Objective Background and aims. Patients with functional (psychogenic) neurological symptoms are commonly seen in neurological practice. Though emotional/psychological causes are often proposed to underlie their symptoms, patients characteristically deny such problems, even when objective evidence for (for example) anxiety or panic is present. Interception is the perception of sensations from inside the body and includes the perception of physical sensations related to internal organ function. Heartbeat perception is considered a standard method for the assessment of interceptive sensitivity and it could be considered as a measure of self-awareness of internal stimuli which may have relevance for determining emotional state. The aim of our study was to evaluate interceptive awareness in patients with functional (psychogenic) movement symptoms (FMS). In addition we assessed the sense of body ownership using the rubber hand illusion (RHI).
Method We included in the study 17 patients with FMS according to Fahn and Williams criteria. Eighteen healthy controls (HC), matched for age and gender served as a control group. Patients and HC were asked to complete the Toronto Alexithymia Scale (TAS-20) and the self-consciousness scale (self-objectification questionnaire), also we administered the Montgomery depression scale. Heart beat perception task: heart rate was recorded by means of a commercial heart rate monitor and subjects were asked to count their heart beats (only by concentration on their body and not by taking their pulse) during a signalled time interval. The reported number of beats was then compared to the actual number of beats. All subjects were tested before and after a stress-induction task. RHI: illusionary experience was measured by self-report and by proprioceptive alteration.
Results FMS patients showed a poorer interceptive sensitivity than HC in the pre stress condition (p=0.048), but no difference was seen between groups in the post stress condition. No significant differences were revealed between patients with FMS and HC in the RHI on both perceptual (i.e. proprioceptive drift) and subjective (i.e. self-report questionnaire) measures.
Conclusion Patients with FMS have poor interoceptive sensitivity. This could relate to impairments of assessment of emotional state in these patients.