The ponto-cerebellar angle is the depression between the pons, medulla oblongata, and cerebellum. This area is often affected by neoplasms that compress the nerves, vessels and cerebrospinal fluid passing there. The topicality of the issue of removal of tumors of the cerebellopontine angle is due to the impossibility of their treatment with modern radiosurgical methods, including the gamma knife and linear accelerator. Thus, the method in this case is surgical treatment, which in turn requires adequate anesthetic support and technical equipment.

My name is Gavrilov Anton Grigoryevich, a neurosurgeon at the N. N. Burdenko Research Institute of Neurosurgery. I have 20 years of practical experience, including the removal of tumors of the cerebellopontine angle. My clinical base (the aforementioned research institute) allows for complex interventions: high-tech operating room equipment, combined with a well-coordinated team of anesthesiologists and resuscitators, is an essential condition for achieving an optimal result.

Types of cerebellopontine angle tumors

Approximately every tenth neoplasm of the brain develops in the cerebellopontine angle. At the same time, the most common tumor localized in this area is vestibulocochlear neurinoma - it accounts for 85–95%. Meningiomas and cholesteatoma of the cerebellopontine angle are much less common.

In most cases, vestibulocochlear neuroma is benign. Most often it develops in people of working age, as a rule, in women. Removal of tumors of the cerebellopontine node can be either unilateral or bilateral.

Clinical picture

Timely removal of tumors of the cerebellopontine angle is complicated by the slow development of the disease without sharp clinical manifestations. The patient may be disturbed by noise in one ear for several months and even years (the so-called cochleovestibular syndrome). Then there comes a period when the signs of the disease become more pronounced (deafness, paresis of the facial nerve). In most cases, diagnosis and then removal of tumors of the cerebellopontine angle are carried out at this stage.

Other consistently manifesting symptoms of the disease include:

• headaches;
• loss of corneal and conjunctival reflexes;
• cerebellar phenomena - unilateral hemiataxia and general cerebellar ataxia, adiadochokinesia, unsteady gait, decreased muscle tone, dizziness;
• paralysis of the limbs.

Features of the operation to remove the tumor of the cerebellopontine angle

Removal of the tumor of the cerebellopontine angle is performed surgically. Patients of this profile undergo a general clinical and neurootological examination, CT and MRI before surgery. According to the indications, myo- and angiography, neuropsychological testing are prescribed.

Removal of the cerebellopontine angle tumor is performed using modern methods of endoscopic microsurgery under conditions of constant neurophysiological monitoring (including stimulation and EMG of the facial nerve). After neuroimaging, the doctor develops a plan for the operation, determines its volume and the best access point. The intervention is carried out using high-speed drills and pneumatic drills, which ensure minimal invasiveness and reduce damage to nearby tissues.

Removal of the tumor of the cerebellopontine angle is performed under endotracheal anesthesia in a closed circuit using Propofol and inhalation anesthetics (Sevoflurane, Isoflurane). The necessary conditions for the operation, which is performed in a sitting position, are also Dopplerography of the heart and a special surgical table with supports for the surgeon's hands. During the removal of the tumor of the cerebellopontine angle, it is possible to conduct an express analysis of the removed fragment of the neoplasm, followed by correction of the course of the operation.

The final result of surgical intervention is determined by the features of tumor growth, the degree of damage to the base of the skull, and its fusion with neurovascular structures. In most cases, together with a team of assistants from the N. N. Burdenko Research Institute of Neurosurgery, I manage to solve all the tasks we face.

Of particular importance is the X-ray method of investigation for the diagnosis of tumors of the cerebellopontine angle, i.e., the space limited by the posterior surface of the pyramids of the temporal bones, the bottom of the posterior cranial fossa, the cerebellar tentorium and the pons. In the region of the cerebellopontine angle, two types of pathological processes can occur: tumors and inflammatory changes in the membranes (arachnoiditis).

Arachnoiditis of the region of the cerebellopontine angle is not detected by X-ray methods of examination. In the diagnosis of tumors of this localization, the X-ray method is the leading one.

Initially, the tumor causes irritation of the auditory nerve, patients note noise in the ear, squeaking, ringing. Then the hearing in that ear gradually decreases. As the tumor grows in the internal auditory meatus, it also compresses the facial nerve, which leads to asymmetry in the innervation of the mimic muscles of the face. Subsequently, the tumor leaves the pyramid at the base of the skull and compresses the cerebellum and brain stem.

Depending on the direction of tumor growth, compression and displacement of the brain stem, one or another neurological symptomatology develops. Wedging into the lateral cistern of the bridge, the tumor displaces and stretches the cranial nerves passing here, compresses the vessels. In the late stage, due to compression of the CSF pathways, cerebral symptoms occur.

The clinical picture of the neurinoma of the VIII pair is sometimes very similar to arachnoiditis of the cerebellopontine angle and with multiple sclerosis. In such cases, x-ray examination of the pyramids of the temporal bones is of decisive importance. The internal auditory canal is most often evenly expanded, while its walls remain parallel to each other, but it can also be spindle-shaped and flask-shaped expansion. Changes in the internal auditory canal can be detected on direct x-rays of the skull with the projection of the pyramids into the orbits.

Upon exiting the internal auditory meatus, the tumor can press on the pyramid of the temporal bone, which is manifested by osteoporosis and destruction of its apex. The spread of the tumor posteriorly along the bottom of the posterior cranial fossa can lead to destruction of the edges of the corresponding jugular foramen. Growth forward along the Blumenbach slope can cause destruction of the back of the Turkish saddle and its inclination anteriorly.

In addition to orbital pyramidal and Stenvers imaging, Altschul's posterior semi-axial and skull base imaging can be used. But changes are especially clearly defined on tomograms. Tomograms are performed in the posterior viewing position at depths of 7, 8 and 9 cm. Changes in the petrous part of the pyramid, the bottom of the posterior cranial fossa and the edges of the jugular foramen are clearly visible on the tomograms.

Acoustic neuromas can be bilateral. Bilateral lesion is observed in Recklinghausen's neurofibromatosis. Clinical diagnosis of bilateral tumors is difficult. In addition to damage to the auditory nerves, Recklinghausen's disease reveals small tumor-like nodules under the skin, and other cranial nerves and spinal roots are often affected. Radiographs reveal bilateral destruction of the pyramids of the temporal bones. In addition to acoustic neuromas, other tumors can also occur in the region of the cerebellar pontine angle - sarcomas of the base of the skull, tumors of the gasseo node, cholesteatoma, arachnoyl enlotelioma of the Blumenbach clivus, and others. However, they are much less common. All these tumors can cause destructive changes in the pyramids of the temporal bones and adjacent parts of the bones of the skull base. Summing up the section on craniographic changes in brain tumors, it should be emphasized that tumors of far from any localization and any histological structure can be detected by this method. The leading methods of X-ray diagnostics of brain tumors are contrast studies of the CSF pathways and vessels.

All the nerves of the bridge (5-8) and the cerebellum were involved. All symptoms are on the side of the focus. Causes:

Acoustic neuroma - adhesive process of cerebellar-bridge angle

Acoustic neuromas are more common, followed by meningiomas and cholesteatoma. Neurinomas grow from the shell of the vestibular branch of the VIII nerve, ^ ^ but its lesion is detected here only during otoneurological examination; dizziness is rare. Usually the first symptom is hearing loss accompanied by noise. The trigeminal nerve root (decrease in the corneal reflex, pain, paresthesia in the face) and the vrisberg nerve (taste disorder in the anterior 2/3 of the tongue) are early involved in the process.

In half of the cases, the participation of the facial nerve was noted (pronounced damage is rare), as well as the abducent. As the tumor grows. 5y revealed cerebellar, stem (nystagmus) and cerebral symptoms. Bilateral neuromas of the VIII nerve are found in neurofibromatosis ^ Recklinghausen (see). An important diagnostic value is the radiographically determined expansion of the internal auditory canal.

pyramids of the temporal bone. With meningiomas, cerebral symptoms appear faster than with neurinomas. Cholesteatoma occurs as a result of chronic otitis media. With them, unlike neuromas, the VIII nerve suffers little. 3 x - Tumors of the IV ventricle. Ependymomas are more common, choroid papillomas are less common. Intracranial hypertension appears early, headaches are paroxysmal in nature, often accompanied by vomiting and dizziness, impaired cardiovascular activity, and breathing. Frequent cerebellar disorders (primarily walking disorders). Typically forced position of the head. Of the cranial nerves, the VI and VIII are more likely to suffer than the other 4, less often the V, VII, IX, X nerves. Focal symptoms include bouts of hiccups, respiratory and cardiovascular disorders. There are also attacks of tonic convulsions of the muscles of the trunk and limbs.

Trunk tumors are rare. Among the intracerebral, there are astrocytomas, spongioblastoma multiforme, among the extracerebral meningiomas.

2. Damage to the nervous system in AIDS. Clinical manifestations.

Etiology and pathogenesis. HIV infection is a disease caused by the human immunodeficiency virus. This virus belongs to non-oncogenic human retroviruses, the so-called lentiviruses (slow viruses), the main point of application of the cat is the immune system. Viruses have a long incubation period and are capable of persistence in the body. When they enter the body, the helper population of T-lymphocytes suffers first of all. In addition, they have a clear tropism for certain groups of cells - macrophages, monocytes, hieroglia cells, which causes chronic demyelinating damage to the nerve of the system. Activation of the endogenous - opportunistic flora (herpes virus, yeast-like fungi) and sensitivity to exogenous microbes (mycobacteria, cryptococci, cytomegaloviruses, toxoplasma, etc.) causing secondary damage to various organ systems.

Clinic and diagnostics. Neurological disorders were noted in 1/3 of cases of the disease and usually correspond to III (stage of secondary diseases - cerebral form) and IV (terminal stage - specific damage to the central nervous system) stages. In rare cases, during the period of infection, acute viral meningoencephalitis may develop, manifested by epileptic seizures and impaired consciousness up to coma. The cerebrospinal fluid showed lymphocytic pleocytosis. The most common syndromes of late damage to the nervous system include the AIDS-dementia complex, sensory polyneuropathy, or a combination of both. The cause of the AIDS-dementia complex is brain damage in the form of multifocal giant cell encephalitis and progressive diffuse leukoencephalopathy. In the initial stage of the disease, the patient complains of drowsiness, impaired concentration, and memory disorders. Then, a slight increase in muscle tone, sucking and grasping reflexes, adiadochokinesis, apathy, indifference to one's condition, bradykinesia, and tremor join. In the advanced stage of the disease, against the background of severe dementia, mutism, epileptic seizures, paraplegia, ataxia, and dysfunction of the pelvic organs occur. In the cerebrospinal fluid, a slight pleocytosis is detected. Computed and magnetic resonance imaging revealed atrophy of the cerebral cortex and expansion of the ventricles.

The syndrome of sensory popineuropathy is manifested by pain, paresthesias in the arms and legs of the type of "gloves" and "socks", in combination with a decrease or loss of knee reflexes, flaccid paresis and autonomic "disturbances. Multiple mononeuropathies (lesions of the trigeminal and facial nerves) may occur at different stages of the disease , as well as muscle damage in the form of polymyositis and myopathy.: Treatment. There is currently no pathogenetic treatment. Zidovudine (200 mg 6 times a day) is used, as well as symptomatic therapy. 3. Osteochondrosis g.o..P.

Osteocondritis of the spine- this is a degenerative process that develops in the intervertebral disc and the vertebrae adjacent to it, which together is called the vertebral motion of the PDS segment.

Disk functions; Depreciation, Fixation, Provision of movement. OHP - dystrophic, some of its damage or change, which begins with the nucleus pulposus, spreads to the fibrosis ring and then to other elements of the PDS and often forms a conflict with adjacent neurovascular diseases . Theorim arose OCP: involutional, hormone, vessel, genetic, infectious, mechanical, abnormal, etc. According to etiology Zab-e muptifakotrialnoe. There are 2 main factors: decompensation in trophic systems and local overloads of PDS. Pathogenesis. Stages: Chondrosis is a process only in the disk. Osteochondrosis is a process in the disc and in the bone. Periods: 1 the period of intradiscal displacement of the pulpous tissue. Shrinkage of the nucleus pulposus, the appearance of cracks in the inner section of the annulus fibrosis.

2P-od of PDS instability. The nucleus pulposus was completely cracked. ZP-od forming hernia. 4P-od disc fibrosis and total changes in other structures.

Fibrosis - immobilization by a scar.

Clinic OHP is determined by the level of damage. First of all, these are vertebral syndromes. There are trace manifestations: pain in the affected area (local pain during act and pass movements, limitation of movements, vertebral deformity (scoliosis, smoothness of lordosis / kyphosis), tension of the paravertebral muscles, soreness of protruding str- p, spinous processes), cervical backache, cervicalgia, thoracalgia, lumbar backache (lumbago), lumbalgia (subacute aching pain in the lower back), sacralgia, coccygapgia.

Extrovert syndromes are also distinguished, they develop as follows: post-afferent impulse from the affected PDS along the synovertebra nerve, spreading through the posterior horns to the anterior and lateral horns of the corresponding spin segment of the brain. At the same time, in some b-x forms myso-tonic, in others vasomotor, in others - neurodystrophic,

Flow OHP can. hron (there are no complete remissions), recurrent (series of exacerbations and remissions), hron-recurrent (the appearance of a new syndrome or increased clinical manifestations against the background of a slowly ongoing obstruction). Each exacerbation has 3 stages: progression, stationary, regression.

Vertebral Syndrome - pain in the affected area of ​​the vertebrae 1 .Local pain with active and passive movements. 2.0 movement restrictions.

Z. Vertebral deformity (scoliosis, smoothness of lordosis, kyphosis, asymmetry of the transverse processes).

4. Tension of the paravertebral muscles. b. Soreness of protruding structures affected by PDS Extravertebral syndrome- presence of symptoms at a distance. radicular syndrome:

Root compression can be caused by disc herniation, overgrowth of bone, hypertrophy of the yellow ligament, cicatricial adhesive changes in the epidural fiber; - deficient stage: hyporeflexia, malnutrition, muscle hypotension, hypo- and anesthesia in the zone of the corresponding dermatome; - irritative stage: reflexes are normal or animated, hyperesthesia. Diag. Clinic + X-ray signs:

Local change in the configuration of the vertebra (flattening of the physiological lordosis, the appearance of kyphosis, scoliosis) - a decrease in the height of the disc

The image of the marginal bone growths of "osteophytes" ("whiskers") - subchondral osteosclerosis

Pathological mobility (spondylopisthesis) - displacement of the bodies of adjacent vertebrae. As well as MRI, KG, ultrasound.

Treatment: exhausted and adequate information about the disease b-mu; high-quality, adequate, timely anesthesia; orthopedic regimen in the acute period. First-line analgesics are NSAIDs:

Non-selective COX-1 and -2 inhibitors: ibuprofen, diclofenac, naproxen, indomethacin, piroxicam, lornoxicam, ketoprofen, ketorolac

Highly selective COX-1 ing-ry: low doses of acetylsalicylic acid

Select ing-ry COX-2: nimesulide, meloxicam

Highly selective COX-2: coxibs.

They must be combined with 1 table. Omeprazole (for the stomach)

Muscle relaxants are used: baclofen, tizanidine, topperisone.

Chondroprotectors: stimulate the production of the main components of cartilage in chondrocytes + help slow down the degeneration of cartilage tissue and restore its structure.

Fixation of the neck with the pom of the Shants collar. Manual therapy, massage, IgloReflT, physiotherapy. With chronic pain syndrome - antidepressants.

At home: rubbing, ointments, applications, herbs, can massage, self-massage, needle applicators, reflexology with pepper plaster, metal and magnetic therapy.

Surgical treatment Absolute indication: acute compression of the joint venture of the brain and cauda equina roots, relative indication: severity and persistence of the root. syndromes in the absence of the effect of adequate conservative therapy carried out for more than 3-4 months. 4 .Pseudobulbar syndrome. Research technique in pseudobulbar syndrome.

Central. Developed with damage to the corticonuclear pathways 9,10 and 12 pairs of c.n. and manifested (with bilateral damage): dysarthria, dysphonia, dysphagia and pathological pseudobulbar reflexes (oral automatism - Proboscis reflex. ankylosing spondylitis oral reflex- Light tapping with a hammer on the upper lip of the patient or on his finger, laid across the lips, causes involuntary protrusion of the lips; Sucking reflex. Oppenheim sucking reflex- Stroke irritation of the lips leads to the appearance of sucking movements; Wurp-Toulouse reflex. wurpa lip reflex- Involuntary stretching of the lips, reminiscent of a sucking movement, arising in response to dashed irritation of the upper lip or its percussion; Oppenheim oral reflex- Line irritation of the lips, except sucking reflex, causes chewing, and sometimes swallowing movements; Nasolabial reflex. Astvatsaturov nasolabial reflex - Tapping with a hammer on the back or tip of the nose causes contraction of the circular muscle of the mouth and protrusion of the lips; Palmar-chin reflex. Marinescu-Radovic reflex- Caused by streak irritation of the skin of the palm in the thenar area. At the same time, a contraction of the chin muscle occurs on the same side. Normally caused in children under 4 years of age; enough.), violent crying and laughter

For citation: Kachkov I.A., Podporina I.V. NEUROMA VIII NERVA // BC. 1998. No. 9. S. 2

Neurinoma of the VIII nerve is the most common tumor of the cerebellopontine angle. The clinical picture depends on the location and size of the tumor. Surgical treatment is the method of choice. Radiation therapy, apparently, does not affect the further course of the disease after subtotal removal of the tumor. In elderly patients, as well as in the presence of severe concomitant diseases, expectant management is possible. Bypass surgery can be used as a palliative measure to eliminate hydrocephalus. The article emphasizes the importance of early tumor diagnosis, because this is the key to adequate surgical removal of the tumor. Acoustic neurinoma is a benign, rarely malignant, tumor of the eighth cranial nerve. Its clinical picture is associated with the site and sizes of a tumor. Surgery is the method of choice. Radiation therapy appears to have no impact on disease progression after subtotal tumor removal. Delaying policy may be conducted for elderly patients and in patients with concomitant diseases. One can resort to bypass surgery as a palliative tool in order to eliminate hydrocephalus. I.A. Kachkov - professor, head. neurosurgical department of MONIKI

I.V. Podporina - otoneurologist at MONIKA
Prof. I. A. Katchkov, Head, Neurosurgical Department, Moscow Regional Research Clinical Institute
I. V. Podporina, Otoneurologist, Moscow Regional Research Clinical Institute

Introduction

Neurinoma (neurofibroma, neurolemmoma, schwannoma) of the VIII nerve is the most common tumor of the cerebellopontine angle. According to statistics, it accounts for 5 to 13% of all tumors of the cranial cavity and 1/3 of tumors of the posterior cranial fossa. The tumor is benign, malignant very rarely.
Most often, the tumor affects people of working age - from 20 to 60 years (average age - 50 years). In women, neurinoma of the VIII nerve occurs 2 times more often, than in men.
Bilateral tumors occur in 5% of cases and are more often associated with neurofibromatosis (NF) type II, or "central" NF. NF types I and II is an autosomal dominant disease characterized by the development of benign and malignant tumors of the nervous system. At present, there has been significant progress in the study of this disease, associated with a more complete understanding of the molecular basis of NF. Diagnostic criteria have been developed for NF types I and II, as well as recommendations for the treatment and early diagnosis of NF manifestations in patients and their families. The main place in the diagnosis of the disease is currently given to DNA tests.
In addition to the development of tumors, type I NF is characterized by decreased vision, skeletal lesions, and intellectual impairment, while type II NF is characterized by cataract formation and hearing loss.
The diagnosis of NF types I and II is based on clinical criteria developed by the US National Institutes of Health (see table). A program for the diagnosis and treatment of NF was launched under the auspices of this institution in 1987, in 1990, the NF type I gene was cloned, and in 1993, type II NF.
The development of neurinomas of the VIII nerve, as well as other tumors of the central nervous system, is characteristic of type II NF.

Pathogenesis and pathomorphology

There is a clear dependence of the development of neurinoma on the hormonal background and exposure to ionizing radiation. Pregnancy and exposure to radiation can cause an increase in tumor growth and provoke its clinical manifestation within several months.
The tumor grows from the Schwann cells of the vestibular portion of the VIII nerve.
It is localized most often in the terminal part of the VIII nerve at the entrance to the internal auditory canal. Further growth of the tumor is possible both in the direction of the auditory canal and in the direction of the cerebellopontine angle. Depending on the size and direction of tumor growth, it can compress the cerebellum, the pons, V and VII cranial nerves (CN), and the caudal group of the CN.
The rate of tumor growth is variable, most tumors grow slowly (2 - 10 mm per year). Many tumors grow large or form a cyst before they become clinically significant.
Macroscopically, the tumor looks like a mass, usually irregular in shape, tuberous, surrounded by a capsule, yellowish. The tumor does not grow into the surrounding tissue. Cysts are sometimes seen on cut.
Microscopic examination: Anthony type A and Anthony type B.
Type Anthony A: cells form compact groups with elongated nuclei, often resembling a palisade. Type Anthony B: various patterns of stellate cells and their long processes.

Clinical picture

The clinical picture depends on the location and size of the tumor.
Main clinical syndromes: cochleovestibular syndrome, CN, cerebellum and brainstem compression syndrome, intracranial hypertension.
cochleovestibular syndrome
As a rule, the first manifestations of a tumor are hearing disorders and symptoms of damage to the vestibular apparatus.
The first to appear are symptoms of irritation of the auditory portion of the VIII nerve, expressed in a characteristic noise resembling "surf noise", "whistling", etc., which is sometimes felt for several years, long before the development of symptoms of intracranial hypertension. Noise in the ear, as a rule, corresponds to the localization of the tumor.
Complaints and objective symptoms detected in patients with VIII nerve neuroma (according to S. Harnes, 1981)

Gradually, the phenomena of irritation of the auditory portion of the VIII nerve are replaced by the phenomena of prolapse. Partial deafness develops first, mainly in high tones, and then complete loss of hearing and bone conduction on the side of the tumor. Patients do not pay attention to these changes for a long time, and the presence of deafness in one ear is detected, as a rule, by chance, when there are already a number of symptoms characteristic of a tumor of the cerebellopontine angle.
The latter include a disorder of the vestibular system, which is expressed in systemic vestibular dizziness and spontaneous nystagmus. At the same time, early disappearance of the normal excitability of the vestibular apparatus on the diseased side is noted in the form of the absence of experimental nystagmus and the reaction of hand deflection during caloric and rotational tests. Along with the dysfunction of the VIII nerve, there are often complaints of pain in the occipital region, radiating to the neck, mainly on the side of the tumor.
CN compression syndromes
In the future, compression of other CNs occurs, while the closest of them is facial nerve , which goes next to the auditory, suffers relatively little, showing exceptional resistance compared to more distant nerves. Symptoms of the facial nerve are expressed in mild insufficiency or paresis of its branches on the side of the lesion, less often in spasm of the facial muscles. More severe disorders of the facial nerve develop when the tumor is localized in the internal auditory canal, where the facial nerve is strongly compressed along with its intermediate portion (the so-called XIII CN, or Wrisberg's nerve), which is expressed in loss of taste in the anterior 2/3 of the tongue and impaired salivation on the affected side.
As a rule, there are changes from the side trigeminal nerve . Already in the initial stage, a weakening of the corneal reflex and hypesthesia in the nasal cavity on the side of the tumor are detected. In advanced cases, there is a change in skin sensitivity in the form of hypesthesia in the area of ​​the first and second branches, the absence of a corneal reflex. Often motor disorders are also found, which are expressed in atrophy of the masticatory muscles on the side of the tumor, determined by palpation, and in the deviation of the lower jaw towards paralysis when opening the mouth.
The next place in the frequency of lesions is occupied by the abducens and glossopharyngeal nerves. Violation of the function of the abducens nerve consists in transient diplopia and failure to bring the edge of the iris to the outer commissure of the eyelid when the corresponding eye is abducted towards the tumor. Paresis of the glossopharyngeal nerve is characterized by a decrease in taste or its complete absence in the region of the posterior third of the tongue.
Disorders of XI and XII pairs of CN are less common. Disorders are detected in those tumors that grow in the caudal direction, as well as in cases where the tumor is large. Paresis XI (additional) nerve is characterized by weakness and atrophy of the sternocleidomastoid and upper trapezius muscles on the corresponding side. Unilateral paresis of the XII (hyoid) nerve is expressed in atrophy of the muscles of the corresponding half of the tongue and deviation of its tip towards paralysis.
Defeat vagus nerve manifested by unilateral paresis of the vocal cords, soft palate with impaired phonation and swallowing.
brain stem compression syndrome
With the medial direction of tumor growth, disturbances from both the brain stem and the corresponding half of the cerebellum develop simultaneously. Clinical symptoms from the conductive tracts of the brain stem are mild and often paradoxical. Mild pyramidal symptoms are observed on the side of the tumor, and not contralaterally, due to the fact that the opposite pyramid of the temporal bone exerts more pressure on the pathways than the tumor itself. Sensitivity disorders, as a rule, do not happen.
cerebellar compression syndrome
Cerebellar symptomatology depends not only on the loss of functions of the compressed hemisphere, but also on conduction disturbances in the compressed middle cerebellar peduncle, through which the vestibular pathways from the nucleus of Deiters to the cerebellar vermis pass. The set of cerebellar disorders is expressed by the following symptoms, manifested on the side of the tumor: hypotension of the muscles of the extremities, slowness of their movements and adiadochokinesis, ataxia, overshooting and intentional trembling during finger-nose and knee-heel tests, deviation in the Romberg position, more often towards the affected cerebellar hemisphere, and spontaneous nystagmus, more pronounced towards the tumor.
Syndrome of intracranial hypertension
Symptoms of intracranial hypertension, characterized by headaches that worsen in the morning after waking up, vomiting, congestive optic discs, appear on average 4 years after the onset of the disease.
Features of the clinical picture depending on the direction of tumor growth
There are neuromas with lateral and medial growth.
Lateral neuromas growing into the internal auditory canal are characterized by early loss of hearing, vestibular function, and taste in the anterior 2/3 of the tongue on the side of the tumor. More often, a clear peripheral paresis of the facial nerve is detected. Intracranial hypertension and fundus congestion develop late. Such tumors must be differentiated from tumors of the pyramid of the temporal bone.
Neurinomas with a mediooral growth direction are characterized by an early increase in intracranial pressure and early onset of stem symptoms. The anamnesis in this case is shorter. Dislocation symptoms are more pronounced on the healthy side. On the radiograph of the temporal bone, destruction is often not detected.
Oral growth is characterized by early development of intracranial hypertension, gross dislocation symptoms from the brain stem.
Caudal growth is characterized by early gross dysfunction of the glossopharyngeal, vagus, and accessory nerves.
Features of the clinical picture and tactics depending on the size of the tumor
Depending on the size of the tumor, three stages of its development are distinguished.
Stage I (early), tumor size less than 2 cm.

Rice. 1. Neurinoma of the VIII nerve.
A. On MRI in T1 mode without contrast. In the left cerebellopontine angle, an extracerebral tumor (shown by arrows) is visible, spreading into the auditory canal and compressing the pons.
IN. The same MRI image in T1 mode after contrasting with gadodiamide. The right acoustic neuroma (shown by the white arrow) is better visualized. In addition, after contrasting, a small trigeminal neuroma on the left became visible (shown by the black arrow). The case is typical for type II NF.

On MRI in T1 mode without contrast. In the left cerebellopontine angle, an extracerebral tumor (shown by arrows) is visible, spreading into the auditory canal and compressing the pons. The same MRI image in T1 mode after contrasting with gadodiamide. The right acoustic neuroma (shown by the white arrow) is better visualized. In addition, after contrasting, a small trigeminal neuroma on the left became visible (shown by the black arrow). The case is typical for type II NF.

Rice. 2. Neurinoma of the VIII nerve.
MRI with gadodiamide contrast. A small intratubular neurinoma of the right auditory nerve is visible (indicated by an arrow).

Neurinomas at this stage usually do not cause compression or displacement of the trunk, or their effect on the pons, medulla oblongata, and cerebellum is minimal. Hypertension and stem symptoms are absent or mild. The most common local symptoms are CN lesions in the cerebellopontine angle, with the most common early involvement of the auditory nerve. Therefore, in patients with unilateral hearing loss, neurinoma VIII should be suspected until it can be ruled out. All patients with unilateral hearing impairment should be observed in dynamics by an otoneurologist, neurologist.
At this stage, it is necessary to note the softness of the lesion of the auditory nerve, a large percentage of patients with partial hearing and vestibular excitability on the side of the tumor. Damage to the facial nerve is minimal. Wrisberg's nerve is often affected. Spontaneous nystagmus may not be present at this stage.
Patients at this stage are rarely seen by neurosurgeons, since such tumors are difficult to diagnose. At this stage, the otoneurological and audiological examination, the study of the perception of sound through the bone, are of particular importance.
The operation is indicated for those patients in whom the diagnosis during a comprehensive examination is not in doubt, and with a dynamic otoneurological examination, the symptoms progressively increase.
At this stage, the tumor must be differentiated from arachnoiditis of the cerebellopontine angle, neuritis of the auditory nerve, Meniere's disease, and vascular disorders in the vertebrobasilar basin.
When examining patients at the stage of cochleovestibular disorders, ENT specialists often neglect the caloric test, although it provides valuable information in the diagnosis of neurinomas at an early stage. Such patients are often unsuccessfully treated for a long time for neuritis of the auditory nerve and miss the time favorable for the operation.
Stage II (stage of severe clinical manifestations). A tumor larger than 2 cm affects the brainstem, cerebellum, and begins to cause disturbances in CSF circulation. This stage is characterized by a complete loss of the auditory and vestibular portions of the VIII nerve, increased damage to the V and VII nerves, and a complete loss of taste. The cerebellar and stem symptoms join in the form of multiple nystagmus (clonic horizontal and vertical nystagmus when looking up), there is a weakening of the optonystagmus towards the focus. Violations of the functions of neighboring CNs are more clearly manifested.
Stage III (advanced stage). Spontaneous nystagmus in this stage becomes tonic, spontaneous vertical nystagmus appears when looking down. Optonystagmus falls out in all directions, speech and swallowing disorders appear, cerebellar disorders sharply increase, pronounced secondary hypertensive-hydrocephalic symptoms. Often there are dislocation symptoms on the opposite side.

Diagnostics

Early diagnosis of neurinomas is fundamentally important, since in the early stages of development (with a tumor size of less than 2 cm), complete removal of the tumor is possible with preservation of the function of the facial nerve, and sometimes hearing. Advanced tumors lead to disability, they can be removed only partially, and the facial nerve is almost always damaged.
Therefore, in all patients with unilateral sensorineural hearing loss, especially in combination with vestibular disorders, it is necessary to exclude a tumor of the cerebellopontine angle, in particular neurinoma.
Magnetic resonance imaging (MRI) with contrast (gadodiamide) is the method of choice in the diagnosis of neurinomas of the VIII nerve, as well as other tumors of the cerebellopontine angle. MRI makes it possible to visualize tumors at the earliest stages of development (see Fig. 1, 2).
Computed tomography (CT) with contrast (Iohexol) allows diagnosing tumors no less than 1.5 cm in size. In addition, the method reveals the mass effect of the tumor: compression of the subarachnoid cisterns, hydrocephalus.
Angiography rarely used and only for special indications.
X-ray of the temporal bones according to Stanvers reveals the expansion of the internal auditory canal on the side of the tumor.
auditory evoked potentials change in 70% of cases.
Weber's experience and perception of ultrasound through bone. In Weber's experiment, laterization of sound may be absent, while ultrasound in neuromas always laterizes into the better hearing ear. Sound laterization in Weber's experiment is the main symptom in the differential diagnosis of cochlear and retrocochlear lesions of the auditory nerve.
Study of vestibular function. Unilateral loss of caloric reaction in all components (nystagmus, reactive hand deviation, sensory and vegetative components).
Audiometry. Audiometry reveals unilateral hearing loss of the neurosensory type.

Differential Diagnosis

Tumors of the brain. Differential diagnosis is carried out with other tumors of the cerebellopontine angle: neurinoma of the V nerve, meningioma, glioma, papilloma of the plexus of the IV ventricle. The main role here is played by CT or MRI.
Lateral tumors of the brain bridge. These tumors are characterized by the appearance of local symptoms at the beginning (lesion of nuclei VI, VII CN), isolated vomiting and respiratory failure. Further, a unilateral violation of the functions of V, IX, X, XI, XII CN is added. One-sided paresis or paralysis of gaze towards the tumor develops, combined with an alternating syndrome. Auditory and vestibular disorders are particularly rude. The diagnosis is confirmed by MRI or CT.
Meniere's disease. It is characterized by a paroxysmal course with painful dizziness, nausea, vomiting, tinnitus, imbalance, spontaneous horizontal nystagmus. Occurs more often after 45 years. The sound in Weber's experience laterizes into the better hearing ear. Outside the attack, there are no spontaneous nystagmus, stem and cerebellar symptoms. During the period of remission, the patients feel well.
Acoustic neuritis. Usually there is a bilateral lesion. Vestibular and auditory functions fall out incompletely. History of previous infections, intoxications, use of ototoxic antibiotics. Absence of stem and cerebellar symptoms. There are no changes on the radiograph of the temporal bones.
cholesteatoma. Cholesteatoma, being a predominantly rare complication of chronic otitis media, is a space-occupying lesion and should be included in the diagnostic search with an appropriate history. The disease proceeds rather mildly, with remissions, occurs more often in men. On radiographs, there is no expansion of the internal auditory tract, hearing does not completely fall out.
Clinical manifestation may be associated with the appearance of cerebellar or hydrocephalic symptoms.
Aneurysm of the vertebral artery in connection with the compression of the CN, it may resemble the course of a neurinoma. The diagnosis is confirmed by cerebral angiography.
tuberculous meningitis. Often there is fever, sweating at night. Positive tests for tuberculosis and CSF analysis (lymphocytosis, low glucose and chloride levels) help in the diagnosis.
Platibasia. An x-ray of the skull and upper cervical spine reveals the following changes: the atlas is soldered to the occipital bone, the tooth of the axial vertebra is above the Chamberlain line.
Other diseases with which neurinoma has to be differentiated are vertebrobasilar insufficiency and syphilitic meningitis.

Surgery- selection method. In the initial stages of tumor growth, microsurgical removal is possible with preservation of the function of the facial nerve and sometimes even hearing. In such cases, a translabyrinthine approach to the tumor is used. Hearing preservation is possible if the size of the tumor does not exceed 2 cm. Otherwise, its total removal from the translabyrinthine approach is extremely difficult. In this case, it is more reasonable to use surgical access through the posterior cranial fossa (PCF) using a paramedian soft tissue incision.
The method of tumor removal is determined to a large extent by its size, anatomical and topographic features of the location, the degree of vascularization, and the characteristics of the tumor capsule.
Cardinal changes that have taken place in the surgery of VIII nerve neurinomas are associated with the use of an operating microscope and ultrasonic suction.
The frequency of postoperative complications (primarily paresis of the facial nerve) also depends on the size of the tumor. If the tumor is less than 2 cm, then the function of the facial nerve can be preserved in 95% of cases, if the tumor size is 2–3 cm - in 80% of cases, with tumors larger than 3 cm, intraoperative damage to the facial nerve occurs much more often.
radiological treatment. Radiation therapy is sometimes used for subtotal tumor resection, but it does not seem to affect the further course of the disease.
In some Western clinics, the removal of neurinomas using the so-called "gamma knife" is used, but in terms of cost and level of complications, it is equivalent to conventional surgical resection.
Long-term outcomes after stereotoxic radiosurgery are not yet known.
Expectant management (conservative treatment). Since the tumor grows very slowly, in some cases, especially in elderly patients and in patients with severe concomitant diseases, expectant management is possible, which involves monitoring the condition and performing CT or MRI over time. Palliative treatment is bypass surgery to eliminate hydrocephalus.

Literature:

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5. Bruce JN, Fetell MR. Tumors of the skull and cranial nerves. In: Merritt's textbook of neurology. 9th ed. Williams & Wilkins, 1995;326-9.
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Tumors can affect any organ in the human body. Some of them are famous, others are rarer and more complex. Tumors of the cerebellopontine angle concern the vestibulocochlear nerve, which occupies an intermediate position between the cerebellum and the so-called bridge.

Signs of a tumor

It is difficult to determine the localization of the tumor by signs, the symptoms are similar to any other brain tumor. Here are some of these signs:

1) The appearance of tinnitus, as well as hearing impairment;

2) Deviations in the work of the vestibular apparatus: imbalance;

3) Dizziness;

5) Pain in one half of the face or numbness in this area;

Tumors of the cerebellopontine angle are not the localization of a specific tumor, but a lesion of any structure that is located in this area. Acoustic neuroma is the most common tumor, although the auditory, facial, and vestibular nerves are located here. With this tumor, swelling of the nerve occurs due to mechanical blockage of the passage by the tumor and fluid retention. This can cause, in addition to the above symptoms, headache, fatigue.

Treatment

Tumors of the cerebellopontine angle can be successfully treated depending on how early the tumor is detected. Approaches to the treatment of this oncology are different, with slow growth it is drug therapy, if tumor growth is accelerated, then chemotherapy or radiation exposure is used.

The tumor cannot but cause vascular damage, for the elimination of which the embolization method is used.

As for the surgical method, it is often ineffective in relation to brain tumors: too important structures are located in the head, and the operation has a high risk of affecting them. The exception is the appearance of severe side effects from other therapies or the lack of effect from them. The operation is performed in order to slow down the disturbances that the growth of the tumor causes.

The most modern method of influencing a tumor is ultrasound, when a micro-incision is made in the head, after which the beam acts on the tumor, removing it with a laser scalpel, microsurgical instruments or suction needles.

The nerves of the brain and blood vessels experience compression, that is, pressure on each other, to eliminate which special pads are used during the operation.