[Chronic pain syndrome in musculoskeletal diseases-how different are fibromyalgia and long Covid?-Part 1].

Chronic pain is a common problem in rheumatology. Nociceptive pain is distinguished from neuropathic and nociplastic pain. Mechanistically, the former is explained by persistent inflammation, for example. Included in the second category is nerve damage of various causes. In contrast, nociplastic pain is not caused by tissue damage or a lesion in the somatosensory nerve system. It is caused by an altered sensation of pain through the modulation of stimulus processing. The concept of central sensitization, together with further neurobiological and psychosocial mechanisms, best explains such pain conditions. Fibromyalgia (FM) plays a big part in rheumatology - on the one hand, as a differential diagnosis, and on the other, because the management of inflammatory rheumatic conditions is made more difficult by the simultaneous occurrence of FM. In the context of the coronavirus pandemic, persistent pain syndromes with similarities to FM have been described after COVID-19 infection. There is an increasing scientific controversy whether the so-called long Covid syndrome is an actual entity or "only" a variant of FM. This discussion and the current state of knowledge on the problem are the subject of this review.