Vestibular schwannomas (synonymous with acoustic neuromas) are benign tumours that arise from the hearing and balance nerve. They actually arise from the lining cells of the balance (vestibular) component of this nerve, known as Schwann cells, hence the name.
This picture shows the base of the brain with the cranial nerves emerging from it. The hearing and balance nerve is circled.
Vestibular schwannomas almost always occur as an isolated tumour with no specific risk or predisposing factors. They will usually start growing on the hearing and balance nerve within the internal auditory canal, a narrow canal on the inner aspect of the skull. Due to the confines of this canal, these tumours can cause dysfunction of the hearing and balance nerve whilst still very small (a few millimetres in diameter), and will typically present with hearing loss, tinnitus (abnormal sounds or ringing in the ear), or problems with balance.
Occasionally due to minimal or overlooked symptoms, vestibular schwannomas can go undiagnosed for many years and present when they are significantly bigger. In this situation they have usually grown out of the internal auditory canal into the brain cavity (a region known as the cerebello-pontine angle), and will start to compress the adjacent brain (the cerebellum and brainstem). If brainstem compression is significant, this can cause unsteadiness and clumsiness of the limbs. Other symptoms that can arise from vestibular schwannomas include altered facial sensation, hydrocephalus and swallowing difficulties.
This scan shows a horizontal cross section through the brain at the level where the hearing and balance nerves run from the inner ear to the brain.
The growth pattern of vestibular schwannomas is very variable. Up to 60% of them do not exhibit growth after being diagnosed, even though they must obviously have grown at some point in order to present. For this reason, they can often be safely monitored without any intervention for many years on end. This will only be the case for small and medium size tumours without any significant brain compression.
The “watch, wait and rescan” management option is recommended in the majority of people with a newly diagnosed vestibular schwannoma. The characteristic regime for monitoring a vestibular schwannoma is as follows:
If a tumour remains static, then it is very likely that it will simply remain on this surveillance regime. If there is growth, then a decision will be made as to whether active treatment should be pursued, or whether further surveillance should be undertaken to ensure that the growth is persistent. The size of the tumour will be an important factor in this decision. The treatment options are covered in greater detail in the vestibular schwannoma treatment section of the website.
Whether or not a vestibular schwannoma is growing may have little effect on the severity or progression of symptoms. This is particularly true for hearing loss and tinnitus. If you still have useful hearing in the affected ear, your surgeon will have an in-depth discussion with you about which management strategy is likely to offer you the best chance of preserving your hearing.
The management of your tumour will not only be discussed between you and your surgeon, but also at a Skull Base Multidisciplinary Team (MDT) Meeting. These are held fortnightly at Salford Royal Hospital, with a team of experts with a huge combined experience of managing such problems. Your surgeon will convey the outcome and recommendations of this meeting to you. Whilst this will provide you with all the information you require about your vestibular schwannoma, as well as a detailed analysis of the advantages and disadvantages of all management options, the most important factor in the final decision is you. Your personal opinion of what is best for you is undoubtedly the most relevant aspect of how you will be managed.