Functional somatic pain syndromes: summary of hypotheses of their overlap and etiology

Abstract

Currently it is unclear whether functional somatic syndromes can be explained by one common underlying functional syndrome. In any case it does not seem justified to view functional somatic syndromes as purely psychological disorders (somatized anxiety or depression). Psychiatric comorbidity and life time stress including traumatisations are mainly, but not exclusively responsible for triggering health care utilisation. The lowered pain threshold that can be demonstrated clinically and experimentally in fibromyalgia, irritable bowel syndrome, tension headache and temporomandibular disorders is currently seen primarily as result of an altered central nervous processing of nociceptive input. In addition some results also hint at a disturbance in the hypothalamus-pituitary-adrenal axis. The predominance of female patients can be due to gender specific illness behaviour as well as to estrogen-induced changes in pain sensitivity. In sum, functional somatic syndromes currently are best explained by a biopsychosocial model of predisposing, triggering and maintaining factors. More research is needed particularly to clarify the role of genetic and of cultural factors.