Optical-chiasmal arachnoiditis: causes, symptoms, diagnosis, treatment

Optichohiasmal arachnoiditis, in essence, is an intracranial complication of an infection that penetrates to the basal brain envelopes that surrounds the visual crossover. The most common cause of the appearance of optic-chiasmal arachnoiditis is the sluggish current inflammatory process in the sphenoid sinus.

The contributing factor are the anomalies of the ratio of these sinuses and visual channels. Optic-chiasmal arachnoiditis, by the definition of AS Kiselev and co-authors. (1994), is the most common form of arachnoiditis of the base of the brain, in the clinical picture which is dominated by visual impairment. With optical-chiasmal arachnoiditis, there is a diffuse productive process in the basal membranes of the brain and adjacent areas of the brain substance with a predominant lesion of the basal cisterns of the brain, the shells of the optic nerves, and the visual crossover. Thus, the concept of optico-chiasmal arachnoiditis unites two nosological forms - retrobulbar neuritis and optic neuritis proper in the area of their intersection, in which case the primary pathological process is arachnoiditis, and secondary - optic neuritis.

[1], [2], [3], [4], [5], [6], [7], [8]

What causes optic-chiasmal arachnoiditis?

According to many authors, optic-chiasmal arachnoiditis refers to polyethiologic diseases, among which there are such as common infections, paranasal sinuses, TBI, family predisposition, etc. According to ON Sokolova et al. (1990), 58 to 78% of all cases of opticchiosmal arachnoiditis are caused by infectious and allergic processes with the predominant involvement of paranasal sinuses.

The polyethiologic nature of optic-chiasmal arachnoiditis determines the variety of pathological forms that this disease manifests, as well as the pathological processes underlying it. Of great importance in this regard are allergies, autoimmune processes, head injury, the presence of a focal infection, for one reason or another having access to the cerebral membranes of the base of the skull. The result of these factors is the emergence of inflammatory proliferative-productive processes in the membranes of the brain and cerebrospinal fluid, which are both a feeding medium and a protective barrier for the brain. The change in metabolism in these media contributes to the formation of sensitization to the resulting catabolites (autoantigens), which disrupt intracellular metabolism and lead to the disintegration of nerve cells. The products of the disintegration of the substance and the membranes of the brain close the vicious circle, strengthening the general pathological process, bringing it sometimes to the state of irreversibility. Since the main allergic processes develop in the arachnoid membrane, it can be considered as the main substrate on which the pathogenetic mechanisms of optic-chiasmal arachnoiditis arise and develop.

The appearance of cerebral arachnoiditis is closely related to the state of the body's immune system. So, N.S. Blagoveshchenskaya and co-authors. (1988) found that with rhinogenic cerebral arachnoiditis, there are significant changes in immunological parameters of cellular and humoral immunity, accompanied by secondary immune depression or immunodeficiency state. A major role in this is played by a viral infection. Thus, it was found that the defeat of the nervous system can occur not only with acute flu disease, but also due to its subclinical forms, expressed in the prolonged presence of the virus in the cerebrospinal fluid. According to VS Lobzin (1983), the latter fact is the reason for the emergence of so-called fibrotic arachnoiditis, which can play a decisive role in the appearance of optic-chiasmal arachnoiditis of "unclear etiology".

A certain importance in the development of optic-chiasmal arachnoiditis, according to many authors, may have a hereditary predisposition to this disease, or a specific form of it in the form of Leber's syndrome-bilateral reduction in visual acuity, central scotoma, edema of the optic disc followed by complete atrophy of the optic nerves.

Symptoms of optic-chiasmal arachnoiditis

The main symptom of optic-chiasmal arachnoiditis is a sharp, often fast-onset impairment of vision on both eyes, caused by the bitemporal hemianopsia, characteristic of the lesion of the central part of the visual crossover. Along with a decrease in visual acuity and changes in its fields, with optical-chiasmal arachnoiditis, color sensitivity also suffers, especially in red and green. With optic-chiasmal arachnoiditis, there are almost always some signs of inflammation on the fundus.

With optico-chiasmal arachnoiditis, neurological and endocrine symptoms are often not expressed. Periodically, there is a mild or moderate headache, some diencephalic, hypothalamic and hypophyseal symptoms, such as increased thirst, sweating, subfebrile condition, violation of carbohydrate metabolism, rhythm in the alternation of sleep and wakefulness, etc. An increase in headaches indicates a further spread of the inflammatory productive-proliferative process on the membranes of the brain with the formation in them of adhesions and cysts, which violate liquorodynamics. In this case, there may be an increase in intracranial pressure.

Diagnosis of optic-chiasmal arachnoiditis

Diagnosis, as a rule, in the initial stage of optic-chiasmal arachnoiditis is difficult. However, the suspicion of the presence of optic-chiasmal arachnoiditis should cause a complaint of a patient suffering from any form of inflammation in the paranasal sinuses, to reduce the severity and "volume" of vision. Such a patient must urgently undergo a thorough comprehensive otorhinolaryngological, ophthalmological and neurological examination. With the review of x-ray craniography, signs of an increase in intracranial pressure may be revealed, and in radiography, CT, MRI of paranasal sinuses - the presence of pathological changes in them, among which significant for establishing the diagnosis of optic-chiasmal arachnoiditis are even a small parietal edema of the mucous membrane of the sphenoid sinus or a slight veil of the posterior cells of the latticed labyrin ta. The most valuable diagnostic method is pneumocystinography, with the help of which it is possible to detect a cystic-adhesive process in the region of basal cisterns of the brain, including the cyst of the optic crossover, in the event of damage to which it is either not completely filled with air, or overextended. The CT method made it possible to reveal deformations of various sections of the subarachnoid space, resulting from the formation of cysts and adhesions in the cross-over tank, as well as the presence of hydrocephalus, and MRI - structural changes in the brain tissue.

Differential diagnosis of optic-chiasmal arachnoiditis is carried out with tumors of the pituitary and chiasmatic-selar region, in which the most common symptom, as well as with optic-chiasmal arachnoiditis, is the bitemporal hemianopsia. For hemiapopsies of tumor nature, in contrast to optico-chiasmal arachnoiditis, the sharpness of their contours is characteristic and the appearance of a central scotoma is not typical. The optic-chiasmal arachnoiditis is also differentiated from the aneurysms of the vessels of the arterial circle of the large brain located above the sphenoid sinus, in which paraccentral hemianopsic fallouts can be observed. These changes in the field of view can be difficult to distinguish from paracentral cattle, which in optic-chiasmatic arachnoiditis occur in 80-87% of cases. Optic-chiasmal arachnoiditis in the acute stage should also be differentiated from thromboembolism of the cavernous sinus and other volumetric processes in the area of the optic chiasm and the base of the skull.

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

Treatment of optic-chiasmal arachnoiditis

Methods of treatment of patients with optic-chiasmal arachnoiditis are determined by its etiology, localization of the primary focus of infection, the stage of the disease, the depth of pathomorphological changes both in the structure of the optic nerves and in the surrounding tissues, the general condition of the organism, its specific (immune) and nonspecific resistance . As a rule, in the debut stage of the disease, non-operative treatment is used; if there is no effect or if the primary focus of infection is determined, the non-operative treatment is combined with a surgical one, for example, in case of chronic ethmoiditis or sphenoiditis - opening of the indicated sinuses and elimination of pathological contents.

Non-surgical treatment in the acute stage: antibiotics, sulfonamides, desensitizing drugs, immunocorrectors and immunomodulators, dehydration methods, angionotectors, antiginoxants, B vitamins, neurotropic drugs. The use of biostimulants, steroid drugs and proteolytic drugs in the acute stage is not recommended due to the risk of generalization of the process. These drugs are used in the chronic stage or in the postoperative period, when an effective outflow from the sinus is established. Their purpose is indicated for the prevention of intensive scar tissue in the field of surgical intervention. To achieve a greater effect, some authors recommend carrying out an intra-carotid injection of appropriate antibiotics.

With the achievement of positive dynamics, along with the continuation of complex anti-inflammatory treatment, it is advisable to design neuroprotectors and drugs that improve nerve conduction. Positive results are obtained from the application of the method of percutaneous electrical stimulation of the optic nerves. Promising methods of nonoperative treatment of optic-chiasmal arachnoiditis are HBO and extracorporeal therapy methods, in particular plasmapheresis, UFO-autohemotherapy.

With chronic optic-chiasmal arachnoiditis, the application of proteolytic enzymes of complex action is expedient for resolving adhesions in the optic-chiasmatic region. These include lekosim, which includes active proteolytic substances of papaya, chymopapain, lysozyme, and a set of proteinases.

With the ineffectiveness of drug treatment, some authors recommend the use of X-ray therapy, focused on the optic-chiasmal region, the introduction of air into the subarachnoid region. In general, with nonoperative treatment of patients with optic-chiasmal arachnoiditis, visual improvement occurs in 45% of cases, before the other patients there is a question of surgical treatment, otherwise they are doomed to progressive reduction in visual acuity, up to blindness. According to different authors, as a result of surgical treatment with various forms of optic-chiasmal arachnoiditis, on average 25% of patients who are visually impaired get better vision, of which 50% have partial labor rehabilitation. The optimal time for surgical treatment is the first 3-6 months after the onset of visual acuity reduction, because at that time it becomes clear whether the non-operative treatment is effective or not. Neurosurgical treatment is usually administered to patients with visual acuity below 0.1. The aim of the operation is to free the optic nerves and the visual crossover from arachnoid adhesions and cysts.

Surgical treatment of optic-chiasmal arachnoiditis. In the complex treatment of patients with optic chiasmal arachnoiditis, it is important to sanitize chronic foci of infection. With respect to sanation of the paranasal sinuses, there are two points of view. According to the first, all paranasal sinuses are subject to dissection, in which only the minimal indication of the pathological process is suspected. In such cases LS Kiselev et al. (1994) recommend conducting polysynosotomy by endonasal dissection of the trellis labyrinth, maxillary sinus through the middle nasal passage and the sphenoid sinus transseptal. According to the second point of view, only those paranasal sinuses are subject to dissection, in which signs of purulent inflammation are found. The experience of recent years shows that preference should be given to preventive opening of all paranasal sinuses even in the absence of signs of any form of inflammation in them. The benefits of this technique are indicated by the facts that even opening an obviously normal sphenoid sinus and other paranasal sinuses leads to an improvement in vision. This is probably due not only to accidental "entry" into the latent focus of the infection, but also to the unloading humoral effect resulting from the appearance during the operation of unavoidable bleeding, the interruption of hemato- and lymphogenous ways of infection, the destruction of barriers that cause stagnant phenomena in the optico- chiasmatic region.

In the postoperative period, patients are prescribed antibacterial, dehydration and desensitizing therapy, using proteolytic enzymes and complex antineuritic treatment. After careful haemostasis, the sinuses loosely tamponize using tampons soaked in a suspension of the appropriate antibiotic and sulfonamide in a sterile vaseline oil. The next day, some of the most easily removable swabs are removed, the rest is removed after 2 days. Subsequently, the sinuses are washed with various antiseptics, followed by the introduction into them of various agents that accelerate the epithelialization of the sinus and minimize scarring of its internal surface. The main non-operative treatment against optic-chiasmal arachnoiditis, carried out by ophthalmologists, begins 3-4 weeks after the operation on the paranasal sinuses. However, in our opinion, it should begin 2-3 days after the removal of the last tampons from the operated sinuses.