According to WHO statistics, auditory nerve neuroma is detected on average in one person for every 100 thousand subjects. This pathology occupies about 12% of all neoplasms of the brain. This disease is found in both young patients and elderly people, but recently such an ailment has been increasingly diagnosed in people from 30 to 40 years old. In addition, it was noted that neurinoma is almost never found in children, but in women it is diagnosed three times more often than in men.
What it is
Neuromas are tumors of the auditory nerve, which are benign neoplasms formed from cells of the Schwann membrane. That is why their second name is schwannomas. Despite the specific name, this pathology does not affect the auditory nerve, consisting of a pair of roots with different physiological purposes: the cochlear is responsible for the transmission of auditory signals to the brain, and the vestibular - for the sense of balance. It is in the tissues of the vestibular root that schwannoma is formed.
According to medical reviews, auditory nerve neuromas look like a dense nodular formation with a tuberous surface. Sometimes in the tissues of this formation there are small cystic cavities with fluid inside.
Despite the fact that neuromas develop slowly and do not spread to neighboring organs, the appearance of these pathologies can significantly worsen the quality of life and the condition of the patient. They lead to hearing loss and impaired functioning of the vestibular apparatus. Very often, with this disease, the facial (trigeminal) nerve is affected.
Although neuromas of the auditory nerve do not belong to cancer, they can be dangerous to human health. Growing to large sizes, one or several neoplasms at once begin to put pressure on the brain stem. As a result, the patient begins to feel constant headaches (in extremely rare cases, disturbances in clarity of consciousness are possible).
Reasons for the appearance
The exact reasons for the development of this pathology have not yet been established, as are the unknown factors that affect the development of auditory nerve neuroma. However, according to many researchers, one of the causes of a tumor is a genetic predisposition.
Risk factors
The only scientifically based risk factor, experts call a genetically determined pathology - type II neurofibromatosis. For this disease, the formation of benign tumor processes in various tissues of the nervous system is typical (for example, the appearance of neurofibromas, gliomas, meningiomas or neurin).
Morphology of neuromas
Macroscopically, auditory nerve neurinoma looks like a rounded or irregularly shaped nodular formation with a tuberous surface. Outside it is covered with connective tissue, and cystic formations filled with a brownish liquid are often found inside. The color on the cut is determined by the quality of blood supply: under normal conditions - pale pink, with stagnation - cyanotic, with hemorrhage in the tissue of the resulting node - brown.
Microscopic examination consists of cells whose nuclei are similar in shape to rods. With the growth of neurinoma, fibrosis and hemosiderin deposits are observed inside it.
Symptoms of the auditory nerve neuroma
The development of this disease can occur in different scenarios. In some cases, a tumor develops up to one and a half centimeters in diameter, but at the same time does not interfere with a person's usual life. With this course of the disease, removal of the auditory nerve neuroma is not required: it is enough to control its condition here by visiting a specialist once a year.
In other cases, the tumor grows significantly and begins to affect the root of the auditory nerve or even the brain stem. In this case, the following changes occur in the patient's body:
- gradual or sudden hearing loss in one ear;
- ringing is heard in the ear (tinnitus);
- ear congestion is felt;
- problems with balance begin (instability and dizziness);
- there is a feeling of numbness and tingling on the face (from the affected area);
- in severe cases, paralysis of the facial or abducent nerve may appear;
- visual impairment may begin, as well as difficulties in chewing food and swallowing it;
- dull or aching headache (usually observed in the late stages of neurinoma).
With such symptoms of auditory nerve neuroma, treatment is often a vital step, but many people mistakenly associate them with age-related changes and ignore these manifestations.
Over time, schwannomas increasing in size lead to a complete loss of the auditory nerve functions from the side of the lesion and disturbances of the vestibular apparatus.
In addition, irreversible manifestations of a cut of the facial (trigeminal) nerve are possible. The pain accompanying this process over time becomes permanent. In some cases, the patient takes them for a toothache. However, as the neoplasm grows in the tissues of the vestibular root, peripheral lesions of the trigeminal and abducent nerves occur, manifesting as:
- paresis of the muscles involved in facial expressions;
- asymmetries of the face;
- strabismus;
- loss of taste and other symptoms.
Pathogenesis of neoplasm
Specialists distinguish three stages of the tumor process that occurs in the tissues of the vestibular root:
- Initial stage. The diameter of the neoplasm does not exceed 2.0 cm. In this case, the patient notes hearing impairment and the vestibular apparatus. Mild facial nerve damage may occur.
- Second stage. Education grows larger and reaches the size of a walnut. Clinical manifestations of neurinoma become more pronounced: hearing and coordination disorders become more severe, severe headaches are added. Sometimes such manifestations are accompanied by nausea and vomiting.
- The last stage. The tumor reaches the size of a chicken egg. Due to pressure on the brain or its trunk, compression of its cerebral structures, hydrocephalus and visual impairment occur. Such changes lead to irreversible consequences in the brain, therefore, surgery to remove auditory nerve neuromas at this stage is impossible. For this reason, advanced forms of the disease are fatal.
Diagnosis of the disease
An otoneurologist can diagnose this disease. In some situations, consultation with the vestibulologist, ophthalmologist and dentist may additionally be required. The patient is assigned a neurological examination, audiometry, otoscopy, electrocochleography, electron-histagography, auditory auditory EP, vestibulometry and stabilography.
Radiography and neuroimaging techniques can provide a more accurate diagnosis of the neoplasm. Auditory nerve neuroma is difficult to diagnose even with computed tomography (CT), therefore, the patient is given an X-ray of the cranium with an aimed picture of the temporal region of the head. If the image clearly shows the expansion of the internal auditory canal, then this indicates the formation of a tumor. Schwannomas are detected in the diagnosis of the disease using MRI (magnetic resonance imaging).
Treatment of auditory nerve neuroma
Today, there are two methods for the radical treatment of schwannoma - surgical intervention and radiosurgical methods. In addition, it is sometimes advisable to use radiation therapy. The choice of a particular method of exposure is determined in each case individually and depends on:
- neoplasm size;
- age category of the patient;
- general condition of the patient;
- hearing level;
- patient preferences.
If the symptoms of auditory nerve neuromas do not cause particular concern to the patient (the tumor is small and does not compress nearby nerves), a wait-and-see tactic is chosen. Surgery can also be abandoned due to the weakening of the patient's body or old age. In this case, the doctor recommends annual monitoring and examination of MRI.
Surgery
Removal of auditory nerve neuroma - the operation is very complex. It is carried out only for young people, when the neoplasm increases in size and at the same time bothers the patient.
Such surgical interventions are performed under general anesthesia, while this implies trepanation of the skull. Such operations can be carried out in various ways: through the mastoid process (trans-labyrinth path), behind the ear (retro-sigmoid path) or through trepanation above the ear (through the middle fossa).
The recovery period after surgery on the neuroma of the auditory nerve is a long process that requires regular medical monitoring, and takes from 6 to 12 months.
Radiosurgery
Methods of stereotactic radiosurgical intervention are possible to remove relatively small schwannomas, whose diameter does not exceed 2.5-3 cm in diameter. However, such procedures do not always give the expected therapeutic effect. Radiosurgery is performed to preserve the activity of the organs of vision, hearing and the facial nerve. Usually, stereotactic radiosurgery is prescribed for elderly people with a prolonged course after subtotal surgical interventions in cases where the risks of resections are much greater due to somatic pathologies.
Radiation Therapy: Gamma Knife
This technique is a bloodless (non-invasive) technique for the treatment of auditory nerve neuroma. Its goal is to stop the tumor with minimal risk of damage to neighboring neural structures. The effectiveness of this method is based on the destruction of tumor DNA and the blockage of blood vessels that feed the tumor.
This operation is indicated for patients with small schwannomas, the size of which does not exceed 3 cm in diameter, as well as for individuals with residual and recurrent phenomena after resections.
The advantages of this technique are that such a point radiation allows preserving the functions of the facial nerve (in 95% of cases) and the organs of hearing (in 79%). After the procedure, there are never complications associated with conducting open interventions (for example, meningitis or liquorrhea).
This procedure is carried out in one session and the very next day the patient can return to a normal lifestyle.
Radiosurgery: cyber knife
The application of this technique has no restrictions on the size of neoplasms, although the principle of using a cyber knife is similar to the previous irradiation method. After using this technique, patients no longer show growth of neoplasms in 95% of cases.
Expectant Tactics
With small sizes of the neoplasm or with the localization of the tumor in areas that do not affect the compression of nearby nerves, expectant treatment tactics are recommended. No therapeutic measures are also taken in cases where surgical intervention is not possible due to the patient's advanced age or general weakness of the body.
In this case, the patient should regularly visit a medical institution to control the size of the neoplasm and receive symptomatic treatment for the manifestations of the clinical picture of the disease.
Forecast
The outcome of neurinoma of the auditory nerve is largely determined by the timeliness of contacting a specialist to diagnose the disease. A favorable prognosis of the course and treatment of this pathology can be discussed with adequate treatment of schwannomas in the first or second stages. With stereotactic radiosurgical interventions at the initial stages of the development of neurinoma in 90% of cases, the development of the neoplasm is stopped and the patient is completely restored. Surgical interventions have a high percentage of hearing loss and facial nerve function.
At the last stage of auditory nerve neurinoma, the prognosis is unfavorable: fatal outcome is possible due to compression of the vital cerebral structures of the brain.