Acoustic neuroma, also known as vestibular schwannoma, is a benign intracranial tumor. It is the most common tumor found in the cerebellopontine angle and originates from the Schwann cells that cover nerves—in this case, the vestibular nerve.
Etiology
Most patients diagnosed with an acoustic neuroma do not have any apparent risk factors. The only well-established risk factor is exposure to high doses of ionizing radiation, which has been linked to an increased likelihood of developing this tumor.
There is also a hereditary condition known as Neurofibromatosis Type II, which is frequently associated with the development of acoustic neuromas, typically affecting both sides (bilateral tumors), as well as other brain and spinal cord tumors.
What are the symptoms of an acoustic neuroma?
Most patients (80%) with an acoustic neuroma initially present with unilateral hearing loss, while tinnitus is the second most common symptom (7%). Affected individuals may also experience dizziness and vertigo, headaches, and facial movement disturbances.
Left-sided acoustic neuroma
How is an acoustic neuroma diagnosed?
The definitive diagnostic test for an acoustic neuroma is magnetic resonance imaging (MRI), ideally with contrast enhancement. Contrast helps increase diagnostic sensitivity and ensures that small tumors are not overlooked.
Treatment options for acoustic neuroma
The choice of treatment depends on several factors, including the patient’s age, overall medical condition, tumor size and location, hearing status, and of course, the patient’s preference.
Acoustic neuromas can be managed in the following three ways:
Observation and periodic monitoring
Monitoring without immediate treatment may be appropriate in cases such as:
- Older adult patients
- Patients with very small tumors and few or no symptoms
- Patients with other medical conditions that pose a high surgical risk
- Patients who decline more aggressive treatment
- Patients with tumors affecting their only hearing ear
In these cases, the patient should undergo regular follow-ups, typically every 6 to 12 months, which include MRI scans and hearing assessments (audiometry or in-office evaluations).
Surgery
Surgical removal is the preferred option for tumor eradication, mainly in:
- Younger patients with large tumors (>2.5–3 cm)
- Some patients with small tumors and preserved hearing
The procedure is done under general anesthesia and can involve different surgical approaches—either through the inner ear or via an incision in the skull. The choice of approach depends on the size and exact location of the tumor.
The current mortality rate for this surgery is below 1%. Main risks include facial paralysis, worsening or total hearing loss in the affected ear, and balance disorders. However, thanks to advancements in techniques and earlier diagnosis, complications have become increasingly rare, and hearing preservation is even possible in some cases.
Stereotactic radiosurgery
Stereotactic (or stereotaxic) radiosurgery has emerged as a valid alternative to surgery for patients with acoustic neuroma.
Despite its name, it is a non-surgical procedure. It is a highly precise form of radiotherapy that delivers high doses of radiation directly to the tumor while minimizing exposure to surrounding healthy tissue, unlike conventional radiotherapy. Treatment may be performed in a single session or over several sessions. The goal is to halt tumor growth, preserve hearing when possible, and protect the facial nerve.
Depending on the type of energy used, three types of stereotactic radiotherapy can be distinguished:
- Gamma Knife®
- Linear accelerators that deliver high-energy X-rays or photons (e.g., CyberKnife®)
- Proton beam therapy
This is usually the preferred treatment in:
- Patients with small tumors (<2.5–3 cm)
- Older adults
- Patients for whom surgery is contraindicated