Zdenek Vrozina Profile picture
Oct 7 12 tweets 2 min read Read on X
Your nerves remember COVID.
A new study shows the virus can leave a measurable scar in your muscles - electrical, structural, and lasting for over a year.🧵
Researchers followed 70 people - after mild and severe COVID - for 12 months.
They focused on two key lower-leg muscles-
tibialis anterior (lifts the foot)
gastrocnemius lateralis (part of the calf).
Using electrodiagnostics, they measured chronaxie - the time it takes for a nerve to trigger a muscle contraction.
Higher values = impaired nerve–muscle communication (neuromuscular electrophysiological disorder, NED).
Results.
Among severe COVID cases,
55% had NED in the tibialis anterior shortly after infection,
33% after 3 months,
16% still after a year.
Mild cases and controls - almost none.
Ultrasound revealed persistent structural changes - muscles appeared brighter (higher echogenicity), meaning fatty/fibrotic infiltration and loss of healthy tissue, especially in tibialis anterior.
The link was clear.
Higher echogenicity - longer chronaxie.
In other words, the more structurally damaged the muscle, the slower it responds to electrical stimulation.
This isn’t fatigue.
It’s measurable bioelectrical and structural dysfunction of the nerve–muscle unit - resembling the polyneuromyopathy seen in ICU survivors, but here, persisting long after COVID.
Clinically, this can mean gait instability, weakness, even foot drop.
Rehabilitation should be targeted - focusing on specific affected muscles and timing of recovery phases.
Sum:
Severe COVID leaves measurable, long-lasting changes in peripheral nerve and muscle function.
Not post-viral fatigue - but true neuromuscular dysfunction.
Recently, another study (Ribeiro et al., Annals of Neurology, 2025) used microneurography - directly recording activity from individual nerve fibers.
In 89% of Long COVID patients, they found objective abnormalities in unmyelinated C fibers - spontaneous firing, sensitization, and impaired sympathetic recovery.
Together, these findings show that Long COVID doesn’t just damage muscles - it disrupts the small sensory and autonomic fibers that connect nerves, vessels, and immunity.
A pattern strikingly similar to HIV neuropathy, only accelerated - unfolding over weeks instead of years.
Almeida et al., Scientific Reports (2025). Persistent neuromuscular disorders associated with changes in tibialis anterior and gastrocnemius lateralis muscle architecture in long-covid: an observational longitudinal study. nature.com/articles/s4159…

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More from @ZdenekVrozina

Oct 9
7-12% of patients recovering from moderate to severe COVID-19 show persistently low counts of B cells, CD4 T cells, and Tregs, even after clinical recovery.🧵
This sustained adaptive immune deficit may represent a important mechanism underlying Long COVID, resembling immunological patterns seen in chronic infections such as HIV and EBV.
The authors highlight a possible link with low serotonin levels, which support B and T cell proliferation - a hypothesis drawn from the work of Wong et al., 2023.
Read 14 tweets
Oct 9
Yes, we wrote about this study. It is important.
A study from Cambridge in Brain shows that even months after COVID-19, survivors still carry measurable inflammation-related changes in the brainstem - the part of the brain that keeps you breathing, awake, and alive🧵
Using ultra–high-field 7 Tesla MRI, researchers found abnormal magnetic signals (quantitative susceptibility mapping, QSM) in key brainstem areas.
medulla oblongata
pons
especially in the raphe nuclei and reticular formation - core hubs for breathing and autonomic control.
What does that mean?
Higher magnetic susceptibility usually reflects iron accumulation, microglial activation, or loss of myelin - all signs of neuroinflammation.
These changes weren’t random - they tracked with how severe the original infection was.
Read 19 tweets
Oct 7
SARS-CoV-2 can create an oncogenic-like cellular environment - switching off tumor suppressors, activating growth pathways, reshaping epigenetic control, and fueling inflammatory metabolism.
If these effects persist, the virus could act as a cofactor in carcinogenesis🧵
The authors don’t claim SARS-CoV-2 causes cancer like HPV or EBV.
They show that the virus interferes with the same cellular checkpoints and signaling pathways commonly disrupted in tumors.
It’s about strong oncogenic potential, not direct oncogenicity.
In normal cells infected with SARS-CoV-2, scientists observed changes resembling those seen in cancer cells.
Loss of tumor suppressors (p53, pRB), activation of growth and survival cascades (PI3K/AKT, MAPK), and disruption of epigenetic balance.
Read 14 tweets
Oct 5
COVID was never just a respiratory virus - it’s a systemic one.
A pathogen that rewires immunity, disrupts mitochondria, and infiltrates the nervous system -
sharing striking parallels with HIV.
Here’s part of what we already know🧵
Different viruses, same strategy -
silence interferon
erase MHC-I visibility
crash mitochondria
hijack calcium signaling
The goal? Evade, persist, and reshape the host from within.
SARS2 ORF8 removes MHC-I = CD8 T cells can’t see infected cells.
HIV Nef does the same by rerouting MHC-I for degradation.
Both viruses hide in plain sight
= immune invisibility as a survival tool.
Read 25 tweets
Oct 1
COVID and brain fog.
For millions, it’s the most disabling legacy of the pandemic.
Now, a new brain imaging study reveals a clear biological basis - and the parallels with other diseases are not encouraging.🧵
Researchers used PET scans with a tracer ([11C]K-2) that binds to AMPA receptors - the tiny gates that neurons use to fire signals via glutamate, the brain’s main excitatory messenger.
These receptors are crucial for learning, memory, and attention.
In people with cognitive long COVID, AMPA receptors weren’t just slightly higher in one region.
They were globally increased across the entire brain!
It’s like the brain’s excitatory volume knob was turned way up everywhere.
Read 17 tweets
Oct 1
This is the strongest evidence yet that ignoring the chronic impacts of COVID in children carries population-level consequences.
A massive Lancet Infect Dis study of >465,000 kids shows:
Reinfections double the risk of long COVID.🧵
After the first infection: about 903 cases of long COVID per million children (within 6 months).
After the second infection: ~1884 cases per million.
That’s more than double the risk (RR = 2.08).
And it’s not just fatigue. Reinfection raised risks across many systems-
myocarditis (RR 3.6),
arrhythmias,
blood clots
kidney injury,
electrolyte issues,
liver enzyme spikes
brain fog, headaches, POTS
anxiety, depression, exhaustion
Read 13 tweets

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