A couple of days ago, I was listening to a radio programme (“The Current” with host Matt Galloway, on CBC Radio One). The Sept. 7, 2020 episode was a national call-in show, “How concerned are you about schools reopening amid the COVID-19 pandemic?” As a senior, the topic interested me as I have several school-age grandchildren whose wellbeing (and that of their parents!) is dear to my heart.
As a physician, however, my ears perked up when a woman called in and expressed her fear that the nasal swab test for COVID-19 can "irritate the brain tissue". The medical expert for the show, an epidemiologist, responded that the swab does not touch the brainstem. Of course, that is correct, but it did not address the woman's concern.
It needs to be pointed out the the woman's fear is founded on reality. Let’s go through why.
First, anatomically, the olfactory bulb, a part of the brain, sends neuronal processes through the roof of the nasal cavity (the cribriform plate) into the olfactory epithelium. Thus, the tissue in the roof of the nasal cavity and partially extending down the sides, has actual brain tissue in it.
Second, it is an unfortunate fact that a lot of swab testing is performed by improperly trained (or just careless) personnel who insert the swab pointing up into the nasal cavity, thus hitting its roof and irritating the olfactory epithelium and the brain tissue it contains, just as the woman caller feared.
When the nasal swab test is done properly, the swab comes nowhere near the olfactory epithelium. The correct technique involves inserting the swab into the nose, pointing straight back when the head is erect, so that it moves along the floor of the nasal cavity, eventually contacting the back of the nasopharynx, where the swab should be rotated in order to pick up mucosal cells. Visually, the swab should be pointing towards the ear lobe. A video produced by the Nebraska Medical Center https://youtu.be/J7lLZEZ6u_w illustrates this well. Unfortunately, other videos from normally reputable sources demonstrate various ways of doing it wrong!
What might be the consequences of irritating the brain tissue in the olfactory epithelium? I doubt that this issue has been researched in the context of COVID-19, but we need to keep in mind that the COVID-19 virus may gain entry into the brain via the olfactory epithelium (early symptoms can include loss of smell), so if this tissue becomes irritated and inflamed after prodding by a test swab, could this increase the likelihood of becoming infected in someone who tests negative?
Until a reliable saliva test becomes widely available, I encourage anyone going for nasal swab testing to inquire about the technique being used by the test person, and confirm that they will direct the swab along the floor of the nasal cavity, not to its roof; that is, toward the ear lobe.
Dr. Henry Olders