The Neuroma of Acoustics
The neuroma of acoustics is a benign nervous tumor that develops on the vestibular nerve, that is to say the nerve responsible for the balance. This nerve is located inside the cranium, very close to the auditory nerve, with which it creates what is called the cochleo-vestibular nerve, or the cranial nerve.
The vestibular nerve emerges from the brain, and more precisely from the cerebral trunk, into the internal auditory canal. It is on the path between the brainstem and the inner ear that a neuroma of the acoustic can develop.
Neuroma usually occurs as a small tumor mass inside the inner ear, and can extend into the brain. Early diagnosis and appropriate management make it possible to monitor its progress.
Generally, this tumor affects people between 40 and 60 years of age, but can also affect younger patients.
Most of the time, the neurinoma is unilateral and therefore involves only one side. However, in rare cases, patients develop an acoustic neuroma on both sides. It is then necessary to make additional examinations to look for a possible genetic disease (rare), neurofibromatosis type 2.
When the diagnosis of acoustic neuroma is established, the physician who takes care of the patient is an ENT physician or a surgeon of the face and neck.
The exact causes of acoustic neuroma are not known. If genetic factors probably have a weight in the genesis of this benign non-cancerous, they have not yet been defined.
The neuroma of acoustics develops in the cells of the sheath of nerve fibers which surround the vestibular nerve, and which are called Schwann cells. The scientific name of this benign tumor is the “vestibular Schwannoma”.
If we have not yet identified the causes, the intrinsic factors responsible for the development of an acoustic neuroma, extrinsic factors have been suspected.
Although this has not yet been confirmed, several recent studies have shown that excessive use of mobile phones and exposure to radiation from these devices could favor the development of an acoustic neuroma.
It has not yet been established with certainty that the mobile phone can be the cause of a harmful effect on health. However, it is advisable to avoid long conversations by placing the device in strict contact with the ear as a precautionary measure. In case of doubt, it is advisable to use headsets or a hands-free kit, in order to avoid direct contact of the phone with the head.
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The neuroma of the acoustic reaches the nerve of the balance (vestibular nerve). However, rarely the people who suffer from it exhibit disturbances of balance. And this is because the vestibular nerve is affected by the tumor in such a slow and gradual manner that patients do not have time to feel real vertigo. And even when they start having balance problems, their body will compensate as it can.
The first symptoms of acoustic neuroma will be caused by compression of the auditory nerve; this will lead to progressive unilateral deafness, a gradual decrease in unilateral hearing.
Of tinnitus unilateral can also occur, and be a sign of developing a neuroma. Tinnitus is a fairly common hearing disorder, but usually affects both ears. If these buzzing occurs only on one side, they may be the symptom of an acoustic neuroma.
Often the hearing loss and buzzing are associated.
It is very rare that this benign nervous tumor manifests itself by a brutal deafness: this represents less than 10% of cases of acoustic neuroma. In this case, the patient presents a sudden and sudden loss of hearing.
Sometimes, in rare cases, dizziness and balance disorders can also be symptoms that manifest themselves.
If the doctor suspects the presence of an acoustic neuroma, he will examine the patient’s ear. In order to identify the cause of the decline in hearing loss, the clinical examination will be followed by a hearing test. In the presence of this benign tumor, this test will reveal a particular deafness, deafness of perception, which indicates that the inner ear does not work anymore and that the problem lies in the auditory nerve.
If this perception is unilateral, it will be necessary to proceed with a complementary examination, the MRI, which will show exactly what is going on in the deep ear, the possible presence of a neurinoma, its exact location and its size. All these elements will make it possible to establish a precise diagnosis on the neuroma of the acoustic, to decide the treatment.
The evolution of the tumor
The neuroma of the acoustic is a rather “capricious” tumor that can evolve very differently according to the patients.
In some people the tumor remains stable, and hardly grows. About one in two cases, the tumor progresses, increasing in volume slowly: it takes about one or two millimeters per year. In other rare cases, the tumor grows very rapidly. In others, very rare also, the tumor may regress spontaneously.
When an acoustic neuroma grows, it can cause brain damage, but it really takes a long time, due to the slow development of the tumor.
Once the diagnosis of acoustic neuroma is made, three treatment alternatives are possible to treat the tumor.
A simple monitoring of the neuroma is sometimes offered to the patient. When the size of the benign tumor is minimal, it is usually monitored. There are possibilities that it does not increase. An MRI is then carried out every six months, to check the possible evolution of the lesion. If after one year the tumor does not increase in size, it will continue to be monitored by performing an annual MRI without special treatment.
The second therapeutic possibility consists in surgical treatment: we intervene to surgically remove the tumor. The intervention, carried out by a team of otourosurgeons, is very delicate and presents risks. The greater the lesion, the greater the risk. During surgery, one can damage the facial nerve, which allows the facial movements, causing facial paralysis. There is also a risk of partial or total loss of hearing due to the proximity of the vestibular and auditory nerves.
The third type of treatment is radiation therapy. In this case, the principle is not to remove the tumor, but rather to stop the development process, stabilize it and prevent it from growing. Currently, the two reference techniques for radiotherapy of acoustic neuroma are the gamma knife and the cyber knife, two devices using high-precision irradiation methods.
Thanks to these devices, it is possible to organize targeted radiotherapy treatments of these benign tumors, in order not to irradiate the surrounding healthy tissues.
The risks of radiotherapy concern the possibility of damaging the auditory nerve, the facial nerve and the brain cells that are near the tumor. But this risk remains lower than with surgery. There is also a low risk of cancer induced by radiotherapy that can occur several years after irradiation.
In general, the focus will be on radiotherapy for slightly older patients and surgery for younger patients. The decision regarding acoustic neuroma treatments will be made on a case-by-case basis by the specialist and the patient who will be informed of the advantages and disadvantages of each of the treatment options.