558 A Surface Electrode Adjacent to Vagal Nerve Stimulator Lead Can Aid in Characterizing VNS Mediated Sleep Disordered Breathing

Introduction Vagal nerve stimulators (VNS) are a nonpharmacological treatment for patients with refractory epilepsy. The VNS can decrease seizure frequency by over 75% in 40% of pediatric patients with refractory epilepsy. An underrecognized side effect is sleep disordered breathing (SDB). The purpose of this study was to demonstrate how a sensor placed adjacent to the VNS lead can distinguish whether SDB is due to VNS discharge. Methods Five pediatric patients (ages: 5–8) with refractory epilepsy with VNS were referred to our sleep center for concern for SDB. Each patient underwent a polysomnogram (PSG) that included a standard PSG montage with a surface electrode placed adjacent to their left lateral neck to detect VNS discharge. VNS associated apnea hypopnea index (vAHI) was calculated by determining the number of hypopneas and obstructive apneas occurring during VNS discharge. Results Of the 5 patients, three met pediatric criteria for obstructive sleep apnea (OSA). Patient 1 had an obstructive AHI (oAHI) of 21.3 events/hr with a vAHI accounting for 79% of the total (16.8 events/hr), patient 2 had an oAHI of 16.6 events/hr with a vAHI accounting for 57% of the total (9.5 events/hr), and patient 3 had an oAHI of 1.9 events/hr with vAHI accounting for 68% of the total (1.3 events/hr). Because of these findings, the VNS settings of all 3 patients were changed with the goal of reducing SDB due to VNS discharge. Upon repeat PSG, patient 2 had reduced OSA with an oAHI of 3 events/hr, with no events associated with VNS discharge. The remaining 2 patients did not exhibit VNS associated SDB, however, both experienced increased respiratory rate during VNS discharge. Conclusion We demonstrated that a surface electrode adjacent to the VNS is able to temporally co-register VNS discharges and enabled us to directly correlate SDB to VNS stimulation in 3 patients with refractory epilepsy. Because of our findings, we titrated the VNS parameters in all 3 patients, with one showing resolution of VNS associated SDB on repeat PSG. We propose that an added surface electrode to detect VNS discharge be considered as standard practice in PSG studies of patients with VNS. Support (if any):

Hyperglycemia With Use of Vagal Nerve Stimulator

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

The Impact of COVID-19 Lockdown on People With Epilepsy and Vagal Nerve Stimulation

Objectives: Restrictive measures adopted during the COVID-19 pandemic, in order to limit contagion, have had a severe impact on mental health. The burden of lockdown has been particularly heavy on patients with chronic neurologic diseases such as People with Epilepsy (PwE). Our survey aims to describe the struggles and needs of Drug-Resistant (DR) PwE with implanted Vagal Nerve Stimulator (VNS) during the first wave of the COVID-19 lockdown in order to find strategies that help patients cope with present or future periods of restriction.Methods: We collected answers from 30 respondents who underwent an online survey including socio-demographic and clinical information and COVID-19-related information. Depression, anxiety symptoms, and sleep quality were investigated in patients through BDI II, GAD-7, and the PSQI scale.Results: In all, 46% of our sample reported an increase in the number of seizures; the entire sample complained of epilepsy-related issues (medication availability, VSN adjustments, anxiety, sleep disturbance); one out of three participants reported major epilepsy issues felt urgent; 30% had to postpone scheduled examination. Significantly higher scores for depression and anxiety scales were found in patients who perceived seizure frequency worsening and reported major epilepsy-related issues.Conclusion: Preliminary findings showed that the first lockdown influenced the clinical and psychological status of PwE and was related to seizures worsening. The lack of medical assistance and control on VNS therapy left patients to cope with the situation without a chance to contact a specialist. We discuss how a wider implementation of telemedicine programs could facilitate remote assistance of PwE with a VNS implant.

Vagal Nerve Stimulator Placement by a Vascular Surgeon

Background Refractory seizure activity represents a difficult problem for both patients and practitioners. Implantation of the vagal nerve stimulator has been posited as an effective treatment for refractory seizure activity. These devices are inserted by placing leads into the carotid sheath along the vagus nerve. We evaluated a vascular surgeon’s experience placing vagal nerve stimulators. Methods We examined all patients treated with placement of vagal nerve stimulator by a single surgeon from October 2016 to October 2018. Data collected included demographics, medical and surgical history, intraoperative variables, and complications. Results Thirty-four patients underwent placement of a vagal nerve stimulator. About 29.4% had a previous vagal nerve stimulator placed on the ipsilateral side. Intraoperative bradycardia was seen in 1 patient. Postoperative complications were identified in 5 patients, all of which were transient dysphagia or changes in voice quality which did not require intervention. There was no significant difference between patients with the previous operation and those without for developing postoperative complications ( P = .138). Average blood loss was higher in patients who had undergone previous stimulator placement than those who had not ( P = .0223), and the operative time was longer ( P ≤ .0001). Discussion Given the anatomical location of placement, vascular surgeons may be called upon to place these devices. In our single surgeon series, we found that the placement was safe, with minimal complications. Intraoperatively, this case appears to be more difficult (with higher blood loss and longer operative time) in patients who have had previous device placement, but this does not appear to lead to increased complications.