What is the relationship between sensitization syndromes like fibromyalgia and chronic fatigue syndrome and persistent COVID or "Long COVID"?

The coronavirus disease 2019 (COVID-19) pandemic is resulting in a growing population of individuals recovering from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and accumulating observational data suggest that some of these patients may experience a wide range of symptoms after recovery from acute illness, referred to as "Long COVID" or "post-acute sequelae of SARS-CoV-2 infection". Some of these patients meet diagnostic criteria for fibromyalgia and/or chronic fatigue syndrome.

The relationship between sensitization syndromes like fibromyalgia and chronic fatigue syndrome and persistent COVID, commonly referred to as "Long COVID" or "post-acute sequelae of SARS-CoV-2 infection" could be partly related to the hypothesis of viral infections as one of the triggers of these diseases.

Over the years, considerable effort has been done into investigating possible causes of fibromyalgia and chronic fatigue syndrome, describing among the many possible precipitants viruses. Other causes that have been thoroughly studied are immune dysfunction, endocrine-metabolic dysfunction, and neuropsychiatric factors.

As we mentioned at the beginning, after the COVID-19 pandemic, patients have been seen developing post-coronavirus SARS-CoV-2 disease 2019 (COVID-19) conditions following acute infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), regardless of illness severity.

Such patients present with a broad range of symptoms (physical and mental) that develop during or after COVID-19, continue for ≥3 months following the onset of illness, and are not explained by an alternative diagnosis. Many of these meet criteria for fibromyalgia and chronic fatigue syndrome with SARS-CoV-2 being a possible viral trigger. There are probably also a number of other different mechanisms involved in the genesis of these clinical manifestations, including tissue damage from the infection as well as treatment, post-traumatic stress disorder, and post-intensive care unit syndrome.

Both fibromyalgia and chronic fatigue syndrome involve central sensitization, where the central nervous system becomes hypersensitive to stimuli.

Some individuals with persistent COVID (Long COVID) may have lingering viral particles, contributing to ongoing inflammation and la maladaptación/ dysregulation of the immune system may lead to prolonged inflammation and symptomatology.

Treatment involves a combination of medications, physical therapy, cognitive-behavioral therapy, and lifestyle modifications.

Psychological Support and Physical Therapy and Exercise address psychosocial aspects focus on improving mobility and function.

Analgesics, antidepressants, and anticonvulsants are used to manage symptoms.

The heterogeneous nature of persistent COVID (Long COVID)makes predicting outcomes challenging. Prognosis varies, with some experiencing improvement and others having a chronic course but identifying and managing triggers, including psychosocial stressors, can improve outcomes. Secondary anxiety and depression may be common in both conditions and are a diagnosis that is important to address in time.

Understanding the relationship between sensitization syndromes like fibromyalgia and chronic fatigue syndrome and persistent COVID (Long COVID) is a currently evolving research field.

The overlap in symptoms, potential synergies, and complex etiology underscore the need for a multidisciplinary approach in both diagnosis and management.