Asymmetrical Hearing Loss

Generally, hearing will decline evenly in each ear over time. This is often referred to as symmetrical hearing loss. However, sometimes individuals will experience a hearing loss that is disproportionate, in which one ear has worse hearing when compared to the other ear. Asymmetrical hearing loss is especially common in the older population.

Causes:

The mechanisms by which asymmetrical hearing loss can occur include:

• Acoustic neuroma or other tumors: Masses or tumors can push on the hearing nerve which will cause a decline in hearing at a faster rate in the affected ear than in the other ear
  
• Asymmetrical exposure to noise: Individuals who are repeatedly exposed to noise damaging equipment (firearms, dental drills, etc) on one side of the body can cause asymmetrical hearing loss
  
• Ototoxic medications, head injury, surgery, or infections
  
• Viral infection can occur on the hearing nerve, causing an asymmetric hearing loss and tinnitus

When to get an MRI?

An MRI scan of the brain and inner ear is often performed to assess for tumors or cysts that put pressure on the hearing nerve that carries sound to the brain. The current recommendation is to obtain an MRI of the head when there is a 15 dB difference over three frequencies, a 20 dB difference in two frequencies, or a 25 dB difference in one or more frequencies.

Treatment:

After full otologic evaluation to assess for causes of the asymmetric hearing loss, patients may benefit from hearing aids and devices