The therapeutic dilemma of vagus nerve stimulator-induced sleep disordered breathing

Vagal nerve stimulator-associated sleep disordered breathing secondary to vagal-induced laryngospasm in pediatric populations: Case presentation and systematic review

OBJECTIVES

Sleep disordered breathing (SDB) is a well-documented complication of vagus nerve stimulation (VNS) in the literature. Yet, a formal consensus on its management has not been established, particularly in the pediatric population. This study aims to evaluate the current literature on VNS-associated SDB in order to further characterize its presentation, pathogenesis, diagnosis, and treatment.

METHODS

A literature review from 2001 to November 8, 2021 was conducted to search for studies on SDB during vagal nerve stimulation in pediatric populations.

RESULTS

Of 277 studies screened, seven studies reported on pediatric patients with VNS-associated SDB. Several investigators found on polysomnogram that periods of apnea/hypopnea correlated with VNS activity. When VNS settings were lowered or turned off, symptoms would either improve or completely resolve.

CONCLUSION

VNS-associated SDB is a well described complication of VNS implantation, occurring due to an obstructive process from vagal stimulation and laryngeal contraction. Diagnosis can be made via polysomnogram. Recommended treatment is through adjustment of VNS settings. However, those who are unable to tolerate this, or who have had pre-existing obstructive issues prior to VNS, should pursue other treatment options such as non-invasive positive pressure or surgery directed by DISE findings.

Effects of Vagus Nerve Stimulation on Sleep-Disordered Breathing, Daytime Sleepiness, and Sleep Quality in Patients With Drug-Resistant Epilepsy

Background and Purpose

This study aimed to determine the long-term effects of vagus nerve stimulation (VNS) on sleep-disordered breathing (SDB), daytime sleepiness, and sleep quality in patients with drug-resistant epilepsy (DRE). It also investigated the relationships among these main effects, clinical characteristics, and VNS parameters.

Methods

Twenty-four patients were recruited. Paired t-tests and multiple linear regression analyses were performed to determine how the demographic and clinical characteristics of the patients influenced the variables that changed significantly after VNS treatment.

Results

After VNS, the patients showed significant increases in the apnea-hypopnea index (AHI), respiratory disturbance index (RDI), apnea index, hypopnea index, and oxygen desaturation index (ODI), as well as a significant decrease in the lowest arterial oxygen saturation (SaO₂ nadir) (p<0.05). The multiple linear regression analyses demonstrated that the predictor of larger increases in AHI and RDI was being older at baseline, and that the predictor of a larger increase in apnea index was a longer epilepsy duration. The strongest predictor of a larger increase in ODI was a higher frequency of aura episodes at baseline, followed by a longer epilepsy duration. The strongest predictor of a larger decrease in SaO₂ nadir was a higher frequency of aura episodes at baseline, followed by a longer epilepsy duration.

Conclusions

This study has confirmed that VNS improves seizure control in patients with DRE, whereas it increases obstructive sleep apnea (OSA). Furthermore, the increase in OSA is affected by age and the duration of epilepsy. Therefore, careful observation and monitoring of SDB is recommended in patients who undergo VNS.

Autonomic Dysfunction in Sleep Disorders: From Neurobiological Basis to Potential Therapeutic Approaches

Sleep disorder has been portrayed as merely a common dissatisfaction with sleep quality and quantity. However, sleep disorder is actually a medical condition characterized by inconsistent sleep patterns that interfere with emotional dynamics, cognitive functioning, and even physical performance. This is consistent with sleep abnormalities being more common in patients with autonomic dysfunction than in the general population. The autonomic nervous system coordinates various visceral functions ranging from respiration to neuroendocrine secretion in order to maintain homeostasis of the body. Because the cell population and efferent signals involved in autonomic regulation are spatially adjacent to those that regulate the sleep-wake system, sleep architecture and autonomic coordination exert effects on each other, suggesting the presence of a bidirectional relationship in addition to shared pathology. The primary goal of this review is to highlight the bidirectional and shared relationship between sleep and autonomic regulation. It also introduces the effects of autonomic dysfunction on insomnia, breathing disorders, central disorders of hypersomnolence, parasomnias, and movement disorders. This information will assist clinicians in determining how neuromodulation can have the greatest therapeutic effects in patients with sleep disorders.

Vagus Nerve Stimulation Unequally Disturbs Circadian Variation of Cardiac Rhythms in Male and Female Rats

Vagus nerve stimulation (VNS) is a neurostimulation therapy for epilepsy and severe depression and has been recently shown to be effective for other conditions. Despite its demonstrated safety and efficacy, long-term and off-target effects of VNS remain to be fully determined. One of the complications reported in epilepsy is stimulation-induced sleep abnormalities. As epilepsy itself can impact sleep quality, contribution of VNS alone in such off-target effects remain mainly unknown. In this study, we analyzed data from long-term VNS experiments in rats to characterize effects of VNS on circadian rhythms derived from heart rate and heart rate variability (HRV). We have also explored possible sex differences in long-term effects of VNS on intrinsic biological rhythms. Compared with control animals, significant VNS-induced changes in circadian rhythms were observed particularly in female rats over 24h and 6h light cycles (1PM-7PM). These findings enhance our understanding of VNS contribution and biological sex role on sleep difficulties reported by using VNS therapy.

Case of an In-Laboratory Vagal Nerve Stimulator Titration for Vagal Nerve Stimulator-Induced Pediatric Obstructive Sleep Apnea

None

We present the case of a 12-year-old girl with medically refractory epilepsy and a vagal nerve stimulator (VNS), who experienced severe obstructive sleep apnea (OSA) with respiratory events closely matching her VNS settings. We demonstrated a real-time decrease in OSA through an in-laboratory VNS titration study, decreasing her VNS frequency from 20 Hz to 10 Hz. We were able to demonstrate a baseline level of OSA by turning off the VNS. We then effectively treated her residual OSA with continuous positive airway pressure (CPAP). Novel to our case is that this in-laboratory VNS titration did not result in any subsequent increase in seizure frequency. After 5 months, her seizure frequency had decreased. Our case demonstrates that in-laboratory VNS titration can be an efficient tool for optimizing treatment of VNS-induced OSA and assert that polysomnography before VNS placement is important for guiding future care.

Treatment of vagus nerve stimulator-induced sleep-disordered breathing: A case series

Objective

Vagus nerve stimulation (VNS) is a treatment option for patients with drug-resistant seizures, but it is also associated with sleep-disordered breathing (SDB). We present four patients with VNS who underwent polysomnography (PSG) concurrently with VNS stimulation monitoring and adjustment, and positive airway pressure (PAP) treatment. We demonstrate the importance of sleep apnea screening prior to VNS placement and the dilemma of optimizing VNS settings.

Background

VNS is a common adjunct therapy for refractory epilepsy. Despite its low side effect profile, complications of VNS include delayed arrhythmias, laryngopharyngeal dysfunction, obstructive sleep apnea, and tonsillar pain mimicking glossopharyngeal neuralgia. Risk of developing or exacerbating existing obstructive sleep apnea (OSA) limits the VNS settings, as there appears to be a dose dependent effect. OSA can further cause sleep fragmentation and cause hypoxia, potentially worsening seizures.

Methods

Four patients with drug-resistant epilepsy with VNS underwent PSG with concurrent VNS leads to monitor correlation of SDB and VNS. AHI was calculated to quantify SDB, and it was scored as non-VNS related when the VNS was off, and VNS-induced when the onset of SDB corresponded to VNS activation. Subsequent PAP and VNS adjustment was performed to treat the SDB episodes.

Results

Three out of four patients had non-VNS associated SDB, which improved with PAP treatment. All four patients had VNS-induced SDB episodes but none improved with PAP. The VNS-induced SDB events decreased in a dose dependent manner, when VNS was adjusted down and disappeared when turned off completely.

Conclusion

Our case series provides further evidence of VNS-induced SDB secondary to VNS. PAP treatment alone is ineffective for VNS-induced SDB. Screening for OSA before VNS implant is crucial; further research is needed to establish optimal VNS parameters for prevention andminimization of VNS-induced SDB along with other possible treatments.

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Further evidence of VNS-induced SDB as a side effect of VNS

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PAP treatment alone is not effective in eliminating VNS-induced SDB

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VNS setting titration showed dose-dependent effect on SDB

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Screening of primary OSA before and after VNS implant is crucial

Investigating the Effect of Short Term Responsive VNS Therapy on Sleep Quality Using Automatic Sleep Staging

OBJECTIVE

The goal of this work is to objectively evaluate the effectiveness of responsive (or closed-loop) Vagus nerve stimulation (VNS) therapy in sleep quality in patients with medically refractory epilepsy.

METHODS

Using quantitative features obtained from electroencephalography, we first developed a new automatic sleep-staging framework that consists of a multi-class support vector machine (SVM) classification, based on a decision tree approach. To train and evaluate the performance of the framework, we used polysomnographic data of 23 healthy subjects from the PhysioBank database where the sleep stages have been visually annotated. We then used the trained classifier to label the sleep stages using data from 22 patients with epilepsy, treated with short term responsive VNS therapy during an epilepsy-monitoring unit visit, one month after VNS implantation, and ten VNS-naïve patients with epilepsy.

RESULTS

Application of multi-class SVM classifier to classify the three sleep stages of awake, light sleep + rapid eye movement, and deep sleep achieved a classification accuracy of 90%. Results of the application of this methodology to VNS-treated and VNS-naïve patients revealed that the patients treated with short term responsive VNS therapy showed significant increase in sleep efficiency, and significant decrease in seizures plus interictal epileptiform discharges and awakenings.

CONCLUSION

These results indicate that VNS treatment can reduce the epileptiform activities and thus help in achieving better sleep quality for patients with epilepsy.

SIGNIFICANCE

The proposed approach can be used to investigate the effect of long-term VNS therapy on sleep quality.

Impact of vagus nerve stimulation on sleep-related breathing disorders in adults with epilepsy

BACKGROUND

Vagus nerve stimulation (VNS) can induce a sleep apnea syndrome (SAS), which in turn can worsen seizure control and represents a cardiovascular risk factor. Epidemiology of VNS-induced SAS has received little attention to date. The purpose of this study was to estimate the VNS-induced SAS prevalence and to explore clinical variables potentially correlating with its development.

METHODS

We analyzed the computerized medical records of 18 consecutive adults treated for refractory epilepsy with VNS, implanted between May 2008 and October 2015. Patients underwent sleep polygraphy or polysomnography before and after VNS implantation. Between patients with and without SAS, we compared variables related to epilepsy type and device parameters.

RESULTS

Two patients had SAS and were treated before implantation; one improved after VNS, the other worsened. Four other patients developed SAS after VNS: induced/aggravated SAS occurred in 5/18 patients (prevalence: 27.8%). Only 2 of them had symptoms: one complained of important snoring, the other reported seizure worsening. All 5 patients were successfully treated by combinations of continuous positive airway pressure (cPAP), positional therapy, or VNS parameters modification. There was no statistically significant difference between potential predictors.

CONCLUSION

Despite the relatively modest clinical impact on epilepsy, in view of the associated cardiovascular risk factor development, easy treatment, and the relatively high SAS prevalence, routine screening for SAS before and after VNS implantation may represent a reasonable practice.

Changes in sleep patterns after vagus nerve stimulation, deep brain stimulation or epilepsy surgery: Systematic review of the literature

PURPOSE

Perform a systematic review of the literature on the effects of vagus nerve stimulation (VNS), deep brain stimulation (DBS) and epilepsy surgery in subjective and objective sleep parameters.

METHODS

We performed a literature search in the main medical databases: Medline, Embase, Cochrane, DARE and LILACS, looking for studies that evaluated the effects of VNS, DBS or epilepsy surgery on sleep parameters. In all, 36 studies, coming from 11 countries, including reviews, cohort studies, case series and case reports were included.

RESULTS

VNS induces sleep apnoea dependent of the stimulation variables. This condition can be reverted modifying these settings. Surgical procedures for epilepsy cause an improvement in objective and subjective sleep parameters that depend on the success of the procedure evaluated through ictal frequency control. There is evidence that non-pharmacologic treatment of epilepsy has different effects on sleep patterns.

CONCLUSION

It is advisable to include objective and subjective sleep parameters in the initial evaluation and follow-up of patients considered for invasive procedures for epilepsy control, especially with VNS due to the risk of sleep apnoea. More high quality studies are needed.