Somatic symptoms of medically unknown origin are highly prevalent in the community and clinical settings.  Functional somatic syndrome (FSS) refers to several related syndromes that are characterized more by symptoms, suffering, and disability than by demonstrable abnormalities.  Two aspects should be considered in the underlying pathophysiology of FSS: dysregulation of the stress response in autonomic nervous systems and psychological factors that modulate the expression of symptoms.

 Psychophysiological Stress Profiling (PSP) is a method of estimating the response to a stress by measuring multiple physiological parameters and psychological indices.
Physiological indices were hypo-reactive to mental work stress and psychological tension was high in the FSS compared with controls.  These findings suggest FSS patients have hypo-functional stress responses, and couldn't cope with the stress properly.


<Physiological Measurements>
  The measurement of PSP was made using the ProComp Infinity™/ BioGraph Infinity (Thought Technology Ltd., Montreal) biofeedback system.  The following indices were measured (Table 2).

<Psychological Measurements>
  To evaluate the temporary mood states, the Profile of Mood States (POMS) test was administered. The POMS assesses six affective mood dimensions: tension-anxiety (TA), depression-dejection (D), anger-hostility (A), vigor-activity (V), fatigue-inertia (F), and confusion-bewilderment(C).

  The subjective symptom score (subjective severity of symptoms) and the subjective tension score (subjective feelings of tension) were also obtained using a visual analogue scale.

  After the psychological measurements were administered, the physiological measurements were made during the following three periods (5 minutes each, total of 15 minutes).  The subject was seated in a chair with eyes closed.

a) Baseline resting period: the subject was instructed to relax and make himself/ herself comfortable
b) Stress period (mental arithmetic task): the subject was instructed to subtract 7 serially from 1000.
c) Post stress period: the subject was instructed to relax.


  Somatic symptoms of medically unknown origin are highly prevalent in the community and clinical settings; not only the primary care setting but also the secondary care setting(1-3), and are clinically important(4).  Functional somatic syndrome (FSS) refers to several related syndromes that are characterized more by symptoms, suffering, and disability than by disease-specific, demonstrable abnormalities of structure or function(6). 

   FSSs include various diseases in many medical specialties such as irritable bowel syndrome, functional dyspepsia, fibromyalgia syndrome, and chronic fatigue syndrome.

  FSSs are expected to share a common underlying pathophysiology (6).  Among the regulating systems in human body, we have been focusing on autonomic nervous system (ANS) and its relationship to stress.  The following two aspects should be considered in the pathophysiology of FSS: a) dysregulation of the stress response in ANS and b) psychological factors that modulate the expression of symptoms.  These two aspects of pathophysiology interact with one another.

  The origin of functional somatic symptoms cannot be detected by regular medical examination, because the abnormalities don't accompany visual changes typically.  Moreover, functional somatic symptoms are involved in stress.  Considering these things and pathophysiology, we evaluated the response of ANS-related physiological parameters to stress.


  Psychophysiological stress profiling (PSP) is a method of estimating the response to a stress by simultaneously measuring multiple physiological parameters based on the concept of autonomic response specificity (7,8).  PSP also include psychological measurements as we consider both pathophysiology a) and b) above.

Summary of Results

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  Overall, physiological indices relevant to ANS were hypo-reactive to mental work stress and psychological tension indices were high in the FSS patients compared with healthy controls.  These findings suggest that FSS patients have hypo-functional stress responses, and could not cope with the stress properly, so felt higher subjective tension feelings.

  While these findings were results by averaging, the cluster analysis divided the FSS patients into two clusters by autonomic response to the stress: high-lability and low-lability group (the number of low-lability group was larger).  The mood scores were higher in the high-lability group than in the low-lability group.

  Moreover, heart rate variability, well known as an index of autonomic function, was reduced at the pre-stress resting period in FSS patients.  This finding suggests that both reduced autonomic lability in pre-stress period and attenuated autonomic response to stress exist, and both dysfunctions would interactively yield the maladaptive process.

  These tendencies were not depend upon diagnosis, suggesting the existence of common pathophysiology in FSS patients.

  Although FSS are common worldwide and in all areas of medicine, diagnostic and therapeutic approaches are still controversial and not confirmed.

  Several studies as to the concept and the structure of the syndrome have been performed using questionnaire or interview (9,13,14).  Wessely et al. reviewed literatures and concluded that the similarities between individual syndromes outweigh the differences (4).  A meta-analytic review confirmed that FSSs are related to anxiety and depression but relatively independent to them (10).  Henningsen et al. reviewed management of FSS on literatures and recommended that a balance between biomedical (somatic) and interpersonal (psychological) approaches is important (5).

  There have been several studies of the PSP on individual syndromes such as irritable bowel syndrome or fibromyalgia syndrome, but few studies on FSS as a whole.  The bias of disease is small in our series of studies, so the findings could suggest the pathology of whole FSS independent upon diagnostic category.

  The relationship between objective assessment and subjective symptoms or feelings is important in FSS.  But almost studies are based on either objective or subjective index.

  Both objective assessment, i.e. physiological measuring, and subjective feelings, i.e. subjective score or psychological questionnaire, were used in our studies.  Relationship between them was also estimated.

・While many problems are exist in FSS, which embarrasses medical stuff and come out economic loss, the pathology, assessment and managements isn't yet established.  Therefore the impact of our study would be large for widespread medical field universally.

・Population of functional somatic symptoms or peripheral symptoms, especially involved in psychosocial problems, are increasing more and more.  Traditional medical approaches have limitations for such diseases.  Management of FSS would be widely applied for such syndromes more in the future.

・Psychophysiological Stress Profiling have potential demand in not only FSS but also in various difficult-to-assess disorders such as psychosomatic disease, stress-related disorder, so-called autonomic nervous disorder, social anxiety disorder (excessive mental or physical tension), panic disorder, somatization disorder, etc.

・The relationship or dissociation between objective findings and subjective feelings are a essential theme, which has widely application possibility.


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