Acoustic Neuroma: The One-Sided Hearing Loss You Shouldn't Write Off as Aging

What an Acoustic Neuroma Is

An acoustic neuroma, more precisely called a vestibular schwannoma, is a benign, slow-growing tumor that develops on the nerves connecting the inner ear to the brain, the nerves responsible for hearing and balance. It comes from an overgrowth of Schwann cells, the cells that normally wrap and insulate nerve fibers. ^[1] "Benign" means it does not spread to other parts of the body, but as it grows it can press on the hearing nerve, the balance nerve, and eventually nearby structures. ^[2]

It's uncommon. NIDCD estimates that about one in every 100,000 people develops one each year, usually between ages 30 and 60. ^[1] Diagnoses have become more frequent with wider MRI use: a population study in Olmsted County, Minnesota, found incidence rose from 1.5 to 4.2 per 100,000 person-years between the late 1960s and the 2006 to 2016 period, reaching 18.3 per 100,000 among people 70 and older, and the median age at diagnosis rose to 62. ^[4] About 90 percent of cases occur without any known genetic cause; tumors on both sides are usually linked to a genetic condition called neurofibromatosis type 2 (NF2). ^{[1] [2]}

Symptoms, and Why They're Easy to Miss

Because these tumors grow slowly, StatPearls notes an average of about 1.4 mm per year, symptoms tend to creep in rather than arrive suddenly. ^[2] The most common signs are: ^{[1] [3]}

• Hearing loss in one ear, or noticeably worse in one ear. A Brazilian Society of Otology review reports one-sided hearing loss in 94 percent of patients.
• Tinnitus in one ear. Reported in 83 percent of patients in the same review. (For tinnitus in general, which is usually not caused by a tumor, see our guide to tinnitus causes and treatment.)
• Unsteadiness or dizziness. Often mild, because the brain gradually compensates for the slow loss of balance input on one side.
• Facial numbness or weakness. Usually only with larger tumors pressing on nearby nerves.

The trouble is that each of these sounds ordinary on its own. A gradual dip in hearing gets blamed on age or earwax, ringing gets blamed on noise, and mild unsteadiness gets blamed on getting older. Many people also notice the problem first on the phone, when they always hold it to the "good" ear without thinking about why. In the Minnesota study, the median time from first symptoms to diagnosis was still 12 months in recent years, down from 25 months decades earlier. ^[4]

How It Differs From Age-Related Hearing Loss

The key word is asymmetry. NIDCD describes age-related hearing loss as typically occurring in both ears as we age, and it usually progresses at a similar pace on each side. ^[5] Acoustic neuroma is almost always one-sided, so the classic red flag is a hearing difference between your two ears that isn't explained by something obvious, such as a history of shooting firearms on one side. Our comparison of age-related vs. noise-induced hearing loss explains the typical patterns of those more common causes.

A second clue sometimes appears on testing: speech understanding can be worse than the hearing thresholds alone would predict, because the tumor affects the nerve carrying the signal rather than just the sensitivity of the cochlea. It's also worth knowing that symptoms like one-sided hearing loss, tinnitus, and dizziness overlap with Meniere's disease, which is one more reason a proper evaluation matters rather than guessing.

How It's Diagnosed

Diagnosis usually starts with a hearing test (audiogram) that shows a difference between the ears, often alongside balance testing. ^[1] If the pattern is suspicious, the next step is an MRI. Gadolinium-enhanced MRI, using a contrast dye, is considered the gold standard because it can detect even small tumors. ^[3]

Imaging is also part of the workup for sudden hearing loss. The American Academy of Otolaryngology's clinical practice guideline recommends that clinicians evaluate patients with sudden sensorineural hearing loss for retrocochlear causes, meaning problems behind the inner ear such as a tumor on the hearing nerve, using MRI or an auditory brainstem response test. ^[6] In other words, a sudden drop in one ear is not only an urgent issue in itself, it's also one of the ways these tumors are found.

Treatment: Watch, Radiation, or Surgery

Finding an acoustic neuroma doesn't automatically mean surgery. Treatment depends on tumor size, growth, symptoms, age, and overall health, and the main options are: ^{[1] [2] [7]}

• Observation ("watch and wait"). For small tumors with few symptoms, doctors often repeat the MRI over time. StatPearls describes scans every 6 months at first, then yearly if the tumor is stable. In the Brazilian review, up to 75 percent of tumors did not grow during observation, though more than half of patients still lost useful hearing over time even when the tumor stayed the same size. ^{[2] [3]}
• Stereotactic radiosurgery. Focused radiation (such as gamma knife) aims to stop the tumor from growing rather than remove it.
• Microsurgery. Surgical removal, more often considered for larger or growing tumors. Risks include hearing loss on that side and facial nerve weakness; the Brazilian review reports persistent facial paralysis rates ranging from 3 to 46 percent depending largely on tumor size. ^[3]

Because complication risk generally rises with tumor size, earlier diagnosis tends to keep more options open.

When to Ask About It

Most hearing loss is not a tumor, and this article isn't meant to cause alarm. But these situations are worth raising with a doctor or audiologist specifically, rather than assuming it's just age:

• Hearing that is clearly worse in one ear than the other
• Ringing, buzzing, or fullness in only one ear that doesn't go away
• Unexplained unsteadiness combined with any of the above
• Any sudden hearing loss, which needs prompt medical attention
• New facial numbness, tingling, or weakness

After Your Checkup: A Daily Wellness Routine

One-sided hearing changes always deserve a proper medical evaluation first, and that comes before anything else. Once you have been checked and your doctor knows your plans, many people enjoy adding a simple daily routine for general hearing wellness. Audifort is a once-a-day liquid designed to support healthy hearing, and the 90-day money-back guarantee makes it a low-risk way to try one.

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