An acoustic neuroma, also known as a vestibular schwannoma, is a benign (noncancerous) tumor that forms on the vestibular nerve - the main nerve connecting the inner ear to the brain. This nerve plays a key role in both hearing and balance. As the tumor grows, it can put pressure on the nerve, leading to symptoms such as hearing loss, ringing in the ear (tinnitus), and balance difficulties.

Acoustic neuroma symptoms

An acoustic neuroma grows on the nerve that handles hearing and balance. The most common symptoms include:

• hearing loss that gets worse over time (90% of patients experience unilateral hearing loss as a first symptom)

• tinnitus

• ear fullness

• unsteadiness and loss of balance

• dizziness/vertigo

• facial numbness, weakness, tingling or pain

Less common symptoms include:

• frequent headaches

• earache

• visual problems

• fatigue and lack of energy

Acoustic neuroma causes

The cause of an acoustic neuroma is unknown, and the condition is rare and generally affects only a small proportion of the population. As with other brain tumors, there are several risk factors - such as age, family history and any head injuries - which can increase the possibility of a tumor developing.

Around 7% of cases are caused by a rare genetic disorder known as neurofibromatosis type 2 (NF2). This condition typically causes acoustic neuromas that affect both ears at the same time.

Acoustic neuroma diagnosis

Diagnosing an acoustic neuroma can be difficult, as many symptoms mimic a range of other conditions. Similarly, as the first indication is generally hearing loss, an acoustic neuroma is often misdiagnosed and minimized to this particular symptom.

Acoustic neuromas are generally diagnosed with:

• A physical examination: a doctor will examine both the patient’s body and inner ear to check for any other underlying issues.

• A  hearing test (audiogram): generally, the first specific test used to diagnose an acoustic neuroma, an audiogram determines how well patients can hear sounds and speech.

• Balance testing (electronystagmography or ENG): an ENG records electrical activity and is used to measure the brain, eyes and inner ear's response to balance and positioning.

• Imaging (typically an MRI or CT scan): used to determine the size and placement of the tumor, and the best course of action.

Acoustic neuroma treatment

There are three treatment options for patients with an acoustic neuroma. These depend on factors such as the size of the tumor, whether or not it’s growing, any underlying medical conditions, the patient's age and the severity of symptoms.

Treatment options include:

• Monitoring the tumor: acoustic neuromas aren’t generally life-threatening; if the tumor doesn’t appear to be growing, immediate and invasive treatment isn’t always necessary. In these cases, doctors will typically monitor the tumor with regular MRI scans and will treat any symptoms as they occur.

• Brain surgery: a neurosurgeon or EMT surgeon will operate if the tumor is large or if it’s continuing to grow and causing a range of other symptoms. Depending on the size of the tumor, either all or part of it will be removed. While surgery can’t reverse hearing loss, removing the tumor aims to maintain nerve function in the face and preserve existing hearing.

• Stereotactic radiosurgery: a non-invasive procedure directly targeting the tumor without damaging the surrounding tissue. Stereotactic surgery aims to slow the growth of the tumor, rather than to remove it.