Understanding Acoustic Neuromas

A neurosurgeon explains that these rare brain tumours are very unlikely to kill you but they can seriously erode hearing & balance

 

For many, the first noticeable problem is a loss of hearing in one ear. Others might feel unsteady on their feet, whilst tinnitus can also act as a calling card.

Many things can cause these symptoms. One fairly rare cause is an acoustic neuroma. Vanderbilt’s Skull Base Center treats more of these tumors than almost any other hospital in the United States. Neurosurgeon Reid C. Thompson, M.D., director of the Vanderbilt Brain Tumour Centre, explains these mysterious growths.

What is an acoustic neuroma?

“An acoustic neuroma is a benign, slow-growing tumour arising from the cranial nerves for hearing and balance,” Thompson said. These tumours grow near the brain stem, in the skull base. The brain stem is part of the brain, extending from the bottom of the brain into the spinal cord. The skull base is the floor of the skull, where the brain rests. Acoustic neuromas are sometimes called vestibular schwannomas.

How common are these tumours?

Acoustic neuromas are rare. In the United States, the Acoustic Neuroma Association has estimated that they affect 3.5 people out of 100,000, with around 5,000 Americans being diagnosed with an acoustic neuroma every year.

If it’s a tumour, does that mean it’s cancerous?

No, acoustic neuromas are not cancer. They’re considered benign tumours — meaning they won’t take your life, and they won’t metastasise (spread) to other parts of the body, like many cancers do. Malignant tumours are fast-growing ones; if you study malignant cells under a microscope, Thompson said, you can see them dividing to produce a new generation of cells. Acoustic neuromas grow far more slowly than malignant cancers.

What symptoms would someone with an acoustic neuroma experience?

Typically the first symptom people notice is a some loss of hearing in one ear, or the onset of tinnitus, which is a ringing, buzzing or other disturbing sound in the ear, which occurs in the absence of any outside sound. Other early symptoms can include having trouble with balance: feeling dizzy or unsteady on your feet or even having difficulty walking.

This is because, though the word “acoustic” refers to sound or hearing, acoustic neuromas don’t actually begin growing along the hearing nerve. Rather, they develop on the vestibular nerve, which controls balance, Thompson said. Four nerves — two vestibular (balance) nerves, the hearing nerve and the nerve that controls movement in the face — are bundled tightly together in that part of the skull. So although acoustic neuromas begin growing along the balance nerve, they typically press against the hearing nerve, causing problems with hearing. The facial nerve is usually draped over the tumour, although it is rare for the facial muscles to be affected.

How are acoustic neuromas treated?

“Usually, the treatment is to not treat them,” Thompson said. This is because these tumours grow slowly and are not life-threatening. But the treatment team will carefully consider many factors when recommending treatment: the size of the tumour, what symptoms or difficulties it’s causing, the age and medical condition of the patient and the pros and cons of treatment. Some people might have a very small tumour but have terrible difficulty walking; another patient might have a larger tumour but fewer symptoms.

“If it’s squashing the brain stem, we’ll treat it,” Thompson said. The brain stem controls important functions such as breathing and heart rate.

There are two main types of interventional treatments for acoustic neuromas. The first is focused radiation, sometimes called stereotactic radiosurgery. This doesn’t actually involve cutting, but rather is it “surgically precise radiation” to destroy the tumour, Thompson said. The second type of treatment is microsurgery to remove the tumour.

For the vast majority of cases, however, directly interventional treatment is not required, and patients will be monitored. Many will also receive additional assistance from occupational and physical therapists, as well as psychologists. These specialists work to help patients manage, relieve and adjust to symptoms such as balance and tinnitus.

How do people usually get diagnosed?

People with acoustic neuromas are typically referred to an ENT specialist (ear, nose and throat) by their GP, because they’ve noticed a hearing problem in one ear. The specialist will usually sends them for an MRI scan and, if the scan reveals a tumour, they patient will be sent for further assessment by either of neurologist or, more typically, a neurological surgeon specialising in skull base problems. If the first symptoms to appear are more to do with movement and balance, the GP may bypass the ENT specialist and refer the patient directly to a neurologist.

Explore more
To read about medication-free, alternative healthcare options, to help manage symptoms of tinnitus, please see here

Source Material:
This primary source of material for this article was provided by the Vanderbildt University Medical Centre news publication ‘My Southern Health.’ It is published here under CCL copyright provisions, and has been updated, edited and added to, in order to account for our readership, which is primarily based in the UK & Europe. First published here on 2nd March, 2018.

 


 

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