Covid-19 is not just a respiratory disease. The early cases of the non respiratory symptomps have made the society in doubt about the existence of SARS-CoV-2, virus that caused the Covid-19, and the unawareness has brought a bigger number in positive cases and thus the fatalities.
Covid extrapulmonary symptomps varies from gastrointestinal, cardiac, renal to neurological and etc. Covid neuroinvasion symptomps are various and when we look at the brain autopsies we can see the virus has the ability to pass the Blood Brain Barrier (BBB). Hyperinflammations and olfactory nerve pathways are two most mentioned as the cause of Covid neuroinvasion. This article background was from a review by Mukerji et al. including 24 peer-reviewed studies of autopsy findings published in English between January 1, 2020, and November 5, 2020. These papers presented autopsies of Covid postmortem patients' brains.
Eight papers stated that the autopsied brains had SARS-CoV-2 protein or viral RNA. The results of qRT-PCR tests were positives some for : E genes, N genes, Orf 1/a, Orf 1ab, S genes, RdRp. They were located in frontal lobe and/or medulla, olfactory nerve and brain tissue, olfactory bulb, optic nerve, nasal epithelium, cerebellar clot, and cerebellum.
The eleven papers found neither viral protein nor viral RNA in the brain. The evaluations were hemorrhage, herniation, petechial bleedings, hypoxic alterations, lymphocytic meningitis and encephalitis, brainstem neuronal cell loss in, axon degeneration, gliosis, neuronal loss, prominent leukocytic infiltrates in olfactory epithelium, mild brain swelling and hemorrhagic white matter lesions, ADEM (Acute disseminated encephalomyelitis)-like lesions, microinfarcts (can take longer to affect neuronal death progress, at up to 28 days, rathe than hours), damaged axons, etc.
Brain herniation occurs when something inside the skull produces pressure that moves brain tissues. Brain hemorrhages, stroke, bacterial or fungal infections are few of the factors that cause brain herniation. Petechial bleedings (capillaries break open) in brain usually is because of hemorrhage in the brain.
Solomon et al. found that Hypoxic-ischemic injury—caused by oxygen deprivation to the brain—is similar injury to patients with long intensive care unit (ICU) admissions and those who died shortly after presentation. This raises questions about the potential for brain damage caused by mild or even asymptomatic cases of Covid. Hypoxia may also induce acute ischemic stroke in patients with a particular risk of developing the cerebrovascular disease. Severe hypoxia injury may result in subsequent nervous system damage.
Covid patients diagnosed with meningitis/encephalitis had diverse clinical neurological manifestations, including consciousness disturbance, epileptic attacks, psychotic syndrome and meningeal irritation signs. CSF (Cerebrospinal fluid) tests revealed elevated protein, lymphocytes and cytokines. In a Japanese patient (24 years old, man), specific SARS-CoV-2 RNA was not detected in the nasopharyngeal swab but was detected in a CSF. This shows that Covid has the potential to damage the nervous system.
Gliosis is a process leading to scars in the central nervous system that involves the production of a dense fibrous network of neuroglia in areas of damage. Gliosis is a prominent feature of many diseases of the central nervous system, including multiple sclerosis and stroke. After a stroke, neurons die and disappear with replacement gliosis.
In the brain, the ACE2 (a cardio-cerebral vascular protection factor receptors, favored by Spike of SARS-CoV-2) have been detected in the glial cells and neurons. The Spike proteins binding to the ACE2 receptors can lead to high blood pressure and cerebral hemorrhage. SARS-CoV-2 Spike proteins can interact with ACE2 expressed in the capillary endothelium, the virus may also enter the CNS (Central Nervous System) through attacking the vascular system and damaging the BBB (Baig et al., 2020).
While composing this article, picturing the patients’ last moments and their loneliness, I have to say that Covid is indeed a heart tearing apart disease. The pains and the broken minds they endured especially in neuroinvasion symptomps, will not be understood by people who have never experienced or see it by themselves.
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