Self-administered non-invasive vagus nerve stimulation therapy for severe pharmacoresistant restless legs syndrome: outcomes at 6 months

Tonic and Event-Related Phasic Transcutaneous Auricular Vagus Nerve Stimulation Alters Pupil Responses in the Change-Detection Task

BACKGROUND

Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a potential modulator of cognitive behavior by activating the locus ceruleus-noradrenaline (LC-NA) system. Previous studies explored both phasic and tonic taVNS by investigating their impact on LC-NA markers such as pupil dilation and heart rate variability (HRV).

OBJECTIVE

Inconsistencies persist in the identification of reliable markers for assessing the effects of taVNS on noradrenergic activity. Furthermore, it remains unclear whether the effects of taVNS extend beyond pure vagal nerve responses, particularly in specific cognitive domains such as working memory. In the present study, we investigated the effects of taVNS on working memory capacity and LC-NA markers using a change-detection task.

MATERIALS AND METHODS

Twenty-two healthy, right-handed university students participated in a sham-controlled, randomized cross-over experiment with four sessions. We applied two types of phasic and event-related stimulation (Pre-event and Event-synchronous), tonic stimulation (Pre-task), and sham stimulation across different sessions. Pupil size and electrocardiogram data were recorded during the tasks.

RESULTS

taVNS did not significantly modulate behavioral performance on the change-detection task, specifically working memory capacity. However, both tonic and event-related phasic taVNS significantly influenced the pupillary response during the task. In addition, the Pre-task condition of the taVNS affected the low-frequency parameter of HRV.

CONCLUSIONS

Our findings suggest that tonic and event-related phasic taVNS may modulate noradrenergic activity, as evidenced by pupil responses and HRV changes during the change-detection task. This study provides new evidence regarding the impact of taVNS on cognitive tasks, thus supporting the development of noninvasive neuromodulation interventions.

Clinical application of transcutaneous auricular vagus nerve stimulation: a scoping review

PURPOSE

Transcutaneous auricular vagus nerve stimulation (taVNS) is an emerging non-invasive neuromodulation therapy. This study aimed to explore the therapeutic use of taVNS, optimal stimulation parameters, effective sham protocols, and safety.

METHODS

A scoping review was conducted. Five databases and grey literature were searched. The data extracted included stimulation parameters, adverse events (AEs), and therapeutic effects on clinical outcomes.

RESULTS

109 studies were included. taVNS was used across 21 different clinical populations, most commonly in psychiatric, cardiac, and neurological disorders. Overall, 2,214 adults received active taVNS and 1,017 received sham taVNS. Reporting of stimulation parameters was limited and inconsistent. taVNS appeared to have a favourable therapeutic effect across a wide range of clinical populations with varied parameters. Three sham protocols were reported but their effectiveness was documented in only two of the 54 sham-controlled studies. Most reported adverse events were localised to stimulation site.

CONCLUSION

There is growing evidence for taVNS therapeutic effect. taVNS appears safe and tolerable. Sham protocols need evaluation. Standardised and comprehensive reporting of both stimulation parameters and adverse events is required. Two different questionnaires have been proposed to evaluate adverse events and the effectiveness of sham methods in blinding participants.

Current updates in Restless Legs Syndrome: A pragmatic review

Restless legs syndrome (RLS), also called Willis–Ekbom disease (WED), affects approximately 3% of the global population, with higher incidence in Caucasians and women. This review explores the latest advancements in the diagnosis, pathophysiology, and management of RLS, and it highlights the recent changes in diagnostic criteria that improve specificity. The diagnostic spectrum now includes atypical presentations involving the upper limbs and other body parts. The new diagnostic specifiers categorize RLS more effectively into chronic-persistent or intermittent types, and a clinical significance specifier has been introduced to better address the disorder’s effects on daily life. RLS management has shifted toward a balanced approach with non-pharmacological strategies and lifestyle changes, supported by updated pharmacological treatment protocols including iron therapy designed to mitigate risks such as augmentation. Notably, gabapentinoids have emerged as a superior treatment option over dopamine agonists owing to their lower risk of augmentation and superior safety profile. Innovative treatments, such as the FDA-approved tonic motor activation device and new pharmacological agents, serve as alternatives for treating medication-refractory RLS, thereby expanding the therapeutic landscape. Additionally, this review addresses the specific considerations for managing RLS in special groups, including pregnant women, individuals with chronic kidney disease, and patients with comorbid conditions such as Parkinson’s disease and multiple sclerosis. We emphasizes the dynamic nature of RLS research and highlight the critical need for ongoing studies to further elucidate the complex mechanisms underlying RLS, as well as to refine the treatment modalities to enhance patient outcomes.