Functional somatic syndrome

FSS refers to disturbances in bodily functioning where aetiology is unknown,{{cite journal | doi=10.1038/s41598-020-66685-4 | title=Comorbidities of Patients with Functional Somatic Syndromes Before, During and After First Diagnosis: A Population-based Study using Bavarian Routine Data | date=2020 | journal=Scientific Reports | volume=10 | issue=1 | page=9810 | pmid=32555301 | pmc=7299983 | bibcode=2020NatSR..10.9810D | vauthors = Donnachie E, Schneider A, Enck P }} including that psychogenesis is not assumed.{{Cite journal|url=https://www.bmj.com/content/325/7358/265.full|title=Functional somatic symptoms and syndromes|first1=Richard|last1=Mayou|first2=Andrew|last2=Farmer|date=August 3, 2002|journal=BMJ|volume=325|issue=7358|pages=265–268|via=www.bmj.com|doi=10.1136/bmj.325.7358.265|pmid=12153926|pmc=1123778 }}

"Medically unexplained physical symptoms" include FSS situations, but also situations where the symptoms are sporadic and where psychogenesis may be suspected.{{Cite web|url=https://www.nhs.uk/conditions/medically-unexplained-symptoms/|title=Medically unexplained symptoms|date=October 19, 2017|website=nhs.uk}}

"Persistent physical symptoms"{{Cite journal|url=https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(24)00623-8/fulltext|title=Persistent physical symptoms: definition, genesis, and management|first1=Bernd|last1=Löwe|first2=Anne|last2=Toussaint|first3=Judith G. M.|last3=Rosmalen|first4=Wei-Lieh|last4=Huang|first5=Christopher|last5=Burton|first6=Angelika|last6=Weigel|first7=James L.|last7=Levenson|first8=Peter|last8=Henningsen|date=June 15, 2024|journal=The Lancet|volume=403|issue=10444|pages=2649–2662|via=www.thelancet.com|doi=10.1016/S0140-6736(24)00623-8|pmid=38879263}} 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.

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{{cite journal | vauthors = Fink P, Schröder A | title = One single diagnosis, bodily distress syndrome, succeeded to capture 10 diagnostic categories of functional somatic syndromes and somatoform disorders | journal = Journal of Psychosomatic Research | volume = 68 | issue = 5 | pages = 415–426 | date = May 2010 | pmid = 20403500 | doi = 10.1016/j.jpsychores.2010.02.004 }}{{cite journal | vauthors = Lacourt T, Houtveen J, van Doornen L | title = "Functional somatic syndromes, one or many?" An answer by cluster analysis | journal = Journal of Psychosomatic Research | volume = 74 | issue = 1 | pages = 6–11 | date = January 2013 | pmid = 23272982 | doi = 10.1016/j.jpsychores.2012.09.013 | doi-access = free }} or into one general functional somatic disorder given the finding of correlations between symptoms and underlying etiologies.{{cite journal | vauthors = Wessely S, White PD | title = There is only one functional somatic syndrome | journal = The British Journal of Psychiatry | volume = 185 | issue = 2 | pages = 95–96 | date = August 2004 | pmid = 15286058 | doi = 10.1192/bjp.185.2.95 | doi-access = free }}{{cite journal | vauthors = Teodoro T, Oliveira R | title = The conceptual field of medically unexplained symptoms and persistent somatic symptoms | journal = CNS Spectrums | volume = 28 | issue = 5 | pages = 526–527 | date = October 2023 | pmid = 36321347 | doi = 10.1017/S1092852922001031 | s2cid = 253256995 | hdl = 10362/147363 | hdl-access = free }}

A large (n = 43,676) 2020 study found that 5 years prior to diagnosis, FSS patients consulted more frequently for a range of psychological and somatic conditions than did controls. Around half this cohort were ME/CFS patients (normally not termed an FSS).{{Cite journal|title=Comorbidities of Patients with Functional Somatic Syndromes Before, During and After First Diagnosis: A Population-based Study using Bavarian Routine Data|first1=Ewan|last1=Donnachie|first2=Antonius|last2=Schneider|first3=Paul|last3=Enck|date=June 17, 2020|journal=Scientific Reports|volume=10|issue=1|pages=9810|doi=10.1038/s41598-020-66685-4|pmid=32555301 |pmc=7299983 |bibcode=2020NatSR..10.9810D }}

FSS disorders include

• fibromyalgia (FM),
• temporomandibular disorder,
• irritable bowel syndrome,{{cite journal | vauthors = Afari N, Ahumada SM, Wright LJ, Mostoufi S, Golnari G, Reis V, Cuneo JG | title = Psychological trauma and functional somatic syndromes: a systematic review and meta-analysis | journal = Psychosomatic Medicine | volume = 76 | issue = 1 | pages = 2–11 | date = January 2014 | pmid = 24336429 | pmc = 3894419 | doi = 10.1097/PSY.0000000000000010 }}
• Electromagnetic hypersensitivity
• lower back pain,
• tension headache,
• atypical face pain,
• non-cardiac chest pain,
• insomnia,
• palpitation,
• dyspepsia,
• dizziness.{{cite journal | vauthors = Mayou R, Farmer A | title = ABC of psychological medicine: Functional somatic symptoms and syndromes | journal = BMJ | volume = 325 | issue = 7358 | pages = 265–268 | date = August 2002 | pmid = 12153926 | pmc = 1123778 | doi = 10.1136/bmj.325.7358.265 }}
• certain claims of food allergies (when no true allergy can be demonstrated)
• Gulf War syndrome
• certain claims of hypoglycaemia (symptoms appearing when the blood sugar is normal)
• Chronic Lyme disease
• Multiple chemical sensitivity{{Citation |title=2.2 The Putative Disappearance of Somatic Manifestations of Hysteria |date=2022-12-31 |work=From Photography to fMRI |pages=219–237 |publisher=transcript Verlag |doi=10.1515/9783839461761-009 |isbn=978-3-8394-6176-1 |quote=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.|doi-access=free }}
• Sick building syndrome
• Chronic whiplash

A large overlap of symptoms exist between the FSS diagnoses, causing high rates of comorbidity between them; the prevalence of comorbid FSS diagnoses ranges from 20% to 70%, while comorbid affective disorders with a fibromyalgia diagnosis ranges from 20% to 80%.{{cite journal | vauthors = Häuser W, Kosseva M, Üceyler N, Klose P, Sommer C | title = Emotional, physical, and sexual abuse in fibromyalgia syndrome: a systematic review with meta-analysis | journal = Arthritis Care & Research | volume = 63 | issue = 6 | pages = 808–820 | date = June 2011 | pmid = 20722042 | doi = 10.1002/acr.20328 | doi-access = free }}

Studies have found prevalence in the general population of having at least one FSS of 16.3% (n = 9656),{{Cite journal|url=https://pubmed.ncbi.nlm.nih.gov/31409218|title=Prevalence of functional somatic syndromes and bodily distress syndrome in the Danish population: the DanFunD study|first1=Marie Weinreich|last1=Petersen|first2=Andreas|last2=Schröder|first3=Torben|last3=Jørgensen|first4=Eva|last4=Ørnbøl|first5=Thomas Meinertz|last5=Dantoft|first6=Marie|last6=Eliasen|first7=Tina Wisbech|last7=Carstensen|first8=Lene|last8=Falgaard Eplov|first9=Per|last9=Fink|date=July 1, 2020|journal=Scandinavian Journal of Public Health|volume=48|issue=5|pages=567–576|via=PubMed|doi=10.1177/1403494819868592|pmid=31409218}} and 9.3% (n = 3054).{{Cite journal|url=https://pubmed.ncbi.nlm.nih.gov/23055025|title=Prevalence, overlap, and predictors of functional somatic syndromes in a student sample|first1=Susanne|last1=Fischer|first2=Jens|last2=Gaab|first3=Ulrike|last3=Ehlert|first4=Urs M.|last4=Nater|date=June 1, 2013|journal=International Journal of Behavioral Medicine|volume=20|issue=2|pages=184–193|via=PubMed|doi=10.1007/s12529-012-9266-x|pmid=23055025}}

Some 10% of the general population, and around 33% of adult patients in clinical populations, suffer from functional somatic symptoms.{{Cite journal|title=Functional Somatic Symptoms|first1=Casper|last1=Roenneberg|first2=Heribert|last2=Sattel|first3=Rainer|last3=Schaefert|first4=Peter|last4=Henningsen|first5=Constanze|last5=Hausteiner-Wiehle|date=Aug 9, 2019|journal=Deutsches Ärzteblatt International|volume=116|issue=33–34|pages=553–560|doi=10.3238/arztebl.2019.0553|pmid=31554544|pmc=6794707}}

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.{{cite journal | vauthors = Åkerblom S, Perrin S, Rivano Fischer M, McCracken LM | title = The Impact of PTSD on Functioning in Patients Seeking Treatment for Chronic Pain and Validation of the Posttraumatic Diagnostic Scale | journal = International Journal of Behavioral Medicine | volume = 24 | issue = 2 | pages = 249–259 | date = April 2017 | pmid = 28194719 | pmc = 5344943 | doi = 10.1007/s12529-017-9641-8 | doi-access = free }}

Patients with somatic syndromes such as fibromyalgia and irritable bowel syndrome have significantly higher rates of both physical and sexual abuse prior to the onset of their physiological symptoms, as well as higher rates of previous emotional abuse, emotional neglect, and physical neglect compared to the general population.{{cite journal | vauthors = Yavne Y, Amital D, Watad A, Tiosano S, Amital H | title = A systematic review of precipitating physical and psychological traumatic events in the development of fibromyalgia | journal = Seminars in Arthritis and Rheumatism | volume = 48 | issue = 1 | pages = 121–133 | date = August 2018 | pmid = 29428291 | doi = 10.1016/j.semarthrit.2017.12.011 | s2cid = 205143853 }} Further, childhood trauma such as sexual abuse or maltreatment can indicate an increased propensity for later somatic syndrome onset.

"Attentional bias" has been posited as the psychological mechanism by which trauma and somatic symptoms are tied.{{cite journal | vauthors = Golding JM | title = Sexual assault history and physical health in randomly selected Los Angeles women | journal = Health Psychology | volume = 13 | issue = 2 | pages = 130–138 | date = March 1994 | pmid = 8020456 | doi = 10.1037/0278-6133.13.2.130 }}{{Cite journal| vauthors = Carleton RN, Duranceau S, McMillan KA, Asmundson GJ |date=April 2018|title=Trauma, Pain, and Psychological Distress|journal=Journal of Psychophysiology|volume=32|issue=2|pages=75–84|doi=10.1027/0269-8803/a000184|s2cid=151333609 |issn=0269-8803}} The concept of attentional bias refers to the idea that traumatic events can cause individuals to become more attuned to their bodies, thus intensifying the perception of pain, fatigue, and other common somatic symptoms. 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 a "health anxiety," where the patient becomes increasingly concerned that common somatic symptoms are related to a physical disease or injury, and therefore, another potential bodily threat. An initial perception of lost control can further lead to this 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.{{Cite book| vauthors = Pennebaker JW |date=1982|title=The Psychology of Physical Symptoms|doi=10.1007/978-1-4613-8196-9|isbn=978-1-4613-8198-3}} 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, certain physiological symptoms, such as heart palpitations, dizziness, and breathlessness.{{Cite journal| vauthors = Antony MM, Brown TA, Craske MG, Barlow DH, Mitchell WB, Meadows EA |date=September 1995|title=Accuracy of heartbeat perception in panic disorder, social phobia, and nonanxious subjects|journal=Journal of Anxiety Disorders|volume=9|issue=5|pages=355–371|doi=10.1016/0887-6185(95)00017-i|issn=0887-6185}}

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.{{cite book | vauthors = Bryant RA |chapter=Psychological Interventions for Trauma Exposure and PTSD|date=2011-07-15|pages=171–202|publisher=John Wiley & Sons, Ltd |isbn=9781119998471 |doi=10.1002/9781119998471.ch5 |title=Post-Traumatic Stress Disorder }} When an individual experiences a traumatic event, the HPA-axis causes the increased release of cortisol, activating the sympathetic nervous pathway and causing negative feedback to be sent to the hypothalamus and pituitary gland. In people who have experienced significant trauma, this reaction can become dysfunctional and can cause a chronic decrease in cortisol production, though the rates of this decrease in cortisol levels varies across different types and frequencies of trauma.{{cite journal | vauthors = Weber DA, Reynolds CR | title = Clinical perspectives on neurobiological effects of psychological trauma | journal = Neuropsychology Review | volume = 14 | issue = 2 | pages = 115–129 | date = June 2004 | pmid = 15264712 | doi = 10.1023/b:nerv.0000028082.13778.14 | s2cid = 24172922 }}

Diagnosis of a FSS is usually a diagnosis of exclusion, where physicians rule out other disorders that could explain the dysfunctions being experienced.{{Cite journal|title=Functional somatic syndromes: asking about exclusionary medical conditions results in decreased prevalence and overlap rates|first1=Susanne|last1=Fischer|first2=Urs M.|last2=Nater|date=October 4, 2014|journal=BMC Public Health|volume=14|pages=1034|doi=10.1186/1471-2458-14-1034|doi-access=free |pmid=25280494|pmc=4286915}}

CBT can be helpful for FSS. Medications such as antidepressants may play a role.{{Cite web|url=https://my.clevelandclinic.org/health/diseases/17976-somatic-symptom-disorder-in-adults#management-and-treatment|title=Somatic Symptom Disorder: What It Is, Symptoms & Treatment|website=Cleveland Clinic}}{{Cite web|url=https://www.mayoclinic.org/diseases-conditions/somatic-symptom-disorder/diagnosis-treatment/drc-20377781|title=Somatic symptom disorder - Diagnosis and treatment - Mayo Clinic|website=www.mayoclinic.org}}

The term functional somatic syndrome was used in a 1999 paper.{{Cite journal|url=https://pubmed.ncbi.nlm.nih.gov/10375340|title=Functional somatic syndromes|first1=A. J.|last1=Barsky|first2=J. F.|last2=Borus|date=June 1, 1999|journal=Annals of Internal Medicine|volume=130|issue=11|pages=910–921|via=PubMed|doi=10.7326/0003-4819-130-11-199906010-00016|pmid=10375340}}

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Category:Rheumatology