Auditory nerve neurinoma (also known as vestibular schwannoma)

Auditory Nerve Neurinoma

What is an auditory nerve neurinoma (schwannoma)?

An auditory nerve neurinoma (also known as vestibular schwannoma, vestibulocochlear schwannoma, n. vestibulocochlearis schwannoma, or neurinoma) is a benign, slow-growing tumor that develops from the auditory and balance nerve (VIII cranial nerve). The changes caused by the tumor and the pressure on the healthy parts of the nerve can lead to gradual hearing deterioration and loss, tinnitus (ear ringing), and balance disorders.

This VIII nerve tumor originates from Schwann cells, which form the outer sheath of the nerve. It can grow very slowly (1-1.5 mm per year) or even stop growing altogether. Notably, a tumor measuring 25-30 mm in this location is considered relatively large. In rare cases, an auditory nerve schwannoma may grow rapidly, which can lead to compression of the brainstem, causing disruptions to vital functions.

What are the symptoms of vestibulocochlear schwannoma?

The initial symptoms of this condition can be subtle and may develop gradually over many years. Most symptoms arise from tumor-induced changes in the auditory and balance nerves. In some cases, the tumor may also compress nearby nerves (such as the facial or trigeminal nerves) or the brainstem, leading to other serious health problems unrelated to hearing and balance.

The most common signs of vestibular neurinoma include:

• Gradual hearing loss (usually on one side, though in rare cases it may affect both ears)
• Tinnitus (ringing in the affected ear)
• Dizziness and balance disorders
• Facial numbness
• Rarely, facial muscle weakness or hemifacial spasms (one-sided facial twitching)

Why does an auditory nerve neurinoma develop?

One possible cause of this tumor is a genetic defect on chromosome 22, which normally produces a tumor-suppressing protein that controls the growth of Schwann cells in the nerve sheath.

This genetic defect can be inherited, as seen in neurofibromatosis type 2 (NF2)—a rare condition that can cause bilateral auditory nerve tumors (bilateral vestibulocochlear schwannomas).

Neurofibromatosis Type 2 (NF2)

NF2 is an autosomal dominant genetic disorder characterized by benign nerve tumors. It can cause bilateral auditory nerve schwannomas as well as tumors on other nerves in the body. Only a small percentage of vestibulocochlear schwannoma cases are linked to NF2.

Since NF2 is autosomal dominant, each child of an affected parent has a 50% chance of inheriting the condition.

How is an auditory nerve neurinoma diagnosed?

These tumors can be challenging to detect early, as symptoms often develop gradually and may resemble other inner or middle ear conditions. If you experience hearing loss or tinnitus, your doctor may refer you for the following tests:

• Audiometry (hearing test) – Conducted by an ENT specialist, audiometry evaluates hearing acuity, thresholds, and sound sensitivity using an electroacoustic device. The patient wears headphones and responds to various sound signals. The results are plotted on an audiogram, which shows the degree and type of hearing impairment. Vestibular schwannomas often cause sensorineural hearing loss.
• Imaging diagnostics – MRI with contrast is considered the gold standard for detecting even very small (1-2 mm) auditory nerve tumors. If MRI is unavailable or contraindicated, CT scanning can be used, though small VIII nerve tumors may not be visible on CT scans.

If an auditory nerve neurinoma is confirmed, what next?

Patients diagnosed with an auditory nerve neurinoma should consult a neurosurgeon to discuss treatment options. We are happy to provide expert consultation and recommend the best possible solution for your case.

If an in-person consultation is not feasible, we also offer remote consultations via video call. You can schedule an appointment online, by phone, or via email. Remote consultations should be arranged by contacting us directly.

Vestibular Neurinoma: What are the treatment options?

The treatment approach for auditory nerve schwannomas depends on the tumor’s size, growth rate, symptoms, and overall health status. Possible management strategies include observation, surgery, or radiotherapy, and these may change over time.

• Observation – If the tumor is very small, asymptomatic, or found incidentally, and if the patient is elderly or at high risk for surgery, doctors may recommend monitoring instead of active treatment. This means MRI scans and audiometry tests every 6-12 months to track tumor growth. If symptoms worsen or the tumor enlarges, surgery or radiation therapy may be advised.
• Surgery – Surgical treatment aims to remove as much of the tumor as possible while preserving facial nerve function. Since the facial nerve (VII cranial nerve) is located very close to the vestibulocochlear nerve (VIII cranial nerve), facial nerve injury is one of the most significant surgical risks.

Modern facial nerve monitoring during surgery has dramatically reduced the risk of nerve damage, with about 72% of patients achieving full preservation of facial nerve function.

Surgical removal is performed under general anesthesia through a small cranial bone opening. If the tumor extends into the internal auditory canal, additional surgical techniques may be required. In complex cases, surgeons may opt not to remove the entire tumor to prevent severe complications, particularly if the tumor is very large (>3 cm) or deeply embedded in the inner ear structures.

Potential surgical risks

• Facial nerve paralysis
• Hearing loss (if hearing was intact pre-surgery)
• CSF leakage from the surgical site or nose
• Tinnitus
• Balance disorders
• Headaches
• Infection (e.g., meningitis)
• Stroke or bleeding in the surgical area
• Tumor recurrence

If you are considering surgical treatment, feel free to read patient reviews of their experiences with our Latvian and international neurosurgical team.

Radiotherapy options for vestibular schwannoma

Radiotherapy can be delivered in multiple ways, depending on tumor size and location:

• Stereotactic radiosurgery (SRS) – Recommended for small tumors (<3 cm), bilateral schwannomas (e.g., in NF2 patients), or residual tumors after surgery. This high-precision radiation is delivered in a single session using specialized equipment.
• Fractionated stereotactic radiotherapy – Similar to SRS but spread over multiple sessions instead of one-time treatment.

Radiotherapy goals are similar to surgery:

• Stop tumor growth
• Preserve facial nerve function
• Potentially maintain hearing

Is follow-up needed after treatment?

Even though vestibular schwannomas are benign and slow-growing, regular follow-up is essential—even after full tumor removal.

A 2017 study published in the Journal of Neurosurgery, involving 414 patients, found that even after total tumor resection, 44% of patients experienced tumor recurrence within 20 years. In cases of subtotal resection (where a very small portion or the tumor capsule remains), 53% of patients showed tumor progression or recurrence within just five years.

It is crucial to perform MRI follow-up examinations in institutions with neuroradiology specialists.

After total tumor resection, the first MRI scan should be conducted three months after surgery. If the neuroradiologist confirms no residual tumor, the next MRI scans with contrast should be performed after two years, then after seven years, and subsequently every five years.

If the tumor was partially (partial resection) or nearly completely removed (subtotal resection), MRI with contrast should be conducted once a year for three years, followed by every two years thereafter.

For patients undergoing radiation therapy, follow-up imaging should be conducted annually or even more frequently.

Surgical treatment provides a higher chance of complete long-term cure.