrence over 14 months of follow-up. This case highlights a therapeutic dilemma in cases of refractory epilepsy, with limited therapeutic options if seizure activity requires VNS to be controlled.
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Affiliation(s)
- Jarrod Warnock
- Internal Medicine, Brooke Army Medical Center, San Antonio, USA
| | - Cody Ashcroft
- Internal Medicine, Brooke Army Medical Center, San Antonio, USA
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Broderick L, Tuohy G, Solymos O, Lakhani S, Staunton B, Ennis P, Clark N, Moppett IK, Chalissery A, Kilbride RD, Sweeney KJ, O'Brien D, O'Hare A, Harvey A, Larkin CM. Management of vagus nerve simulation therapy in the peri-operative period: Guidelines from the Association of Anaesthetists: Guidelines from the Association of Anaesthetists. Anaesthesia 2023; 78:747-757. [PMID: 37096456 DOI: 10.1111/anae.16012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2023] [Indexed: 04/26/2023]
Abstract
Vagus nerve stimulation is a well-established treatment option for patients with drug-resistant epilepsy and has an expanding range of other clinical indications. Side effects of vagus nerve stimulation therapy include: cough; voice changes; vocal cord adduction; rarely, obstructive sleep apnoea; and arrhythmia. Patients with implanted vagus nerve stimulation devices may present for unrelated surgery and critical care to clinicians who are unfamiliar with their function and safe management. These guidelines have been formulated by multidisciplinary consensus based on case reports, case series and expert opinion to support clinicians in the management of patients with these devices. The aim is to provide specific guidance on the management of vagus nerve stimulation devices in the following scenarios: the peri-operative period; peripartum period; during critical illness; and in the MRI suite. Patients should be aware of the importance of carrying their personal vagus nerve stimulation device magnet with them at all times to facilitate urgent device deactivation if necessary. We advise that it is generally safer to formally deactivate vagus nerve stimulation devices before general and spinal anaesthesia. During periods of critical illness associated with haemodynamic instability, we also advise cessation of vagus nerve stimulation and early consultation with neurology services.
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Affiliation(s)
| | - G Tuohy
- Rotunda Hospital, Dublin, Ireland
| | - O Solymos
- St Vincent's University Hospital, Dublin, Ireland
| | - S Lakhani
- The Walton Centre NHS Foundation Trust, Liverpool, UK
| | | | - P Ennis
- Beaumont Hospital, Dublin, Ireland
| | - N Clark
- Bristol Children's Hospital, Bristol, UK
| | | | | | | | | | | | - A O'Hare
- Beaumont Hospital, Dublin, Ireland
| | - A Harvey
- Royal Cornwall Hospital Trust, Cornwall, UK
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Brandt C. Vagus nerve stimulation in people with epilepsy and intellectual disability—English version. ZEITSCHRIFT FÜR EPILEPTOLOGIE 2022. [DOI: 10.1007/s10309-022-00545-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Jeong H, Cho A, Ay I, Bonmassar G. Short-pulsed micro-magnetic stimulation of the vagus nerve. Front Physiol 2022; 13:938101. [PMID: 36277182 PMCID: PMC9585240 DOI: 10.3389/fphys.2022.938101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/01/2022] [Indexed: 11/30/2022] Open
Abstract
Vagus nerve stimulation (VNS) is commonly used to treat drug-resistant epilepsy and depression. The therapeutic effect of VNS depends on stimulating the afferent vagal fibers. However, the vagus is a mixed nerve containing afferent and efferent fibers, and the stimulation of cardiac efferent fibers during VNS may produce a rare but severe risk of bradyarrhythmia. This side effect is challenging to mitigate since VNS, via electrical stimulation technology used in clinical practice, requires unique electrode design and pulse optimization for selective stimulation of only the afferent fibers. Here we describe a method of VNS using micro-magnetic stimulation (µMS), which may be an alternative technique to induce a focal stimulation, enabling a selective fiber stimulation. Micro-coils were implanted into the cervical vagus nerve in adult male Wistar rats. For comparison, the physiological responses were recorded continuously before, during, and after stimulation with arterial blood pressure (ABP), respiration rate (RR), and heart rate (HR). The electrical VNS caused a decrease in ABP, RR, and HR, whereas µM-VNS only caused a transient reduction in RR. The absence of an HR modulation indicated that µM-VNS might provide an alternative technology to VNS with fewer heart-related side effects, such as bradyarrhythmia. Numerical electromagnetic simulations helped estimate the optimal coil orientation with respect to the nerve to provide information on the electric field’s spatial distribution and strength. Furthermore, a transmission emission microscope provided very high-resolution images of the cervical vagus nerve in rats, which identified two different populations of nerve fibers categorized as large and small myelinated fibers.
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Affiliation(s)
- Hongbae Jeong
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Annabel Cho
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
- Department of Bioengineering, Harvard University, Cambridge, MA, United States
| | - Ilknur Ay
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
- *Correspondence: Giorgio Bonmassar,
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Scott H, Moore A, Paydak H, Hundley K, Palys V. Reproducible asystole following vagal nerve stimulator lead replacement: a case report. BMC Neurol 2022; 22:75. [PMID: 35246068 PMCID: PMC8896151 DOI: 10.1186/s12883-022-02585-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/09/2022] [Indexed: 11/21/2022] Open
Abstract
Background Vagal nerve stimulation (VNS) is approved therapy for the treatment of intractable epilepsy. The stimulation of either nerve, left or right, is effective. However, due to the anatomic and physiological effects of cardiac innervation, the right vagus nerve is typically avoided in order to minimize the risk of cardiac bradyarrhythmias. The location of the VNS lead contacts on the nerve can also have an effect, namely, more distally placed contacts have been associated with lower risk of cardiac arrhythmias, presumably by avoiding vagal cervical cardiac branches; however, our case demonstrates reproducible asystole despite left sided, distal VNS lead placement. Case presentation We report a 28-year-old male patient with pharmacoresistant generalized clonic-tonic seizures. The VNS therapy with 1.5 mA output and 16% duty cycle drastically reduced his seizure burden for several years. The breakthrough seizures along with stabbing pain episodes at the implantable pulse generator (IPG) site have prompted the VNS lead revision surgery with new lead contacts placed more caudally than the old contacts. However, the intraoperative device interrogation with 1 mA output resulted in immediate asystole for the duration of stimulation and it was reproducible until the output was decreased to 0.675 mA. Conclusions Our case highlights the possibility of new severe cardiac bradyarrhythmias following surgical VNS lead replacements even in patients without preoperatively known clinical side effects. We suggest preoperative electrocardiography and cardiology consultation for detected abnormalities for all patients undergoing new VNS implantations, as well as revision surgeries for VNS malfunctions. Intraoperatively, the surgeon and anesthesia team should be vigilant of cardiac rhythms and prepared for the immediate management.
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Affiliation(s)
- Hayden Scott
- College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - Alexandra Moore
- College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Hakan Paydak
- Department of Cardiology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Kelsey Hundley
- Department of Neurosurgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Viktoras Palys
- Department of Neurosurgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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Kato H, Fujimoto A, Okanishi T, Sugiura R, Ijima K, Enoki H. New onset syncopal events following vagus nerve stimulator implantation might be key to preventing vagus nerve stimulation-induced symptomatic bradycardia - A case report and review. EPILEPSY & BEHAVIOR CASE REPORTS 2018; 10:57-60. [PMID: 30073143 PMCID: PMC6068316 DOI: 10.1016/j.ebcr.2018.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 04/08/2018] [Accepted: 04/10/2018] [Indexed: 04/29/2023]
Abstract
PURPOSE To identify risk factors for VNS-associated arrhythmia. METHODS A literature review identified 14 papers with 21 patients. We compared patients with VNS associated arrhythmia (arrhythmia group, n = 22) and patients without VNS associated arrhythmia (control group of our VNS implanted patients, n = 29). RESULTS New onset syncopal events following VNS placement were seen in the arrhythmia group (p < 0.001). CONCLUSION Even though arrhythmia could be symptomatic, most cases associated with syncope were treated as new-onset epileptic seizures with adjustment of anti-seizure drugs. To detect cardiac asystole during VNS treatment, clinicians should be alert to the possibility of new onset syncopal events that differ from habitual seizures.
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Affiliation(s)
- Hiroko Kato
- Department of Cardiology, Seirei Hamamatsu General Hospital, Japan
| | - Ayataka Fujimoto
- Comprehensive Epilepsy Center, Seirei Hamamatsu General Hospital, Japan
- Corresponding author at: Seirei Hamamatsu General Hospital, 2-12-12 Sumiyoshi, Nakaku, Hamamatsu, Shizuoka 430-8558, Japan.
| | - Tohru Okanishi
- Comprehensive Epilepsy Center, Seirei Hamamatsu General Hospital, Japan
| | - Ryo Sugiura
- Department of Cardiology, Seirei Hamamatsu General Hospital, Japan
| | - Kentaro Ijima
- Comprehensive Epilepsy Center, Seirei Hamamatsu General Hospital, Japan
| | - Hideo Enoki
- Comprehensive Epilepsy Center, Seirei Hamamatsu General Hospital, Japan
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Garamendi-Ruiz I, Gómez-Esteban JC. Cardiovascular autonomic effects of vagus nerve stimulation. Clin Auton Res 2017; 29:183-194. [DOI: 10.1007/s10286-017-0477-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/09/2017] [Indexed: 12/15/2022]
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Should we deactivate vagus nerve stimulator in patients undergoing general anesthesia? J Clin Anesth 2016; 32:70-1. [DOI: 10.1016/j.jclinane.2015.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 11/09/2015] [Indexed: 11/24/2022]
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Cantarín-Extremera V, Ruíz-Falcó-Rojas ML, Tamaríz-Martel-Moreno A, García-Fernández M, Duat-Rodriguez A, Rivero-Martín B. Late-onset periodic bradycardia during vagus nerve stimulation in a pediatric patient. A new case and review of the literature. Eur J Paediatr Neurol 2016; 20:678-83. [PMID: 27056279 DOI: 10.1016/j.ejpn.2016.02.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 01/17/2016] [Accepted: 02/26/2016] [Indexed: 11/29/2022]
Abstract
BACKGROUND Epilepsy is a common disease in the world. Around 10-40% of patients who suffer epilepsy will have intractable seizures. When resective epilepsy surgery is not possible, vagus nerve stimulation (VNS) can be an option. The most common side effects associated with VSN therapy are hoarseness, throat pain and coughing. Cardiac arrhythmia has been reported during lead tests performed during implantation of the device, but few cases during regular treatment. We report a new child where vagally induced bradyarrhythmia, perfectly correlated with the stimulation periods. CLINICAL REPORT 13-year-old girl with refractory myoclonic-astatic epilepsy since the age of two. When she was five years old, a VNS was implanted with complete resolution of her seizures. But when she was 13, she began with sudden falls with loss of consciousness lasting less than 10 s, which were similar to her previous epileptic drop-attacks. Continuous ECG recording was normal but electrocardiography showed a bradycardia of 45 bpm with a syncope-like episode. It was necessary to turn off the VNS. CONCLUSIONS To our knowledge, there are just three pediatrics and four adults patients described in the literature with this severe and life-threatening side effect. Cardiac complications of VNS therapy are very infrequent but should alert clinicians to its possibility. A cardiac evaluation is mandatory before VNS implantation and periodically thereafter (probably between one or three years).
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Affiliation(s)
- Verónica Cantarín-Extremera
- Department of Pediatric Neurology, Hospital Infantil Universitario Niño Jesús, Avd. Menéndez Pelayo 65, 28009 Madrid, Spain.
| | - María-Luz Ruíz-Falcó-Rojas
- Department of Pediatric Neurology, Hospital Infantil Universitario Niño Jesús, Avd. Menéndez Pelayo 65, 28009 Madrid, Spain.
| | - Amalia Tamaríz-Martel-Moreno
- Department of Pediatric Cardiology, Hospital Infantil Universitario Niño Jesús, Avd. Menéndez Pelayo 65, 28009 Madrid, Spain.
| | - Marta García-Fernández
- Video-EEG Monitoring Unit, Neurophysiology Section, Hospital Infantil Universitario Niño Jesús, Avd. Menéndez Pelayo 65, 28009 Madrid, Spain.
| | - Anna Duat-Rodriguez
- Department of Pediatric Neurology, Hospital Infantil Universitario Niño Jesús, Avd. Menéndez Pelayo 65, 28009 Madrid, Spain.
| | - Belén Rivero-Martín
- Department of Pediatric Neurosurgery, Hospital Infantil Universitario Niño Jesús, Avd. Menéndez Pelayo 65, 28009 Madrid, Spain
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Pascual FT. Vagus nerve stimulation and late-onset bradycardia and asystole: Case report. Seizure 2015; 26:5-6. [DOI: 10.1016/j.seizure.2015.01.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 01/04/2015] [Accepted: 01/07/2015] [Indexed: 11/26/2022] Open
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Ben-Menachem E, Revesz D, Simon BJ, Silberstein S. Surgically implanted and non-invasive vagus nerve stimulation: a review of efficacy, safety and tolerability. Eur J Neurol 2015; 22:1260-8. [PMID: 25614179 PMCID: PMC5024045 DOI: 10.1111/ene.12629] [Citation(s) in RCA: 177] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 10/27/2014] [Indexed: 12/12/2022]
Abstract
Vagus nerve stimulation (VNS) is effective in refractory epilepsy and depression and is being investigated in heart failure, headache, gastric motility disorders and asthma. The first VNS device required surgical implantation of electrodes and a stimulator. Adverse events (AEs) are generally associated with implantation or continuous on-off stimulation. Infection is the most serious implantation-associated AE. Bradycardia and asystole have also been described during implantation, as has vocal cord paresis, which can last up to 6 months and depends on surgical skill and experience. The most frequent stimulation-associated AEs include voice alteration, paresthesia, cough, headache, dyspnea, pharyngitis and pain, which may require a decrease in stimulation strength or intermittent or permanent device deactivation. Newer non-invasive VNS delivery systems do not require surgery and permit patient-administered stimulation on demand. These non-invasive VNS systems improve the safety and tolerability of VNS, making it more accessible and facilitating further investigations across a wider range of uses.
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Affiliation(s)
- E Ben-Menachem
- Institution of Clinical Neuroscience and Physiology, Sahlgrenska Academy, Göteborgs University, Göteborg, Sweden
| | - D Revesz
- Institution of Clinical Neuroscience and Physiology, Sahlgrenska Academy, Göteborgs University, Göteborg, Sweden
| | - B J Simon
- electroCore LLC, Basking Ridge, NJ, USA
| | - S Silberstein
- Jefferson Headache Center, Thomas Jefferson University, Philadelphia, PA, USA
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Evidence-based guideline update: vagus nerve stimulation for the treatment of epilepsy: report of the guideline development subcommittee of the american academy of neurology. Epilepsy Curr 2013; 13:297-303. [PMID: 24348133 DOI: 10.5698/1535-7597-13.6.297] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 04/29/2013] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE To evaluate the evidence since the 1999 assessment regarding efficacy and safety of vagus nerve stimulation (VNS) for epilepsy, currently approved as adjunctive therapy for partial-onset seizures in patients >12 years. METHODS We reviewed the literature and identified relevant published studies. We classified these studies according to the American Academy of Neurology evidence-based methodology. RESULTS VNS is associated with a >50% seizure reduction in 55% (95% confidence interval [CI] 50%-59%) of 470 children with partial or generalized epilepsy (13 Class III studies). VNS is associated with a >50% seizure reduction in 55% (95% CI 46%-64%) of 113 patients with Lennox-Gastaut syndrome (LGS) (4 Class III studies). VNS is associated with an increase in ≥50% seizure frequency reduction rates of ~7% from 1 to 5 years postim-plantation (2 Class III studies). VNS is associated with a significant improvement in standard mood scales in 31 adults with epilepsy (2 Class III studies). Infection risk at the VNS implantation site in children is increased relative to that in adults (odds ratio 3.4, 95% CI 1.0-11.2). VNS is possibly effective for seizures (both partial and generalized) in children, for LGS-associated seizures, and for mood problems in adults with epilepsy. VNS may have improved efficacy over time. RECOMMENDATIONS VNS may be considered for seizures in children, for LGS-associated seizures, and for improving mood in adults with epilepsy (Level C). VNS may be considered to have improved efficacy over time (Level C). Children should be carefully monitored for site infection after VNS implantation. Neurology® 2013;81:1-7.
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Morris GL, Gloss D, Buchhalter J, Mack KJ, Nickels K, Harden C. Evidence-based guideline update: vagus nerve stimulation for the treatment of epilepsy: report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology 2013; 81:1453-9. [PMID: 23986299 DOI: 10.1212/wnl.0b013e3182a393d1] [Citation(s) in RCA: 206] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVE To evaluate the evidence since the 1999 assessment regarding efficacy and safety of vagus nerve stimulation (VNS) for epilepsy, currently approved as adjunctive therapy for partial-onset seizures in patients >12 years. METHODS We reviewed the literature and identified relevant published studies. We classified these studies according to the American Academy of Neurology evidence-based methodology. RESULTS VNS is associated with a >50% seizure reduction in 55% (95% confidence interval [CI] 50%-59%) of 470 children with partial or generalized epilepsy (13 Class III studies). VNS is associated with a >50% seizure reduction in 55% (95% CI 46%-64%) of 113 patients with Lennox-Gastaut syndrome (LGS) (4 Class III studies). VNS is associated with an increase in ≥ 50% seizure frequency reduction rates of ≈ 7% from 1 to 5 years postimplantation (2 Class III studies). VNS is associated with a significant improvement in standard mood scales in 31 adults with epilepsy (2 Class III studies). Infection risk at the VNS implantation site in children is increased relative to that in adults (odds ratio 3.4, 95% CI 1.0-11.2). VNS is possibly effective for seizures (both partial and generalized) in children, for LGS-associated seizures, and for mood problems in adults with epilepsy. VNS may have improved efficacy over time. RECOMMENDATIONS VNS may be considered for seizures in children, for LGS-associated seizures, and for improving mood in adults with epilepsy (Level C). VNS may be considered to have improved efficacy over time (Level C). Children should be carefully monitored for site infection after VNS implantation.
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Affiliation(s)
- George L Morris
- From the Aurora Epilepsy Center (G.L.M.), St. Luke's Medical Center, Milwaukee, WI; Barrow Neurologic Institute (D.G.), Phoenix, AZ; University of Calgary (J.B.), Canada; Mayo Clinic (K.J.M., K.N.), Rochester, MN; and Hofstra University North Shore-Long Island Jewish Medical College (C.H.), Great Neck, NY
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Shankar R, Olotu VO, Cole N, Sullivan H, Jory C. Case report: Vagal nerve stimulation and late onset asystole. Seizure 2013; 22:312-4. [DOI: 10.1016/j.seizure.2012.12.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 12/10/2012] [Accepted: 12/12/2012] [Indexed: 12/01/2022] Open
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Clark AJ, Kuperman RA, Auguste KI, Sun PP. Intractable episodic bradycardia resulting from progressive lead traction in an epileptic child with a vagus nerve stimulator: a delayed complication. J Neurosurg Pediatr 2012; 9:389-93. [PMID: 22462703 DOI: 10.3171/2011.12.peds11124] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Vagus nerve stimulation (VNS) is used as palliation for adult and pediatric patients with intractable epilepsy who are not candidates for curative resection. Although the treatment is generally safe, complications can occur intraoperatively, perioperatively, and in a delayed time frame. In the literature, there are 2 reports of pediatric patients with implanted VNS units who had refractory bradycardia that resolved after the stimulation was turned off. The authors report the case of a 13-year-old boy with a history of vagus nerve stimulator placement at 2 years of age, who developed intractable episodic bradycardia that persisted despite the cessation of VNS and whose imaging results suggested vagus nerve tethering by the leads. He was subsequently taken to the operating room for exploration, where it was confirmed that the stimulator lead was exerting traction on the vagus nerve, which was displaced from the carotid sheath. After the vagus nerve was untethered and the leads were replaced, the bradycardia eventually resolved with continual effective VNS therapy. When placing a VNS unit in a very young child, accommodations must be made for years of expected growth. Delayed intractable bradycardia can result from a vagus nerve under traction by tethered stimulator leads.
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Affiliation(s)
- Aaron J Clark
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
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Castoro MA, Yoo PB, Hincapie JG, Hamann JJ, Ruble SB, Wolf PD, Grill WM. Excitation properties of the right cervical vagus nerve in adult dogs. Exp Neurol 2010; 227:62-8. [PMID: 20851118 DOI: 10.1016/j.expneurol.2010.09.011] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 08/12/2010] [Accepted: 09/09/2010] [Indexed: 10/19/2022]
Abstract
Vagus nerve stimulation (VNS) is an approved treatment for epilepsy and depression, and it is currently under investigation for applications in Alzheimer's disease, anxiety, heart failure, and obesity. However, the mechanism(s) by which VNS has its effects are not clear, and the stimulation parameters for obtaining therapeutic outcomes appear highly variable. The purpose of this study was to quantify the excitation properties of the right cervical vagus nerve in adult dogs anesthetized with propofol and fentanyl. Input-output curves of the right cervical vagus nerve compound action potential and laryngeal muscle electromyogram were measured in response to VNS across a range of stimulation parameters: amplitudes of 0.02-50mA, pulsewidths of 10, 50, 100, 200, 300, 500, and 1,000μs, frequencies of 1-2Hz, and train lengths of 20 pulses with 3 different electrode configurations: monopolar cathode, proximal anode/distal cathode, and proximal cathode/distal anode. Electrode configuration and stimulation waveform (monophasic vs. asymmetric charge-balanced biphasic) did not affect the threshold or recruitment of the vagal nerve fibers that were activated. The rheobase currents of A- and B-fibers were 0.4mA and 0.7mA, respectively, and the chronaxie of both components was 180μs. Pulsewidth had little effect on the normalized threshold difference between activation of A- and B-fibers. The results provide insight into the complement of nerve fibers activated by VNS and guidance to clinicians for the selection of optimal stimulation parameters.
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Affiliation(s)
- Mark A Castoro
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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