Neurinoma of the pre-cochlear nerve

Neurinoma of the pre-cochlear nerve is a disease to which a large number of works are devoted. In recent years, in connection with the development of radiation and other technologies for visualization of tumor formations of the pyramid of the temporal bone and the bridge-cerebellar angle, as well as video and microsurgical methods, the neurinoma of the pre-collateral nerve cone from the extremely complicated early 20th century. In our time has become decidable.

By the middle of the last century, neurinoma of the pre-cochlear nerve with respect to brain tumors was 9%, compared to tumors of the posterior cranial fossa - 23%, while tumors of the posterior cranial fossa relative to all brain tumors were 35%, in the same time neurinoma of the pre-collateral nerve was 94.6% of the tumors of the lateral cistern of the brain. The disease is most often diagnosed at the age of 25-50 years, but it can occur in children and the elderly. In women neurinoma of the pre-cochlear nerve is twice as common.

[1], [2], [3], [4], [5], [6], [7]

Pathogenesis of neurinoma of the pre-vertebral nerve

Neurinoma of the pre-cochlear nerve is a benign encapsulated tumor that primarily develops in the internal auditory canal from the neuromeme of the vestibular nerve with further growth in the direction of the bridge-cerebellar angle. The tumor in the process of growth fills the entire space of the lateral cistern of the brain, considerably stretching and thinning the bridge-cerebellar angle (pre-cochlear, facial, intermediate and trigeminal) appearing on its surface, leading to trophic disturbances and morphological changes in these nerves their conductivity and distortion of the functions of the organs innervated by them. Filling the entire internal auditory canal, the tumor squeezes the internal auditory artery that feeds the structure of the inner ear, and exiting the area of the bridge-cerebellar angle exerts pressure on the arteries feeding the cerebellum and the brain stem. Applying pressure to the bony walls of the internal auditory canal, the tumor causes their resorption, which leads to the radiographic evidence of its expansion, and upon reaching the apex of the pyramid, its destruction, after which the tumor rushes into the bridge-cerebellar angle, without testing in its free space mechanical obstacles, or a lack of nutrients. It is here that its rapid growth begins.

Large tumors shift and squeeze the medulla oblongata, the bridge, the cerebellum, causing the corresponding neurological disorders, caused by the defeat of the nuclei of the scapular nerves, vital centers and their conducting pathways. Small tumors (2-3 mm) with a long development cycle can be asymptomatic and can be detected by accident during biopsy. Such cases, according to BG Yegorov et al. (1960), were in the last century up to 1.5%. In 3% of cases bilateral tumors are observed; they occur, as a rule, with widespread neurofibromatosis (Recklinghausen's disease). This disease should be distinguished Gardner-Turner syndrome, which occurs with hereditary bilateral neurinoma of the pre-collateral nerve.

Symptoms of neurinoma of the pre-cochlear nerve

The classical division of the clinical forms of the neurinoma of the pre-collar nerve into four periods does not always correspond to the chronological sequence of the emerging features characteristic of these periods. And although in most cases the clinical manifestations of the neurinoma of the pre-collar nerve are directly related to the growth rate of the tumor and its size, there can be atypical cases when ear symptoms (noise, hearing loss, dizziness) can be observed with small tumors, and vice versa neurological signs that arise when the tumor leaves the bridge-cerebellum angle, are manifested, bypassing the otiatric symptoms of the neurinoma of the pre-collateral nerve.

There are four clinical periods of development of neurinoma of the pre-collar nerve.

The otiatric period

In this period, the tumor is located in the internal auditory canal and the symptoms of the neurinoma of the pre-cochlear nerve are caused by the degree of compression of the nerve trunks and vessels. Usually the first signs of impaired auditory and taste functions (ear noise, hearing loss perceptual type without FUNG). At this stage, the vestibular symptoms are less constant, but it is possible that they go unnoticed due to the fact that they are quickly leveled by the mechanism of central compensation. However, in the case of a bithermal caloric sample with the use of video-histogram, at this stage it is often possible to establish a sign of asymmetry in the labyrinth within 15% or more, indicating the inhibition of the vestibular apparatus on the side of the lesion. At the same stage, in the presence of dizziness, spontaneous nystagmus can also be recorded, first directed toward the "sick" ear (irritation due to the hypoxia of the labyrinth), then towards the "healthy" ear due to compression of the vestibular portion of the pre-collateral nerve. At this stage, the OCN, as a rule, is not violated.

Sometimes, in the otiatric period, there may be lesser-like seizures that can mimic Meniere's disease or vertebrogenic labyrinthopathy.

The otoneurological period

A characteristic feature of this period, along with a sharp increase in otiatric symptoms due to the lesion of the pre-collar nerve, is the appearance of signs of compression of other cranial nerves in the bridge-cerebellum, in connection with the release of the tumor into its space. Usually this stage occurs 1-2 years after the otiatric; it is characterized by X-ray changes in the internal auditory meatus and the tip of the pyramid. Characteristic and pronounced hearing loss or deafness in one ear, a strong noise in the ear and the corresponding half of the head, ataxia, a violation of coordination of movements, a deviation of the body towards the affected ear in the Romberg pose. The attacks of dizziness, accompanied by spontaneous nystagmus, are increasing and intensifying. With a significant tumor size, a gravitational positional nystagmus appears when the head tilts to a healthy side, due to the displacement of the tumor toward the brainstem.

In this period, there are and are progressing disorders of the function of other cranial nerves. Thus, the effect of the tumor on the trigeminal nerve causes paresthesia on the corresponding half of the face (Barre's symptom), trismus or paresis of the chewing musculature on the side of the tumor (Christiansen's symptom). Simultaneously, there is a symptom of a decrease or disappearance of the corneal reflex on the same side. At this stage, the disruption of the function of the facial nerve is manifested only by the paresis, most pronounced for its lower branch.

Neurological period

In this period, otiatric disorders recede into the background, the neurological symptoms of the neurinoma of the pre-collateral nerve, which are caused by the defeat of the nerves of the bridge-cerebellar angle and the tumor pressure on the trunk, bridge and cerebellum, begin to occupy a dominant position. These symptoms include paralysis of the oculomotor nerves, trigeminal pain, loss of all sensitivities and corneal reflex on the corresponding half of the face, decrease or loss of taste sensitivity in the posterior third of the tongue (lesion of the glossopharyngeal nerve), paresis of the recurrent nerve (voice fold) on the tumor side (lesion vagal nerve), paresis of the sternocleidomastoid and trapezius muscles (lesion of the accessory nerve) - all on the side of the tumor. At this stage, the vestibular-cerebellar syndrome is pronounced, manifested as a rough ataxia, multidirectional large-scale, often undulating nystagmus, culminating in gaze-paresis, marked vegetative disturbances. On the fundus there are stagnant phenomena on both sides, signs of increased intracranial pressure.

Terminal period

With further growth of the tumor, cysts filled with yellowish fluid form in it; the tumor increases and presses on the vital centers - the respiratory and vasomotor, compresses the fluids, which increases intracranial pressure and causes cerebral edema. Death comes from the blockade of the vital centers of the brainstem - stopping breathing and cardiac activity.

In modern conditions, the third and fourth stages of neurinoma of the pre-cochlear nerve practically do not occur; the existing methods of diagnosis, with the appropriate oncological alertness of the doctor, to which the patient addresses complaints of permanent noise in one ear, a decrease in hearing on him, dizziness, provides for the conduct of appropriate diagnostic techniques to determine the origin of these complaints.

Diagnosis of neurinoma of the pre-cochlear nerve

Diagnosis of neurinoma of the anterior-cochlear nerve is difficult only in the otiatric stage, in which in most cases there are no x-ray changes in the internal auditory canal, at the same time, such a patient may have x-ray changes in the cervical spine, especially since, according to A .D Abdelhalim (2004, 2005), every second person, starting from the age of 22, has an initial radiologic signs of cervical osteochondrosis and complaints, often similar to subjective sensations Arising from the neuroma vestibulocochlear nerve. Beginning with the neurological (second) stage, the tumor of the internal auditory canal is practically revealed in all cases, especially when using such highly informative methods as CT and MRI.

The X-ray projections, such as the Stenvers projection, the Highway III, the transorbital projection with the visualization of the temporal pyramids, are also very informative.

Differential diagnosis of neurinoma of the pre-collar nerve causes difficulty in the absence of radiological changes in the internal auditory canal. Differential diagnosis is carried out with cochleovestibular disorders with vertebral-basilar vascular insufficiency, auditory nerve neuritis, eroded forms of Meniere's disease, Lermuaye syndrome, Paranasymal dizziness syndrome in the Barani, meningioma and cystic arachnoiditis of the bridge-cerebellar angle. For the qualified conduct of differential diagnosis, in addition to the use of modern radiotherapy, the participation of an otoneurologist, neurologist, and ophthalmologist is necessary.

A definite value in the diagnosis of neurinoma of the pre-vertebral nerve is the investigation of the cerebrospinal fluid. With neurinoma of the pre-nerve-cochlear nerve, the number of cells in it remains at the normal level and does not exceed 15x10 ⁶ / l, while at the same time there is a significant increase in the content of protein in the cerebrospinal fluid (0.5 to 2 g / l and more) isolated from the surface of large neurin, prolabirovali in the bridge-cerebellar angle.

[8], [9], [10], [11], [12], [13], [14]

Treatment of neurinoma of the pre-cochlear nerve

The neurinoma of the pre-collateral nerve is treated exclusively surgically.

Depending on the size and direction of the tumor, its clinical stage, use such surgical approaches as suboccipital retrosigmoidal, translabirintny.