One-Sided Ringing and a Diagnosis You Weren’t Expecting
Hearing that a tumour might be the cause of ringing in your ear is frightening, even when a doctor reassures you it is benign. If you are in that position right now, you are dealing with something genuinely alarming, and that reaction makes complete sense. The good news is substantial: acoustic neuroma is non-cancerous, does not spread to other parts of the body, grows slowly (often over many years), and affects roughly 1 in 100,000 people per year. The medical term is vestibular schwannoma — acoustic neuroma is the older, more commonly used name, and both refer to the same thing.
This article explains what acoustic neuroma is, why it causes one-sided tinnitus, how the diagnosis is reached, and — most importantly — what you can realistically expect regarding your tinnitus across the three main management paths.
What Is Acoustic Neuroma and Why Does It Cause Tinnitus?
Acoustic neuroma grows from Schwann cells on the vestibulocochlear nerve (cranial nerve VIII), the nerve responsible for both hearing and balance. As the tumour expands within the internal auditory canal, it compresses the cochlear branch of that nerve, disrupting the normal flow of auditory signals to the brain. The brain perceives this disruption as sound, which is the tinnitus you hear.
Because the tumour sits on one side, this tinnitus is ipsilateral: it occurs in the same ear as the tumour. That one-sided, persistent quality is precisely what makes it clinically significant. Common tinnitus is usually bilateral or affects both ears at different times. When tinnitus is persistent and confined to a single ear, particularly when it is accompanied by hearing change on the same side, it is the defining red flag that warrants further investigation. Approximately 70% of people with acoustic neuroma have tinnitus at the point of diagnosis.
Symptoms: What Acoustic Neuroma Feels Like
Acoustic neuroma produces a recognisable pattern of symptoms, though their severity varies considerably depending on tumour size and how quickly it has grown.
Progressive unilateral hearing loss is the most common symptom and is usually the first to appear. It tends to be gradual, affecting high frequencies first, and may be so slow that you attribute it to ageing or background noise. In around one in ten cases, hearing loss arrives suddenly rather than gradually, and sudden hearing loss in one ear is a medical urgency (more on this below).
Tinnitus is present in roughly 70% of patients at diagnosis. It typically sounds like a persistent ringing, buzzing, or hissing, and occurs in the affected ear only. It may be constant or come and go. This ipsilateral quality — same ear as the hearing loss — is what separates acoustic neuroma tinnitus from the far more common bilateral tinnitus that affects millions of people without any structural cause.
Vestibular symptoms — including dizziness, unsteadiness, or a sense of imbalance — are common because the tumour also affects the balance branch of cranial nerve VIII. Acute spinning vertigo (the room-spinning sensation of classic vertigo) is less typical; more often, people describe a general unsteadiness or feeling of being slightly off-balance.
As the tumour grows larger, it may compress neighbouring structures, producing additional symptoms:
- Facial numbness or tingling, from pressure on the trigeminal nerve (cranial nerve V)
- Facial weakness, from involvement of the facial nerve (cranial nerve VII), which runs in close proximity
- Headache or a feeling of pressure, which can develop if the tumour grows large enough to raise intracranial pressure
Smaller tumours, which are increasingly found because of greater awareness and improved imaging, often produce only hearing loss and tinnitus, without any of these later-stage features.
How Is Acoustic Neuroma Diagnosed?
The diagnostic process follows a well-established sequence, and most small tumours are identified before they cause serious problems.
Step 1: GP or ENT assessment. The process typically begins when you report persistent one-sided tinnitus, asymmetric hearing loss, or unexplained dizziness to your GP. Based on your symptom history, they will refer you for a hearing test or directly to an ENT specialist.
Step 2: Audiogram. A formal hearing test (audiogram) is usually the first investigation. Acoustic neuroma typically produces asymmetric sensorineural hearing loss, meaning the nerve-based hearing loss is noticeably worse in one ear than the other. In the UK, NICE guidelines recommend MRI referral when there is an asymmetry of 15 dB or more at two adjacent frequencies (NICE NG98). An audiogram that shows this pattern is the key trigger for imaging.
Step 3: MRI with gadolinium contrast. MRI is the gold standard for diagnosing acoustic neuroma. The gadolinium contrast agent makes even small tumours visible on the scan. CT scanning is not reliable for detecting small acoustic neuromas and may miss them entirely, which is why MRI is always preferred when this diagnosis is being considered.
Two additional tests may be ordered to gather more information about nerve function:
- Auditory brainstem response (ABR) testing assesses how efficiently the auditory nerve transmits signals to the brain
- Electronystagmography (ENG) evaluates vestibular function and may reveal reduced response on the affected side
Neither of these confirms the diagnosis on its own, but both can guide the clinical picture before or alongside MRI.
The Three Management Options — and What They Mean for Your Tinnitus
This is where acoustic neuroma management differs from what many patients expect, and where honest information matters most.
There are three established approaches: watchful waiting (observation), microsurgery, and stereotactic radiosurgery. The 2024 Clinical Practice Guideline on vestibular schwannoma management confirms that none of these approaches consistently eliminates tinnitus, and that treatment decisions should be made through shared decision-making based on tumour size, growth rate, symptoms, and patient preference (Lassaletta et al., 2024). There is almost never a clinical reason to rush a decision.
Watchful waiting (observation)
For small or stable tumours, active monitoring with serial MRI scans every 6 to 12 months is a legitimate and commonly chosen path. The aim is to detect any significant growth before it becomes a problem, rather than to treat a tumour that may never progress meaningfully.
From a tinnitus perspective, watchful waiting neither reliably worsens nor improves it. A systematic review comparing watchful waiting against stereotactic radiosurgery in 1,635 patients found no significant difference in tinnitus outcomes between the two groups (Vasconcellos et al., 2024). This is both reassuring and realistic: observation is not a passive acceptance of worsening symptoms, but it is not a tinnitus treatment either.
Microsurgery
Surgical removal aims to take out the tumour entirely. For many patients, particularly those with larger or growing tumours, it remains the most appropriate option.
Regarding tinnitus, the evidence is clear and patients deserve to know it: surgery does not reliably eliminate tinnitus. A systematic review and meta-analysis of 13 studies involving 5,814 patients found no significant difference in tinnitus outcomes between microsurgery and stereotactic radiosurgery, and the authors concluded that “no definitive conclusions could be drawn favouring either treatment” (Ramkumar et al., 2025). A separate observational study of 450 surgical patients found that surgery can worsen pre-existing tinnitus, and can even trigger new-onset tinnitus in patients who had none beforehand (Geng et al., 2025). Patients with serviceable hearing before surgery faced higher odds of both worsened and new-onset tinnitus post-operatively.
Hearing preservation is more likely when the tumour is smaller and detected early, which is another reason prompt investigation of one-sided symptoms matters.
Stereotactic radiosurgery (e.g., Gamma Knife)
Radiosurgery uses precisely targeted radiation to stop the tumour from growing; it does not remove the tumour. Most patients treated this way retain a stable but present tumour for the rest of their lives, without it causing further harm.
Tinnitus outcomes after radiosurgery are similarly variable and unpredictable. A network meta-analysis across multiple treatment modalities suggested radiosurgery may offer a slight advantage over microsurgery for tinnitus improvement, though the certainty of evidence was rated low given that most included studies were observational rather than randomised (Huo et al., 2024). Radiosurgery’s main advantage is avoiding the operative risks of open surgery while still controlling tumour growth.
The honest picture
Across all three paths, the consistent finding is that tinnitus outcomes are unpredictable. Some people see improvement; others experience no change; a proportion find tinnitus worsens, particularly after surgery. What treatment does reliably accomplish is controlling the tumour, and for a benign growth that is not going to spread, that is the primary goal. Tinnitus management after diagnosis typically involves the same approaches used for tinnitus of other causes: counselling, sound therapy, and hearing rehabilitation where relevant.
When to See a Doctor: Red Flags You Shouldn’t Ignore
If you have tinnitus and are wondering whether it warrants medical attention, the following guidance is intended to help you decide clearly, without alarm, but without delay where delay matters.
Persistent tinnitus in one ear only, particularly if it has lasted more than a few weeks and is accompanied by any hearing change on the same side, should prompt a visit to your GP to arrange an audiogram. Most one-sided tinnitus has far more common causes than acoustic neuroma, such as earwax, middle ear fluid, or noise exposure, but acoustic neuroma is the most important condition to exclude, which is why the investigation pathway exists.
Sudden hearing loss in one ear is a medical urgency. If you wake up with significantly reduced hearing in one ear, or if hearing drops sharply over a few hours, seek same-day medical attention. Corticosteroid treatment for sudden sensorineural hearing loss should begin as soon as possible, ideally within the first two weeks; benefit has been reported up to six weeks from onset, but outcomes are better with earlier treatment (AAO-HNS 2019 CPG). Do not wait for a routine appointment.
Tinnitus combined with dizziness, balance problems, or facial weakness or numbness warrants prompt ENT referral, as this combination suggests involvement of structures beyond the cochlear nerve alone.
Acoustic neuroma affects roughly 1 in 100,000 people per year. The vast majority of one-sided tinnitus is not caused by a tumour. But the investigation, an audiogram followed by MRI if asymmetry is confirmed, is straightforward, and identifying a small acoustic neuroma early gives you and your clinical team the widest range of options.
Key Takeaways
Acoustic neuroma is a rare but important cause of one-sided tinnitus. It is benign, does not spread, and in most cases grows slowly enough that you and your doctors have real time to consider options carefully.
The key red flag is persistent tinnitus in one ear, especially when combined with hearing loss on the same side. That combination warrants an audiogram and, if asymmetry is confirmed, an MRI.
If you receive a diagnosis, the most important thing to understand upfront is that none of the three management options, whether observation, surgery, or radiosurgery, reliably eliminates tinnitus. Knowing this from the start allows you to set realistic expectations and focus treatment decisions on what they do achieve: controlling the tumour. Diagnosis is not a crisis. Most people with acoustic neuroma lead full, active lives.
