The pandemic of the coronavirus disease that began in 2019 (COVID 19) has posed a number of challenges for patients and for physicians. Its observed consequences are changing rapidly, and our understanding of the disease itself is evolving.
The Covid-19 pathogen (technically called "severe acute respiratory syndrome coronavirus type 2" or "SARS CoV 2") belongs to a family of coronaviruses, which are single-stranded RNA viruses contained in a lipid bilayer envelope from which there protrude spike glycoproteins that comprise the "hooks" that let the viruses gain entry into host cells, where they replicate and whence they propagate. These "hooks" attach particularly well to angiotensin-converting enzyme receptors (Ceccarelli, Berretta M Fau - Venanzi Rullo et al. 2020, Yan, Zhang et al. 2020) that are densely expressed in cells in the lungs, which is thought to be why some of the initial and most prominent symptoms of infection involve the respiratory tract, though unfortunately, the disease is not limited to the respiratory tract.
The mechanism by which coronaviruses enter the central nervous system (CNS), and the factors that make specific people vulnerable to this, are incompletely understood (Dales 1995, Dube, Le Coupanec et al. 2018), though recent evidence (Baig, Khaleeq et al. 2020) has demonstrated that there are cells within the CNS that express angiotensin converting enzyme receptors ? albeit at a lower density than in the lower respiratory tract. In any case, once the viruses have gained entry into the CNS, they appear capable of advancing by axonal transport (Dube, Le Coupanec et al. 2018).
Other members of the coronavirus family have long been known to invade the central nervous system, and have been found the brain/spinal cord tissue or the cerebrospinal fluid of patients suffering from a variety of neurological diseases, prominent among which are multiple sclerosis (Burks, DeVald et al. 1980, Salmi, Ziola et al. 1982, Hovanec and Flanagan 1983), Parkinson's disease (Fazzini, Fleming et al. 1992), optic neuritis (Dessau, Lisby et al. 1999), encephalitis (Arabi, Harthi et al. 2015, Li, Li et al. 2016, Morfopoulou, Brown et al. 2016, Nilsson, Edner et al. 2020) and acute disseminated encephalomyelitis (Yeh, Collins et al. 2004). In some of these diseases (e.g., optic neuritis, encephalitis and encephalomyelitis) it is reasonable to suspect that the virus itself is the cause of the disease, while in other conditions (e.g., multiple sclerosis, Parkinson's disease) it is unclear whether the virus has any causative role.
Early in the pandemic it was noted that patients infected with COVID 19 could exhibit neurologic symptoms (Koralnik and Tyler 2020, Pinzon, Wijaya et al. 2020), particularly when the illness was severe enough to warrant hospitalization (Liotta, Batra et al. 2020) and management in an intensive care unit (Pinna, Grewal et al. 2020). The accumulating evidence (Filatov, Sharma et al. 2020, Nath 2020, Poyiadji, Shahin et al. 2020) specifically about the virus causing COVID 19 suggests that it can affect the CNS similarly to other members of coronavirus family (Zubair, McAlpine et al. 2020), though there are differences as well (Ceccarelli, Berretta M Fau - Venanzi Rullo et al. 2020), such as its apparent predilection to impair smell and taste (Gautier and Ravussin 2020, Giacomelli, Pezzati et al. 2020, Mao, Jin et al. 2020, Mermelstein 2020, Vavougios 2020). It is thus reasonable to consider whether it might also be the mechanism for other focal neurological manifestations, including the auditory and vertiginous disorders that we see in clinic ? though to be clear, this disease is so new that there has not yet been adequate opportunity to study this in any systematic fashion. Emerging clinical literature (Saniasiaya and Kulasegarah 2021) describes dizziness as a symptom associated with COVID 19, which matches our own clinical experience; a few months into the pandemic we began encountering patients with a laboratory-confirmed diagnosis of COVID 19 who complained of dizziness.
One case series from the United Kingdom noted that >10% of COVID 19 confirmed patients self-reported auditory symptoms of hearing loss and/or tinnitus (Munro, Uus et al. 2020). Dusan et al (2021) reported hearing loss of some degree in 40% of 74 patients.Kokoglu et al (2021) reported that when hearing loss occured, it did not persist on followup, and said "Mild and moderate COVID-19 and its treatments did not affect the hearing function permanently."
Regarding dizziness, a large case series (799 patients) from Wuhan described dizziness as a symptom in 8% of confirmed COVID 19 patients (Chen, Wu et al. 2020), though another study (214 patients) from Wuhan specifically querying neurological symptoms among confirmed cases of COVID 19 reported dizziness in 16.8% of patients (Mao, Jin et al. 2020); a study from a network of Chicago area hospitals (509 patients) reported dizziness in 29.7% of cases (Liotta, Batra et al. 2020).
Reviews of the emerging literature note variability among studies (Saniasiaya and Kulasegarah 2021).
The ability of COVID 19 to cause auditory and vestibular symptoms appears to be distinct from the other SARS coronaviruses (Almufarrij, Uus et al. 2020). The mechanism by which COVID 19 may cause hearing loss, tinnitus and dizziness is unclear; since the disease appears to be capable of affecting individual cranial nerves — as happens in anosmia (Gautier and Ravussin 2020, Giacomelli, Pezzati et al. 2020, Mao, Jin et al. 2020, Mermelstein 2020, Vavougios 2020), optic neuritis (Dessau, Lisby et al. 1999) and ophthalmoparesis (Dinkin, Gao et al. 2020) — it is conceivable that it causes vestibular neuritis and/or cochlear neuritis, or labyrinthitis, though this remains a conjecture requiring further study.
In some patients COVID 19 appears to provoke autonomic dysfunction (Eshak, Abdelnabi et al. 2020, Dani, Dirksen et al. 2021, Goodman, Khoury et al. 2021, Lo 2021, Shouman, Vanichkachorn et al. 2021), so another mechanism by which COVID 19 may provoke dizziness is through orthostatic intolerance, usually as postural orthostatic tachycardia (Kanjwal, Jamal et al. 2020, Miglis, Prieto et al. 2020, Novak 2020, Blitshteyn and Whitelaw 2021, Goldstein 2021, Johansson, Ståhlberg et al. 2021, Schofield 2021).
As of this writing there are no proven treatments specifically targeting otovestibular (ear-related) symptoms from COVID 19. A case-report has been published (Rahimi, Asiyabar et al. 2021) regarding intratympanic steroid injection for sudden onset sensorineural hearing loss apparently related to COVID 19, but prospective, double-blinded, randomized, placebo-controlled trials are lacking.
The literature regarding adverse effects from the Pfizer vaccine (BNT162b2 mRNA) is somewhat difficult to interpret as it pertains to this symptom. The original trial (Polack, Thomas et al. 2020) of 43,548 participants (of whom 21,720 received the intervention) does not list dizziness/vertigo as an adverse event, even in the supplementary material. In contrast, in a much smaller study Kadali, Janagama et al. 2021) of 1,245 recipients of the vaccine, of 803 patients with "generalized" or "neurological" symptoms, 67 (8.34%) reported "dizziness," and 20 (2.49%) reported "vertigo." There has been a case report of postural orthostatic tachycardia occurring after administration of this vaccine (Reddy, Reddy et al. 2021).
The literature regarding adverse effects from the Moderna vaccine (mRNA-1273) is also difficult to interpret as it pertains to this symptom. The original trial (Baden, El Sahly et al. 2021) studied 30,420 participants (15,210 received the vaccine), and the supplementary material reported adverse effects of "dizziness" and "vertigo" as occurring in zero individuals. In contrast, a much smaller study (Kadali, Janagama et al. 2021) of 432 vaccine recipients (Kadali, Janagama et al. 2021) stated that 15 (3.47%) reported "vertigo like symptoms" and 63 (14.58%) reported "dizziness."
The original trial (Sadoff, Gray et al. 2021) of the Johnson & Johnson vaccine (Ad26.COV2.S) studied 39,260 participants (of whom 19,630 received the vaccine). The trial's supplementary material reported "dizziness" in 0 vaccine recipients, and "vertigo" in 0 vaccine recipients. However, the product monograph (https://www.rcdhu.com/wp-content/uploads/2021/03/janssen-covid-19-vaccine-product-monograph.pdf) reviewed data from 43,783 participants (of whom 21,895 received the vaccine) stated that the symptom of "vertigo" was reported by 13 patients in the treatment group and 7 patients in the placebo group.
As of this writing, an analysis of publicly available data from the Centers for Disease Control's Vaccine Adverse Effects Reporting System (CDC VAERS) pertaining to the two mRNA vaccines (Pfizer and Moderna) revealed 40 cases of what was believed to be unilateral sensorineural hearing loss (confirmed on audiometric testing) deemed "most likely" to be attributable to the vaccines themselves (Formeister, Chien et al. 2021). These data suggested that the unilateral hearing loss occurred within 3 weeks (mean 4 days) of having received the vaccines, and had an incidence of 0.3 cases per 100,000 individuals (i.e., 3 per million).
Newer version (PDF) is here (Papers are proliferating, and we have not been able to keep up with the web page formatting, but here is the latest output).