Laryngopharyngeal dysfunction from the implant vagal nerve stimulator

Vagus Nerve Stimulation Therapy in Epilepsy: An Overview of Technical and Surgical Method, Patient Selection, and Treatment Outcomes

Epilepsy affects over 65 million people worldwide. One-third of people with epilepsy do not respond to medication and may benefit from surgery. Vagus nerve stimulation (VNS) is the first neuromodulation therapy for the treatment of drug-resistant epilepsy. This method is used in combination with anti-seizure medications in adults and in the pediatric population. VNS has also been demonstrated to have benefits for some epilepsy comorbidities, such as depression, and can be used in combination with other neuromodulation therapies in epilepsy. The authors present an overview of VNS physiology, patient selection, surgery and risks, neuromodulation therapy, and application to epilepsy comorbidities.

Evaluation and management of exercise-induced dyspnea in otherwise healthy adolescents and young adults: A critical review

Dyspnea on exertion in otherwise healthy adolescents and young adults is often brought to the attention of a pediatric pulmonologist when it interferes with an athletic activity. Assessment of the cause and management has been controversial. Skilled pediatric pulmonologists may suspect the cause from a careful history, but a more definite diagnosis is needed to provide the most appropriate management. Suspecting that laryngeal obstruction is the major cause, continuous laryngoscopy during exercise has been proposed. However, that method tends to over diagnose laryngeal obstruction and does not consider that the larynx is not the major cause of dyspnea on exertion (DOE). The cause of DOE can generally be best identified by a treadmill test using cardiopulmonary monitoring to determine the physiology associated with reproduced symptoms. Management of DOE requires a specific diagnosis and may involve medication, surgery, or education and training.

Reversible Vagal Nerve Stimulation-Induced Vocal Cord Paralysis and Intractable Neck Pain Following a Syncopal Fall: A Case Report

Vagal nerve stimulation (VNS) is a well-tolerated procedure for patients with medication-resistant and non-focal epilepsy. It does, however, have potential complications (e.g., hoarseness and cough) thought to be from vagus nerve irritation. These arise postoperatively and generally improve without intervention. If these symptoms present later or do not improve, it suggests a more insidious etiology. Herein we report the case of a patient in their 50s with medication-resistant epilepsy, who subsequently underwent VNS electrode array and pulse generator implantation to aid seizure management. Three years after the initial implantation, the patient experienced vocal cord paralysis and neck pain following a syncopal fall. The pain radiated to their jaw and chest and was eliminated when their VNS was turned off. The patient was taken to the OR for removal and replacement of their entire VNS system. Their original electrodes were unable to be removed secondary to being scarred in place. The patient's preoperative pain symptoms completely resolved after the removal of their old VNS and implantable pulse generator (IPG) and replacement with a new system 14 days postoperatively. While short-term postoperative sequelae and lead fractures/displacements have been reported in the literature, this is the first case to our knowledge of a patient experiencing a likely symptomatic traction injury without displacement of the VNS coils or obvious vagus nerve injury. Furthermore, the removal and replacement of the entire VNS system led to complete relief of their presenting symptoms.

Management of vagus nerve simulation therapy in the peri-operative period: Guidelines from the Association of Anaesthetists: Guidelines from the Association of Anaesthetists

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.

Use of inhaled ipratropium bromide to improve exercise-induced laryngeal obstruction cannot be recommended

Introduction

Exercise-induced laryngeal obstruction (EILO) is a common cause of exertional breathing problems in young adults. Current management generally consists of breathing advice, speech therapy, inspiratory muscle training or supraglottoplasty in highly motivated subjects with supraglottic collapse. Inhaled ipratropium bromide (IB) is a muscarinic receptor antagonist used to treat asthma that is suggested in a few reports to improve EILO symptoms. The aim of the present study was to investigate effects of inhaled IB in EILO diagnosed by continuous laryngoscopy exercise (CLE) test and classified by CLE scores.

Methods

A randomised crossover trial was conducted at Haukeland University Hospital, Bergen, Norway, enrolling participants diagnosed with EILO defined by characteristic symptoms and CLE score ≥3 (range 0-12). Two consecutive CLE tests were performed within 2 weeks, one test with and one test without prior administration of inhaled IB in a randomised order. Main outcomes were the CLE score, dyspnoea measured using a modified BORG scale (range 0-10) and cardiopulmonary exercise data provided by the CLE test.

Results

20 participants (14 females) aged 12-25 years participated, and all ran to exhaustion on both tests. Mean CLE score, BORG score and peak oxygen consumption were similar in tests performed with and without IB; mean differences (95% confidence interval) were 0.08 (-0.28-0.43), 0.35 (-0.29-0.99) and -0.4 (-1.9-1.1) mL·kg^-1·min^-1, respectively.

Conclusion

Inhaled IB did not improve CLE score, dyspnoea or exercise capacity in subjects with EILO. The study does not support the use of inhaled IB to treat EILO.

The Clinical Impact of Vagal Nerve Stimulator Implantation on Laryngopharyngeal Function in Children: A Single-Center Experience

OBJECTIVE

A vagal nerve stimulator (VNS) has been established as the treatment of choice for children with refractory epilepsy. The outcomes of the procedure have been well documented in adults but are less clear in children. The goal of our study was to review laryngopharyngeal (LP) function following VNS implantation in children.

STUDY DESIGN

Case series with chart review.

SETTING

Tertiary-care children's hospital.

METHODS

Voice, swallowing, and sleep apnea symptoms were extracted from the charts of children who underwent VNS implantation between 2013 and 2021. A questionnaire was sent to parents of implanted children to ascertain the degree of the social and functional impact of the implant.

RESULTS

There were 69 patients, aged 2.3 to 21.4 years old, who met the inclusion criteria. LP symptoms were most common during the first year following implantation; 26 patients (37.6%) demonstrated at least 1 symptom (voice alteration, chronic cough, sleep-disordered breathing, or dysphagia), and 15 patients required adjustments to their implant settings. The incidence of symptoms and the need to adjust VNS settings significantly dropped during years 2 to 5 and 6 to 8 (22% vs 7% and 5%, respectively, p = .0002). The mean score of the Pediatric Voice Handicap Index differed greatly from a normal control group on each subscale and the total score.

CONCLUSION

LP dysfunction in children following VNS implantation is comparable to adults, with the most burden noticed during the first year after implantation. The presence of voice alterations did not correlate with the presence of dysphagia and sleep-disordered breathing. Thorough evaluation, preferably by a multidisciplinary team, is required to assess LP dysfunction postoperatively.

Intra-operative monitoring as an adjuvant to standard vagus nerve stimulation implantation

PURPOSE

The treatment of refractory epilepsy by vagus nerve stimulation (VNS) is a well-established therapy. Complications following VNS insertion may be procedure-related or stimulation-related. Herein, we describe our technique of intra-operative neuro-monitoring (IONM) in an attempt to diminish these adverse events.

METHODS

This retrospective study describes 66 consecutive patients between the ages of 3 and 12 years who had undergone primary VNS implantation. The study population consisted of two cohorts, one in which the VNS device was implanted according to the standard described technique and a second group in which IONM was used as an adjuvant during the VNS device placement. Prior to VNS insertion, a Pediatric Voice Handicap Index (PVHI) was performed to assess voice-related quality of life, and this was repeated at 3 months following VNS insertion.

RESULTS

Sixty-six patients underwent the VNS implantation. Forty-three patients had a "standard" VNS insertion technique performed, whereas 23 had IONM performed during the VNS implantation. There were significant changes in the PVHI scores across both cohorts at 3-month follow-up. There were no statistically significant differences in PVHI scores between the monitored group and non-monitored group at 3-month follow up.

CONCLUSIONS

IONM can be used during VNS insertions to ensure correct placement of the leads on CNX. IONM may minimise vocal cord stimulation by placing the lead coils on the area of nerve eliciting the least amount of vocal cord EMG response. IONM however does not appear to improve voice outcomes at early follow up.

Intermittent Vagal Nerve Stimulation-Associated Vocal Fold Movement Impairment

OBJECTIVES

Implanted vagal nerve stimulators (VNS) are an accepted therapy for refractory seizures. However, VNS have been shown to affect vocal fold function, leading to voice complaints of hoarseness. We present a case of intermittent VNS-related vocal fold paralysis leading to dysphonia and dysphagia with aspiration in a pediatric patient.

METHODS

This is a case report of a patient at a tertiary hospital evaluated in pediatric swallow and voice clinics. Patient and mother gave verbal consent to be included in this case report.

RESULTS

Indirect laryngeal stroboscopy was performed demonstrating full vocal fold mobility with VNS off and left vocal fold paralysis in lateral position and glottic gap with VNS on. Voice measures were performed demonstrating decreased phonation time, lower pitch, and decreased intensity of voice with VNS on. Flexible endoscopic evaluation of swallowing demonstrated deep penetration alone with VNS off and deep penetration with concern for aspiration with VNS on.

CONCLUSIONS

While the majority of cases of vocal fold movement impairment associated with VNS have been noted to have a medialized vocal fold with VNS activation, we describe a case of intermittent vocal fold lateralization associated with VNS activation with resultant voice changes and aspiration.

Complete section of the left vagus nerve does not preclude the efficacy of vagus nerve stimulation: illustrative case

BACKGROUND

Vagus nerve stimulation (VNS) represents a valid therapeutic option for patients with medically intractable seizures who are not candidates for epilepsy surgery. Even when complete section of the nerve occurs, stimulation applied cranially to the involved nerve segment does not preclude the efficacy of VNS. Complete vagus nerve section with neuroma causing definitive left vocal cord palsy has never been previously reported in the literature.

OBSERVATIONS

Eight years after VNS implant, the patient experienced worsening of seizures; the interrogation of the generator revealed high impedance requiring surgical revision. On surgical exploration, complete left vagus nerve section and a neuroma were found. Vocal cord atrophy was found at immediate postoperative laryngeal inspection as a confirmation of a longstanding lesion. Both of these events might have been caused by direct nerve injury during VNS surgery, and they presented in a delayed fashion.

LESSONS

VNS surgery may be complicated by direct damage to the left vagus nerve, resulting in permanent neurological deficits. A complete section of the nerve also enables an efficacious stimulation if applied cranially to the involved segment. Laryngeal examination should be routinely performed before each VNS surgery to rule out preexisting vocal cord dysfunction.

Management and outcome of vagus nerve stimulator implantation: experience of an otolaryngeal/neuropediatric cooperation

OBJECTIVE

Vagus nerve stimulator (VNS) implantation is an established therapy for pharmacoresistant epilepsy that is not amenable to curative epilepsy surgery. Historically, VNS implantation has been performed by neurosurgeons, but otolaryngologist involvement is increasingly common. In this retrospective study, we aimed to evaluate the efficacy and safety of VNS implantation in children and adolescents from the otolaryngologists' perspective.

METHODS

This study included children and adolescents who had undergone VNS implantation at the study center between 2014 and 2018. Patient files were analyzed with regards to the durations of device implantation and hospitalization, postoperative complications, and clinical outcome, including seizure frequency, clinical global impression of improvement (CGI-I) score, and quality of life (QoL).

RESULTS

A total of 73 children underwent VNS surgery. The median age at implantation was 9.3 ± 4.6 years, and median epilepsy duration before VNS surgery was 6 ± 4 years. Lennox-Gastaut syndrome was the most common syndrome diagnosis (62.3%), and structural abnormalities (49.3%) the most frequent etiology. Operation times ranged from 30 to 200 min, and median postoperative hospitalization length was 2 ± 0.9 days. No complications occurred, except for four revisions and two explantations due to local infections (2.7%). Among our patients, 76.7% were responders (≥ 50% reduction in seizure frequency), 72.1% showed improved CGI-I scores, and 18.6-60.5% exhibited considerable improvements in the QoL categories energy, emotional health, and cognitive functions.

CONCLUSION

Our results indicate that VNS implantation is a highly effective and safe treatment option for children and adolescents with AED-refractory epilepsies who are not candidates for curative epilepsy surgery.

Selective Vagus Nerve Stimulation as a Therapeutic Approach for the Treatment of ARDS: A Rationale for Neuro-Immunomodulation in COVID-19 Disease

Acute respiratory distress syndrome (ARDS) is the most severe form of acute lung injury. It is induced by sepsis, aspiration, and pneumonia, including that caused by SARS coronavirus and human influenza viruses. The main pathophysiological mechanism of ARDS is a systemic inflammatory response. Vagus nerve stimulation (VNS) can limit cytokine production in the spleen and thereby dampen any systemic inflammation and inflammation-induced tissue damage in the lungs and other organs. However, the effects of increased parasympathetic outflow to the lungs when non-selective VNS is applied may result in bronchoconstriction, increased mucus secretion and enhance local pulmonary inflammatory activity; this may outweigh the beneficial systemic anti-inflammatory action of VNS. Organ/function-specific therapy can be achieved by imaging of localized fascicle activity within the vagus nerve and selective stimulation of identified organ-specific fascicles. This may be able to provide selective neuromodulation of different pathways within the vagus nerve and offer a novel means to improve outcome in ARDS. This has motivated this review in which we discuss the mechanisms of anti-inflammatory effects of VNS, progress in selective VNS techniques, and a possible application for ARDS.

Functional Respiratory Disorders in Children

Functional respiratory disorders (FRDs) are those characterized by respiratory symptoms without anatomic or organic etiology. Clinicians caring for children encounter these disorders and should be familiar with diagnosis and treatment. FRDs encompass the habit cough syndrome and its variants, vocal cord dysfunction, hyperventilation disorders, functional dyspnea, and sighing syndrome. Failure to identify these disorders results in unnecessary testing and medication. This article reviews the clinical presentation, manifestation, and treatment of respiratory FRDs in children. How health care providers can successfully identify and treat these reversible conditions in the clinical setting is discussed.

Stridor during sleep: description of 81 consecutive cases diagnosed in a tertiary sleep disorders center

Study Objectives

To describe the characteristics of stridor during sleep (SDS) in a series of adults identified by video-polysomnography (V-PSG).

Methods

Retrospective clinical, V-PSG, laryngoscopic, and therapeutic data of patients diagnosed with SDS in a tertiary referral sleep disorders center between 1997 and 2017.

Results

A total of 81 patients were identified (56.8% males, age 61.8 ± 11.2 years). Related etiologies were multiple system atrophy (MSA), amyotrophic lateral sclerosis, spinocerebellar ataxia type 1, anti-IgLON5 disease, fatal familial insomnia, brainstem structural lesions, vagus nerve stimulation, recurrent laryngeal nerve injury, the effect of radiotherapy on the vocal cords, cervical osteophytes, and others. Stridor during wakefulness coexisted in 13 (16%) patients and in MSA was only seen in the parkinsonian form. Laryngoscopy during wakefulness in 72 (88.9%) subjects documented vocal cord abductor impairment in 65 (90.3%) and extrinsic lesions narrowing the glottis in 2 (2.4%). The mean apnea–hypopnea index (AHI) was 21.4 ± 18.6 and CT90 was 11.5 ± 19.1. Obstructive AHI > 10 occurred in 52 (64.2%) patients and central apnea index >10 in 2 (2.4%). CPAP abolished SDS, obstructive apneic events and oxyhemoglobin desaturations in 58 of 60 (96.7%) titrated patients with optimal pressure of 9.0 ± 2.3 cm H20. Tracheostomy in 19 (23.4%) and cordotomy in 3 (3.7%) subjects also eliminated SDS.

Conclusions

SDS in adults is linked to conditions that damage the brainstem, recurrent laryngeal nerve, and vocal cords. V-PSG frequently detects obstructive sleep apnea and laryngoscopy usually shows vocal cord abductor dysfunction. CPAP, tracheostomy, and laryngeal surgery abolish SDS.

The Effect of Cranial Nerve Stimulation on Swallowing: A Systematic Review

This systematic review summarizes published studies on the effect of cranial nerve stimulation (CNS) on swallowing and determines the level of evidence of the included studies to guide the development of future research on new treatment strategies for oropharyngeal dysphagia (OD) using CNS. Studies published between January 1990 and October 2019 were found via a systematic comprehensive electronic database search using PubMed, Embase, and the Cochrane Library. Two independent reviewers screened all articles based on the title and abstract using strict inclusion criteria. They independently screened the full text of this initial set of articles. The level of evidence of the included studies was assessed independently by the two reviewers using the A-B-C rating scale. In total, 3267 articles were found in the databases. In the majority of these studies, CNS was used for treatment-resistant depression or intractable epilepsy. Finally, twenty-eight studies were included; seven studies on treatment of depression, thirteen on epilepsy, and eight on heterogeneous indications. Of these, eight studies reported the effects of CNS on swallowing and in 20 studies the swallowing outcome was described as an adverse reaction. A meta-analysis could not be carried out due to the poor methodological quality and heterogeneity of study designs of the included studies. These preliminary data suggest that specific well-indicated CNS might be effective in reducing OD symptoms in selective patient groups. But it is much too early for conclusive statements on this topic. In conclusion, the results of these studies are encouraging for future research on CNS for OD. However, randomized, double-blind, sham-controlled clinical trials with sufficiently large sample sizes are necessary.

Behavioral Management of Laryngeal Complaints Caused by Vagal Nerve Stimulation for Medically Refractory Epilepsy

OBJECTIVES/HYPOTHESIS

This study investigated behavioral management of dysphonia and laryngeal dyspnea secondary to use of vagal nerve stimulation (VNS) in an individual with medically refractory epilepsy.

STUDY DESIGN

Retrospective chart review.

METHODS

Medical records from a single patient were reviewed. The patient received treatment with the speech-language pathologist (SLP) and laryngologist to observe patterns of laryngeal hyperfunction using biofeedback, and treatment with the SLP to learn to perform rescue breathing techniques, relaxation techniques, and awareness of muscle tension to aid the control of symptoms during activation. Data collected included neurology and laryngology notes. Neurology notes were used to track VNS settings, tolerance, and incidence of seizures. Laryngology notes included documentation of diagnosis, treatment, and measures of patient perception of severity (ie, Voice Handicap Index, Dyspnea Index, Cough Severity Index).

RESULTS

Prior to treatment, the patient was unable to receive benefits from VNS due to severe laryngeal adverse effects, such that the device remained off for eight months postimplantation. Following treatment, the patient effectively managed laryngeal side effects and was able to tolerate increases in VNS output current, signal frequency, and duration.

CONCLUSIONS

Voice therapy was effective in managing changes in vocal fold mobility and laryngeal tension. As the number of individuals receiving VNS for epilepsy and inflammatory conditions increases, the SLP and laryngologist may play a key role in interdisciplinary management of laryngeal side effects secondary to vagal nerve stimulation.

Vagus Nerve Stimulation-Induced Laryngeal Motor Evoked Potentials: A Possible Biomarker of Effective Nerve Activation

Vagus nerve stimulation (VNS) therapy is associated with laryngeal muscle activation and induces voice modifications, well-known side effects of the therapy resulting from co-activation of the recurrent laryngeal nerve. In this study, we describe the non-invasive transcutaneous recording of laryngeal motor evoked potentials (LMEPs), which could serve as a biomarker of effective nerve activation and individual titration in patients with drug-resistant epilepsy. We recruited drug-resistant epileptic patients treated for at least 6 months with a VNS. Trains of 600-1200 VNS pulses were delivered with increasing current outputs. We placed six skin electrodes on the ventral surface of the neck, in order to record LMEPs whenever the laryngeal muscular threshold was reached. We studied the internal consistency and the variability of LMEP recordings, and compared different methods for amplitude calculation. Recruitment curves were built based on the stimulus-response relationship. We also determined the electrical axis of the LMEPs dipole in order to define the optimal electrode placement for LMEPs recording in a clinical setting. LMEPs were successfully recorded in 11/11 patients. The LMEPs threshold ranged from 0.25 to 1 mA (median 0.50 mA), and onset latency was between 5.37 and 8.77 ms. The signal-to-noise ratio was outstanding in 10/11 patients. In these cases, excellent reliability (Intraclass correlation coefficient, ICC > 0.90 across three different amplitude measurements) was achieved with 10 sample averages. Moreover, our recordings showed very good internal consistency (Cronbach's alpha > 0.95 for 10 epochs). Area-under-the-curve and peak-to-peak measurement proved to be complementary methods for amplitude calculation. Finally, we determined that an optimal derivation requires only two recording electrodes, aligned on a horizontal axis around the laryngeal prominence. In conclusion, we describe here an optimal methodology for the recording of VNS-induced motor evoked responses from the larynx. Although further clinical validation is still necessary, LMEPs might be useful as a non-invasive marker of effective nerve activation, and as an aid for the clinician to perform a more rational titration of VNS parameters.

The vagal nerve stimulation outcome, and laryngeal effect: Otolaryngologists roles and perspective

INTRODUCTION

Epilepsy is one of the most common neurologic disorders. Vagus nerve stimulation (VNS), first investigated in 1938 and subsequently studied as a potential therapy for epilepsy. The FDA approved the use of VNS in 1997 as an adjunctive non-pharmacologic symptomatic treatment option for refractory epilepsy for adults and adolescents over 12years. VNS can cause laryngeal and voice side effects that can be managed by otolaryngologists safely and effectively.

OBJECTIVES

This study is to review the outcomes of vagal nerve stimulator (VNS) implantation in terms of the surgical procedures, complications, seizure frequency, and the clinical effect on larynx and vocal folds motion.

METHODS

Series of thirty consecutive patients who had VNS implantation between 2007 and 2014 were recruited. Seizure-frequency outcome, surgical complications and device adverse effects of VNS were retrospectively reviewed. Additional evaluation included use of the Voice Handicap Index and Maximum Phonation Time (MPT) were conducted before and after the implantation. Videolaryngoscopy was used to evaluate the vocal fold mobility before and after the VNS implantation.

RESULTS

Seizure frequency reduction over a minimum of 2years of follow up demonstrated: 100% in seizure frequency reduction in 1 patient, drastic reduction in seizure frequency (70-90%) in 9 patients, a good reduction in terms of seizure frequency (50%) in 8 patients, a 30% reduction in 5 patients, no response in 6 patients, and 1 patient had increased frequency. The most commonly reported adverse effects after VNS activation were coughing and voice changes with pitch breaks, as well as mild intermittent shortness of breath in 33% of patients. For those patients secondary supraglottic muscle tension and hyper function with reduced left vocal fold mobility were noticed on videolaryngoscopy, though none had aspiration problems. Surgical complications included a wound dehiscence in one patient (3%) which was surgically managed, minor intra-operative bleeding 3%; a superficial wound infection in one patient (3%) which was treated conservatively, none of the complications necessitated VNS removal.

CONCLUSIONS

VNS appears to be an effective non-pharmacologic adjuvant therapy in patients with medically refractory seizures. With the favorable adverse-effect profile previously described, VNS is generally well tolerated and of a great benefit to such patients. Laryngeal side effects, of which hoarseness being of the greatest repetition, are the most common after the VNS implantation. VNS can affect the voice and reduced vocal cord motion on the implantation side with secondary supraglottic muscle tension. Otolaryngologists are not only capable of performing VNS implantation, but can also manage surgical complications, assess laryngeal side effects and treat them as needed.

Vocal cord dysfunction: a functional cause of respiratory distress

VCD has several clinical and physiological phenotypes, which should be individually identifiedhttp://ow.ly/orfb309fMxh.

Impact of Vagal Nerve Stimulation on Objective Vocal Quality, a Pilot Study

OBJECTIVE

The purpose of this study was to determine the impact of vagal nerve stimulation (VNS) on the vocal quality using the dysphonia severity index (DSI). It was hypothesized that the objective vocal quality and other vocal characteristics are disordered in comparison with an age- and gender-matched control group. In addition, the acoustic vocal parameters were compared during three conditions: at rest, during normal stimulation, and raised stimulation. A significant relation between the amount of stimulation and the presence of disturbed acoustic parameters was hypothesized.

METHODS

Subjective (auditory-perceptual evaluation and voice handicap index) and objective (aerodynamic, vocal range, acoustic measurements and determination of the DSI) measurements were used to determine the vocal quality in 13 subjects with VNS in three different conditions (at rest and during normal and raised stimulation) and the age- and gender-matched control group.

RESULTS

The subjects with VNS had a disordered perceptual vocal quality mainly characterized by the presence of a moderate roughness and slight breathiness, and the objective vocal quality by means of the DSI value is -2.4. During stimulation and especially during raised stimulation, the fundamental frequency is significantly increased. However, the subjects experienced no psychosocial handicapping effect of the vocal quality on the quality of life.

CONCLUSIONS

Subjects with VNS have typical vocal characteristics. Ear, nose, and throat specialists and voice therapist must be aware of the presence of this vocal pattern at rest and during normal and raised stimulation. Especially, professional voice users and elite vocal performers must be informed before implantation.

Complications of vagal nerve stimulation for drug-resistant epilepsy: a single center longitudinal study of 143 patients

PURPOSE

To longitudinally study surgical and hardware complications to vagal nerve stimulation (VNS) treatment in patients with drug-resistant epilepsy.

METHODS

In a longitudinal retrospective study, we analyzed surgical and hardware complications in 143 patients (81 men and 62 women) who between 1994 and 2010 underwent implantation of a VNS-device for drug-resistant epilepsy. The mean follow-up time was 62 ± 46 months and the total number of patient years 738.

RESULTS

251 procedures were performed on 143 patients. 16.8% of the patients were afflicted by complications related to surgery and 16.8% suffered from hardware malfunctions. Surgical complications were: superficial infection in 3.5%, deep infection needing explantation in 3.5%, vocal cord palsy in 5.6%, which persisted in at least 0.7% for over one year, and other complications in 5.6%. Hardware-related complications were: lead fracture in 11.9% of patients, disconnection in 2.8%, spontaneous turn-off in 1.4% and stimulator malfunction in 1.4%. We noted a tendency to different survival times between the two most commonly used lead models as well as a tendency to increased infection rate with increasing number of stimulator replacements.

CONCLUSION

In this series we report on surgical and hardware complications from our 16 years of experience with VNS treatment. Infection following insertion of the VNS device and vocal cord palsy due to damage to the vagus nerve are the most serious complications related to the surgery. Avoiding unnecessary reoperations in order to reduce the appearances of these complications are of great importance. It is therefore essential to minimize technical malfunctions that will lead to additional surgery. Further studies are needed to evaluate the possible superiority of the modified leads.

Vagal nerve stimulation for pharmacoresistant epilepsy in children

Vagus nerve stimulation (VNS) is an adjunctive treatment for adult patients with pharmacoresistant epilepsy. Little is known about VNS therapy for children with epilepsy. This article will: (1) Review the contemporary medical literature related to VNS therapy in children with epilepsy, (2) describe the experience of VNS treatment in 153 children less than 18 years of age, in the University of California, Los Angeles (UCLA) Pediatric Epilepsy Surgery Program, from 1998 to 2012, and (3) describe the surgical technique used for VNS implantation at UCLA. Review of the literature finds that despite different etiologies and epilepsy syndromes in children, VNS appears to show a similar profile of efficacy for seizure control compared to adults, and low morbidity and mortality. The UCLA experience is similar to that reported in the literature for children. VNS constitutes about 21% of our pediatric epilepsy surgery volume. We have implanted VNS in infants as young as six months of age and the most common etiology is the Lennox-Gastaut Syndrome. About 5% of the patients are seizure-free with VNS therapy and there is a low rate of surgically related complications. The UCLA surgical approach emphasizes minimal direct manipulation of the vagus nerve and adequate wire loops, to prevent a lead fracture. In summary, VNS is a viable palliative treatment for medically refractory epilepsy in children, with outcomes and complications equal to adult patients. Being a small child is not a contraindication for VNS therapy, if needed for refractory epilepsy.

Lead breakage and vocal cord paralysis following blunt neck trauma in a patient with vagal nerve stimulator

Patients with medically intractable seizures who are not candidates for epilepsy surgery are left with few options. Vagal nerve stimulation therapy is often a viable alternative for these patients and can have a positive impact on quality of life. Rarely complications may occur. We report a case of mild blunt neck trauma resulting in VNS malfunction and delayed vocal cord paralysis. A systematic review of the literature on VNS malfunction, self-inflicted injuries, vagal nerve injury, and common side effects including voice changes was performed. Only a handful of relevant publications were found. Symptoms following VNS dysfunction include pain, dyspnea, and dysphonia. These symptoms are usually nonspecific, and in many cases, do not help differentiate from vagal nerve traction, lead breakage, or pulse generator malfunction. In our case, lead fracture and visible traction injury to the left vagus nerve were seen during surgical exploration. The vocal cord function completely recovered after revision of the leads. Prompt medical attention including appropriate diagnostic studies and early surgical exploration is necessary in cases of delayed vocal cord dysfunction and can help prevent long-term complications such as neuroma formation. The authors present a unique case of reversible vocal cord injury from blunt neck trauma leading to left vagus nerve damage.

Obstructive sleep apnea and respiratory complications associated with vagus nerve stimulators

Intermittent vagus nerve stimulation can reduce the frequency of seizures in patients with refractory epilepsy. Stimulation of vagus nerve afferent fibers can also cause vocal cord dysfunction, laryngeal spasm, cough, dyspnea, nausea, and vomiting. Vagus nerve stimulation causes an increase in respiratory rate, decrease in respiratory amplitude, decrease in tidal volume, and decrease in oxygen saturation during periods of device activation. It usually does not cause an arousal, or a change in heart rate or blood pressure. Most patients have an increase in their apnea-hypopnea index (AHI). Patients with VNS can have central apneas, obstructive hypopneas, and obstructive apneas. These respiratory events can be reduced with changes in the vagus nerve stimulator operational parameters or with the use of CPAP. In summary, there are complex relationships between epilepsy and obstructive sleep apneas. In particular, patients with refractory epilepsy need assessment for undiagnosed and untreated obstructive sleep apnea before implantation of vagus nerve stimulator devices. Patients with vagus nerve stimulators often have an increase in apneic events after implantation, and these patients need screening for sleep apnea both before and after implantation.

Operative and Technical Complications of Vagus Nerve Stimulator Implantation

BACKGROUND:

The treatment of refractory epilepsy by vagus nerve stimulation (VNS) is a well-established therapy option for patients not suitable for epilepsy surgery and therapy refractory depressions.

OBJECTIVE:

To analyze surgical and technical complications after implantation of left-sided VNS in patients with therapy-refractory epilepsy and depression.

METHODS:

One hundred five patients receiving a VNS or VNS-related operations (n = 118) from 1999 to 2008 were investigated retrospectively.

RESULTS:

At the time of operation, 84 patients were younger than 18 years, with a mean age of 10.5 years. Twenty (19%) patients had technical problems or complications. In 6 (5.7%) patients these problems were caused by the operation. The device was removed in 8 cases. The range of surgically and technically induced complications included electrode fractures, early and late onset of deep wound infections, transient vocal cord palsy, cardiac arrhythmia under test stimulation, electrode malfunction, and posttraumatic dysfunction of the stimulator.

CONCLUSION:

VNS therapy is combined with a wide spread of possible complications. Technical problems are to be expected, including electrode fracture, dislocation, and generator malfunction. The major complication in younger patients is the electrode fracture, which might be induced by growth during adolescence. Surgically induced complications of VNS implantation are comparably low. Cardiac symptoms and recurrent nerve palsy need to be taken into consideration.

[Perioperative anaesthetic management of an epileptic patient treated with a vagus nerve stimulation]

The vagal nerve stimulation is approved for medically refractory epilepsy and major depression. We report the perioperative management of an epileptic patient with this indwelling device. This observation summarizes the physiologic implications and the specific anaesthetic considerations for procedures with this pre-existing device.

[Perioperative considerations in vagal nerve stimulator implantation]

Vagal nerve stimulation has become an a important tool in the treatment of refractory epilepsy, which continues to be the main indication for this technique. Other therapeutic indications are emerging, however, and vagal nerve stimulation has now been approved for major depression. Additional possible uses under study include morbid obesity, Alzheimer disease, chronic pain syndromes, and certain neuropsychologic disorders. This review considers perioperative aspects relevant to using this therapeutic procedure with a view to facilitating better and more integrated management of its application.

Paradoxical vocal cord motion disorder: past, present and future

Paradoxical vocal cord motion disorder (PVCM), also called vocal cord dysfunction, is an important differential diagnosis for asthma. The disorder is often misdiagnosed as asthma leading to unnecessary drug use, very high medical utilisation and occasionally tracheal intubation or tracheostomy. Laryngoscopy is the gold standard for diagnosis of PVCM. Speech therapy and psychotherapy are considered the cornerstone of management of this disorder. The aim of this article is to increase the awareness of PVCM among doctors, highlighting the main characteristics that distinguish it from asthma and discuss the recent medical achievements and the possible future perspectives related to this disorder.

Vocal cord paralysis after vagus nerve stimulator battery replacement successfully treated with medialization thyroplasty

The vagus nerve stimulator (VNS) has been used effectively for partial seizure disorders, however many patients suffer from side effects of alterations in voice. This case describes a new remediable adverse effect of the VNS. A patient with medically intractable epilepsy had improvement of his seizure control with VNS therapy after titrating him to a high output and rapid cycling paradigm with essentially no side effects. After a battery replacement, he was restarted on his previous settings and subsequently developed a hoarse voice. He was found to have complete left vocal cord paralysis, an adverse effect attributed to a rapid titration to his previous high output and rapid cycling paradigm. This side effect has not been previously described in the literature. The patient subsequently had a medialization thyroplasty with resolution of his hoarse voice.

Pseudo-asthma: when cough, wheezing, and dyspnea are not asthma

Although asthma is the most common cause of cough, wheeze, and dyspnea in children and adults, asthma is often attributed inappropriately to symptoms from other causes. Cough that is misdiagnosed as asthma can occur with pertussis, cystic fibrosis, primary ciliary dyskinesia, airway abnormalities such as tracheomalacia and bronchomalacia, chronic purulent or suppurative bronchitis in young children, and habit-cough syndrome. The respiratory sounds that occur with the upper airway obstruction caused by the various manifestations of the vocal cord dysfunction syndrome or the less common exercise-induced laryngomalacia are often mischaracterized as wheezing and attributed to asthma. The perception of dyspnea is a prominent symptom of hyperventilation attacks. This can occur in those with or without asthma, and patients with asthma may not readily distinguish the perceived dyspnea of a hyperventilation attack from the acute airway obstruction of asthma. Dyspnea on exertion, in the absence of other symptoms of asthma or an unequivocal response to albuterol, is most likely a result of other causes. Most common is the dyspnea associated with normal exercise limitation, but causes of dyspnea on exertion can include other physiologic abnormalities including exercise-induced vocal cord dysfunction, exercise-induced laryngomalacia, exercise-induced hyperventilation, and exercise-induced supraventricular tachycardia. A careful history, attention to the nature of the respiratory sounds that are present, spirometry, exercise testing, and blood-gas measurement provide useful data to sort out the various causes and avoid inappropriate treatment of these pseudo-asthma clinical manifestations.

Vocal fold paresis: evidence and controversies

PURPOSE OF REVIEW

To present and assess the current state of knowledge regarding vocal fold paresis.

RECENT FINDINGS

Neurogenic compromise of vocal fold function exists along a continuum encompassing partial denervation (paresis), complete denervation (paralysis), and variable degrees and patterns of reinnervation. Not abundantly recognized clinically until recently, paresis typically presents with symptoms of glottic insufficiency. As a result of preserved vocal fold mobility, paresis can be difficult to diagnose and to distinguish from innocent vocal fold asymmetry. Laryngoscopy alone has proved an unreliable means of diagnosis, and laryngeal electromyography, although not immune to error itself, is often helpful. Treatment consists of medialization procedures that do not compromise remaining nerve function. Significant disagreement exists regarding the incidence, causes and relationship to other pathologies. In the absence of evidence, natural history must be inferred.

SUMMARY

Vocal fold paresis is probably a significant source of vocal disability, especially among cases that have eluded straightforward diagnosis. An accurate assessment of its clinical impact, patterns of dysfunction, natural history and relationship to other pathologies depends on diagnostic rigor and accuracy and is still evolving.

Vagal Nerve Stimulation: Overview and Implications for Anesthesiologists

Vagal nerve stimulation is an important adjunctive therapy for medically refractory epilepsy and major depression. Additionally, it may prove effective in treating obesity, Alzheimer's disease, and some neuropsychiatic disorders. As the number of approved indications increases, more patients are becoming eligible for surgical placement of a commercial vagal nerve stimulator (VNS). Initial VNS placement typically requires general anesthesia, and patients with previously implanted devices may present for other surgical procedures requiring anesthetic management. In this review, we will focus on the indications for vagal nerve stimulation (both approved and experimental), proposed therapeutic mechanisms for vagal nerve stimulation, and potential perioperative complications during initial VNS placement. Anesthetic considerations during initial device placement, as well as anesthetic management issues for patients with a preexisting VNS, are reviewed.

Vagal nerve stimulator implantation: an otolaryngologist's perspective

OBJECTIVE

This study was conducted to compare an otolaryngologist's experience with a cohort of epilepsy patients implanted with a vagal nerve stimulator (VNS) to previously published data.

METHODS

Demographics, preoperative seizure frequency, medications, and complications were retrospectively collected from patients implanted by the senior author. Postoperative medications and seizure frequency were obtained from referring neurologists.

RESULTS

Seventeen patients were implanted over a 24-month period. Average age was 28.3 years. Patients presented with petit mal (n = 3), tonic-clonic (n = 6), complex partial (n = 5), and grand mal (n = 8) seizures. Mean follow-up postimplantation was 13.5 months. Most patients had at least a 50% reduction of seizure frequency, with 3 patients being seizure free. There were no postoperative infections. One patient had left vocal cord immobility. The most common side effect was voice disturbance during device activation.

CONCLUSION

Otolaryngologists are well equipped to perform VNS implantation and to diagnose and treat possible laryngeal side effects.

EBM RATING

C-4.

Long-term outcome of vocal cord dysfunction

BACKGROUND

Vocal cord dysfunction (VCD) is an involuntary functional disorder commonly misdiagnosed as asthma. Previous reports describe the disorder and treatment but not the long-term outcome.

OBJECTIVE

To determine the long-term outcome of VCD.

METHODS

A retrospective medical record review identified 49 patients, ages 8 to 25 years, diagnosed as having VCD from 1989 to 2002. Telephone contact was attempted in all.

RESULTS

Of the 49 patients, 41 had previously been treated for asthma; that diagnosis was confirmed by us as a comorbidity in only 12 patients. Two distinct phenotypes of VCD were observed. Symptoms were limited to exercise-induced VCD (EIVCD) in 29 and spontaneously occurring VCD (SVCD) in 20, only 4 of whom additionally had EIVCD. Twenty-eight of the 49 were successfully contacted by telephone. Eight of the 11 contacted patients with SVCD followed the recommendation to see our speech therapist, all of whom learned to control symptoms. However, 2 who also had EIVCD continued with that problem. Pretreatment with an anticholinergic inhaler prevented EIVCD in 6 patients in whom this was tried. Complete absence of symptoms, at times ranging from 1 week to 5 years (median, 5 months), was reported in 26 of the 28 contacted patients.

CONCLUSIONS

VCD continues to be frequently misdiagnosed as asthma. Two phenotypes of VCD are apparent: EIVCD and SVCD. Speech therapy provides relief of symptoms for SVCD. Prevention of EIVCD with an anticholinergic inhaler in 6 patients suggests that a controlled clinical trial is warranted. Regardless of treatment, eventual spontaneous resolution was common.

Predictors of laryngeal complications in patients implanted with the Cyberonics vagal nerve stimulator

OBJECTIVES

Since its approval by the US Food and Drug Administration in 1997 for management of medically refractory seizures, more than 35,000 patients have been implanted with the Cyberonics vagal nerve stimulator. Preliminary reports described transient vocal changes in the majority of subjects, which were thought to be short-term. However, these reports were for the most part based upon perceptual evaluations by the subjects themselves. Later reports described possibly more permanent recurrent laryngeal nerve injury and recommended measuring the nerve diameter to use the safest spiral cuff electrode. To date, no study has systematically evaluated vocal fold mobility in subjects before and after implantation. The objectives of this study were to determine the true incidence of both short- and long-term recurrent laryngeal nerve injuries and determine whether there are any potential indicators to predict in which patients long-term nerve deficits may develop.

METHODS

Thirteen subjects underwent preimplantation laryngeal electromyography, videolaryngoscopy, measurement of the maximum phonation time, Voice Handicap Index determination, and Consensus Auditory-Perceptual Evaluation of Voice. Two weeks after implantation, all subjects underwent videolaryngoscopy. Three months after implantation and activation of the device, all subjects were reevaluated.

RESULTS

Six of the 13 subjects had significant vocal fold mobility abnormalities at 2 weeks. Significant electromyographic abnormalities were detected before implantation in 5 subjects. All 5 of these subjects, at 3 months after implantation, had prolonged left vocal fold paresis.

CONCLUSIONS

The authors conclude that perioperative vocal fold paresis occurs in approximately 50% of subjects. Further, laryngeal electromyography performed before implantation of the vagal nerve stimulator is a statistically significant predictor (p < .05) of which patients may be at risk for extended vocal fold abnormalities. Possible explanations for this phenomenon are offered. Surgical modifications to limit vagal nerve injury are offered.

Complications of vagal nerve stimulation for epilepsy in children

Vagal nerve stimulation (VNS) is a surgical option to treat drug-resistant epilepsy. A few side effects have been described, mainly as anecdotal reports. We analysed our material concerning a juvenile population to identify the most common and most important complications, discussing them with the literature. Thirty-six patients were studied (18 months-18 years old). The children were assessed before the VNS implant and 3, 6, 12, 24 and 36 months after surgery. The mean follow-up was 30 months. Four patients required a second surgery: two for changing the device 3 years after implant; one for revision of an imperfect implant; one for removing a non-functioning device. In one patient a transient vocal cord paralysis was observed. Hoarseness was the main complaint (38.8%). More infrequent was mild sleep apnoea (8.3%), sternocleidomastoid muscle spasm, drooling and snoring in one patient each. Skin scars were reported with a different frequency according to the surgical technique. At variance with the literature reports, we did not observe infections. Side effects of VNS can be minimised, but not avoided completely, with a correct technical procedure, which in turn depends upon a thorough knowledge of vagus nerve anatomy.

Improving the lives of patients with medically refractory epilepsy by electrical stimulation of the nervous system

Vagal nerve stimulation proved effective in animal models of epilepsy, and in open and double-blinded trials, in over 450 patients. Seizure reduction improved for at least 2 years. Almost 50% of treated patients achieve at least a 50% reduction in seizure frequency. Other advantages include termination of a seizure and improved alertness. Benefits were demonstrated in children, partial and generalized epilepsies, and in specific neurologic syndromes.

Recurrent laryngeal nerve paralysis: anatomy and etiology

Etiologies of adult vocal paralysis are varied by the site of the lesion as well as the extent and cause of the damage. Most large series point to surgery and neoplastic causes for recurrent nerve paralysis. A detailed history is important when working up a patient with this voice disorder. Knowledge of the anatomy of the head, neck, and chest as well as the mechanisms behind vocal fold paralysis is essential in the evaluation and treatment of recurrent nerve paralysis. Many of the surgical and traumatic causes of hoarseness are from compression type injuries. Recovery is dependent on the type, extent, and site of nerve lesion. Familiarity with this data allows the otolaryngologist to tailor management to suit each patient with vocal fold paralysis.