Acoustic Neuroma Review

As a healthcare provider, seeing patients with various medical conditions is part and parcel of our daily routine. However, there are certain conditions that are relatively rare, but require keen attention and understanding for effective management should they occur. One such condition is an acoustic neuroma, also known as vestibular schwannoma. In this blog, I will provide insights into what an acoustic neuroma is, its prevalence, clinical presentation, conservative treatment principles, and indications for surgery. Then, if you want to take a deeper dive, I'll provide some of my favourite resources at the end of the this blog. 

Understanding Acoustic Neuroma:

Acoustic neuroma is typically a slow-growing tumor that arises from the Schwann cells of the vestibulocochlear nerve (the 8th cranial nerve). These tumors usually begin at the porus acusticus, where the central nervous system transitions into the peripheral nervous system. While they are often benign, they can slowly grow and compress surrounding structures including the cranial nerves, labyrinth, brainstem, and potentially the cerebellum.

Prevalence:

In the United States, acoustic neuromas are relatively rare, with an estimated incidence of 1 in 100,000 individuals. Annually, there are approximately 2500 to 3000 new cases diagnosed [source], making it a condition that healthcare providers may encounter periodically, but not frequently.

Acoustic Neuroma Signs & Symptoms:

Slow, progressive hearing loss affecting one ear is the most common symptom present at the time of diagnosis. It is also the symptom that generally leads to one seeking medical attention in the first place. Other symptoms can include:
Tinnitus - Especially unilateral
Dizziness, vertigo and/or disequilibrium
Headaches
Facial numbness

On examination, patients present with sensorineural hearing loss (most commonly high frequency hearing loss) and signs of a unilateral vestibular hypofunction that can include, but is not limited to gaze evoked nystagmus, as well as positive hyperventilation and head impulse tests. Depending on the size and location of the tumour there can be other cranial nerve, brainstem, and cerebellum findings.

As far as investigations go, besides hearing tests, MRI also helps confirm the diagnosis and rule out other causes to one's symptoms.

Conservative Treatment Principles:

Given the slow-growing nature of acoustic neuromas, conservative management is often the initial approach. Observation through regular imaging and monitoring of symptoms is typically recommended for small, asymptomatic tumors. For patients experiencing symptoms such as hearing loss or imbalance, vestibular rehabilitation and hearing aids may prove be beneficial. 

Indications for Surgery:

The decision to proceed with surgery is often based on factors such as tumour size, rate of growth, and if the acoustic neuroma poses a threat to vital neurological structures. 

Note: regardless of the treatment performed, hearing typically remains impaired.

Conclusions:

In conclusion, while acoustic neuromas may be relatively rare, they still occur and often require a multidisciplinary approach.

At North 49 we recently saw a patient post operatively after her surgeon excised the majority of the tumour. Her findings included unilateral hearing loss and bedside clinical tests indicative of a vestibular hypofunction effecting the same ear. In this case we have been focusing on adaptation and balance exercises, along with monitoring her return to her regular daily activities.

By providing a comprehensive vestibular program in consultation with her other care providers, we can make a significant difference in her quality of life and others we see who also have this not so common condition.

More Resources:

For more specifics about diagnosis of a vestibular hypofunction and exercise parameters click HERE. 

For a deeper dive HERE is my favourite webpage regarding acoustic neuromas.