Tu1901 – Low Frequency Vagal Nerve Stimulation Using an Implantable Pulse Generator for Controlling Blood Glucose in Dogs

Vagal nerve stimulation (VNS) has been explored as a potential therapy for chronic heart failure. The contribution of the afferent pathway to myocardial interstitial acetylcholine (ACh) release during VNS has yet to be clarified. In seven anesthetized Wistar-Kyoto rats, we implanted microdialysis probes in the left ventricular free wall and measured the myocardial interstitial ACh release during right VNS with the following combinations of stimulation frequency (F in Hz) and voltage readout (V in volts): F0V0 (no stimulation), F5V3, F20V3, F5V10, and F20V10. F5V3 did not affect the ACh level. F20V3, F5V10, and F20V10 increased the ACh level to 2.83 ± 0.47 ( P < 0.01), 4.31 ± 1.09 ( P < 0.001), and 4.33 ± 0.82 ( P < 0.001) nM, respectively, compared with F0V0 (1.76 ± 0.22 nM). After right vagal afferent transection (rVAX), F20V3 and F20V10 increased the ACh level to 2.90 ± 0.53 ( P < 0.001) and 3.48 ± 0.63 ( P < 0.001) nM, respectively, compared with F0V0 (1.61 ± 0.19 nM), but F5V10 did not (2.11 ± 0.24 nM). The ratio of the ACh levels after rVAX relative to before was significantly <100% in F5V10 (59.4 ± 8.7%) but not in F20V3 (102.0 ± 8.7%). These results suggest that high-frequency and low-voltage stimulation (F20V3) evoked the ACh release mainly via direct activation of the vagal efferent pathway. By contrast, low-frequency and high-voltage stimulation (F5V10) evoked the ACh release in a manner dependent on the vagal afferent pathway.

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Hyperglycemia With Use of Vagal Nerve Stimulator

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.787 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A386-A386

Author(s):

Jessica Castellanos-Diaz ◽

Morolake Amole ◽

Swapna Surabhi ◽

Sushma Kadiyala

Keyword(s):

Blood Glucose ◽

Nerve Stimulation ◽

Blood Glucose Concentration ◽

Vagal Nerve ◽

Vagal Nerve Stimulation ◽

Nerve Stimulator ◽

Output Current ◽

Diabetes Clinic ◽

Vagal Nerve Stimulator ◽

History Of

Abstract Introduction: In patient with diabetes and refractory epilepsy requiring vagal nerve stimulator (VNS), glycemic management can be challenging. Clinical experience is limited in this scenario. Case Report: A 67-year-old male, BMI 30 kg/m2, with history of type 2 diabetes and hemispheric hemangioma complicated by seizure disorder is referred to our diabetes clinic for evaluation of persistent hyperglycemia. The patient reports 25-year history of seizures that have been difficult to control with antiepileptic drugs alone and eventually requiring VNS placement. Patient has normal kidney (eGFR > 60mL/min) and liver function. His antiepileptic drug regimen consisted of gabapentin and as needed lorazepam. He was never on glucocorticoids. Glycated hemoglobin (HgA1c) at our initial evaluation was 10.1%. His anti-glycemic regimen consisted of glipizide monotherapy. Fasting and pre-prandial blood glucose were in the 200-400mg/dL range with occasional values higher than 500mg/dL. This was confirmed with 14-day continuous glucose monitoring that showed average blood glucose of 287mg/dL with 100 percent above target (higher than 180 mg/dL). We optimized therapy by adding once daily glargine, pioglitazone and continued glipizide. At follow up visit, HgA1c still remained high at 10.5%, despite medication adherence. Patient emphasized that hyperglycemia was related to VNS use and given documented hyperglycemia with blood glucose range 500–600 mg/dL when on higher output current of 2 milliamps, his neurologist approved a trial off VNS for 4 weeks. His glucose improved to average less than 200 mg/dL and HgA1c decreased to 9.1% on the same anti-glycemic regimen. Device was re-started due to recurrence of seizures, however the output current and “on time” were reduced to minimal effective range for optimizing seizure therapy while avoiding hyperglycemia. Subsequent HgA1C improved to 8.7%. Discussion: VNS is a FDA approved device for epilepsy and depression. It works by intermittent stimulation or “on/off” periods. In animal studies, elevation of blood glucose was noted with afferent stimulation. Conversely, efferent activation lowers blood glucose. There are limited human studies on the effects of vagal nerve stimulation on glycemic control. The few available, showed variation in blood glucose based on output current and length of on/off period. This should be factored in during glycemic evaluation and management and close collaboration with neurology is essential. Reference: (1) Strauss H, et al. Cervical Vagal Nerve Stimulation Impairs Glucose Tolerance and Suppresses Insulin Release in Conscious Rats. Physiological Reports 2018; 6(24): 1–9 (2) Strauss H, et al. Effect of Vagus Nerve Stimulation on Blood Glucose Concentration in Epilepsy Patients - Importance of Stimulation Parameters. Physiological Reports 2019; 7(14): 1–10

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Benefit of vagal nerve stimulation in epilepsia partialis continua: a case report

Neuropediatrics ◽

10.1055/s-2006-953550 ◽

2006 ◽

Vol 37 (03) ◽

Author(s):

C Bussmann ◽

HM Meinck ◽

HH Steiner ◽

W Broxtermann ◽

CG Bien ◽

...

Keyword(s):

Case Report ◽

Nerve Stimulation ◽

Vagal Nerve ◽

Vagal Nerve Stimulation ◽

Epilepsia Partialis Continua

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Implanted vagus nerve stimulation in 126 patients: surgical technique and complications

Perspectives in Surgery ◽

10.33699/pis.2020.99.7.304-310 ◽

2020 ◽

Vol 99 (7) ◽

Keyword(s):

Vagus Nerve ◽

Vocal Cord ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Pulse Generator ◽

Operative Procedure ◽

Intractable Epilepsy ◽

Vagal Nerve ◽

University Hospital ◽

Nerve Stimulator

Introduction: Vagus nerve stimulation is a palliative treatment for patients with refractory epilepsy to reduce the frequency and intensity of seizures. A bipolar helical electrode is placed around the left vagus nerve at the cervical level and is connected to the pulse generator placed in a subcutaneous pocket, most commonly in the subclavian region. Methods: Between March 1998 and October 2019, we performed 196 procedures related to the vagal nerve stimulation at the Neurosurgery Department in Motol University Hospital. Of these, 126 patients were vagal nerve stimulator implantation surgeries for intractable epilepsy. The cases included 69 female and 57 male patients with mean age at the time of the implantation surgery 22±12.4 years (range 2.1−58.4 years). Results: Nine patients (7.1%) were afflicted by complications related to implantation. Surgical complications included postoperative infection in 1.6%, VNS-associated arrhythmias in 1.6%, jugular vein bleeding in 0.8% and vocal cord paresis in 2.4%. One patient with vocal cord palsy also suffered from severe dysphagia. One patient (0.8%) did not tolerate extra stimulation with magnet due to a prolonged spasm in his throat. The extra added benefit of vagus stimulation in one patient was a significant reduction of previously regular severe headaches. Conclusion: Vagus nerve stimulation is an appropriate treatment for patients with drug-resistant epilepsy who are not candidates for focal resective surgery. Implantation of the vagus nerve stimulator is a relatively safe operative procedure.

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