Acoustic neuroma (vestibular schwannoma)

Acoustic neuroma (vestibular schwannoma)

Introduction to vestibular schwannoma

An acoustic neuroma, or vestibular schwannoma, is a benign (non-cancerous), usually slow-growing tumour originating on the nerve for balance and hearing (cochleovestibular nerve). It occurs in about 4-5 persons per 100,000 per year. At least one out of 500 people will develop a vestibular schwannoma in their lifetime.


Vestibular schwannoma occurs most commonly in the age group of 40- 60 years. It rarely occurs in children. It occurs evenly in male and female patients

In 95% of cases, patients will present with a solitary tumour. These cases are not inherited (genetic).

In 5% of cases, patients present with a genetic form of which Neurofibromatosis type 2 is the most common cause.

What causes vestibular schwannoma?

The cause of vestibular schwannoma is unknown in 95% of cases. It has a genetic origin in 5 % of cases, most often related to neurofibromatosis type 2 (NF2).

There is no evidence that cell phones cause vestibular schwannomas.

mobile phone
Cell phones do not cause vestibular schwannoma

Where does a vestibular schwannoma originate?

A vestibular schwannoma originates from the Schwann sheath of the cochleovestibular nerve. Schwann cells are specialized cells that form the myelin sheath around nerves to provide insulation and support. When these cells grow uncontrollably, they can create a tumour known as a schwannoma.

Symptoms of vestibular schwannoma

Unilateral hearing loss is the most common presenting symptom, followed by tinnitus and balance problems. Vertigo, headaches, impaired facial sensation, facial nerve problems and other neurological symptoms are less common.



One of the reasons for this is that with the availability of MRI, tumours are picked up much earlier while being smaller. These smaller tumours usually have fewer symptoms, with some even being asymptomatic. It may, therefore, be an incidental finding while performing an MRI for another reason, such as for headaches, epilepsy or neck problems.

Larger vestibular schwannoma may present with more neurological problems and even raised intracranial pressure due to hydrocephalus. It can then become life-threatening.

Diagnosis of vestibular schwannoma

The gold standard examination for a patient with symptoms suggestive of a vestibular schwannoma is a magnetic resonance image with an intravenous contrast enhancement agent called gadolinium. An MRI is able to detect a vestibular schwannoma as small as 2 mm. As mentioned, vestibular schwannoma is sometimes picked up incidentally.

When a vestibular schwannoma is seen on MRI, depending on where it is located, one can be about 90- 95% certain of the diagnosis. Technically, it is challenging to perform biopsies, which is usually not done.

The only way someone can be 100% sure about the diagnosis is to obtain tissue, have it microscopically analyzed by a pathologist, and confirm the histology. This requires surgery. Tissue confirmation is not necessary for treatment planning.

Hearing tests, vestibular tests, balance tests, computed tomography (CT) and quality of life assessments are some other investigations that may have to be performed to plan treatment.

MRI image of a large right sided acoustic neuroma
A vestibular schwannoma

The natural behaviour of vestibular schwannoma

The majority of vestibular schwannoma will continue to grow after diagnosis. The growth pattern is irregular, with some vestibular schwannoma continuously growing and others on growth spurts with stationary periods in between. Some vestibular schwannomas may not grow, and small vestibular schwannomas may even disappear in a few cases.

The management of vestibular schwannoma

Vestibular schwannoma management requires a careful balance between the potential risks and benefits of treatment and the individual patient’s preferences and quality of life. It is important to emphasize that vestibular schwannoma is a benign tumour, not a cancerous growth and that the primary goal of treatment should be to maintain or improve the patient’s quality of life.

Several treatment options are available for vestibular schwannoma, including observation, microsurgery, and radiotherapy. Each option has pros and cons, and no single treatment modality is considered superior.

Observation, also known as watchful waiting or watchful scanning, involves monitoring the tumour through imaging studies to track its growth. This approach may be appropriate for patients with small or slow-growing tumours, as surgery or radiation therapy may carry unnecessary risks.

Microsurgery involves removing the tumour through an open surgical procedure. While surgery can be effective in completely removing the tumour, it also carries risks such as hearing loss, facial nerve damage, and cerebrospinal fluid leakage.

Radiation therapy, including stereotactic radiosurgery, uses high-dose radiation to target and shrink the tumour. While this approach can be effective in controlling tumour growth, it may not completely eliminate the tumour and could result in hearing loss and many late complications.

Chemotherapy is not currently an option for solitary vestibular schwannoma.

Microsurgery for vestibular schwannoma

Microsurgery for vestibular schwannoma involves removing the tumour while preserving as much hearing and facial nerve function as possible. The three common approaches are the translabyrinthine, retrosigmoid, and middle fossa.

The translabyrinthine approach involves opening the mastoid bone and removing the inner ear structures known as the labyrinth. This approach provides excellent exposure to the tumour and is often used for larger tumours where hearing preservation is not a priority.

The retrosigmoid approach involves an incision behind the ear and removing a small portion of the skull bone to access the tumour. This approach allows for better hearing and facial nerve function preservation compared to the translabyrinthine approach.

The middle fossa (transtemporal supralabyrinthine ) approach involves an incision above the ear and removing a portion of the temporal bone to access the tumour. This approach is used for smaller tumours near the internal auditory canal and provides the best chance for hearing preservation.


Transtemporal supralabyrinthine approach

Microsurgery for vestibular schwannoma requires a skilled and experienced surgeon to navigate the delicate structures of the inner ear and surrounding nerves to achieve the best possible outcomes for the patient.

Ultimately, the treatment choice for vestibular schwannoma should be individualized based on the patient’s medical history, tumour characteristics, and personal preferences. Patients need to discuss the risks and benefits of each treatment option with their healthcare provider to make an informed decision that aligns with their goals for quality of life.

Primary inner ear schwannoma (PIES)

Primary inner ear schwannoma (PIES) is a rare tumour originating from the inner ear’s Schwann cells rather than the cochleavestibular nerve. These cells are responsible for providing support and insulation to nerve cells. PIES typically presents with symptoms of hearing loss, vertigo, and tinnitus. Diagnosis is usually confirmed through imaging studies such as MRI or CT scans. Treatment options for PIES may include observation, surgical removal, or radiation therapy, depending on the size and location of the tumour. Early detection and management are crucial in preventing complications and preserving hearing function.

Primary inner ear schwannoma

Neurofibromatosis type 2

Neurofibromatosis type 2 (NF2) is a rare genetic disorder characterized by the growth of tumours on the nerves. The most common tumour associated with NF2 is the bilateral vestibular schwannoma, which affects the nerves responsible for balance and hearing. These tumours typically grow on both sides of the head, leading to hearing loss, ear ringing, balance problems, and headaches. Treatment options for NF2 and bilateral vestibular schwannomas include surgery, radiation therapy, and medication to manage symptoms. Regular monitoring and early intervention are crucial in managing the condition and preserving quality of life.

Bilateral vestibular schwannoma in NF2

Dr Hofmeyr’s expierence

Dr Hofmeyr has managed over 600 patients with acoustic neuromas/vestibular schwannoma. He has surgical experience in the middle cranial fossa (transtemporal supralabyrinthine ), translabyrinthine (TL), and retrosigmoid (RS) approaches.

Further reading