Name: Transauricular Vagus Nerve Stimulation and Electroencephalographic Assessment in Disorders of Consciousness (Video) | JoVE Journal
Uploaded: 2025-07-11T15:20:00.000+00:00
Duration: 4 min 4 s
Description: Learn transauricular vagus nerve stimulation for disorders of consciousness using EEG and CRSR assessments. This protocol evaluates clinical outcomes in unresponsive wakefulness syndrome and minimally conscious state patients.

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All patients at IRENEA-Vithas Sevilla Aljarafe Hospital, along with their relatives, and all professionals, deserve special recognition for their invaluable support during the completion of this research. Additionally, this study was conducted as part of the Marie Sk&#322;odowska-Curie Actions DOC-BOX project (#101131344).

The authors have nothing to disclose.

Transauricular vagus nerve stimulation is a promising non-invasive technique for treating disorders of consciousness. However, the lack of consensus on ethical procedures and protocols complicates efforts to clarify the true effects of this stimulation technique in this patient cohort12. 
The care of patients with disorders of consciousness presents several ethical challenges and legal considerations that require careful evaluation64. Decisions r...

Disorders of Consciousness (DoCs), such as unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS), are severe outcomes of brain injury, characterized by impaired arousal and awareness1. Patients with disorders of consciousness face high medical risks and present emotional, ethical, and legal challenges for families and healthcare providers2,3. Ethical dilemmas primarily concern patient best interests, family well-being, and professional decision-making4. Therefore, identifying effective treatments and establishing ethical guidelines is crucial in this context.
Therapeutic options remain highly limited, although electromagnetic brain stimulation techniques have recently been explored for their potential to modulate brain activity and promote cognitive recovery. Among these techniques, deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS) have yielded inconsistent results in enhancing arousal and awareness in patients, whereas transcranial direct current stimulation (tDCS) has shown Class II evidence supporting its efficacy5. Transauricular Vagus Nerve Stimulation (taVNS) is an emerging, non-invasive therapeutic approach for the treatment of disorders of consciousness6. The use of this stimulation technique in this patient cohort is rationally supported by previous anatomical studies, which have suggested that the auricular branch of the vagus nerve innervates specific regions of the ear7. Therefore, stimulation of these areas via taVNS is expected to modulate autonomic and central nervous system activity, engaging serotonin and norepinephrine pathways that connect key brain regions associated with consciousness, such as the ascending reticular activating system, the salience network, the default mode network, and the external network8. In addition, compared to other non-invasive electromagnetic stimulation techniques, such as TMS or tDCS, taVNS appears to more effectively modulate key brain networks associated with consciousness, particularly through its bottom-up neural transmission pathway9. Furthermore, various neurophysiological changes have been detected through electroencephalographic biomarkers following taVNS10, thereby strengthening its potential as a diagnostic tool. Although the safety and feasibility of taVNS have been documented in clinical interventions11, a standardized stimulation protocol for this patient population has not been fully established and widely implemented, with its efficacy still insufficiently explored12.
Some studies have investigated the effects of taVNS on disorders of consciousness, employing various methodologies and stimulation parameters13. Although clinical research has indicated improvements in patients receiving taVNS, as assessed by behavioral scales such as the Coma Recovery Scale-Revised (CRS-R)14, these outcomes remain inconsistent across different studies13. Additionally, recent trials have identified electroencephalographic patterns following taVNS10, suggesting diagnostic and prognostic potential in disorders of consciousness. However, research on the effects of taVNS in this population remains inconclusive13. Lastly, existing protocols have lacked emphasis on ethical considerations. Given the lack of consensus on the parametrization and other ethical or methodological aspects of taVNS in disorders of consciousness, further research is essential to clarify its impact and effectiveness in this patient cohort.
The primary objective of the proposed protocol is to establish a standardized methodological framework for the application of taVNS in disorders of consciousness, emphasizing both ethical and methodological rigor. By outlining stimulation parameters, ethical guidelines, and clinical assessment strategies, this study aims to facilitate reproducibility and strengthen the reliability of taVNS as a potential therapeutic intervention. As a first step, ethical considerations are addressed in accordance with Spanish15,16 and European Union (EU)17,18 regulations, including informed consent requirements for legal representatives and necessary approvals from Ethics Committees and the Spanish Agency for Medicines and Health Products (AEMPS)19. Strict inclusion and exclusion criteria are defined to ensure patient safety. Participants must have a stable disorder of consciousness diagnosis for at least 28 days, whether UWS or MCS, and meet specific age requirements. Exclusion criteria include epilepsy, cardiovascular, metabolic, or autonomic disorders, metal implants, pregnancy, and medications affecting autonomic function, while specific criteria for study withdrawal include uncontrolled seizures or severe infections.
Methodological guidelines for taVNS research in disorders of consciousness are also presented, including specific recommendations. The stimulation device must be in optimal condition, and patients should be comfortably positioned20. Different stimulation targets in the ear, such as the tragus or cymba, are outlined, along with device parameters, including recommendations for frequency, intensity, pulse duration, and the number of sessions13. Similarly, follow-up assessment approaches are proposed to effectively evaluate the impact of taVNS on disorders of consciousness, incorporating both behavioral scales and electroencephalographic methods. Additionally, the main findings from taVNS research in disorders of consciousness are discussed, highlighting recovery in patients as measured by both behavioral scales and electroencephalographic data.
Finally, the standardization of the taVNS protocol in disorders of consciousness could increase its clinical impact, helping to identify the most effective parameters and thereby improving patients&#39; quality of life. Given the limited treatment options available for this pathology, this technique represents a promising avenue for improving patient outcomes, provided that rigorous methodological and ethical guidelines are followed. Additionally, this method is particularly suitable for clinicians and researchers working on neuromodulation in disorders of consciousness, particularly during the chronic and stable stages, as outlined by the inclusion and exclusion criteria mentioned above. It is also relevant for those interested in behavioral and neurophysiological monitoring to assess treatment responses.

<table><tbody><tr><td>64-electrode Active Two</td><td>BioSemi</td><td>https://www.biosemi.com/products.htm</td><td>Electroencephalography recording device</td></tr><tr><td>ActiCHamp Plus / BrainAmp 64 MRplus</td><td>Brain Products</td><td>https://brainvision.com/products/</td><td>Electroencephalography recording device</td></tr><tr><td>Brain Vision Analyzer 2.0</td><td>Brain Products</td><td>https://brainvision.com/products/analyzer-2/</td><td>Electroencephalography analysis software</td></tr><tr><td>EASY-Clip / RELIfit-Tragus / RELI-Stick</td><td>Soterix Medical</td><td>https://soterixmedical.com/research/tavns</td><td>taVNS device</td></tr><tr><td>Electro Gel</td><td>Telic Group</td><td>G-10</td><td>Electroencephalographic gel</td></tr><tr><td>Enobio/ Startim</td><td>Neuroelectrics</td><td>https://www.neuroelectrics.com/</td><td>Electroencephalography recording device</td></tr><tr><td>E-Prime</td><td>Psychological Software Tools</td><td>https://pstnet.com/products/e-prime/</td><td>Paradigm design software</td></tr><tr><td>G*Power</td><td>Universit&amp;auml;t D&amp;uuml;sseldorf</td><td>https://www.psychologie.hhu.de/arbeitsgruppen/allgemeine-psychologie-und-arbeitspsychologie/gpower</td><td>Statistical software</td></tr><tr><td>g.NAUTILUS</td><td>G.Tec</td><td>https://www.gtec.at/</td><td>Electroencephalography recording device</td></tr><tr><td>JY-VNS-200</td><td>Jingyi Medical Technology</td><td>https://www.jingyimed.com/</td><td>taVNS device</td></tr><tr><td>MATLab and EEGLab</td><td>MathWorks</td><td>https://www.mathworks.com/products/matlab.html</td><td>Electroencephalography analysis software</td></tr><tr><td>Nemos</td><td>Cerbomed / tVNS Technologies</td><td>https://t-vns.com/</td><td>taVNS device</td></tr><tr><td>Nicolet Monitor</td><td>Nicolet / Natus Medical Incorporated</td><td>https://natus.com/es/neuro/monitor-nicolet/</td><td>Electroencephalography recording device</td></tr><tr><td>Parasym</td><td>Parasym</td><td>https://www.parasym.co/</td><td>taVNS device</td></tr><tr><td>Python</td><td>Python Software Foundation</td><td>https://www.python.org/</td><td>Electroencephalography analysis software</td></tr><tr><td>R</td><td>R Foundation for Statistical Computing</td><td>https://www.r-project.org/</td><td>Statistical software</td></tr><tr><td>SDZ-IIB</td><td>Suzhou Medical Appliance Factory / Hwato&amp;nbsp;</td><td>http://www.hwato-med.com/</td><td>taVNS device</td></tr><tr><td>SPSS</td><td>IBM</td><td>https://www.ibm.com/es-es/products/spss-statistics</td><td>Statistical software</td></tr><tr><td>Statistica</td><td>StatSoft</td><td>https://www.statsoft.de/en/data-science-applications/tibco-statistica/</td><td>Statistical software</td></tr><tr><td>taVNS501</td><td>Changzhou Rishena Medical Device</td><td>https://www.rishena.com/?l=en</td><td>taVNS device</td></tr><tr><td>TEN-20</td><td>Bionic</td><td>D-04-00WV</td><td>Electroencephalographic conductive paste</td></tr><tr><td>TENS-200A</td><td>Everyway Medical Instruments Co., Ltd</td><td>E200A16A000144</td><td>taVNS device</td></tr></tbody></table>

transauricular vagus nerve stimulation and electroencephalographic assessment in disorders of consciousness

Transauricular Vagus Nerve Stimulation and Electroencephalographic Assessment in Disorders of Consciousness

The technique of transauricular vagus nerve stimulation (taVNS) is methodologically applied by placing electrodes on the auricular region, specifically on the cymba, cavum, or tragus, to stimulate the vagus nerve non-invasively. Additionally, the earlobe, which is not innervated by the vagus nerve, can serve as a placebo site for control stimulation. The stimulation intensity is adjusted between 0.5-3.0 mA, with session durations ranging from 20-60 min, administered either daily or weekly, depending on the study protocol. The total number of sessions varies according to the protocol, extending from a few weeks to several months. Ethically, research involving taVNS must adhere to regulations set by the local Agency for Medicines and Health Products and European Union guidelines. Approval from an Ethical Committee is required for studies involving healthy participants, while a Medical Ethical Committee is necessary for clinical research, ensuring that written information and informed consent are provided. Additionally, rigorous exclusion criteria must be established to safeguard participant safety, excluding pregnant individuals, those with cardiovascular, pulmonary, or metabolic diseases, psychiatric disorders, epilepsy, hypertension, or those using medications affecting the autonomic nervous system. In terms of clinical outcomes, the current study protocol demonstrated promising results with taVNS in patients with Disorders of Consciousness, showing significant improvement in alertness recovery and response to stimuli. Patients treated with taVNS experienced neurophysiological changes compared to the control group. Moreover, electroencephalographic biomarkers can be utilized to evaluate treatment efficacy, even in the absence of observable behavioral indicators. These findings suggest significant clinical potential for taVNS in managing Disorder of Consciousness, although the lack of specific regulations for taVNS underscores the need to adhere to international scientific best practices and seek consensus on European guidelines for its research application.

Behavioral assessments 
Several outcomes have been documented following taVNS in individuals with disorders of consciousness following similar protocol, whose feasibility, safety, and efficacy were initially validated in a study conducted by our research group46. This study included six UWS patients and eight MCS patients who underwent taVNS, with CRS-R assessments conducted at baseline, after four weeks of treatment, and at a 4-week follow-up. The UWS patients had a mean basel...

This protocol aims to provide novel methodological insights into non-invasive neurostimulation, specifically transauricular vagus nerve stimulation (taVNS), in patients with disorders of consciousness. Additionally, a clinical and electroencephalographic analysis protocol is proposed to assess the efficacy of the treatment in this cohort, along with the discussion of relevant ethical considerations.

The technique of transauricular vagus nerve stimulation (taVNS) is methodologically applied by placing electrodes on the auricular region, specifically on ...

transauricular-vagus-nerve-stimulation-electroencephalographic

Research

JoVE Journal

Neuroscience

Source: Badran, B. W., et al. Laboratory Administration of Transcutaneous Auricular Vagus Nerve Stimulation (taVNS): Technique, Targeting, and Considerations. J. Vis. Exp. (2019)This video demonstrates transcutaneous auricular vagus nerve stimulation (taVNS), a noninvasive method for modulating brain activity. Electrodes are placed on the anterior wall of the outer ear canal and the tragus, targeting the auricular branch of the vagus nerve (ABVN). When stimulated, the resulting nerve impulse...

Transcutaneous Auricular Vagus Nerve Stimulation on the Human Ear

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has shown initial therapeutic effects in several neurological conditions. The main mechanism underlying these therapeutic effects is the modulation of cortical excitability. Therefore, online monitoring of cortical excitability would help guide stimulation parameters and optimize its therapeutic effects. In the present article we review the use of a novel device that combines simultaneous tDCS and...

Simultaneous EEG Monitoring During Transcranial Direct Current Stimulation

The present protocol aims at assessing cognitive-emotional functions in the basal ganglia by simultaneous neurophysiological recording of local field potentials and non-invasive brain cortical activity (EEG). The procedure is exemplified by the use of paradigms involving speech stimuli with emotional connotation or the Flanker task involving cognitive control.

Combined Invasive Subcortical and Non-invasive Surface Neurophysiological Recordings for the Assessment of Cognitive and Emotional Functions in Humans

In this article we explain how to set up a concurrent transcranial alternating current stimulation and EEG experiment.

Concurrent Electroencephalography Recording During Transcranial Alternating Current Stimulation (tACS)

With this experiment, one might be able to detect consciousness in people with disorders of consciousness. Furthermore, the approach can create a simple communication channel that enables people to give simple YES/NO answers to questions.

Assessment and Communication for People with Disorders of Consciousness

Vagus nerve stimulation (VNS) has been shown to be effective as an adjunct treatment for treatment-resistant depression (TRD). VNS leads to antidepressive and antisuicidal effects and quality of life improvements. This protocol offers a step-by-step guide to managing and adjusting a vagus nerve stimulator for efficient treatment of TRD.

Vagus Nerve Stimulation As an Adjunctive Neurostimulation Tool in Treatment-resistant Depression

A methodological description of the technique, potential targets, and proper administration of transcutaneous auricular vagus nerve stimulation (taVNS) on the human ear is described.

Laboratory Administration of Transcutaneous Auricular Vagus Nerve Stimulation (taVNS): Technique, Targeting, and Considerations

Existing approaches for constructing chronically implantable peripheral nerve cuff electrodes for use in small rodents often require specialized equipment and/or highly trained personnel. In this protocol we demonstrate a simple, low-cost approach for fabricating chronically implantable cuff electrodes, and demonstrate their effectiveness for vagus nerve stimulation (VNS) in rats.

Preparation of Peripheral Nerve Stimulation Electrodes for Chronic Implantation in Rats

We describe a protocol for assessing dose-response curves for extracranial stimulation in terms of brain electrical field measurements and a relevant biomarker-cerebral blood flow. Since this protocol involves invasive electrode placement into the brain, general anesthesia is needed, with spontaneous breathing preferred rather than controlled respirations.

Placement of Extracranial Stimulating Electrodes and Measurement of Cerebral Blood Flow and Intracranial Electrical Fields in Anesthetized Mice

The present protocol describes the surgical technique for implanting an electrode array onto the abdominal vagus nerve in rats, along with methods for chronic electrophysiology testing and stimulation using the implanted device.

Implantation Surgery for Abdominal Vagus Nerve Stimulation and Recording Studies in Awake Rats

This protocol provides information on how to apply transcutaneous auricular vagus nerve stimulation (taVNS) in a clinical trial, including potential biomarkers such as EEG metrics and heart rate variability (HRV) to measure the effect of this treatment on the autonomic nervous system.

Understanding the Effects of Non&#45;Invasive Transauricular Vagus Nerve Stimulation on EEG and HRV

Learn transauricular vagus nerve stimulation for disorders of consciousness using EEG and CRSR assessments. This protocol evaluates clinical outcomes in unresponsive wakefulness syndrome and minimally conscious state patients.

Transauricular Vagus Nerve Stimulation and Electroencephalographic Assessment in Disorders of Consciousness

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