Functional somatic syndrome

Functional somatic syndrome (FSS) (sometimes termed "non-specific physical disorders") refers to a cluster of chronic conditions, characterized by persistent physical symptoms without demonstrable structural or organic disease despite extensive medical testing. Contemporary theories describe the aetiology as involving a dysregulation in the brain-body signaling, which includes negative emotional states pathologically activating somatosensory and nociceptive circuits, generating genuine physical sensations through central sensitization, maladaptive stress response systems and learned neuroplastic rewiring, with symptoms resulting from complex interactions between the autonomic nervous system, hypothalamo-pituitary axis and possibly the immune system, rather than from peripheral tissue damage.

Source: Wikipedia — Functional somatic syndrome (CC BY-SA 4.0)