Hiazma glioma — the tumoral education originating from the glial cages located in the field of a visual recross. The glioma of a hiazma is shown by decrease in visual acuity, narrowing or loss of a part of fields of vision, symptoms of hydrocephaly and neuroendocrine violations. The complex of diagnostic inspections at a glioma of a hiazma includes a viziometriya, an oftalmoskopiya, perimetry, a research of visual VP, MRT and KT of a brain, a stereotaksichesky biopsy. The hiazma glioma depending on its characteristics, localization and age of the patient is treated. It can be surgical intervention (removal or a partial resection of a glioma, restoration of a likvorotsirkulyation), himio-or radiotheraphy.
The glioma of a hiazma makes about 2% of brain gliomas. Most often it has a histologic structure to the corresponding astrotsitoma. Unlike the majority of gliomas of an optic nerve, the glioma of a hiazma meets not only at children's age, but also at patients 20 years are more senior. Approximately in 33% of cases the glioma of a hiazma accompanies a neurofibromatosis of Recklinghausen — , characterized by formation of pigmentary spots and numerous neurofibromas, emergence nevriny, gliomas and meningiy various localization.
Development of a glioma of a hiazma in children and persons of young age does its timely diagnostics and effective treatments by an important task on which solution the neurology, ophthalmology and neurosurgery in common work.
Hiazma represents the partial optic chiasm located in the brain basis. Over hiazmy there is a hypothalamus which is carrying out neuroendocrine regulation and first of all influencing sekretorny activity of a hypophysis. Near a visual recross the III ventricle is localized.
In the field of a hiazma the fibers of an optic nerve going from nasal (medial) half of a retina of the right and left eye cross. The fibers originating in temporal (lateral) half of a retina remain on the party. The right and left visual ways containing nervous fibers from a medial part of a retina of an opposite eye and a lateral part of a retina of an eye in return depart from a hiazma. As the image gets on a retina in the turned look (from the right field of vision to the left half of a retina and vice versa), each visual way brings to a cerebral cortex information from half of fields of vision of both eyes opposite to it.
Hiazma glioma symptoms
The glioma of a hiazma can initially arise also owing to distribution to area of a visual recross of a glioma of an optic nerve. In return the glioma of a hiazma is capable to extend on an optic nerve in an orbit cavity, to sprout in a hypothalamus and the III ventricle. Most of authors indicate that the hiazma glioma usually is followed by the optokhiazmalny jet arakhnoidit leading to formation of solderings and subarakhnoidalny cysts. Clinical manifestations of a glioma of a hiazma depend first of all on an arrangement of a tumor and the direction of its growth. Generally they are presented by decrease in visual acuity, changes of visual fields, endocrine and exchange violations and a likvorno-gipertenzionny syndrome (intra cranial hypertensia).
Violations from sight can be caused both by a sdavleniye a glioma of a hiazma of an optic nerve, and destruction by the sprouting tumor of its visual fibers. At growth of a glioma of a hiazma on the course of an optic nerve there is a thickening infiltrirovanny a tumor of visual fibers that conducts to a nerve sdavleniye in the visual channel. Decrease in visual acuity has bilateral character more often. Sometimes in an initial stage the glioma of a hiazma gives only unilateral deterioration in sight, and damage of the second eye is shown several months later or even years. The glioma of a hiazma differs slowly progressing and often in asymmetric decrease in visual acuity. If the glioma of a hiazma extends to an eye-socket, then along with easing of sight is observed progressing .
Change of fields of vision directly depends on the location of a glioma of a hiazma. Most often the glioma of a hiazma is in a forward part of a visual recross and strikes visual fibers before their transition to the opposite side. In such cases the bitemporal nature of narrowing of fields of vision of both eyes is noted. Perhaps concentric narrowing of fields of vision and education is central the located scotomas (sites of loss of the image). If the glioma of a hiazma settles down in its back part behind an optic chiasm, then loss of the half of the same name of fields of vision (a gomonimny gemianopsiya) is observed.
Endocrine and exchange frustration by which the hiazma glioma at its germination in a hypothalamus is followed can include: hypothalamic syndrome, not diabetes, gipersomniya, dientsefalny syndrome, obesity, giperkortitsizm, premature puberty, violations of mentality.
The glioma of a hiazma can proceed with signs of increase in intra cranial pressure: a headache, weight in eyeballs, nausea. Often these symptoms are caused by a jet arakhnoidit. They when the glioma of a hiazma sprouts to the area III of a ventricle are most expressed and, causing okklyuzionny liquorodynamic violations, leads to development of hydrocephaly.
Diagnostics of a glioma of a hiazma
As the glioma of a hiazma begins to be shown with sight violations, primary address of patients happens mainly to the ophthalmologist. The doctor holds ophthalmologic testing: visual acuity definition, usual or computer perimetry, and also survey of structures of an eye. In diagnostics of a glioma of a hiazma carrying out perimetry which results allow to determine the level of defeat of visual ways is important and to gain an approximate impression about localization of a tumor. In an initial stage of growth the glioma of a hiazma can not give any changes at an eye bottom. Further at an oftalmoskopiya stagnant disks of optic nerves, signs of primary atrophy of an optic nerve are noted. The research of visual VP allows to define degree and level of damage of optic nerves.
The results of a complex ophthalmologic research testifying about existence of intra cranial volume process of visual ways is a reason for consultation of the neurologist and carrying out MPT or KT of a brain. In the absence of a possibility of a tomographic research carry out a skull X-ray analysis which reveals pear-shaped deformation of the Turkish saddle, characteristic of a hiazma glioma. Carry in addition out a X-ray analysis of orbits in a slanting projection. In cases when the glioma of a hiazma sprouts in an orbit, on roentgenograms one is defined - or bilateral expansion of visual openings to 9 mm.
Tomographic methods of a research of a brain are much more informative. They allow to determine precisely existence of a tumor, its arrangement, the sizes and extent of germination by the course of optic nerves, in tissue of a brain and hypothalamus. However the tomography does not give the chance to distinguish a hiazma glioma from other tumors of this localization (a ganglionevroma, a teratoma, a retikuloendotelioma, etc.). It can be made only by a histologic research of the cells of tumor received by a stereotaksichesky biopsy or during operation.
Treatment of a glioma of a hiazma
Surgical treatment of a glioma of a hiazma can be applied with its ekzofitny growth when violations of sight are caused generally sdavleniy an optic nerve. If the glioma of a hiazma sprouts in an optic nerve, then usually resort to its full removal only in case of development of a blindness. The widespread glioma of a hiazma is subject only to a partial resection as its full removal leads to a bilateral blindness and considerable endocrine violations. At germination of a glioma of a hiazma in the III ventricle surgery is necessary for elimination of the progressing hydrocephaly. With the same purpose carrying out operation on a section of solderings and opening of the cysts formed as a result of a jet arakhnoidit can be required. The choice of medical tactics at patients with the diagnosis "a hiazma glioma" is carried out by the neurosurgeon depending on localization and the sizes of a tumor, age of the patient, a histologic type of a tumor and so forth.
Along with surgical treatment radiation therapy and chemotherapy can be applied to a glioma of a hiazma. However at children's age because of high radio sensitivity of dientsefalny area radiation therapy leads to the expressed endocrine frustration, behavioural and intellectual violations. Than the age of the child is less, especially side effects of radiation of a tumor are expressed at it. Therefore at children with a glioma of a hiazma apply mainly chemotherapy (, ), and carry out beam influence only in the absence of effect of himiopreparat.
Forecast of a glioma of a hiazma
The growing limited glioma of a hiazma concerning which full surgical removal worked well has the optimum forecast ekzofitno. The partial resection and the subsequent chemotherapy in most cases allow to stop growth of a glioma. However in 20-30% of cases after such treatment the progressing growth of a tumor is observed.