SONY MORENO
Madrid
Updated Friday, 21 January 2022-14:26
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Coronavirus The rate of deaths from Covid is up to 48 times lower with the third dose than without a vaccine
Since the SARS-CoV-2 coronavirus burst into our lives, it was clearly seen that this respiratory virus was behind a
wide variety of neurological symptoms
. For many,
anosmia
was the first warning sign of infection, although with the
omicron
variant it seems that it is no longer one of the common initial manifestations. Among the
neurological complications described
in the acute phase of covid are
confusion
(what has been called "mental fog"),
strokes
and
neuromuscular disorders
; but also
sequels
such as concentration problems, headaches, sensory disturbances, depression and even psychosis can persist for months after infection, sometimes as part of a persistent covid picture.
This is how a review in
Science
that is published on the impact of the coronavirus on the central nervous system
presents it
.
In this scientific article,
Serena Spudich
, a neurologist and specialist in Infectious Diseases at Yale University, and
Avindra Nath
, a neurologist at the US National Institute of Neurological Diseases and Stroke, break down what is known about the
pathophysiological mechanisms
that cause these complications and what Possible
consequences
arrive
after the initial infection
, aspects that still pose gaps and on which doctors and scientists remain vigilant.
This is how the virus damages the brain
Despite initial speculation that SARS-CoV-2 could enter the central nervous system through the nasal cavity and the olfactory pathway, even circulating across the blood-brain barrier,
analysis of cerebrospinal fluid
from patients with clinical manifestations Neuropsychiatric studies have not detected viral RNA, nor have many cells infected by the virus been seen in the
brain tissue of autopsies
of deaths from covid-19. In contrast,
infiltration
of macrophages, CD8+ T lymphocytes in perivascular regions, and generalized microglial activation in the brain
have been observed in these studies .
Therefore, the authors infer that "the
main drivers
of
neurological disease
in acute covid they are
immune activation
and
inflammation
in the central nervous system."
The central nervous system is not 'your playground'
When (albeit few) infected cells are detected in the brain, studies indicate that they "lack surrounding clusters of inflammatory cells, suggesting that the
presence
of
SARS-CoV-2
in the central nervous system (CNS) does not cause
encephalitis.
" classic virus.
The president of the Spanish Society of Neurology, José Miguel Láinez, abounds in this, stating that "
it is not a neurotropic virus
, there is little direct involvement of the brain. In the acute phase, brain disorders are a secondary consequence of
hypoxia
,
toxicity
,
neuroinflammation
and
vascular alteration
, but not by direct invasion of the virus.
Is there a 'covid stroke'?
"Acute COVID-19 is associated with an
increased
risk of stroke
compared
with
influenza -like illness of
similar
severity
, even after correcting for stroke risk factors. Overt cerebrovascular events during the acute phase of COVID-19 19 often occur in people with
vulnerability
to vascular disease (such as older age and heart disease)," the authors write in
Science
.
"Increases in blood markers of vascular inflammation, as well as thrombosis and infarction in other tissues can also be found in patients with covid-19 and stroke, suggesting that the
endothelial inflammation
and
coagulopathy
contribute to these events". Professor Láinez also comments that "directly there is no stroke caused by covid, but
indirectly
covid can act on the
endothelium
in the vessel walls and generate a prothrombotic state, factors that may
contribute to precipitating
stroke. Stroke has been seen in a young person in which the trigger factor was probably covid."
Spudich and Nath go a step further and state that "it is plausible that
subtle forms of generalized vascular dysfunction
, including thrombotic microangiopathy (microscopic blood clots) in the brain, may cause neurological symptoms even in the absence of clinically apparent stroke."
Persistent Covid, also in young people and after mild infection
"Among the neurological and psychiatric disorders that persist in some patients after acute covid infection, alterations in memory, concentration and the ability to perform daily tasks, frequent headaches, alterations in skin sensitivity, autonomic dysfunction, intractable fatigue, and, in severe cases, delusions and paranoia Many people who experience neurological symptoms that persist after acute covid-19 are
under 50 years of age and
were healthy and active before infection
In particular, most she was never hospitalized during her acute phase of covid-19, reflecting mild initial illness," the American neurologists note in this review.
At the last congress of the SEN, the series on persistent covid presented draw a promising perspective, adds Láinez.
"On the one hand,
no structural lesions are seen
in the imaging tests, which in principle is usually a symptom of a good prognosis. In addition, in most patients, the
evolution
is towards
improvement
. There are even cases in which that improvement occurs after vaccination, which is a very positive fact. In principle, it seems that most of these cases are not going to present major problems. However, we remain
vigilant
and attentive to the fact that in certain patients with some
special genetic
susceptibility
this improvement does not occur, but they would be exceptional cases".
The 'dejà vu' of chronic fatigue
Many of the symptoms experienced by people with persistent covid or
long covid
"are similar to those of
myalgic encephalomyelitis
/
chronic fatigue syndrome
(MME/CFS)", another syndrome that has been linked to various infectious agents, they expose in this review .
Since this condition is also little known and without curative treatment, the authors trust that the study of persistent covid will also benefit these patients.
However, they have an arduous task ahead of them because, as they also recognize "the
heterogeneity
of the
symptoms
that affect people with
long covid
and the
difficulties
in
determining
which symptoms may be a
consequence of SARS-CoV-2 infection
versus
aggravation of pre-existing
or coincident conditions pose enormous challenges for mechanistic understanding and treatment approaches."
Watch out for Alzheimer's and Parkinson's disease
As is obvious in a disease that emerged two years ago, the
full extent
of its
long-term
complications is not known.
Without leaving the field of neurological disease, the authors of the review speculate on the possibility that neuroinflammation and neuronal injury in acute cases of covid trigger or accelerate
neurodegenerative diseases such
as Alzheimer's or Parkinson's.
A hypothesis against which the president of the SEN is cautious, because "there is no data to
speculate
in that negative sense; in my opinion, it is a somewhat alarmist vision."
Sick, not disease
As always in medicine, we must take into account factors contributed by each patient.
These researchers remind us that the
characteristics that explain the wide variability
in clinical
manifestations
, due to which some patients develop persistent post-infectious complications, have yet to be identified.
And of special importance, these neurologists also point out, is the need for "
intervention trials
based on these discoveries to determine approaches to reduce or reverse the effects of covid-19 on the nervous system."
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