Investigating the Neurophysiology of the Motor System and the Feasibility of Vagus Nerve Stimulation in Functional Neurological Disorder (FND)

NCT07710677 | Not Yet Recruiting DMC

• 1 other identifier: 2026-D0047
• Study Type: interventional
• Target: 68
• Locations: 1 country
• Sites: 1

Brief Summary

This clinical study will test if adding a non-invasive stimulation of the vagus nerve through the ear during physiotherapy brings an improvement to FND (Functional Neurological Disorder) patients with motor symptoms. First, the investigators will test the normal functioning of the motor regions of the brain in FND patients and in healthy volunteers for comparison, using a painless method called TMS (Transcranial Magnetic Stimulation). Then, the investigators will further test how brain regions communicate with each other in FND patients, using fMRI (functional Magnetic Resonance Imaging, also painless). Additionally, the investigators will ask both FND patients and healthy volunteers to answer questions about their health and wellbeing, and will assess the exact symptoms of FND patients. The FND patients will then be assigned to two groups randomly, and neither they nor the researchers will know in which group they are. Both groups will do 5 sessions of their usual physiotherapy - one group with a real stimulation of the vagus nerve, and the other group with a fake stimulation. This is important to obtain reliable results. At the end, both groups of patients will be tested again to see if the way brain regions communicate with each other has changed. They will also answer again questions about their health and wellbeing, and their symptoms will be assessed again, to see if any changes happen. The results of the two groups of patients will be compared to isolate the effects of vagus nerve stimulation from the effects of physiotherapy alone.

Conditions

Functional Neurological Disorder; Motor Symptoms

Keywords

Functional Neurological Disorder; FND; vagus nerve stimulation; VNS; TMS; fMRI; motor

Outcome Measures

Primary Outcomes (1)

• Self-reported quality of life

  The change in self-reported quality of life, measured through intervention sessions with the Euro Quality of Life questionnaire (EQ-5D-5L), compared between the active stimulation group and the sham stimulation group. This questionnaire includes 5 subscales (1-best, 5-worstest) about mobility, self-care, usual activities, pain/discomfort, anxiety/depression. In addition it includes a continue scale evaluation (0-worst to 100-best) about the patient evaluation on his health.

  For each intervention session at weeks 3, 4, 5, 6, 7

Secondary Outcomes (16)

• Neurophysiology investigation of the pathology by comparing Motor-Evoked Potential between FND patients and healthy participant

  At TMS session, week 2 for patients and week 0 for heathy controls

• Neurophysiology investigation of the pathology by comparing resting motor threshold between FND patients and healthy participant

  At TMS session, week 2 for patients and week 0 for heathy controls

• Comparison of motor performance between patients and healthy controls

  At TMS session, week 2 for patients and week 0 for heathy controls

• Satisfaction rating of patients on the intervention

  At the end of the last intervention session at week 7

• Changes in upper limb strength, measured by a grip strength test under different starting conditions, before, during and after taVNS intervention.

  weeks 2, 3, 4, 5, 6, 7

Study Arms (3)

Patient VNS stimulation intervention

EXPERIMENTAL

FND patients received a 30 minutes VNS stimulation for 5 sessions during their usual physiotherapy course treatment.

Device: Vagial Nerve Stimulation (VNS) active stimulation

Patient VNS sham intervention

SHAM COMPARATOR

FND patients received a 30 minutes VNS sham for 5 sessions during their usual physiotherapy course treatment.

Device: Vagial Nerve Stimulation (VNS) sham stimulation

Heathy control without intervention

NO INTERVENTION

Heathy control without intervention

Interventions

Vagial Nerve Stimulation (VNS) active stimulation DEVICE

taVNS sends gentle electric stimuli to the vagus nerve branch located in the outer ear, which are transmitted to the nucleus of the solitary tract in the brainstem, and from there to the rest of the brain. The electrode site is the cymba conchae in in the outer ear. VNS thus acts to enhance the activity of the parasympathetic nervous system.

Also known as: taVNS, tVNS, active

Patient VNS stimulation intervention

Vagial Nerve Stimulation (VNS) sham stimulation DEVICE

taVNS sends gentle electric stimuli for several minutes, during which time the patient will feel a tickling sensation. Then, for the rest of the session, the hidden device will be switched off (there will be no stimulation).

Also known as: taVNS, tVNS, sham

Patient VNS sham intervention

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Over 18 years of age.
• Capable of judgement.
• Willing to participate in the study (by signing the informed consent form).
• FND diagnosis by a certified neurologist or psychiatrist.
• Motor FND symptoms in the upper limb in the form of tremor or weakness.
• Participating in physiotherapy for FND.

You may not qualify if:

• Severe neuropsychiatric comorbidities.
• Pregnancy or breastfeeding.
• Prior knowledge on the effects of attention on the motor system.
• Prior history of epilepsy or epileptic seizures in the person and their family.
• Severe claustrophobia.
• Implanted medical devices.
• Ear anatomy incompatible with the taVNS device (e.g. cauliflower ear).
• Previous use of taVNS.
• Substance abuse.
• Simultaneous participation in another investigation involving an investigational drug or a MD.
• Enrolment of the PI and their dependent persons.
• Over 18 years of age.
• Capable of judgement.
• Willing to participate in the study (by signing the informed consent form).
• Neurological or neuropsychiatric or movement disorders.

Sponsors & Collaborators

• University of Fribourg: lead
• Hôpital Cantonal de Fribourg: collaborator

Study Sites (1)

University of Fribourg

Fribourg, Canton of Fribourg, 1700, Switzerland

Location

MeSH Terms

Conditions

Conversion Disorder

Condition Hierarchy (Ancestors)

Somatoform Disorders; Mental Disorders

Study Officials

• Cristina Concetti, PhD

  University of Fribourg

  STUDY DIRECTOR

Central Study Contacts

Selma Aybek, Professor

CONTACT

+41 26 306 38 02; selma.aybek@unifr.ch

Michael Mouthon, PhD

CONTACT

+41 26 300 85 39; michael.mouthon@unifr.ch

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, CARE PROVIDER
• Masking Details: In addition, half of the investigator will be blind of the intervention groups.
• Purpose: SUPPORTIVE CARE
• Intervention Model: FACTORIAL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Patients will be assigned either to intervention or placebo for the VNS part. The healthy control will not participate to the VNS intervension but to the other part of the study (MRI, TMS).

Study Record Dates

• First Submitted: June 24, 2026
• First Posted: July 17, 2026
• Study Start: July 1, 2026
• Primary Completion (Estimated): July 1, 2028
• Study Completion (Estimated): December 1, 2028
• Last Updated: July 17, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will share
• Shared Documents: ANALYTIC CODE
• Time Frame: The public repositories would be made available to the public after the publication date of the relevant scientific article.

Locations

CH (1)