Functional somatic syndrome (FSS) (sometimes termed "non-specific physical disorders"[1]) is a term used for a group of conditions in which chronic symptoms occur with no identifiable organic cause. Fibromyalgia is the leading FSS condition, among many. ME/CFS has been regarded by some as an FSS condition.[2][3][4][5][6] FSS conditions are highly prevalent, but little is known about their etiology.
Biological markers for the FSS diagnoses are non-existent, making the categorization difficult.[citation needed] Diagnosis is by exclusion.[citation needed]
Definition and Terminology
FSS refers to disturbances in bodily functioning where aetiology is unknown.[7] The term ‘functional somatic disorders’ (FSD) was proposed in 2020.[8]
"Persistent physical symptoms"[10] includes FSS situations but also situations where persistent physical symptoms are caused by a known illness, such as arthritis.
In "somatic symptom disorder" chronic physical symptoms, which may or may not be linked to a known illness, coincide with excessive and maladaptive thoughts, emotions, and behaviors connected to those symptoms. In FSS these features are not present.
Classification
This term does not appear in the ICD-11. Proposals for classifications have been made.[11]
Signs and symptoms
Functional somatic syndromes are characterized by ambiguous, non-specific symptoms that appear in otherwise-healthy people. Overlap in symptomology exists across diagnoses, including gastrointestinal issues, pain, fatigue, cognitive difficulties, and sleep difficulties. Some have proposed to group symptoms into clusters[12][13] or into one general functional somatic disorder given the finding of correlations between symptoms and underlying etiologies.[14][15]
A considerable overlap of symptoms exists between the FSS diagnoses, with high rates of comorbidity between them. For example, the prevalence of comorbid FSS diagnoses ranges from 20% to 70%, while comorbid affective disorders with a fibromyalgia diagnosis ranges from 20% to 80%.[19]
Prevalence
Studies have found prevalence in the general population of having at least one FSS of 16.3% (n = 9656),[20] and 9.3% (n = 3054).[21]
Some 10% of the general population, and around 33% of adult patients in clinical populations, suffer from functional somatic symptoms.[22]
Comorbidity
PTSD
Rates of PTSD are roughly 9.5–43.5% higher in people seeking treatment for a functional somatic syndrome as opposed to the general population.[23][unreliable medical source?]
Potential causes
A mixture of physical and psychological factors may predict FSS.[1][24]
Psychological factors
Low-quality evidence suggests that patients with somatic syndromes, such as fibromyalgia and irritable bowel syndrome, tend to have a more frequent history of both physical and sexual abuse prior to the onset of their physiological symptoms. Additionally, patients show higher rates of previous emotional abuse, emotional neglect, and physical neglect when compared to the general population.[25]
Attentional bias has been posited as the psychological mechanism by which trauma and somatic symptoms are tied.[26][27][unreliable medical source?] Attentional bias refers to the idea that traumatic events can cause individuals to become more attuned to their bodily functions, thus intensifying the perception of pain, fatigue, and other common somatic symptoms.[27][unreliable medical source?] The initial traumatic event is interpreted as a threat to the body, and therefore the stress response of the body takes on a new, heightened awareness to any potential subsequent threats. This attentional bias leads to health anxiety, wherein the patient becomes increasingly concerned that common somatic symptoms are related to a physical disease or injury, and therefore, another potential bodily threat.[26][unreliable medical source?] An initial perception of lost control can further intensify attentional bias; sense of control is negatively associated with symptom reporting, suggesting that somatic symptoms are more closely monitored when psychologically recovering from an incident of lost control.[28][unreliable medical source?] Functional somatic syndromes are thought to be a result of conditioned hyperarousal following a trauma; victims are conditioned to respond more sensitively to the somatic symptoms following a trauma by their attention to and reinforcement of the symptom existence. This feedback loop is similar to that of panic disorder, in which fear of a subsequent panic attack causes an increased hyper-vigilance towards, and exacerbation of, physiological symptoms, such as heart palpitations, dizziness, and breathlessness.[29][unreliable medical source?]
Biological factors
One hypothesis implicates the hypothalamic–pituitary–adrenal axis (HPA axis) in the manifestation of somatic symptoms following trauma. The HPA axis plays a major role in moderating the body's stress response to both emotional and physical pain, relating to both the experience of psychological symptoms prevalent following trauma as well as the physiological symptoms prevalent in FSS conditions.[30] When an individual experiences a traumatic event, the HPA axis causes the increased release of cortisol, activating the sympathetic nervous system and causing negative feedback to be sent to the hypothalamus and pituitary gland. In people who have experienced major trauma, this reaction can become dysfunctional and can cause a chronic decrease in cortisol production, though the rates of this decrease in cortisol levels vary across different types and frequencies of trauma.[31]
Diagnosis
Diagnosis of a FSS is usually a diagnosis of exclusion, where physicians rule out other disorders that could explain the dysfunctions being experienced.[32]
Management and Treatment
CBT can be helpful for FSS. Medications such as antidepressants may play a role.[33][34] More direct medication has little if any positive long-term impact.[1]
According to guidance from the German Federal Ministry of Health "the extent to which functional somatic syndromes affect people’s lives partly depends on how the people affected deal with them."[1]
History
The term functional somatic syndrome was used in a 1999 paper.[35]
1 2 3 4 5 6 7 8 9 "2.2 The Putative Disappearance of Somatic Manifestations of Hysteria", From Photography to fMRI, transcript Verlag, pp.219–237, 2022-12-31, doi:10.1515/9783839461761-009, ISBN978-3-8394-6176-1, In the late 1990s, it became a matter of heated debate if hysteria's nosological successors were conceptually and diagnostically distinguishable from a range of possibly related clinical conditions that were equally characterised by the lack of any demonstrable physical abnormality. Jointly referred to as functional somatic syndromes, these conditions include multiple chemical sensitivity, sick building syndrome, chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome, chronic whiplash, chronic Lyme disease, the Gulf War syndrome, food allergies, hypoglycaemia. To this date, the delineation between present-day forms of hysteria and other functional somatic syndromes remains unresolved.
↑ Petersen MW, Schröder A, Jørgensen T, Ørnbøl E, Dantoft TM, Eliasen M, etal. (July 1, 2020). "Prevalence of functional somatic syndromes and bodily distress syndrome in the Danish population: the DanFunD study". Scandinavian Journal of Public Health. 48 (5): 567–576. doi:10.1177/1403494819868592. PMID31409218.
↑ Fischer S, Gaab J, Ehlert U, Nater UM (June 1, 2013). "Prevalence, overlap, and predictors of functional somatic syndromes in a student sample". International Journal of Behavioral Medicine. 20 (2): 184–193. doi:10.1007/s12529-012-9266-x. PMID23055025.
↑ Yavne Y, Amital D, Watad A, Tiosano S, Amital H (August 2018). "A systematic review of precipitating physical and psychological traumatic events in the development of fibromyalgia". Seminars in Arthritis and Rheumatism. 48 (1): 121–133. doi:10.1016/j.semarthrit.2017.12.011. PMID29428291. S2CID205143853.
1 2 Golding JM (March 1994). "Sexual assault history and physical health in randomly selected Los Angeles women". Health Psychology. 13 (2): 130–138. doi:10.1037/0278-6133.13.2.130. PMID8020456.
↑ Antony MM, Brown TA, Craske MG, Barlow DH, Mitchell WB, Meadows EA (September 1995). "Accuracy of heartbeat perception in panic disorder, social phobia, and nonanxious subjects". Journal of Anxiety Disorders. 9 (5): 355–371. doi:10.1016/0887-6185(95)00017-i. ISSN0887-6185.
↑ Bryant RA (2011-07-15). "Psychological Interventions for Trauma Exposure and PTSD". Post-Traumatic Stress Disorder. John Wiley & Sons, Ltd. pp.171–202. doi:10.1002/9781119998471.ch5. ISBN9781119998471.
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