How is Coronavirus Getting Into the Brain?

by Marco Cáceres

Published August 16, 2020 | Opinion

Recently, studies have been published suggesting a link between the SARS-CoV-2 virus, brain inflammation and neurological dysfunction. One study involving 60 patients who recovered from COVID-19, for example, found that 55 percent of them displayed “structural changes” in the brain that manifested with loss of memory and smell for three months. The study, published in The Lancet on Aug. 3, 2020, found evidence that the SARS-CoV virus had invaded the olfactory epithelium—tissue within the human nasal cavity that play a role in the ability to smell.^{1 2}
The encyclopedia Britannica describes the olfactory epithelium as containing “olfactory receptor
cells, which have specialized cilia extensions.” It explains that the “cilia trap odor molecules as they pass across the epithelial surface” and that [i]nformation about the molecules is then transmitted from the receptors to the olfactory bulb in the brain.”³

Studies Link SARS-CoV-2 to Changes in Brain

According to the results of The Lancet study, “significant enlarged volumes [of the SARS-CoV-2 virus] were observed in the bilateral olfactory cortices, hippocampi, insulas, left Heschl’s gyrus, left Rolandic operculum and right cingulate gyrus”—”structures” that make up the “central olfactory system.” However, the study was unable to ascertain how the virus managed to infect the olfactory epithelium.¹ The study noted:

Several possible invasion routes of SARS-CoV-2 were raised including hematogenous, lymphatic and neuro retrograde routes, etc., yet the exact route was unknown.¹

In another study published in the journal Brain on July 8, 2020, researchers at University College London (UCL) examined 43 cases of COVID-19 in which the patients suffered from a high incidence of “acute disseminated encephalomyelitis”—severe brain inflammation. This resulted in “temporary brain dysfunction, strokes, nerve damage or other serious brain effects.” Nine of the patients were diagnosed with a rare condition known as acute disseminated encephalomyelitis (ADEM).^{4 5}
Dr. Michael Zandi, a consulting neurologist at UCL’s National Hospital for Neurology and Neurosurgery, said:

We’re seeing things in the way COVID-19 affects the brain that we haven’t seen before with other viruses. What we’ve seen with some of these ADEMm patients, and in other patients, is you can have severe neurology, you can be quite sick, but actually have trivial lung disease.^{6 7}

In a report published in The New England Journal of Medicine on Apr. 15, 2020, a team of physicians said they observed 58 hospitalized COVID-19 patients in Strasbourg, France and found that 84 percent of them had neurological symptoms, including “encephalopathy, prominent agitation and confusion, and corticospinal tract signs” and also “acute ischemic strokes.”^{8 9}
Among all these studies, none has pinpointed just how the SARS-CoV-2 virus may have entered the brain. One possible route, though, could be the olfactory nerve in the nose, which is considered to be the first cranial nerve or C1. It is one of 12 cranial nerves in the head. The C1 leads into the olfactory epithelium and itsolfactory receptors are located in the mucosa of the nasal cavity—essentially your nose.^{3 8}

Olfactory Nerve: Nose a ‘Shortcut” for Viruses Entering the Brain

In January 2015, a study titled “The olfactory nerve: a shortcut for influenza and other viral diseases into the central nervous system” was published in the journal Pathology.⁹ That study found that…

Viral infection of the [central nervous system] can lead to damage from infection of nerve cells per se, from the immune response, or from a combination of both. Clinical consequences range from nervous dysfunction in the absence of histopathological changes to severe meningoencephalitis and neurodegenerative disease.⁹

The study listed viruses that can use the olfactory nerve as a “shortcut” into the brain. Viruses that enter the body through the nose include influenza A virus, herpesviruses, poliovirus, paramyxoviruses (like RSV, measles, mumps), vesicular stomatitis virus, rabies virus, parainfluenza virus, adenoviruses, Japanese encephalitis virus, West Nile virus, chikungunya virus, La Crosse virus, mouse hepatitis virus and bunyaviruses.⁹
The 2015 Pathology study obviously made no mention of SARS-CoV-2 since that virus was not known then. But if all those other viruses can enter the brain via the nose and olfactory nerve, then might it not be possible for SARS-CoV-2 as well?
Neurosurgeon Russell Blaylock, MD referenced the olfactory nerve as a route into the brain in a recent article in Technology News & Trends. Citing a 1989 study the journal Virology titled “Spread of a neurotropic murine coronavirus into the [central nervous system] via the trigeminal and olfactory nerves,”^{10 11} Dr. Blaylock wrote:

In most instances it enters the brain by way of the olfactory nerves (smell nerves), which connect directly with the area of the brain dealing with recent memory and memory consolidation. By wearing a mask, the exhaled viruses will not be able to escape and will concentrate in the nasal passages, enter the olfactory nerves and travel into the brain.¹⁰

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References:

  acute disseminated encephalomyelitis, ADEM, Brain, brain inflammation, Britannica, COVID-19, encephalopathy, Marco Cáceres, masks, National Hospital for Neurology and Neurosurgery, National Vaccine Information Center, NVIC, olfactory epithelium, olfactory nerve, Pathology, Russell Blaylock, SARS-CoV-2, Technology News & Trends, The Lancet, The New England Journal of Medicine, The Vaccine Reaction, University College London, Virology