The SARS-CoV-2 virus, which causes COVID-19, is primarily known for affecting the respiratory system, but its effects extend beyond the lungs. Clinical reports confirm a clear association between COVID-19 infection and symptoms affecting the ears and balance system. This connection is now recognized as a manifestation of the disease, observed globally since the start of the pandemic. The symptoms range from mild, temporary discomfort to severe, potentially lasting changes in hearing and balance.
Specific Auditory and Vestibular Symptoms
The ear-related problems reported by individuals with COVID-19 generally fall into three distinct categories affecting both hearing and balance. The most frequently observed symptom is tinnitus, which involves sounds like ringing, buzzing, roaring, or clicking that do not come from an external source. For some patients, this represents a new onset of the condition, while for others, it is a significant worsening of pre-existing tinnitus. Tinnitus is also commonly reported in people experiencing Long COVID, sometimes persisting for months after the initial infection has resolved.
Hearing loss is another consequence, often presenting as sudden sensorineural hearing loss (SSNHL), which occurs rapidly, sometimes in a single ear. Sensorineural loss indicates damage to the inner ear’s cochlea or the auditory nerve connecting the ear to the brain.
The vestibular system, which governs balance, is frequently involved, leading to generalized dizziness or true vertigo. Dizziness is a feeling of lightheadedness or unsteadiness, but vertigo is a more profound sensation that the environment or the individual is spinning. This spinning sensation suggests a problem within the inner ear’s balance organs, which contain fluid-filled canals and sensors that help the brain orient the body in space.
Biological Pathways of Ear Involvement
The mechanisms by which SARS-CoV-2 affects the inner ear are complex and involve a combination of direct and indirect actions on the auditory and vestibular structures. One leading hypothesis centers on the body’s overwhelming immune response known as systemic inflammation or a cytokine storm. The body releases high levels of pro-inflammatory signaling proteins, such as Interleukin-6 (IL-6), to fight the virus, but this excessive inflammation can cause secondary damage to tissues throughout the body. The delicate hair cells and nerve fibers of the inner ear are sensitive to inflammatory compounds, and exposure to these circulating cytokines can lead to dysfunction or death.
Another proposed pathway is direct viral invasion of the inner ear cells. SARS-CoV-2 gains entry into human cells by binding to the Angiotensin-Converting Enzyme 2 (ACE2) receptor, and studies have confirmed the presence of this receptor, along with cofactors like TMPRSS2, on various inner ear cell types. Notably, the hair cells, which are responsible for converting sound and movement into electrical signals, express these entry factors, suggesting they are vulnerable targets for the virus.
Furthermore, COVID-19 is known to cause vascular and microvascular issues throughout the body, providing a third mechanism of injury. The infection can trigger abnormal blood clotting and inflammation within the small blood vessels, a process known as endothelial dysfunction. Since the inner ear relies on a highly specialized and restricted blood supply, any interruption in blood flow, or ischemia, can quickly deprive the sensitive sensory cells of oxygen and nutrients. This microvascular injury is relevant in cases of sudden sensorineural hearing loss.
Management and Recovery
Seeking immediate medical attention is necessary if sudden hearing loss is experienced during or shortly after a COVID-19 infection, as this is considered a medical emergency. Treatment for sudden sensorineural hearing loss is time-sensitive, with the best outcomes observed when therapy begins within 72 hours of onset. The standard first-line approach involves the use of corticosteroids, which are powerful anti-inflammatory medications. These drugs may be administered orally or via injection directly into the middle ear space, known as intratympanic injection, to reduce swelling and inflammation in the inner ear.
Tinnitus Management
For persistent tinnitus, management focuses on reducing the awareness and distress caused by the sounds. Conservative strategies often include sound therapy, which utilizes quiet background noise, such as white noise or nature sounds, to mask the internal ringing and help the brain habituate to the sound. Counseling or cognitive behavioral therapy may also be used to address the stress and anxiety associated with the condition.
Vestibular Rehabilitation
Dizziness and vertigo resulting from vestibular dysfunction are often treated with a specialized physical therapy called vestibular rehabilitation. This therapy involves specific head, eye, and body movements designed to help the brain retrain and compensate for the faulty signals coming from the inner ear. While many audio-vestibular symptoms may improve as the acute infection passes, for some individuals, these issues can persist as part of the Long COVID syndrome.