Optic nerve meningioma is a predominantly benign intraocular tumor that develops from the arachnoid membrane of the optic nerve or cells of periorbital localization. Depending on the type of growth of the neoplasm, the leading symptoms are a decrease in visual acuity, soreness inside the eye socket and in the corresponding half of the head, limited mobility of the eyeballs, exophthalmos. Diagnostics is based on conducting visiometry, tonometry, ophthalmoscopy, ultrasound, CT, MRI. Surgical methods of treatment are used (resection of the affected area of the optic nerve, enucleation), radiation therapy and stereotactic radiotherapy.
Optic nerve meningioma is a neoplasm that originates from arachnoendothelial cells and is characterized by a predominantly benign course. For the first time, the clinical symptoms of optic nerve meningioma were described by the German ophthalmologist A. Leber in 1877. Since that time, many names and theories of the occurrence of this pathology have changed. H. V. Cushing in 1922 suggested that the tumor develops from the structures of the dura mater and introduced the term “meningothelioma” for its designation.
According to published data by L. I. Smirnov (1962), the source of the neoplasm is arachnoid villi, therefore, the term “arachnoidendothelioma” was also used to designate this nosological unit. The name “meningioma” was introduced in the 70s of the twentieth century and remains relevant to this day. According to statistics, the prevalence of the disease among all tumors of the central nervous system is 1-2%, among neoplasms of the orbit – 5-10%. Neoplasia develops more often at the age of 30-60 years, however, there is information about the occurrence of pathology in young children. Women get sick 3-4 times more often than men.
Optic nerve meningioma can be acquired or congenital. Congenital pathology often develops binocularly. The main causes of occurrence are the reception of teratogenic medications by the mother during pregnancy, smoking, the use of alcoholic beverages or narcotic substances. Family forms of this pathology are not described. The acquired form, as a rule, is formed sporadically. In clinical ophthalmology, primary and secondary meningioma are distinguished. The arachnoid membrane of the optic nerve, arachnoid cells of periorbital localization or small nerve branches may be the sources of the development of primary neoplasms. The secondary tumor spreads into the eye socket from the cranial cavity. The germination of meningioma from the structures of the skull is much less common than the primary lesion of the optic nerve.
Risk factors for the occurrence of optic nerve meningioma are the presence of type 2 neurofibromatosis or Li-Fraumeni syndrome in the anamnesis, high doses of X-ray or radiation exposure, head trauma. Women are at greater risk of developing this tumor than men.
Meningioma of the optic nerve in most cases develops monocularly. Binocular lesion of the optic nerves is a rare phenomenon that is diagnosed in early childhood with a congenital form of the disease. There are two types of tumor growth: the first is subdural, throughout the trunk of the optic nerve, the second is with the germination of the dura mater and spread to the ocular muscles and soft tissues of the orbit. For meningioma of the optic nerve, in most cases, a benign course is characteristic. With the malignant nature of the tumor, irreversible vision loss develops with the germination of neoplasia into the walls of the orbit.
Clinically, subdural meningioma of the optic nerve is manifested by a decrease in the acuity of first peripheral, then central vision. In the early stages of development, concentric or asymmetric narrowing of the visual fields leads to intermittent disturbances of central vision. Total loss of visual functions is noted only with complete atrophy of the optic nerve disc. Manifestations of axial exophthalmos occur on average 2-3 years after a decrease in visual acuity. Usually the displacement of the eyeball forward reaches no more than 5-6 mm. At the same time, the functioning of the intraocular muscles is not impaired. This form of neoplasm in 5% of cases is accompanied by the spread to the structures of the optic nerve channel.
In the second type of growth, the tumor is located on the periphery of the optic nerve, which leads to its displacement. In the early stages of meningioma development, patients note soreness of the eye socket with irradiation into the corresponding half of the head. Visual acuity is within the normal range for 3-4 years, then progressively decreases. This form of optic nerve meningioma is accompanied by a pronounced displacement of the eyeball forward up to 1.4 cm. Exophthalmos is characterized by axial orientation or slight displacement. There is often swelling of the periorbital fiber and the mucous membrane of the eyes without other signs of inflammation. When the neoplasm spreads to the intraocular muscles, patients note a decrease in their ability to make eye movements. Unlike other forms of meningioma, this pathology is not accompanied by hyperostosis of the bone tissue of the orbit.
Diagnosis of optic nerve meningioma includes conducting visiometry, tonometry, ophthalmoscopy, ultrasound, computed tomography, magnetic resonance imaging. With the help of ultrasound, it is possible to characterize the type of tumor growth, the degree of germination into the surrounding structures, the contours of the neoplasm. The advantage of this technique is the ability to perform an analysis in the form of a color cartogram of vascular network flows in the mode of color Doppler mapping. On average, the maximum linear velocity of blood flow in the vessels is 13-15 cm/s. MRI is indicated for patients with the second type of tumor growth or with additional localization of the pathological process in the structures of the brain. CT is prescribed when the optic nerve meningioma spreads beyond the eye socket. During MRI and CT, it is possible not only to detect a neoplasm, but also to study its size, structure and prevalence.
In the second type of optic nerve meningioma, ophthalmoscopy is used to diagnose manifestations of stagnation of the optic nerve disc. In the early stages, the swelling of the peripheral parts and the blurring of the disk boundaries are determined. Then physiological excavation disappears, hyperemia develops, spot or multiple hemorrhages on the disc are possible, followed by involvement in the pathological process of the retina. The detection of opticocilliary shunts, areas of hemorrhage in the fundus area with the first type of growth is associated with the spread of the neoplasm to the posterior pole of the eyeball.
The visiometry method for subdural meningioma of the optic nerve determines a decrease in visual acuity already at the early stages. With the second type of growth, this sign is observed only in the late stages of tumor development. Tonometry indicates an increase in intraocular pressure (IOP) only with a large size of the neoplasm. In the early stages of the IOP process, within the normal range (10-20 mmHg). Diagnosis of subdural meningioma of the optic nerve at the initial stages of development is difficult due to a slight increase in the diameter of the optic nerve. With eccentric growth (type 2 tumor), it is necessary to differentiate meningioma from a tumor of paraneural localization of a different origin. Differential diagnosis of pathology in childhood presents difficulties due to the widespread prevalence of arachnoid hyperplasia against the background of optic nerve glioma.
The tactics of treatment of optic nerve meningioma depends on the type of tumor growth, the prevalence of other structures of the eyeball or brain, the degree of visual impairment. With subdural localization of the neoplasm, surgical intervention is recommended in case of total loss of vision. When only the optic nerve is involved in the pathological process, resection of the affected area is performed. In case of detection of hemorrhage foci or opticocilliary shunts, enucleation of the eyeball is required. The absence of visual impairment in the second type of disease is considered as an indication for radiation therapy.
An alternative to surgical treatment is stereotactic radiotherapy (SRT) of optic nerve meningioma. The advantage of this method of treatment is the ability to preserve or slightly improve vision. Unlike radiation therapy, this technique allows you to achieve a reduction in the size of the tumor. At the same time, acute or delayed side effects from radiation are not observed. However, SRT is recommended for use only in the early stages of the disease.
Prognosis and prevention
Specific measures for the prevention of optic nerve meningioma have not been developed. Women during pregnancy are prohibited from smoking, taking medications with a teratogenic effect, alcohol and narcotic drugs. To prevent the progression of pathology, it is necessary to undergo a timely examination by an ophthalmologist. The prognosis for optic nerve meningioma depends on the timeliness of diagnosis and treatment. With early detection, complete recovery is possible, due to the benign course, the prognosis is favorable. Malignant tumor growth or tumor diagnosis at late stages can cause irreversible vision loss, therefore, this pathology often leads to disability of patients.