Acoustic neuroma treatment
Acoustic neuroma (so-called vestibular schwannoma) is a benign tumour that arises from the nerve responsible for hearing and balance. A formation on one side happens more frequently, and the actual reasons remain unknown. However, bilateral tumours are often associated with neurofibromatosis. Stereotactic radiosurgery is the main treatment. In some cases, neurosurgery or monitoring may be necessary.
Acoustic neuroma is a benign and slow-growing auditory nerve tumour that originates in the brain. The lump is also called vestibular schwannoma because it develops from Schwann cells. These special cells envelop the nerves and participate in the transmission of impulses along the nerve fibres.
Neurinomas are noncancerous, so-called benign tumours. They are unable to spread to other parts of the body. However, in rare cases, the neoplasm multiplies and becomes large enough to start squeezing the surrounding structures. This condition represents about 8% of all brain tumours (about 1 in 100,000 people). This neoplasm might get people of any age and sex. But the median age at diagnosis is 40 years.
Neurosurgeons classify neuromas as:
- Small (up to 15 mm).
- Medium (from 15 to 30 mm).
- Large (from 30 to 40 mm).
- Huge (more than 40 mm).
- One-sided (unilateral) - the more common type, when only one ear is involved.
- Double-sided (bilateral) - the tumour affects both ears (is usually hereditary).
Often vestibular schwannomas accompany a genetic disease - neurofibromatosis (multiple tumours throughout the body). For example, a bilateral lump is characteristic of neurofibromatosis type 2 (about 5% of people with NF2 have acoustic neuromas).
Many neuromas take a long time to grow, several years. Some, having reached a small size, stop growing. Nevertheless, they can assert themselves as they pressure critical surrounding brain tissues. Sometimes the tumour of the acoustic nerve causes facial nerve compression, which provides sensation and facial movement. The large lumps can also affect other nerves and brain cells responsible for eye movements, swallowing or speech.
Causes of a tumour in the auditory nerve
Most often, schwannoma occurs abruptly, with no apparent cause. However, a specific group of people are at high risk (those with NF2). In addition, scientists have discovered that a gene mutation might be a reason for the disease. Other possible sources of increased risk are:
- Constant exposure to loud noise (e.g. in a factory);
- Trauma or radiation to the head or neck.
What are the signs of Schwannoma?
Sometimes, before the tumour causes symptoms, it can grow for several years. Typical signs of a neuroma:
- Ringing in the ear;
- Ear congestion;
- Loss of balance (patients tend to fall to the side of the tumour);
- A feeling of a foreign thing in the ear;
- Decrease or loss of hearing.
Hearing problems can come suddenly or gradually, on one side (more often, it takes 90%) or on both sides.
The pressure of the lump on adjacent parts of the brain, nerves and blood vessels can provoke symptoms such as vertigo, facial numbness or tingling. Compression of the brainstem leads to blockage of the flow of CSF, which causes fluid accumulation in the brain (hydrocephalus). Added headache, nausea and vomiting, loss of vision, and swallowing problems.
How are auditory nerve tumours diagnosed?
The neurologist collects a detailed patient's medical history, complaints, and family history. After that, the doctor conducts a neurological examination. Usually, the first doctor who suspects the disease is an otolaryngologist. That is due to the prevalence of typical ENT symptoms. The main diagnostic methods are instrumental, take 1-2 days in the clinic and include:
Audiogram - is a hearing study. With the help of headphones and various sounds, the physician determines the problem (side and level of hearing loss). Since the tumour often causes hearing loss, patients turn to an ENT doctor. So, as a rule, an audiogram is the first study in a series of neuroma diagnostics.
Magnetic resonance imaging (MRI) or computed tomography (CT) of the head. Imaging is the best method for diagnosing acoustic neuromas. MRI technique is painless and uses radio waves and a magnetic field to image the brain. Usually, doctors recommend an MRI with contrast (a substance injected intravenously); it is more informative. However, if an MRI is not possible, a CT scan using x-rays is the way of choice.
Other practical methods include:
- Electronystagmography - balance check. The test assesses the presence of involuntary eye movements (nystagmus).
- Brainstem auditory evoked response (BAER) tests the brain's response to certain sounds.
Imaging techniques are fundamental, as they recognize the location and size of the tumour. That influences the planning of surgical or radiological treatment.
Treatment options for acoustic neuroma
A neurologist or neurosurgeon makes a proper treatment plan. Doctors identify the following primary treatment options for acoustic tumours: active surveillance, microsurgery, and radiation therapy.
Small tumours are often discovered incidentally, and if they do not interfere with everyday life, they do not require treatment, only observation by doctors and MRI monitoring every 6-12 months. Active surveillance is applied to tumours of small size and in the absence of symptoms of the disease. Patients should undergo other strategies if some neurological, ear, or eye symptoms occur or the scan shows a tumour increase.
Neurosurgery is helpful for advanced tumours and generates warning signs in the patient. Therefore brain surgeons usually choose less invasive surgery for acoustic neuromas than traditional brain tumours. The type of operation depends on the size and the exact place of the tumour. The microsurgical procedure is performed in several ways: rectosigmoid and translabyrinthine approaches (incision behind the ear) and access to the middle fossa (incision above the ear). Such surgeries have a lower risk of postoperative complications than open access operations. If there is a risk of damaging adjacent tissues during surgery, the neurosurgeon decides to remove only a part of the tumour. At the same time, some symptoms go away, and the patient's condition improves as the pressure on neighbouring structures decreases.
Neurosurgical operation of a neuroma is associated with risks. Therefore, the most modern method of tumour treatment is stereotactic radiation therapy. This kind of treatment is indicated for large tumours or when the patient has surgery-related contraindications.
Radiosurgery with CyberKnife. It is a non-surgical effect of a beam of gamma rays on the cells without touching healthy tissues. CyberKnife works from a distance; the patient does not need to make an incision or lean the device against the skin. The procedure is carried out without anaesthesia. Instead, a special apparatus forms a model of the brain, accurately determines the tumour's location and sends a high dose of radiation there. After CyberKnife treatment, the neuroma stops growing and decreases in size.
Intensity-modulated radiotherapy (IMRT). An advanced technique in schwannoma treatment. It is similar to the previous method but has a higher radiation dose. It allows for reducing the number of sessions and speeding up the treatment. IMRI is performed by a team of doctors (neurologist, radiation therapist, medical physicist). An additional innovative and safest method of targeting the tumour is proton beam therapy. Accelerated beams of protons are delivered to the affected area, forcing the neuroma to shrink.
Supportive care is in addition to the primary treatment. Frequently, patients suffering from Schwannomas might have hearing loss. Therefore, doctors recommend installing cochlear implants to improve hearing.
Although the neuroma's location can have an unfavourable course and consequences, the overall prognosis is generally good. Schwannomas usually respond well to treatment and can be cured completely. Survivorship after adequate treatment is about 99.5%.
Approximately 74-88% of patients retain their hearing after surgery, but in other circumstances, there is a complication in the form of hearing loss. However, relapses rarely but can occur (about 5 cases per 100 acoustic neuromas).
What are the latest surgical approaches for vestibular schwannoma?
The best treatment method is the microsurgical removal of vestibular schwannoma. The technique includes retrosigmoid, translabyrinthine, and middle fossa craniotomies. Neurosurgeons will choose the approach depending on the tumour's location and extent.
Is surgery the best option for acoustic neuroma?
To date, the best option for removing acoustic neuroma is stereotactic radiosurgery. It includes CyberKnife, intensity-modulated radiotherapy and proton therapy. The success rate of these procedures is over 90%. However, schwannoma surgery can be used in some instances.
What is the success rate for acoustic neuroma surgery?
The outlook for acoustic neuroma is more than favourable. The mortality rate is low at 0.5%. It means that the survival rate after tumour removal is kept at 99.5%.
Can I treat a vestibular schwannoma without surgery?
Yes, sure. Radiologists and neurologists treat most vestibular schwannoma with modern non-surgical methods. Stereotactic radiation therapy is the most commonly used. This option has several advantages over neurosurgery: a higher success rate and a lower risk of hearing loss.
Is treatment abroad for vestibular schwannomas more effective?
Definitely yes. Treatment of vestibular schwannomas abroad has many advantages. Among them: are leading specialized hospitals with the latest equipment, doctors who undergo international practice and advanced training courses, and fast and painless effective therapy. In addition, proton beam therapy (the most innovative option) is available only in a few clinics abroad.
Where can I get Acoustic neuroma treatment?
What are the best clinics for Acoustic neuroma treatment?
Who are the best doctors for Acoustic neuroma?
Prof. Dr. med. Alexander Muacevic from European Radiosurgery Centre Munich
Prof. Dr. med. Bernhard Meyer from University Hospital rechts der Isar Munich
Dr. med. Peter Madjurov from Academic Hospital Bundeswehr Berlin
Prof. Dr. med. Thomas Gasser from Beta Clinic Bonn
Prof. Dr. med. Marcus Czabanka from University Hospital Frankfurt am Main of Goethe-University