Le schwannoma vestibular is a benign intracranial tumor involving the auditory nerve sheath. Its occurrence is responsible for the progressive appearance and unilateral troubles ofhearing and D'balanced.
Today, thanks to the ease of access to imaging IRM and Gamma Knife surgery, the patient with a schwannoma benefits from better care and the risk of recurrence is minimal or even absent.
What is vestibular schwannoma?
Vestibular schwannoma, commonly called acoustic neuroma " is a nerve tumor benign. It is a type of schwannoma which is born within the sheath of the 8th pair of cranial nerves (cochleovestibular nerve).
Histologically speaking, it is an anarchic and abnormally excessive proliferation of the cells forming the sheath of the auditory nerve, called Schwann cells where the name "vestibular schwannoma" comes from.
Unilateral deafness and balance disorders are the most suggestive signs of this tumour. But the clinical picture is all the more varied and polymorphous as the volume of the tumor is important.
From a statistical point of view, schwannoma is found in subjects aged 30 to 60 with a sex ratio equal to 1.
Causes: What would cause vestibular schwannoma?
In the vast majority of cases, the vestibular schwannoma is of origin genetic but not hereditary. Its cause is linked to abnormalities observed in the genetic material (DNA) of Schwann cells. However, in extremely rare cases, estimated at 1%, this tumor is said to be hereditary when it occurs in the context of a hereditary disease called " Neurofibromatosis type 2 where it stands out for its bilaterality.
Moreover, although their interpretation remains debated, certain environmental factors such as chronic exposure to electromagnetic waves and pesticides could be involved in the occurrence of this tumour.
How to recognize vestibular schwannoma?
Depending on the evolution and size of the tumour, the symptoms of schwannoma appear inconsistently and unilateral. Sometimes they may even be absent, especially in the case of small tumors which are most often discovered so fortuitous.
Usually, this tumor is manifested by two types of symptoms: auditory symptoms and vestibular symptoms.
There are two types of deafness: sensorineural hearing loss and conductive hearing loss.
Sensorineural deafness originates sensorineural and originates either from the hair cells of the inner ear or from the auditory nerve. Conductive hearing loss is related to a problem transmitting the sound signal through the outer ear or the middle ear.
In the case of schwannoma, it is a problem of perception due to the development of the tumor in the auditory nerve.
These are noises perceived in the ear and can take the form of buzzing, hissing, hissing, etc. their unilateral and progressive appearance must be the subject of a meticulous investigation in order to confirm or eliminate the presence of a tumour.
Compared to hearing problems, balance disorders are much rarer and are most often of moderate intensity. But it is the fact of becoming chronic and bothersome on a daily basis that pushes the patient to consult.
The larger the tumor, the more likely it is to compress nearby organs. Consequently, it is likely to cause other more or less suggestive symptoms, such as:
- Otalgia or ear pain
- Paresis or sensory disturbances of the face
- Facial nerve palsy
- Swallowing disorders
- Disorders related to brainstem compression
How to diagnose vestibular schwannoma?
The examination that makes it possible to establish the diagnosis of schwannoma with certainty is magnetic resonance imaging (MRI). It's about a MRI of the internal auditory canals (IAC) which not only makes it possible to make the diagnosis thanks to the very precise visualization of the tumor, but also to monitor the evolution of the disease and the effectiveness of the treatment.
CT scan with injection is less sensitive and precise, but can be performed in addition to MRI to provide additional information or help make a differential diagnosis.
Nevertheless, in the diagnostic process, before having recourse to MRI, the patient must benefit from certain functional explorations in a ORL. Some of these explorations include:
The audiogram : which is generally the first examination to be carried out. It detects a drop or asymmetric hearing loss, which is often the hallmark of schwannoma.
Auditory Evoked Potentials (AEP) : come in addition to the audiogram and allow a precise study of the electrical activity of the auditory nerve.
In practice, these examinations are coupled with the videonystagmography (VGN), a set of tests allowing a deeper exploration of the inner ear in its auditory functions and equilibration.
Vestibular schwannoma treatment
Like any tumour, the therapeutic management of neuroma depends on its size, extension and early diagnosis. In the vast majority of cases, the tumor grows very slowly and often requires simple monitoring using MRI imaging.
However, when the volume of the tumor is large enough at its discovery or it increases rapidly as monitoring progresses, several treatment options are possible.
The goal of radiation therapy is to stop the growth of small to medium-sized tumours. The technique used is called Stereotactic Fractionated Radiation Therapy », it allows the X-rays to be focused on the tumor thanks to its precise 3-dimensional location. In order to prevent recurrences, it is advisable to carry out re-irradiations or even resort to other therapeutic options.
Gamma Knife Surgery (GKS)
Thanks to this surgical tool, the schwannoma can be operated on without having to open the cranial box. This is a real breakthrough in the field of neurosurgery in general, and in the treatment of vestibular schwannomas in particular.
Technically, it involves destroying the tumor without scalpel. The intervention consists in sending very precise and powerful Gamma rays on the tumor to cause its necrosis and therefore its death. The advantage is that the operation is done without general anesthesia and lasts depending on the size of the tumor between 10 minutes and 2 hours. The limit is that it only concerns tumors less than 3cm.
La conventional surgery constitutes another therapeutic aspect of schwannoma. It is indicated in the case of compressive tumors in young patients in good general condition.
Depending on the topography of the tumour, surgeons use different approaches. Most often they opt for the trans-labyrinthine way or suprapetrous pathway.
However, despite the total removal of the tumor, there is always a risk of recurrence and iatrogenic deafness (generated by the approach). This is why it is preferable to complete conventional surgery with radiotherapy or Gamma Knife.
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