The COVID-19 pandemic introduced SARS-CoV-2, a virus that causes a systemic disease extending far beyond the respiratory tract. Research has established a link between this viral infection and various neurological complications, including effects on the auditory and vestibular systems. The virus’s capacity to affect multiple organ systems means it can potentially damage the delicate structures responsible for hearing and balance.
Range of Auditory Symptoms
The most frequently reported auditory and balance problems following a COVID-19 infection involve three main symptoms. These audio-vestibular issues can occur during the acute phase of the illness or emerge weeks to months later as part of a post-COVID condition, sometimes referred to as long COVID. A pooled analysis suggests that approximately 7.6% of patients report hearing loss, 14.8% experience tinnitus, and 7.2% report vertigo.
Sudden Sensorineural Hearing Loss (SNHL) is a specific and potentially severe complication. SNHL is defined as a rapid loss of hearing of at least 30 decibels across three consecutive frequencies, typically occurring within 72 hours. This loss is generally unilateral, affecting only one ear, and can range from mild to profound.
Tinnitus, characterized by the perception of sound like ringing, buzzing, or hissing when no external sound is present, is the most common self-reported auditory symptom. For many, tinnitus begins or worsens after the initial infection, and it can be a temporary annoyance or a persistent, long-term issue. Tinnitus often accompanies hearing loss.
The vestibular system, which controls balance, can also be affected, leading to symptoms like vertigo and dizziness. Vertigo is the sensation of spinning or whirling, even when standing still, and indicates a disruption in the inner ear’s labyrinth or its connections to the brain.
How COVID-19 Impacts the Auditory System
The exact mechanisms by which SARS-CoV-2 causes damage to the auditory system are still under investigation, but several biological pathways are theorized. One prominent theory involves the potential for direct viral invasion of inner ear cells. The virus uses the Angiotensin-Converting Enzyme 2 (ACE2) receptor to enter human cells, and these receptors have been found in the delicate tissues of the inner ear, including the cochlear hair cells and Schwann cells.
This direct cellular attack could lead to the death or malfunction of the hair cells, which convert sound vibrations into electrical signals the brain interprets. Auditory symptoms also arise from indirect damage caused by the body’s immune response. Systemic inflammation and immune overreaction, often called a “cytokine storm,” releases a flood of inflammatory molecules.
These inflammatory mediators, such as interleukins and tumor necrosis factor-alpha, are toxic and can cause damage to the cochlea and the auditory nerve. Inflammation also affects blood vessels, leading to vascular complications and reduced blood flow to the inner ear. The cochlea relies on a finely tuned blood supply, and any blockage from microclots or vascular constriction can result in ischemia, or oxygen deprivation, causing rapid tissue damage and hearing loss.
The virus also affects the regulation of the Renin-Angiotensin System (RAS), which is involved in blood pressure and inflammation. When the virus binds to ACE2, it downregulates the receptor’s protective function, leading to an accumulation of Angiotensin II. This imbalance promotes increased inflammation and a pro-thrombotic state, where blood clots are more likely to form, ultimately leading to sensorineural hearing impairment.
Seeking Treatment and Prognosis
Individuals who experience sudden changes in hearing or balance during or shortly after a COVID-19 infection should seek medical attention immediately. Sudden Sensorineural Hearing Loss (SNHL) is treated as a medical emergency, requiring prompt intervention to maximize the chance of recovery. The window for effective treatment is narrow, ideally within the first few hours to days of symptom onset.
The standard treatment for SNHL involves corticosteroids to reduce inflammation and swelling in the inner ear. These steroids may be given orally as a high-dose systemic course or administered directly into the middle ear space through intratympanic injection. Intratympanic delivery is often preferred as it targets the inner ear tissue directly while reducing the risk of systemic side effects.
Diagnosis typically involves a full audiological evaluation, including pure-tone audiometry, to objectively measure the degree and type of hearing loss. The prognosis for COVID-19-related SNHL is variable, similar to sudden hearing loss from other viral causes. Some patients experience full or partial recovery, especially when treatment is initiated rapidly.
For some individuals, the damage results in permanent hearing loss. The presence of accompanying symptoms like tinnitus or vertigo indicates a more widespread impact on the inner ear system. Ongoing monitoring is often necessary, and if the hearing loss is severe and permanent, management options such as hearing aids or cochlear implants may be explored.