How Radiotherapy Can Help Treat An Acoustic Neuroma

An acoustic neuroma is a kind of tumour that is specifically found in the inner ear. Also known as a vestibular schwannoma, it is benign (non-cancerous), but it can still bring significant problems for patients.

The tumour is often not diagnosed until it is of significant size, because, as is characteristic of benign tumours, the rate of growth is very slow and symptoms may not appear until it is quite large.

Symptoms Of Acoustic Neuromas

A tumour can arise from Schwann cells of the vestibular portion of the vestibulocochlear nerve (cranial nerve VIII) within the internal auditory canal/cerebellopontine angle.

Due to its location, it can have the effect of hampering the delicate systems in the inner ear that regulate balance and hearing. This can result in multiple problems, with a loss of balance and accompanying dizziness being a common symptom of vertigo.

A loss of hearing can be caused not by the tumour blocking the ear canal as such, but by expanding to place pressure on the vestibular nerve, which carries signals between the brain and inner ear. By interrupting these signals, hearing is lost.

A third problem can be tinnitus, which manifests in whooshing, buzzing or tapping sounds inside the ear.

If the tumour grows to a sufficiently large size, it can also press on facial muscles and cause loss of feeling, or place pressure on the brain stem, at which point it can become life-threatening.

When Surgery Is Sometimes Not An Option

In many cases, surgery is possible to remove at least part of the tumour, although this does carry the risk of permanent damage to the inner ear and vestibular nerve and a consequent loss of hearing. Nerves controlling facial movement may also be damaged.

However, in some cases, the tumour is sufficiently large and located in such a difficult position that it is inoperable, particularly if attempting to excise it would pose a direct threat to the brain stem. It is at this point that the one effective option for acoustic neuroma treatment remaining is radiotherapy.

A high-profile case is that of TV presenter Kirsty Gallacher, who recently revealed she has been suffering from an acoustic neuroma. This first became apparent when she lost her hearing in one ear in 2021. It was quickly diagnosed, but it is inoperable because it is located so deep in the inner ear canal that it presents a very high surgical risk.

Consequently, she revealed, she is to start radiotherapy treatment in November, aiming to shrink the tumour.

How Radiotherapy Treats Acoustic Neuromas

The way radiotherapy works on a benign tumour like an acoustic neuroma is essentially the same as with a malignant (cancerous) one. The high dosage of radiotherapy directed at the tumour will damage its DNA and break down the capacity of the tumour cells to divide.

This effect is true for all cells, not just cancerous cells.  While the human body can withstand low levels of radiation, high levels can cause cell death. That is why uncontrolled exposure can be dangerous. In the case of radiotherapy, however, the level and location of radiation exposure are strictly controlled.

Whereas a benign tumour grows because cells do not die when they should and multiply faster than normal, the radiation damage inflicted on the cells reverses the process, causing cell death and preventing replication.

Because the tumour is not cancerous, the dose of radiation does not need to be as high as it would be for a malignant tumour.

Why Stereotactic Radiotherapy Is Used

Stereotactic radiotherapy is the type that will be used for any tumour lying very close to the brain. This is the most precise means of delivering radiation to specific locations while sparing surrounding tissue from exposure as much as possible, which is a high priority in a tumour on or close to the brain.

Although we use the most precise devices available to deliver the radiation in the most accurate way, it is not possible to completely avoid exposure to surrounding tissue. This means that patients undergoing radiotherapy are still likely to suffer from some side effects.

Patients likely to benefit include:

- Those with small to medium vestibular schwannomas on MRI
- Those prioritising hearing preservation and a day-case, non-invasive option
- Older adults or those at higher surgical risk
- Residual or recurrent tumour after prior surgery

Side Effects And Aftercare

These can include symptoms such as transient fatigue/headache, temporary tumour swelling, hearing change, tinnitus fluctuation, balance disturbance, rare facial or trigeminal nerve dysfunction, and very uncommon radiation-induced complications.

However, because the radiation dosage is lower for benign tumours, the symptoms will usually be milder than those experienced by patients undergoing higher dosage radiotherapy.

Furthermore, the side effects are temporary and will ease off once the treatment ends. For example, if you have lost hair or your appetite has diminished, you will soon see them start to return.

If you need radiotherapy treatment for an acoustic neuroma, it is natural to feel apprehensive, as you might before any medical procedure.

However, our skilled team will be on hand to offer reassurance, inform you of everything that is involved and ensure you get the best possible aftercare.

Learn more about our advanced radiotherapy and neurosurgical treatments for acoustic neuromas on the Queen Square website.