Treatment of schwannomas: observation, surgery if necessary + other methods

If the tumour is small in size and does not compress any important brain structures, frequent monitoring with MRI and regular audiometry is appropriate without any therapeutic intervention.

Any treatment is associated with complications and side effects that may even slightly worsen the patient's neurological condition. It is therefore necessary to consider the risk-benefit ratio.

However, if the tumour is already too large, treatment is resorted to. There are several methods to either remove the tumour or stop its growth.

The main methods of treating acoustic neuroma include:

• Neurosurgery
• Stereotactic radiosurgery
• Stereotactic radiotherapy

When deciding whether invasive surgery or a non-invasive method is appropriate, the patient's overall health, age, and the location or size of the tumor are taken into account.

Neurosurgery

This is an invasive procedure which aims to remove all or at least a substantial part of the tumour. The operation is performed under general anaesthesia. The success rate is relatively high. Approximately 90% of tumours are removed.

If the tumour cannot be completely removed because of its complicated localisation or high risk of permanent sequelae, only part of the tumour is removed.

The rest of the tissue left behind is treated with radiotherapy, which stops the growth of the rest of the tumour. This prevents it from starting to press on important brain structures again.

During surgery, the most serious risk is damage to the statoacoustic nerve with permanent and irreversible hearing loss and damage to the facial nerve, which is in close proximity.

Damage to this nerve, the n. facialis, will result in paralysis of the facial muscles of the midface. This condition is very difficult to rehabilitate. Patients are left with permanent sequelae.

Another risk is damage to the brain stem, which can be fatal.

To avoid these risks, neurosurgeons use perioperative neuromonitoring.

Radiotherapy methods

Radiotherapy is a non-invasive method of treatment. It does not break the patient's skin covering and the treatment is applied externally. It is used to treat both malignant and benign tumours.

Radiotherapy is applied to stop the growth of the tumour, which may even shrink.

It involves irradiating a specific area with ionising, radioactive radiation. This radiation interferes with the cell growth of the tumour. As a result, the tumour cells stop multiplying and begin to die.

Stereotactic radiosurgery

In stereotactic radiosurgery, the site of the tumor is irradiated with a high dose of radiation, a specially cut beam, in a single shot with minimal impact on the surrounding healthy brain tissue.

Thin irradiation beams are directed at the target from different directions. They spare the surrounding structures and create an intersection of these high-dose beams in the tumour.

Various modern devices are used to treat brain tumours using stereotactic radiosurgery. For example, the CyberKnife®, which uses a robotic arm, the Gamma Knife or the LINAC linear accelerator.

The difference between them is in the types of radiation they produce. The CyberKnife uses artificially produced ionising radiation. The Gamma Knife uses a natural source of ionising radiation, which is cobalt.

The linear accelerator uses the radiation that is produced when fast flying electrons are braked.

The aim of the procedure is to prevent further growth of the neuroma. Remnants of hearing are preserved and the optic nerve is bypassed, thus preserving vision. It is also used as a post-operative treatment for tumours that have not been completely removed.

The basic step in initiating treatment is to locate the tumour site and fix it with a stereotactic ring.

The stereotactic ring is fixed to the patient's head. It is fixed with four carbon screws with titanium tips directly to the bones of the skull.

Such a ring is most often made of titanium or ceramic. This material does not form so-called artefacts on computed tomography (CT) imaging.

Consistent fixation is essential for correct irradiation of the small tumour deposit. The patient does not move a millimetre, which minimises the risk of healthy tissue being affected.

Stereotactic irradiation takes approximately 30-60 minutes. After removal of the stereotactic ring, the treated patient remains hospitalized for 1 to 2 days, depending on the patient's clinical condition.

This special irradiation is only available in highly specialised oncology departments.

Stereotactic radiotherapy

If the tumour is located near critical structures (brain stem, visual structures, hypothalamus), repeated stereotactic irradiation is performed in smaller doses about 3-7 times.

This prevents high doses of radiation from damaging surrounding healthy critical structures.

The treatment lasts 3-5 days and is well tolerated by patients.

Of course, this treatment has a number of side effects, including hair loss, skin irritation, and neurological problems due to low absorption of radiation by healthy parts of the brain.