Meningioma of an optic nerve

The first data on a meningioma of an orbit have appeared in XIX century when Scarpa in 1816 and Leber in 1877 have described the tumour remote from an orbit. Long time used terms an endothelioma, the mesothelioma, a dural endothelioma, and since 1922, on sentence Cushing, the term a meningioma was ratified. Since then many attempts to challenge existence of a primary meningioma of an orbit, including optic nerve were undertaken. It was offered to regard them, as the secondary tumoral process extending in an orbit from a cavity of a skull. However possibility of visualization of the changed optic nerve with the help of a computer tomography and magneticed - resonant the tomographies (MRT), given the cytologic both morphological control and durable clinical observations confirm existence of primary meningiomas of an orbit.

Thus, in an orbit the meningioma can be primary (a tumour of an optic nerve or soft tissues) and secondary, extending in an orbit from a cavity of a skull. In ophthalmologic practice there is a meningioma of an optic nerve, less often - a primary meningioma of an orbit is more often. The tumour can develop from three sources: the arachnoidal shell of an optic nerve; the arachnoidal cells incorporated in a periorbit; small-sized nervous branches with the arachnoidal cells incorporated along their shells. The meningioma of an optic nerve among all tumours of an orbit makes 5-10 %, and together with gliomas frequency of them achieves 20 %.

The tumour appears, as a rule, on 3-6 decades of a life, is $more often for women. Cases of occurrence of a tumour at children's age are described. However this question it is acute enough it was discussed in the literature. Alongside with opinion on existence of meningiomas of an optic nerve children, have statements about the diagnostic mistakes stipulated by the meeting arachnoidal hyperplasia in an optic nerve, struck with a glioma.

The meningioma of an optic nerve, as a rule, is monolateral, grows in an optic nerve or in the field of its port. The bilateral lesion of optical nerves meets seldom, is diagnosticated in the first decade of a life, weeps aggressively enough and is regarded tile authors, as a congenital tumour.

Observations above 76 patients with a meningioma of an optic nerve within 10-17 years have allowed us to specify features of a clinical picture of this tumour depending on character of its body height.

The first type of a tumour is characterized by subdural body height of a meningioma along a trunk of an optic nerve. Frequency of similar body height on our material has made 41 % of cases. The attention clinically pays to itself early disturbance of peripheric vision with gradual depression central. In the beginning of disease on a background of proof contraction of a field of vision (concentric or azygomorphous) deterioration of the central vision has intermittent character. Proof loss of visual functions occurs late when the atrophy of an optic disk develops. The exophthalmos, more often axial, arises later 2-3 years after appearance of visual disorders, it happens small and never exceeds 6-7 mm (fig. 1). Functions of extraocular muscles are saved in full. To diagnose a meningioma in similar cases difficultly even with the help of a computer tomography or MRT - PROBE as diameter of an optic nerve can be enlarged insignificantly (fig. 2).

Fig. 1. The patient with axial body height of a meningioma of an optic nerve at the left.

Fig. 2. The computer tomogram of the same patient. The shadow of an enlarged optic nerve is visible.

The meningioma of the second type of body height is diagnosed for 59 % of our patients. It is characterized by germination of the hard cerebral shell and infiltration of extraocular muscles, soft tissues of an orbit. As a rule, in the beginning of the body height the tumour has an ecscentric locating, displacing a trunk of an optic nerve (fig. 3). In similar cases it is extremely difficult to differentiate eccentrically growing meningioma from it is paraneuraled a posed tumour of other genesis, especially at absence of changes of visual functions. The most part of patients early show complaints to pains in an orbit and the same half of head. On an eyeground diagnosticate a stagnant optic disk. At the durable anamnesis (about several years) for third of patients on a background of a stagnant disk arise hemorrhages, develop opticed - ciliar shunts for compensation of the sharp difficulty of outflow of a venous blood caused by a tumour in the order a trellised plate. Visual functions are saved on a high level some years. The exophthalmos is expressed in the greater degree and 8-14 mm achieve, can be axial or with shift, is combined with a noninflammatory edema of periorbital tissues and a red hemoz (fig. 4). Limitation of mobility of an eye should be regarded, as a sign of germination by a tumour of one or several extraocular muscles. The closer to top of an orbit body height of a tumour starts, the there is a limitation of functions of extraocular muscles earlier. For a meningioma of an optic nerve absence of a hyperostosis of the bones, so inherent to intracranial meningiomas is characteristic.

Fig. 3. The computer tomogram of the patient with ecscentric body height of a meningioma of an optic nerve.

Fig. 4. The meningioma of an optic nerve infiltrating soft tissues of an orbit.

Long-term observations over character of body height of a tumour confirm its high quality. The local malignant is determined by irreversible loss of visual functions and germination of a tumour in soft tissues of an orbit. Germination in the port of an optic nerve is observed for 5 % of patients, in main at the first type of body height of a tumour.

Treatment of meningiomas of an optic nerve in due time was dramatic enough as setting of the diagnosis of a tumour of an optic nerve, irrespective of a state of visual functions, unambiguously dictated necessity of a neurectomy. In 70th years Wright J. for the purpose conservations of visual functions has offered palliative operation - decompression of shells of an optic nerve. Really, pressure decrease in intercover space of an optic nerve allows to save vision or even to improve it. But it is temporary effect - fenestratinging holes facilitate an output of a tumour for limits of the hard cerebral shell. In the last years validity of surgical treatment at meningiomas of an optic nerve is called in question, as at an output of a tumour for limits of the hard cerebral shell it is impossible to guarantee radicalism of surgical treatment: for 50 % of patients the recurrent tumor is observed, and eventually all is ended by a periosteal exentration of an orbit. Not accidentally Erzurum S. With co-authors recommend to not be limited for prophylaxis of relapses to surgical treatment, and to combine a resection of the struck optic nerve with a postoperative external irradiation.

Our long experience has allowed to formulate algorithm of treatment of meningiomas of an optic nerve depending on type of body height of a tumour.

At the first type surgical treatment is shown in a case of complete loss of visual functions. A place of a resection of a nerve determine before operation on the basis of the information received at a computer tomography or MRT - PROBE. Detection on an eyeground of hemorrhages or opticed - ciliar shunts should be regarded, as the certificate of diffusion of a tumour up to a rear pole of an eye. In such cases the patient should be warned about necessity of excision of the struck optic nerve together with an eye. At diffusion of a tumour up to an outer race of the port of an optic nerve the neurosurgeon should determine character of treatment.

At conservation of visual functions or at the second type of body height it is expedient to recommend an external irradiation of an orbit. The cooperative exposure dose should be not less than 50 Degrees. However patients are necessary for informing that the irradiation is directed on some stabilization of body height of a tumour, instead of on its complete regression, and in the further nevertheless there will occur proof loss of visual functions. It is natural, that patients with a meningioma of an optic nerve, irrespective of character of treatment, are subject to the mandatory ophthalmologic control over an annual CT or MRT - PROBE of orbits and ports of an optic nerve.