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

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

Interventions

DEVICE

Vagial Nerve Stimulation (VNS) active stimulation

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.

DEVICE

Vagial Nerve Stimulation (VNS) sham stimulation

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).

Sponsors & Collaborators

• Hôpital Cantonal de Fribourg

  collaborator OTHER_GOV

• University of Fribourg

  lead OTHER

Principal Investigators

• Cristina Concetti, PhD · University of Fribourg

Study Design

Allocation

RANDOMIZED

Purpose

SUPPORTIVE_CARE

Masking

DOUBLE

Model

FACTORIAL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2026-07-01

Primary Completion

2028-07-01

Completion

2028-12-01

Countries

• Switzerland

Study Locations