Vestibular schwannoma
Vestibular schwannoma
Vestibular schwannoma is a benign tumour that arises from cells that surround the fibres of the cochleovestibular nerve, which transmits information from the inner ear to the central nervous system.
In the Czech Republic, about 200-400 people get sick with this type of tumour every year. Its most common manifestations include unilateral hearing impairment, tinnitus, and balance impairment. Hearing loss tends to be progressive and inconspicuous at first, and may first manifest itself, for example, when talking on the phone.
Over time, difficulties with localisation of sound and understanding speech in a noisy environment appear. Eventually, there may be complete hearing loss on the affected side.
Difficulties in the sense of dizziness or instability affect approximately half of the patients, but tend to be of a mild nature. Really large tumours can also manifest themselves with other neurological symptoms, especially impaired sensitivity of the face, headaches, deterioration of vision, mobility, speech, and, in the worst case, impaired consciousness.
Large schwannomas can threaten the patient by oppressing the cerebellum and brainstem, where the centres of basic vital functions and coordination
of movements are located. Furthermore, the circulation of cerebrospinal fluid may deteriorate.
However, due to modern diagnostic methods and the slow growth of the tumour, the vast majority of patients are detected in time and an adequate therapeutic procedure occurs before the development of these
life-threatening conditions.
Diagnosis is based on clinical manifestations and hearing examination. If the
presence of this tumour is suspected, an imaging examination (magnetic resonance) is added to confirm the finding and determine the stage of the disease.
Treatment options
Patients with vestibular schwannoma come to a specialised consultation room, where the nature of the disease and its treatment are explained to them. Together with the patient, the doctor then chooses the most suitable procedure. Nowadays, there are three basic therapeutic approaches: monitoring (“wait and scan”), microsurgical removal of the tumour, and stereotactic radiotherapy. The size of the tumour and its growth activity, the condition of the hearing and balance system, the patient’s age, his general health, and the patient’s preferences play a role in the decision. The choice of a treatment procedure is therefore a complex and individual process, and the optimal procedure cannot be determined in advance without a proper examination.
Follow-up “wait and scan” – we choose in patients with a smaller tumour, without hearing impairment, or in patients for whom surgery would be too risky. We perform control (repeated) magnetic resonance imaging and hearing assessment. The first imaging examination will most often take place 6 months after diagnosis. If the tumour does not grow during this period
of time, the patient is monitored by magnetic resonance at regular annual intervals
for a minimum of 3 years. If the tumour continues to grow, we can consider extending the follow-up interval.
Stereoradiotherapy – targeted application (single session) of a high dose of ionising radiation to the tumour area to stop its growth. One of the most commonly used systems is Leksell’s Gamma knife and CyberKnife. The advantage of this modality is the short duration of treatment without the need for general anaesthesia. In the case of vestibular schwannomas, we choose this procedure for small and medium-sized growing tumours. Irradiation does not remove the tumour, its growth activity is stabilised.
Microsurgical resection, its goal is radical removal of the tumour under microscopic control. It is indicated primarily for more advanced and growing tumours. For small tumours, we indicate surgery if we are trying to save deteriorating hearing or improve balance problems. It is a procedure under general anaesthesia in which doctors specialising in otorhinolaryngology and neurosurgery collaborate. During the procedure, surgeons try to preserve the function of the adjacent structures as much as possible, especially the facial nerve and, in case of favourable hearing, also the auditory nerve.
Surgical treatment
Before the operation, the patient is examined and informed. A detailed hearing and balance examination is necessary to perform the surgery correctly. Based on the results of the examination, the most suitable surgical approach is selected after consultation with the patient. At the same time, the patient is informed about the method of postoperative balance rehabilitation.
For the operation itself, it is necessary to shave a narrow strip of hair behind the ear on the affected side. The procedure is performed under general anaesthesia under the guidance of a specialised anesthesiologist who is a permanent part of our team. Vascular accesses are established and the patient is connected to vital signs monitoring systems. Electrodes are also placed to detect the function of individual cranial nerves near which the surgical team moves. This is mainly the facial nerve, and in some cases also the auditory nerve. Depending on the size of the tumours, we can also monitor other nerves and nerve pathways.
The operation itself is performed by a multidisciplinary team of otorhinolaryngologist and neurosurgeon. From an approx. 5-8 cm ace-shaped incision behind the ear, it is first necessary to create a path to the tumour through the skull bones. The tumour is then radically removed from the pons and the internal auditory canal under magnification using a digital microscope with a three-dimensional image, which enables a perfect view not only for the operator himself, but also for other members of the operating team. An ultrasound aspirator is used to shrink the tumour, followed by a number of highly specialised micro-instruments for the preparation itself.
After the operation, the patient awakens directly in the operating room, in the case of a long procedure with an interval of a maximum of several hours in the
anesthesiology-resuscitation department. A rest is mandatory on the first postoperative day, and rehabilitation is started under the guidance of a physiotherapist on the second postoperative day.
Rehabilitation
Postoperative rehabilitation focusses mainly on balance and hearing. During radical surgery, the balance nerve from which the tumour grows must be cut. This results in varying degrees of imbalance in patients. With well-planned rehabilitation, in most cases the balance disorder can be very well compensated for by strengthening other components of the balance system. However, early rehabilitation is important under
the guidance of an experienced rehabilitation worker. We usually use virtual reality in these situations, which helps patients manage previously common but now problematic situations, such as riding on escalators or driving a car.
In the event that patients no longer hear in the affected ear, compensation can be accelerated even before surgery by applying an ototoxic antibiotic to the middle ear. This will gradually eliminate the balance apparatus on the affected side. With targeted exercises, the patient achieves compensation of the balance system before surgery, and the postoperative period is then less burdensome for him.
The most common symptom of vestibular schwannoma is hearing impairment. All treatments carry the risk of further hearing loss. There are several ways, how to deal with the hearing loss in affected patients. The simplest method is a hearing aid that acts as a sound amplifier. If the ear is already deaf, different systems can be used to transfer sounds from the deaf side to the hearing side. Two hearing aids that communicate with each other (CROS) or a bone hearing aid that stimulates the inner ear
of the healthy side (BAHD) can be used (Fig). If the auditory nerve is preserved during the operation, then a cochlear implant can also be used. It is the only method that can restore full hearing to the affected party in this case. In case of hereditary occurence of vestibular schwannoma
(Neurofibromatosis type 2) and bilateral deafness, we can consider auditory brainstem implant.
Workplace
The multidisciplinary treatment programme for vestibular schwannoma patients has been running in the Department of Otorhinolaryngology and Head and Neck Surgery of the 1st Faculty of Medicine of the UK and the FN in Motol since 1998. It is the only workplace in the Czech Republic that offers comprehensive treatment from diagnostics to postoperative rehabilitation. The number of more than 700 operated patients ranks us first among surgical workplaces. We perform surgeries in cooperation with the Neurosurgery Clinic of the 2nd Faculty of Medicine of the UK and the Motol Medical Centre. Close cooperation between an otolaryngologist and a neurosurgeon is completely unique in this area in the Czech Republic and gives our patients the benefits of both expertise.
