More recently in LC, we have biopsies also taken at rest. Myopathy as a cause of fatigue in long-term post-COVID-19 symptoms: Evidence of skeletal muscle histopathology (2022, European Journal of Neurology). They also used biceps rather than the usual vastus lateralis —
Post-COVID exercise intolerance is associated with capillary alterations and immune dysregulations in skeletal muscles (2023, Acta Neuropathologica Communications) —
No specific mention of necrosis (+ or -) that I could see.
All biopsies displayed some types of change. None of the biopsies showed necrotic fibers, but degenerative changes were common. In six, we found atrophic fibers seen as small fibers with fragmented fibrils, and excess of basal lamina material. Immunohistochemistry showed three with type 2 atrophy, one with predominantly type 1, and two with mixed type atrophy.
Post-COVID exercise intolerance is associated with capillary alterations and immune dysregulations in skeletal muscles (2023, Acta Neuropathologica Communications) —
Routine histopathological examination revealed a selective atrophy of type-2b muscle fibers of differing extent in 72% (n = 8/11) of individuals with PCS and – by definition of our inclusion criteria – in none (n = 0/8) of the HDC cohort and in all (n = 8/8) of the 2BA cohort.
While patients with PCS did not show overt signs of myositis, increased numbers of CD169+ macrophages were evident. The capillary-to-fiber ratio was decreased and ultrastructural analysis revealed a capillary basement membrane enlargement.
No specific mention of necrosis (+ or -) that I could see.