Managing Acoustic Neuroma: Symptoms, Diagnosis, and Treatment

Acoustic neuroma, also known as vestibular schwannoma, is a benign (non-cancerous) tumour that develops on the vestibulocochlear nerve, which connects the inner ear to the brain. This nerve is responsible for hearing and balance, so an acoustic neuroma can significantly impact these functions.

In this article, we will discuss the symptoms, causes, types, prevention, diagnosis, and treatment options of acoustic neuroma.

---

What is Acoustic Neuroma?

An acoustic neuroma is a slow-growing tumour that typically arises from the Schwann cells covering the vestibulocochlear nerve. Though benign, it can cause serious complications by pressing against adjacent structures, such as other cranial nerves or the brainstem.

---

Symptoms of Acoustic Neuroma

The symptoms of an acoustic neuroma can vary widely, depending on the size and location of the tumour. Common symptoms include:

Hearing Loss

Hearing loss, particularly in one ear (unilateral hearing loss), is often the earliest and most common symptom. Hearing loss is usually gradual but can sometimes occur suddenly.

Tinnitus

Tinnitus, or ringing in the ear, is another frequent symptom. This ringing can be continuous or intermittent and is often described as a high-pitched sound.

Balance Issues

The vestibulocochlear nerve also plays a critical role in maintaining balance. Tumours on this nerve can cause vertigo, unsteadiness, or a sense of imbalance.

Facial Numbness or Weakness

As the tumour grows, it may compress adjacent cranial nerves, leading to facial numbness, tingling, or muscle weakness.

Headaches

Increased intracranial pressure can lead to headaches in larger tumours. This is more common when the tumour compresses the brainstem or obstructs cerebrospinal fluid flow.

---

Causes and Risk Factors

Genetic Factors

Most cases of acoustic neuroma are sporadic, meaning they occur without a known cause. However, in some instances, they are associated with a genetic disorder called Neurofibromatosis Type II (NF2). Individuals with NF2 are at a higher risk of developing bilateral acoustic neuromas.

Environmental Factors

Limited evidence suggests that environmental factors, such as prolonged exposure to loud noise or radiation, may contribute to the development of acoustic neuromas. However, more research is needed to establish these links.

---

Types of Acoustic Neuroma

Unilateral Acoustic Neuroma

This is the most common type and affects only one ear. It is typically sporadic and not inherited.

Bilateral Acoustic Neuroma

This type is less common and usually associated with Neurofibromatosis Type II (NF2). It affects both ears and is inherited in an autosomal dominant pattern.

---

Diagnosis of Acoustic Neuroma

Hearing Tests

An audiogram can assess the extent of hearing loss and help distinguish between conductive and sensorineural hearing loss.

Imaging Studies

Magnetic Resonance Imaging (MRI) is the gold standard for diagnosing acoustic neuroma. It provides detailed images of the brain and inner ear structures, allowing for precise localisation and measurement of the tumour.

Auditory Brainstem Response (ABR) Testing

ABR testing measures the electrical activity of the auditory nerve and brainstem in response to sound. It can help identify abnormalities in nerve function.

---

Treatment Options for Acoustic Neuroma

Observation

In cases of small, asymptomatic tumours, a "watch and wait" approach may be adopted. Regular MRI scans and hearing tests monitor tumour growth and any progression of symptoms.

Microsurgical Removal

For larger or symptomatic tumours, surgical removal may be necessary. The three main surgical approaches are:

Stereotactic Radiosurgery

Stereotactic radiosurgery, such as Gamma Knife or CyberKnife, delivers focused radiation to the tumour, causing it to shrink or stop growing. This non-invasive treatment is often used for smaller tumours or for patients who are not candidates for surgery.

Fractionated Stereotactic Radiotherapy (FSR)

FSR delivers radiation in smaller doses over several sessions, minimising damage to surrounding tissues. It is an alternative to single-session radiosurgery.

---

Preventing Acoustic Neuroma

Currently, there are no established methods to prevent acoustic neuroma, mainly since most cases occur sporadically. However, early diagnosis and intervention can prevent complications and improve outcomes.

Genetic Counseling

For individuals with a family history of Neurofibromatosis Type II (NF2), genetic counselling and testing may help identify at-risk individuals and guide monitoring and early intervention strategies.

Regular Hearing and Balance Assessments

Regular hearing and balance assessments can help detect early signs of acoustic neuroma, especially in individuals with known risk factors.

---

Living with Acoustic Neuroma

Rehabilitation

After treatment, patients may require rehabilitation to address hearing loss, balance issues, and facial nerve function. Physical therapy, occupational therapy, and speech therapy can aid in recovery and improve quality of life.

Support Groups

Joining support groups for acoustic neuroma patients can provide emotional support, practical advice, and a sense of community. These groups often offer resources and information about living with the condition and managing its effects.

Ongoing Monitoring

Even after successful treatment, ongoing monitoring with regular MRI scans and hearing tests is essential to detect any recurrence or growth of residual tumour tissue.