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Leon-Ariza JS, Mosquera MA, Siomin V, Fonseca A, Leon-Ariza DS, Gualdron MA, Leon-Sarmiento FE. The Vagus Nerve Somatosensory-evoked Potential in Neural Disorders: Systematic Review and Illustrative Vignettes. Clin EEG Neurosci 2022; 53:256-263. [PMID: 33709798 DOI: 10.1177/15500594211001221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Objective. To review the scientific publications reporting vagal nerve somatosensory-evoked potential (VSEP) findings from individuals with brain disorders, and present novel physiological explanations on the VSEP origin. Methods. We did a systematic review on the papers reporting VSEP findings from individuals with brain disorders and their controls. We evaluated papers published from 2003 to date indexed in PubMed, Web of Science, and Scielo databases. We extracted the following information: number of patients and controls, type of neural disorder, age, gender, stimulating/recording and grounding electrodes as well as stimulus side, intensity, duration, frequency, and polarity. Information about physiological parameters, neurobiological variables, and correlation studies was also reviewed. Representative vignettes were included to add support to our conclusions. Results. The VSEP was studied in 297 patients with neural disorders such as Parkinson's disease (PD), Alzheimer's disease, vascular dementia, mild cognitive impairment, subjective memory impairment, major depression, and multiple sclerosis. Scalp responses marked as the VSEP showed high variability, low validity, and poor reproducibility. VSEP latencies and amplitudes did not correlate with disease duration, unified PD rating scale score, or heart function in PD patients nor with cerebrospinal fluid β amyloid, phosphor-τ, and cognitive tests from patients with mental disorders. Vignettes demonstrated that the VSEP was volume conduction propagating from muscles surrounding the scalp recording electrodes. Conclusion. The VSEP is not a brain-evoked potential of neural origin but muscle activity induced by electrical stimulation of the tragus region of the ear. This review and illustrative vignettes argue against assessing the parasympathetic system using the so-called VSEP.
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Affiliation(s)
| | - Mario A Mosquera
- Miami Neuroscience Institute, Baptist Hospital South Florida, Miami, FL, USA
| | - Vitaly Siomin
- Miami Neuroscience Institute, Baptist Hospital South Florida, Miami, FL, USA
| | - Angelo Fonseca
- Miami Neuroscience Institute, Baptist Hospital South Florida, Miami, FL, USA
| | | | | | - Fidias E Leon-Sarmiento
- Miami Neuroscience Institute, Baptist Hospital South Florida, Miami, FL, USA.,Parkinson's Disease Research Laboratory, 5450Florida International University, Miami, FL, USA
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Babiloni C, Arakaki X, Bonanni L, Bujan A, Carrillo MC, Del Percio C, Edelmayer RM, Egan G, Elahh FM, Evans A, Ferri R, Frisoni GB, Güntekin B, Hainsworth A, Hampel H, Jelic V, Jeong J, Kim DK, Kramberger M, Kumar S, Lizio R, Nobili F, Noce G, Puce A, Ritter P, Smit DJA, Soricelli A, Teipel S, Tucci F, Sachdev P, Valdes-Sosa M, Valdes-Sosa P, Vergallo A, Yener G. EEG measures for clinical research in major vascular cognitive impairment: recommendations by an expert panel. Neurobiol Aging 2021; 103:78-97. [PMID: 33845399 DOI: 10.1016/j.neurobiolaging.2021.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 02/17/2021] [Accepted: 03/05/2021] [Indexed: 11/22/2022]
Abstract
Vascular contribution to cognitive impairment (VCI) and dementia is related to etiologies that may affect the neurophysiological mechanisms regulating brain arousal and generating electroencephalographic (EEG) activity. A multidisciplinary expert panel reviewed the clinical literature and reached consensus about the EEG measures consistently found as abnormal in VCI patients with dementia. As compared to cognitively unimpaired individuals, those VCI patients showed (1) smaller amplitude of resting state alpha (8-12 Hz) rhythms dominant in posterior regions; (2) widespread increases in amplitude of delta (< 4 Hz) and theta (4-8 Hz) rhythms; and (3) delayed N200/P300 peak latencies in averaged event-related potentials, especially during the detection of auditory rare target stimuli requiring participants' responses in "oddball" paradigms. The expert panel formulated the following recommendations: (1) the above EEG measures are not specific for VCI and should not be used for its diagnosis; (2) they may be considered as "neural synchronization" biomarkers to enlighten the relationships between features of the VCI-related cerebrovascular lesions and abnormalities in neurophysiological brain mechanisms; and (3) they may be tested in future clinical trials as prognostic biomarkers and endpoints of interventions aimed at normalizing background brain excitability and vigilance in wakefulness.
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Affiliation(s)
- Claudio Babiloni
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy; San Raffaele Cassino, Cassino, FR, Italy.
| | | | - Laura Bonanni
- Department of Neuroscience Imaging and Clinical Sciences and CESI, University G D'Annunzio of Chieti-Pescara, Chieti, Italy
| | - Ana Bujan
- Psychological Neuroscience Lab, School of Psychology, University of Minho, Portugal
| | | | - Claudio Del Percio
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy
| | | | - Gary Egan
- Foundation Director of the Monash Biomedical Imaging (MBI) research facilities, Monash University, Clayton, Australia
| | - Fanny M Elahh
- Memory and Aging Center, University of California, San Francisco
| | - Alan Evans
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada
| | | | - Giovanni B Frisoni
- Memory Clinic and LANVIE - Laboratory of Neuroimaging of Aging, University Hospitals and University of Geneva, Geneva, Switzerland; Laboratory of Alzheimer's Neuroimaging and Epidemiology, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Bahar Güntekin
- Department of Biophysics, School of Medicine, Istanbul Medipol University, Istanbul, Turkey; REMER, Clinical Electrophysiology, Neuroimaging and Neuromodulation Lab, Istanbul Medipol University, Istanbul, Turkey
| | - Atticus Hainsworth
- University of London St George's Molecular and Clinical Sciences Research Institute, London, UK
| | - Harald Hampel
- Sorbonne University, GRC No. 21, Alzheimer Precision Medicine, Pitié-Salpêtrière Hospital, Paris, France
| | - Vesna Jelic
- Division of Clinical Geriatrics, NVS Department, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Jaeseung Jeong
- Department of Bio and Brain Engineering/Program of Brain and Cognitive Engineering Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Doh Kwan Kim
- Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, South Korea
| | - Milica Kramberger
- Center for cognitive and movement disorders, Department of neurology, University Medical Center Ljubljana, Slovenia
| | - Sanjeev Kumar
- Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | | | - Flavio Nobili
- Clinica neurologica, IRCCS Ospedale Policlinico San Martino, Genova, Italy; Dipartimento di Neuroscienze, Oftalmologia, Genetica, Riabilitazione e Scienze Materno-infantili (DiNOGMI)
| | | | - Aina Puce
- Department of Psychological and Brain Sciences at Indiana University in Bloomington, Indiana, USA
| | - Petra Ritter
- Brain Simulation Section, Department of Neurology, Charité Universitätsmedizin and Berlin Institute of Health, Berlin, Germany; Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Dirk J A Smit
- Department of Psychiatry Academisch Medisch Centrum Universiteit van Amsterdam, Amsterdam, the Netherlands
| | - Andrea Soricelli
- IRCCS SDN, Naples, Italy; Department of Motor Sciences and Healthiness, University of Naples Parthenope, Naples, Italy
| | - Stefan Teipel
- Department of Psychosomatic Medicine, University of Rostock, Rostock, Germany; German Center for Neurodegenerative Diseases (DZNE) - Rostock/Greifswald, Rostock, Germany
| | - Federico Tucci
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy
| | - Perminder Sachdev
- Centre for Healthy Brain Ageing (CHeBA), School of Psychiatry, University of New South Wales; Neuropsychiatric Institute, The Prince of Wales Hospital, Sydney, Australia
| | | | - Pedro Valdes-Sosa
- Cuban Neuroscience Center, Havana, Cuba; Key Laboratory for Neuroinformation, University of Electronic Science and Technology of China, Chengdu, China
| | - Andrea Vergallo
- Sorbonne University, GRC No. 21, Alzheimer Precision Medicine, Pitié-Salpêtrière Hospital, Paris, France
| | - Görsev Yener
- Izmir Biomedicine and Genome Center. Dokuz Eylul University Health Campus, Izmir, Turkey
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Adair D, Truong D, Esmaeilpour Z, Gebodh N, Borges H, Ho L, Bremner JD, Badran BW, Napadow V, Clark VP, Bikson M. Electrical stimulation of cranial nerves in cognition and disease. Brain Stimul 2020; 13:717-750. [PMID: 32289703 PMCID: PMC7196013 DOI: 10.1016/j.brs.2020.02.019] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 02/13/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023] Open
Abstract
The cranial nerves are the pathways through which environmental information (sensation) is directly communicated to the brain, leading to perception, and giving rise to higher cognition. Because cranial nerves determine and modulate brain function, invasive and non-invasive cranial nerve electrical stimulation methods have applications in the clinical, behavioral, and cognitive domains. Among other neuromodulation approaches such as peripheral, transcranial and deep brain stimulation, cranial nerve stimulation is unique in allowing axon pathway-specific engagement of brain circuits, including thalamo-cortical networks. In this review we amalgamate relevant knowledge of 1) cranial nerve anatomy and biophysics; 2) evidence of the modulatory effects of cranial nerves on cognition; 3) clinical and behavioral outcomes of cranial nerve stimulation; and 4) biomarkers of nerve target engagement including physiology, electroencephalography, neuroimaging, and behavioral metrics. Existing non-invasive stimulation methods cannot feasibly activate the axons of only individual cranial nerves. Even with invasive stimulation methods, selective targeting of one nerve fiber type requires nuance since each nerve is composed of functionally distinct axon-types that differentially branch and can anastomose onto other nerves. None-the-less, precisely controlling stimulation parameters can aid in affecting distinct sets of axons, thus supporting specific actions on cognition and behavior. To this end, a rubric for reproducible dose-response stimulation parameters is defined here. Given that afferent cranial nerve axons project directly to the brain, targeting structures (e.g. thalamus, cortex) that are critical nodes in higher order brain networks, potent effects on cognition are plausible. We propose an intervention design framework based on driving cranial nerve pathways in targeted brain circuits, which are in turn linked to specific higher cognitive processes. State-of-the-art current flow models that are used to explain and design cranial-nerve-activating stimulation technology require multi-scale detail that includes: gross anatomy; skull foramina and superficial tissue layers; and precise nerve morphology. Detailed simulations also predict that some non-invasive electrical or magnetic stimulation approaches that do not intend to modulate cranial nerves per se, such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), may also modulate activity of specific cranial nerves. Much prior cranial nerve stimulation work was conceptually limited to the production of sensory perception, with individual titration of intensity based on the level of perception and tolerability. However, disregarding sensory emulation allows consideration of temporal stimulation patterns (axon recruitment) that modulate the tone of cortical networks independent of sensory cortices, without necessarily titrating perception. For example, leveraging the role of the thalamus as a gatekeeper for information to the cerebral cortex, preventing or enhancing the passage of specific information depending on the behavioral state. We show that properly parameterized computational models at multiple scales are needed to rationally optimize neuromodulation that target sets of cranial nerves, determining which and how specific brain circuitries are modulated, which can in turn influence cognition in a designed manner.
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Affiliation(s)
- Devin Adair
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Dennis Truong
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Zeinab Esmaeilpour
- Department of Biomedical Engineering, City College of New York, New York, NY, USA.
| | - Nigel Gebodh
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Helen Borges
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Libby Ho
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - J Douglas Bremner
- Department of Psychiatry & Behavioral Sciences and Radiology, Emory University School of Medicine, Atlanta, GA, USA; Atlanta VA Medical Center, Decatur, GA, USA
| | - Bashar W Badran
- Department of Psychiatry & Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Vitaly Napadow
- Martinos Center for Biomedical Imaging, Department of Radiology, MGH, Harvard medical school, Boston, MA, USA
| | - Vincent P Clark
- Psychology Clinical Neuroscience Center, Dept. Psychology, MSC03-2220, University of New Mexico, Albuquerque, NM, 87131, USA; Department of Psychology, University of New Mexico, Albuquerque, NM, 87131, USA; The Mind Research Network of the Lovelace Biomedical Research Institute, 1101 Yale Blvd. NE, Albuquerque, NM, 87106, USA
| | - Marom Bikson
- Department of Biomedical Engineering, City College of New York, New York, NY, USA.
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Burger AM, D'Agostini M, Verkuil B, Van Diest I. Moving beyond belief: A narrative review of potential biomarkers for transcutaneous vagus nerve stimulation. Psychophysiology 2020; 57:e13571. [PMID: 32202671 DOI: 10.1111/psyp.13571] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/15/2020] [Accepted: 02/01/2020] [Indexed: 12/25/2022]
Abstract
Transcutaneous vagus nerve stimulation (tVNS) is a non-invasive neurostimulation technique that is currently being tested as a potential treatment for a myriad of neurological and psychiatric disorders. However, the working mechanisms underlying tVNS are poorly understood and it remains unclear whether stimulation activates the vagus nerve for every participant. Finding a biological marker of tVNS is imperative, as it can help guide research on clinical applications and can inform researchers on optimal stimulation sites and parameters to further optimize treatment efficacy. In this narrative review, we discuss five potential biomarkers for tVNS and review currently available evidence for these markers for both invasive and tVNS. While some of these biomarkers hold promise from a theoretical perspective, none of the potential biomarkers provide clear and definitive indications that tVNS increases the vagal activity or augments activity in the locus coeruleus-noradrenaline network. We conclude the review by providing several recommendations for how to tackle the challenges and opportunities when researching potential biomarkers for the effects of tVNS.
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Affiliation(s)
- Andreas Michael Burger
- Health Psychology Research Group, Faculty of Psychology and Educational Sciences, University of Leuven, Leuven, Belgium.,Biological Psychology Research Group, Faculty of Psychology and Educational Sciences, University of Leuven, Leuven, Belgium
| | - Martina D'Agostini
- Health Psychology Research Group, Faculty of Psychology and Educational Sciences, University of Leuven, Leuven, Belgium
| | - Bart Verkuil
- Department of Clinical Psychology, Leiden University, Leiden, the Netherlands
| | - Ilse Van Diest
- Health Psychology Research Group, Faculty of Psychology and Educational Sciences, University of Leuven, Leuven, Belgium
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Polak T, Herrmann MJ, Müller LD, Zeller JBM, Katzorke A, Fischer M, Spielmann F, Weinmann E, Hommers L, Lauer M, Fallgatter AJ, Deckert J. Near-infrared spectroscopy (NIRS) and vagus somatosensory evoked potentials (VSEP) in the early diagnosis of Alzheimer’s disease: rationale, design, methods, and first baseline data of the Vogel study. J Neural Transm (Vienna) 2017; 124:1473-1488. [DOI: 10.1007/s00702-017-1781-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 08/23/2017] [Indexed: 01/06/2023]
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Weise D, Adamidis M, Pizzolato F, Rumpf JJ, Fricke C, Classen J. Assessment of brainstem function with auricular branch of vagus nerve stimulation in Parkinson's disease. PLoS One 2015; 10:e0120786. [PMID: 25849807 PMCID: PMC4388709 DOI: 10.1371/journal.pone.0120786] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/27/2015] [Indexed: 12/04/2022] Open
Abstract
Background The efferent dorsal motor nucleus of the vagal nuclei complex may degenerate early in the course of Parkinson’s disease (PD), while efferent nucleus ambiguous, the principal source of parasympathetic vagal neurons innervating the heart, and afferent somatosensory nuclei remain intact. Objective To obtain neurophysiological evidence related to this pattern, we tested processing of afferent sensory information transmitted via the auricular branch of the vagus nerve (ABVN) which is known to be connected to autonomic regulation of cardiac rhythm. Methods In this cross-sectional observational study, we recorded (i) somatosensory evoked potentials (ABVN-SEP) and (ii) cutaneo-cardioautonomic response elicited by stimulation of the ABVN (modulation of heart-rate variability (HRV index; low frequency power, ln(LF), high frequency power, ln(HF); ln(LF/HF) ratio)) in 50 PD patients and 50 age and sex matched healthy controls. Additionally, auditory evoked potentials and trigeminal nerve SEP were assessed. Results Neither ABVN-SEP nor any of the other functional brainstem parameters differed between patients and controls. Although HRV index was decreased in PD patients, modulation of ln(LF/HF) by ABVN-stimulation, likely indicating cardiac parasympathetic activation, did not differ between both groups. Conclusions Findings do not point to prominent dysfunction of processing afferent information from ABVN and its connected parasympathetic cardiac pathway in PD. They are consistent with the known pattern of degeneration of the vagal nuclei complex of the brainstem.
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Affiliation(s)
- David Weise
- Department of Neurology, University of Leipzig, Leipzig, Germany
- * E-mail:
| | - Melanie Adamidis
- Department of Neurology, University of Leipzig, Leipzig, Germany
| | - Fabio Pizzolato
- Department of Neurology, University of Leipzig, Leipzig, Germany
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, University of Verona, Verona, Italy
| | | | | | - Joseph Classen
- Department of Neurology, University of Leipzig, Leipzig, Germany
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The relation of SMI and the VSEP in a risk sample for neurodegenerative disorders. J Neural Transm (Vienna) 2014; 122:1167-74. [DOI: 10.1007/s00702-014-1351-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 12/06/2014] [Indexed: 10/24/2022]
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Influence of different stimulation parameters on the somatosensory evoked potentials of the nervus vagus--how varied stimulation parameters affect VSEP. J Clin Neurophysiol 2014; 31:143-8. [PMID: 24691232 DOI: 10.1097/wnp.0000000000000038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Vagus somatosensory evoked potentials are a method for assessing the function of the vagus nerve, which were shown to be altered in neurodegenerative diseases like Alzheimer's and Parkinson's disease. Various parameters of the stimulation such as the electrode position and the stimulus intensity have already been investigated. In this study, the focus is on the systematic examination of the other parameters of the stimulation of the vagus somatosensory evoked potentials: stimulus duration, interstimulus interval, and, again, the stimulation intensity. Thirty young and healthy subjects were examined using five different sets of stimulation parameters, and 24 were included in the further analysis. The results show that a reduction of the stimulus duration and a decrease in stimulus intensity have a significant effect on the amplitudes. A shortening of the interstimulus interval does not seem to have such an effect, but this stimulation is rated more painful and unpleasant than the standard stimulation. Overall, the standard stimulation used so far seems to be the most preferable condition.
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Sun ZY, Wang JH, Sun JL, Wang TJ, Li L, Dong YH, Wu J, Cui WZ, Wu YJ, Lu PY. Magnetoencephalography assessment of evoked magnetic fields and cognitive function in subcortical ischemic vascular dementia patients. Neurosci Lett 2013; 532:17-22. [DOI: 10.1016/j.neulet.2012.10.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 10/13/2012] [Accepted: 10/17/2012] [Indexed: 10/27/2022]
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Metzger FG, Polak T, Aghazadeh Y, Ehlis AC, Hagen K, Fallgatter AJ. Vagus somatosensory evoked potentials--a possibility for diagnostic improvement in patients with mild cognitive impairment? Dement Geriatr Cogn Disord 2012; 33:289-96. [PMID: 22759638 DOI: 10.1159/000339359] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/02/2012] [Indexed: 01/04/2023] Open
Abstract
OBJECTIVE Vagus somatosensory evoked potentials (VSEP) are far-field potentials probably generated in nuclei of then. vagus in the lower brainstem. They represent a putative, easily applicable method for discrimination between patients with Alzheimer's disease (AD), patients with mild cognitive impairment (MCI), and healthy controls (HC). METHODS Thirteen patients with AD, 12 with MCI, and 27 age- and gender-matched HC were investigated by stimulating the cutaneous branch of the n. vagus; 8, 6, and 20, respectively, were included in the main part of the analysis. RESULTS In fronto-central recordings (electrode positions Fz-F4) a grading from HC over MCI to AD could be found, with a significant linear trend over the three groups and significantly increased latencies of the cognitively impaired patients but no significant difference between MCI and AD. CONCLUSION The results indicate that the method of VSEP is able to discriminate between cognitively declined patients and HC, whereas no clear-cut differences were detected between MCI and AD.
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Affiliation(s)
- Florian G Metzger
- Psychophysiology and Optical Imaging, Department of Psychiatry and Psychotherapy, University Hospital Tuebingen, Tuebingen, Germany.
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Auricular transcutaneous electrical nerve stimulation in depressed patients: a randomized controlled pilot study. J Neural Transm (Vienna) 2012; 120:821-7. [PMID: 23117749 DOI: 10.1007/s00702-012-0908-6] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Accepted: 10/19/2012] [Indexed: 10/27/2022]
Abstract
Invasive vagus nerve stimulation has been demonstrated to be an effective treatment in major depressive episodes. Recently, a novel non-invasive method of stimulating the vagus nerve on the outer canal of the ear has been proposed. In healthy subjects, a prominent fMRI BOLD signal deactivation in the limbic system was found. The present pilot study investigates the effects of this novel technique of auricular transcutaneous electric nerve stimulation in depressed patients for the first time. A total of 37 patients suffering from major depression were included in two randomized sham controlled add-on studies. Patients were stimulated five times a week on a daily basis for the duration of 2 weeks. On days 0 and 14, the Hamilton Depression Rating Scale (HAMD) and the Beck Depression Inventory (BDI) were assessed. In contrast to sham-treated patients, electrically stimulated persons showed a significantly better outcome in the BDI. Mean decrease in the active treatment group was 12.6 (SD 6.0) points compared to 4.4 (SD 9.9) points in the sham group. HAMD score did not change significantly in the two groups. An antidepressant effect of a new transcutaneous auricular nerve stimulation technique has been shown for the first time in this controlled pilot study. Regarding the limitations of psychometric testing, the risk of unblinding for technical reasons, and the small sample size, further studies are necessary to confirm the present results and verify the practicability of tVNS in clinical fields.
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