Nevrinoma of an acoustical nerve
Nevrinoma of an acoustical nerve — the good-quality new growth of the VIII cranial nerve consisting of cages of a shvannovsky cover. It is clinically shown by a hearing impairment, noise and a ring in an ear, vestibular frustration on the party of defeat, symptoms of a sdavleniye of the facial, trigeminal, taking-away nerves, a brain trunk and a cerebellum, symptoms of intra cranial hypertensia and hydrocephaly. Nevrinoma of an acoustical nerve is diagnosed thanks to a X-ray analysis of temporal bones, brain MPT or KT. Depending on the amount of education its surgical and radio surgical removal, radiotheraphy is possible. Observation of a tumor in dynamics and the solution of a question of treatment tactics is in some cases expedient only at identification of the progressing education growth.
Nevrinoma of an acoustical nerve
The VIII couple of ChMN — preddverno-ulitkovy, or acoustical, a nerve consists of vestibular and acoustical parts. The first brings to the cerebral centers information from vestibular receptors of a snail, the second — from acoustical. In most cases the nevrinoma develops in a vestibular part of a preddverno-ulitkovy nerve, and symptoms of defeat of acoustical department are connected with its sdavleniye a tumor. Near a preddverno-ulitkovy nerve pass: the trunk of a facial nerve, a trigeminal nerve which is taking away, the yazykoglotochny and wandering nerves. In process of growth of a nevrinoma in a clinical picture there can be symptoms of a sdavleniye of these nerves, and also adjacent structures of a trunk of a brain.
Nevrinoma of an acoustical nerve originates from the shvannovsky cages surrounding axons of nervous fibers. In this regard in practical neurology it is also known as a vestibular (acoustic) shvannoma. Frequency of occurrence of a tumor about 1 diseased on 100 thousand people. At the same time the nevrinoma of an acoustical nerve makes 12-13% of all cerebral tumors and about 1/3 from tumors of a back cranial pole. It develops mainly at the age of 30-40 years. Any case at children of the dopubertatny period is not celebrated.
The etiology nevriny an acoustical nerve remains uncertain so far. Unilateral nevrinoma have sporadic character, their direct link with any etiofaktor is not traced. Bilateral nevrinoma are observed at many patients with a neurofibromatosis of the II type — genetically caused disease for which good-quality tumoral processes of various fabric structures of nervous system are typical (neurofibromas, gliomas, meningioma, nevrinoma). The neurofibromatosis is inherited in the autosomno-prepotent way, the risk of a disease of posterity in the presence of a pathological gene at both parents makes 50%.
Pathogenetic allocate 3 stages of development of a vestibular shvannoma. In the first the small amount of education (to 2,5 cm) leads to a hearing disorder (relative deafness) and vestibular frustration. In the second the new growth grows to the walnut sizes, puts pressure upon a brain trunk that leads to emergence of a nistagm, diskoordination of movements and disorders of balance. In the third stage when the nevrinoma reaches the egg sizes, it causes a sharp sdavleniye of cerebral structures, hydrocephaly, violations of sight and swallowing. At this stage in tissues of a brain there are irreversible changes, a tumor of an inoperabeln and is the reason of a lethal outcome.
Macroscopically the new growth represents roundish or irregular shape dense knot with a hilly surface. Outside it has the soyedinitelnotkanny capsule, the local or diffusion cystous cavities filled with brownish liquid can meet inside. Color of education on a cut depends on its blood supply: usually light pink with rusty sites, at venous stagnation — cyanotic, at hemorrhages in nevrinoma fabric — brown-brown.
Microscopically the nevrinoma of an acoustical nerve consists of cages which kernels remind sticks. These cages form structures as palisades between which the sites consisting of fibers are observed. In process of growth of a tumor in it processes of a fibrozirovaniye, formation of deposits of a gemosiderin are observed.
Slow growth of a vestibular shvannoma causes existence of some asymptomatic period and gradual development of clinic. At 95% of the diseased the first sign is gradually progressing deterioration in hearing. In some cases decrease in hearing happens sharply and suddenly. At 60% of patients the first complaint is emergence of noise or a ring in ears. At its lack and the unilateral nature of damage of an acoustical nerve patients it is often long do not notice the happening deterioration in hearing. Vestibular frustration are noted in 2/3 cases. They are characterized by feeling of instability or dizziness at turns of a trunk and head, emergence of a nistagm. Vestibular crises at which against the background of dizziness there is nausea are sometimes observed and there can be vomiting. Nevrinoma of an acoustical nerve in an initial stage can be mistakenly taken for cochlear neuritis, Menyer's disease, , labirintit.
Progrediyentny growth of a tumor leads to full deafness on the party of defeat, to accession of symptoms of defeat of blizraspolozhenny structures over time. However it is necessary to remember that expressiveness of symptoms not always correlates with tumor sizes. Depending on localization of a nevrinoma and the direction of its growth, at the small sizes it can give heavier picture, than a large new growth and vice versa.
First of all the nevrinoma of an acoustical nerve causes a sdavleniye of a trigeminal nerve that is followed by front pains and paresteziya on the party of a tumor. Face pains have the stupid, aching character; in the beginning proceed as paroxysms, and then become constants. Sometimes they are taken for a toothache or neuralgia of a trigeminal nerve. A little later or along with front pain there are symptoms of peripheral damage of a facial nerve (paresis of mimic muscles and the front asymmetry connected with it, violation of a salivation, loss of taste on forward 2/3 languages) and the taking-away nerve (a diplopiya, the meeting squint). If the nevrinoma of an acoustical nerve settles down in internal acoustical pass, then symptoms of a sdavleniye of a facial nerve can demonstrate during the early period of a disease. In similar cases the exception of neuritis of a facial nerve is necessary.
Further increase in a nevrinoma leads to damage of the wandering and yazykoglotochny nerves with violation of a fonation, a dysphagy, loss of taste on back 1/3 languages and fading of a pharyngeal reflex. At a sdavleniye of a cerebellum the cerebellar ataxy appears. Even in the started cases, at a sdavleniye of a brain trunk, touch and motor conduction violations are expressed extremely poorly; paresis is noted in exceptional cases.
In the third stage of a nevrinom of an acoustical nerve it is characterized by symptoms of intra cranial hypertensia. There is a headache in a nape and frontal area which is followed by vomiting. At an oftalmoskopiya stagnant disks of optic nerves are noted. The perimetry can reveal separate scotomas or a gemianopsiya that is connected with a sdavleniye of a hiazma and optical paths.
Carries out diagnostics , at its absence the neurologist together with the otolaryngologist. In some situations consultation of a vestibulolog, the ophthalmologist and stomatologist in addition is required. To the patient conduct neurologic examination, an audiometriya, an otoskopiya, an elektrokokhleografiya, an elektronistagmografiya, a research of acoustical VP, a vestibulometriya, a stabilografiya.
More precisely the X-ray analysis and methods of neurovisualization helps to establish the diagnosis of "a nevrinom of an acoustical nerve". At early stages at the small sizes of a nevrinoma (to 1 cm) it, as a rule, is not visualized by means of brain KT. Therefore carry out a skull X-ray analysis with an aim picture of a temporal bone. In confirmation of the diagnosis of a vestibular shvannoma expansion of internal acoustical pass testifies. As nevrinoma well absorb contrast, use of KT with contrasting is possible. At the same time education with accurate smooth contours is visualized.
Brain MRT in case of a nevrinoma reveals in the T1-weighed pictures hypo - or isointensive, and on T2-weighed - hyper intensive education. The heterogeneity of a signal connected with existence in them of cystous sites is characteristic of tumors of 3 in size and more than a cm. Visualization of deformation of a trunk of a brain and cerebellum is possible. When carrying out a contrast MR-tomography in 70% heterogeneous accumulation of contrast is observed.
treatment should be carried out only under the supervision of a doctor. Self-treatment is unacceptable!!!
Radical method of treatment is removal of a nevrinoma which can be carried out by an open surgical way or methods of radio surgery. Surgical removal is expedient at a big tumor, at identification of increase in its sizes in dynamics of observations, with a growth of a nevrinoma after radio surgical intervention. Often deafness and paresis of a facial nerve are a consequence of operation. Stereotaksichesky radio surgical removal is possible for nevriny less than 3 cm in size. Also it is carried out at elderly patients with the prolonged growth after a subtotal resection and in cases when the risk of operation is considerably increased because of somatic pathology.
Radiation therapy of a nevrinoma has the indications similar to indications to radio surgery. Radiation is not way of removal of education, but prevents its further growth and allows to avoid operation. To patients with incidentally revealed at KT or MPT nevrinomy without clinical symptomatology, the patient with it is long the existing disorders of hearing and waiting tactics with constant control of the amount of education and dynamics of clinical symptoms is shown to elderly patients with weak symptomatology.
The nevrinoma outcome in many respects depends on timeliness of diagnostics and the sizes of a tumor. The forecast is favorable at adequate treatment of a vestibular shvannoma in I and II stages. During radio surgical removal at early stages in 95% the termination of growth and a complete recovery of working ability of the patient is noted. At surgical intervention the risk of loss of hearing and injury of a facial nerve is high. In the III stage of a nevrinoma the forecast is adverse: the patient can die at a sdavleniye of zhiznennovazhny cerebral structures the increasing tumor.