SENSORY CHARACTERIZATION OF SOMATIC PARIETAL TISSUES IN HUMANS WITH CHRONIC FATIGUE SYNDROME

Patients with chronic fatigue syndrome (CFS) mainly complain of sympto ms in the musculoskeletal domain (myalgias, fatigue). In 21 CFS patien ts the deep (muscle) versus superficial (skin, subcutis) sensitivity t o pain was explored by measuring pain thresholds to electrical stimula tion unilaterally in the deltoid, trapezius and quadriceps and overlyi ng skin and subcutis in comparison with normal subjects. Thresholds in patients were normal in skin and subcutis but significantly lower tha n normal (hyperalgesia) in muscles (P < 0.001) in all sites. The selec tive muscle hypersensitivity corresponded also to fiber abnormalities at muscle biopsy (quadriceps) performed in nine patients which were ab sent in normal subjects (four cases): morphostructural alterations of the sarchomere, fatty degeneration and fibrous regeneration, inversion of the cytochrome oxidase/succinate dehydrogenase ratio, pleio/polymo rphism and monstruosity of mitochondria, reduction of some mitochondri al enzymatic activities and increments of common deletion of 4977 bp o f mitochondrial DNA 150-3000 times the normal values. By showing both sensory (diffuse hyperalgesia) and anatomical (degenerative picture) c hanges at muscle level, the results suggest a role played by periphera l mechanisms in the genesis of CFS symptoms. They would exclude the he ightened perception of physiological signals from all districts hypoth esized by some authors, especially as the hyperalgesia is absent in sk in/subcutis.