Neurovegetative Decoupling in the Visceral-brain Axis and Cognitive-emotional Vulnerability in Somatoform Disorders : Interest of Vagal Biofeedback

Somatoform disorders [SD] are defined as physiological function or organ disturbances unexplained by a specific diagnosis criterion. Some approaches have recently defended the idea of common factors of vulnerability behind the large variability of the clinical symptoms regarding the SD. In this context, the lead of the neurovegetative disturbances started receiving attention following some studies that suggested the autonomic nervous system [ANS] disturbances concerning a somatoform disorder, independently of its form. Two different neurovegetative endophenotypes (individual autonomic profiles) were highlighted: a functional neurovegetative profile (high vagal tone) and a dysfunctional neurovegetative profile (low vagal tone).

A dysfunctional neurovegetative profile could be accompanied by a chronic decoupling in the brain-visceral axis according as the ANS is considered as a bidirectional communication system linked the central nervous system [CNS] and the viscera. Depending on the types of the neurovegetative profiles, different degrees of cognitive-emotional vulnerability and a higher or a lower level of acceptance of the illness could be supposed. Finally, recent findings defend the idea of the traumatic experiences as a determining factor to develop a SD.

In accordance to the last notions regarding the SD, some therapeutic approaches could be interesting specifically techniques focusing on the vagal nerve. In this context, biofeedback [BFB] could provide a powerful method to restore the clinical and physiological impairments.

As a consequence, the main objective is to evaluate the physiological and clinical effects of the BFB training with patients suffering from SD: Irritable Bowel Syndrome [IBS] or Psychogenic Non Epileptic Seizure [PNES]. The investigators make the prediction that the patients will be more or less responding to the biofeedback depending on their neurovegetative profile. A clustering will be performed in advance to identify the patients having a dysfunctional neurovegetative profile and patients having a functional neurovegetative profile. It will also permit to the investigators to confirm the hypothesis about the existence of two neurovegetative profiles related to a visceral-brain decoupling concerning the SD, independently of its form. To attest to it, 2 types of somatoform disorders will be analyzed: the irritable bowel syndrome manifesting by peripheral symptoms and the psychogenic non-epileptic seizures manifesting by central symptoms. Then the investigators will carry out a psycho-social exploration to demonstrate a higher cognitive-emotional vulnerability and a higher traumatic event incidence in this particular population, depending on their autonomic profiles.