Is Functional Neurological Symptom Disorder (FNSD) a (somatic) stress disorder with altered emotion processing? : An approach to an answer via different methods, disorders an over time

Abstract

Functional neurological symptoms (FNS) are neurological symptoms without sufficient medical/neurological explanation. They are common and severe but still little understood. Different factors are discussed to contribute to the origination and maintenance of FNSD: Traumatic experiences are frequently linked with FNSD, which is why the disorder is oftentimes perceived as a stress-related disorder. Alterations in emotion processing are consistently reported for patients with FNSD and targeted in treatment approaches. However, little is known on the variability of such alterations and possibly underlying alterations in neural networks. Somatic sensation is supposed to be altered in FNSD but objective measures in the assessement of such alterations are missing. The objective of the present thesis was to clarify the role of FNSD as a stress-related disorder and to evaluate somatic sensation (via a new method), emotion regulation and their variability (across time and therapy).Study 1: Patients with FNSD frequently report traumatic experiences and show symptoms similar to those of patients with posttraumatic stress disorder (PTSD). Study 1 evaluated the classification of FNSD as a trauma-related disorder by comparing dissociative symptoms, symptoms of posttraumatic stress, lifetime traumata, and affect regulation between patients diagnosed with dissociative disorder (characterized by negative functional neurological symptoms), patients diagnosed with PTSD and healthy comparison participants. FNSD patients with co-occuring PTSD differed from PTSD patients in the amount of reported psychoform dissociation. FNSD patients with co-occuring PTSD reported more emotional maltreatment than those without co-occuring PTSD. Results challenge the conceptualization of FNSD as trauma-related disorder but advocate the consideration of traumatic experiences as an intensifying factor in the generation and maintenance of the disorder.Study 2: The meaning of eventually altered somatic sensation in FNSD seems still unclear, which may be related to the challenging assessment of the concept. Study 2 aimed to contribute to the understanding of alterations in body sensation in patients with FNSD by comparing somatic sensation (defined by perception and discomfort threshold on transcutaneous electric nerve stimulation (TENS)) between patients with FNSD, major depressive disorder (MDD), posttraumatic stress disorder (PTSD) and healthy comparison subjects (HC). Somatic Sensation was measured at baseline as well as before and after an interview on traumatic life experiences, to examine the impact of acute stress. Results revealed similar somatic sensation at baseline across groups. FNSD patients showed higher thresholds for somatic perception post-interview compared to pre-interview. Somatic sensation could not be confirmed as specific feature in FNSD. Results encourage the application of TENS in further studies on somatic sensation in FNSD.Study 3: Altered emotion processing has been established as a prominent feature in FNSD and is targeted in many treatment approaches. Study 3 investigated cortical correlates (experimentally induced emotion regulation task under EEG - monitoring) and behavioural correlates (questionnaires on alexithymia and emotion regulation strategies) of emotion processing as well as symptom intensity and it`s variation in context of a standard treatment program in patients with FNSD. While patients reported an increase in use of cognitive reappraisal strategies of emotion across the assessed time interval, cortical correlates of emotion processing did not change, nor did symptom intensity. Results encourage the consideration of emotion processing in treatment of FNSD and further prolonged studies to determine the contribution of treatment-related changes of emotion regulation on FNS.