optic glioma
Introduction
Introduction to optic glioma Optic nerve glioma (opticnerveglioma) is a benign tumor that occurs in the glial cells of the optic nerve. The glial cells are the supporting cells of the central nervous system and ganglia. Glial cells are divided into astrocytes, oligodendrocytes and microglia, gliomas that occur in the optic nerve, almost all astrocytoma, and occur in children's fibers. Astrocyte, also known as juvenilepilocyticastrocytoma (JPA). basic knowledge The proportion of sickness: 0.00002% Susceptible people: no special people Mode of infection: non-infectious Complications: headache, epilepsy, coma
Cause
Cause of optic glioma
(1) Causes of the disease
Whether optic glioma is a benign hyperplasia of a family of hereditary astrocytes, or a new organism, is still controversial. This disease can occur in the same family and newborn newborns, with slow progress, often accompanied by Congenital small eyeballs and neurofibromatosis, neurofibromatosis is a dominant genetic disease, as many as 15% to 50% of patients with optic glioma associated with this disease, in the past 10 years, many scholars on glioma The chromosomes were studied and found to have abnormal changes. These findings support genetic theory, but family genetics are rare in clinical practice, and genetic material evidence is still insufficient.
(two) pathogenesis
The pathogenesis is not very clear at present.
Prevention
Optic glioma prevention
There is no effective preventive measure for this disease. Early detection and early diagnosis are the key to the prevention and treatment of this disease.
Complication
Optic glioma complications Complications, headache, epilepsy, coma
The intracranial spread of optic glioma to the optic chiasm can cause headache, vomiting, epilepsy and coma.
Symptom
Optic glioma symptoms Common symptoms Visual spatial function impaired pigmented spots Yellow nodules Bleeding Eyeballs Optic atrophy Responsive strabismus ocular tremor
1. More common in children under 10 years of age, women are more involved;
2. Eyeball protrusion: It is an inevitable symptom that is early, usually moderately prominent and cannot be reset;
3. Vision loss: generally occurs before the exophthalmos, which is the oppression of the optic nerve fibers by the tumor tissue;
4. Fundus changes: fundus signs are determined by the tumor site, such as a little further from the eyeball, then the primary optic atrophy, such as close to the optic nerve of the eye, due to compression of the central retinal vein, can cause papilledema, accompanied by Obvious oozing, bleeding, venous engorgement, like central venous obstruction;
5. Visual field change: due to the involvement of the optic nerve stem, various morphological visual fields are reduced, such as chiasm, which may lead to hemianopia;
6. strabismus: loss of vision due to compression of the optic nerve, or pressure on the eye muscle;
7. CT: Since the tumor originates from the internal or intracranial segment, the two can extend each other and expand the optic nerve. Therefore, CT scan or X-ray examination can be found that the optic nerve hole is generally considered to be 6.5-7mm or larger. If the contralateral side is larger than 1 mm, it can be regarded as an expansion of the nerve hole.
Examine
Examination of optic glioma
Pathological examination
Normal astrocytes are divided into two types: fibrosis and protoplasm. Both types of cells can develop tumors. In childhood, optic gliomas are almost all fibrous astrocytoma. According to the degree of cell differentiation, fiber-shaped stars Glioblastoma is further divided into 4 grades: I, II grade is benign, grade III, grade IV is malignant, optic nerve fiber astrocytoma is grade I in childhood, adult optic astrocytoma can be seen II Grade, all belong to benign tumors.
Visual examination of optic nerve astrocytoma showed that the optic nerve was spindle-shaped, the largest transverse diameter was 2.5cm, the surface was smooth, the dura mater was intact, pale white, fresh, similar to translucent, tumor along the optic nerve Longitudinal axis spread, often in the optic canal thinner, or simple optic nerve and visual beam thickening, widening of the optic chiasm, a few cases of chiasm and visual beam widening is limited to the affected side, the tumor cross-section can be seen outside the thickened meninges The inside is a gray-white delicate and brittle tumor essence, which is easy to cut with a curette, and the suction device absorbs. Due to the proliferation of tumor cells, small blood vessels are blocked, affecting the nutrition of nerve fibers, about one-third of the specimens can be seen as cystic changes. The capsule is filled with transparent slurry and viscous liquid. Alcian blue is positive. In severe cystic degeneration, it can be a cystic mass, and only a small amount of tumor tissue remains in the cyst wall.
Microscopically, the invasiveness of the tumor cells is enlarged, and there is no obvious boundary between the normal optic nerve fibers. The tumor is composed of well-differentiated astrocytes. The tumor cells are slender, have hair-like protrusions, parallel or braided, and the pia mater. The connective tissue is thickened and loses its original structure, and is enlarged by the tumor cells. Between the tumor cells, a few normal oligodendrocytes, phosphotungstic acidic hematoxylin (PTAH) staining tumor cells The swells were positive, immunohistochemical staining, collagen fiber acidic protein (GFAP) and neuron specific phosphotungstic acid pyruvate hydratase were positive, and there was eosinophilic Rosenthal body in the cell process, PTAH was Strong positive, on the surface of the tumor, arachnoid cells are obviously proliferated, the meninges are thickened, and sometimes misdiagnosed as meningioma.
Electron microscopy showed that the tumor cells showed fibrous astrocyte characteristics, the star-shaped protrusions were filled with filaments, and the diameter of 50-100 nm and amorphous substances were fused together. This is the Rosenthal body seen by light microscopy, Rosenthal The corpuscles found that the astrocytes were grade II, with more tumor cells, densely arranged, irregularly shaped, and coarser protoplasts, also known as astroblastoma, which remained in a benign range.
X-ray inspection
When the tumor is small, there is often no positive change. The larger tumor causes the centripetal enlargement of the optic nerve hole, but the edge of the cortical bone is clear, and the wall of the tube generally does not have osteosclerosis or destruction. If the size of the optic nerve hole on both sides of the same patient differs by more than 1 mm or single Abnormalities should be considered when the width of the lateral optic nerve hole exceeds 5 mm. When the optic chiasm is involved, the saddle can be "pear-like" or "cucurbit-like" or enlarged on the lateral slice of the skull.
2. Ultrasonic exploration
(1) B-mode ultrasound: showing optic nerve fusiform or elliptic enlargement, clear and sharp borders, lack of internal echo, less or moderate, axial scan of the posterior tumor can not be displayed, probe tilt can show a moderate echo of the posterior tumor, combined In the optic disc edema, the echo of the tumor is connected with the strong echo spot in front of the raised optic disc. When the eyeball rotates, the front end of the tumor moves in the opposite direction, indicating that the tumor is closely related to the eyeball, and the posterior part of the eyeball is flattened.
(2) CDI: blood flow is visible around the tumor, but not abundant.
3.CT scan
Can be unilateral onset, but also bilateral onset, the latter often accompanied by neurofibromatosis, and the order of onset of both sides can be inconsistent, should be paid attention to, optic nerve thickening distortion is the most common manifestation of optic glioma, due to tumor Compression, often the normal subarachnoid space of the front end is enlarged. The optic glioma is divided into optic nerve fusiform or elliptic enlargement. It can also be tubular thickening, clear boundary, uniform density, and low density in the tumor. In the cystic zone, about 3% of the tumors show calcification, and the tumor is closely related to the tip of the sac. When the tumor grows along the optic canal, it can cause the centripetal enlargement of the optic nerve. HRCT can clearly show the bone change, compared with the brain parenchyma. Cross or optic gliomas are of equal density or low density, irregular shape, can invade the hypothalamus, and can also compress the sella, resulting in changes in the shape of the sella, optic glioma enhancement, most of the light to moderate enhancement A small number of gliomas are hardly strengthened. Enhanced scanning helps to determine the extent of the lesion. Optic gliomas involve the sacral cavity at the same time, and the optic canal and the optic chiasm appear as "dumbbells."
4.MRI
The optic nerve is fusiform, coronal or elliptical thickening, mostly central, and a few are eccentric. Compared with normal extraocular muscle, optic glioma has low signal on T1WI, high signal on T2WI, and moderate after enhancement. Intensive, part of the tumor pressure forced the normal subarachnoid space in the front to expand, showing a long T1 and long T2 signal similar to the cerebrospinal fluid signal; a pseudo-envelope formed due to structural hyperplasia such as arachnoid surrounding a few tumors. For long T1, long T2, MRI can clearly show the morphology of optic glioma and its relationship with adjacent structures, can also clearly and accurately show optic canal glioma, more visual display of chiasm or glioma morphology The structure of its invasion, such as the thalamus, temporal lobe, etc., is enhanced by enhanced scanning combined with fat suppression techniques.
Diagnosis
Diagnosis and differentiation of optic glioma
diagnosis
Children's optic glioma is closely related to neurofibromatosis. In glioma cases, 1/5 to 1/2 of the iris yellowish nodules, skin coffee pigmentation spots, subcutaneous soft masses and tibia Signs of neurofibromatosis such as congenital loss, these signs with visual loss and primary optic atrophy should be highly suspected of the possibility of posterior optic glioma, the presence of neurofibromatosis, does not affect glioma The course and prognosis.
The diagnosis of X-ray plain film has limitations. It can only show that the optic nerve hole has certain clinical significance, and it is difficult to display the tumor itself. It is rarely used now. B-ultrasound has a qualitative diagnostic significance for optic glioma, which can clearly show the intraorbital lesion. However, it is difficult to display the lesions in the tube and intracranial, which can be used as a screening method. CT can accurately display the location, shape, boundary, intraorbital and intracranial conditions of the lesion, especially showing the expansion of the optic canal and widening the anterior bed. It is easy to determine the nature and extent of the lesion, but it is difficult to display the smaller glioma in the optic canal. It is also difficult to accurately display the chiasm or glioma. There is also a limit to accurately determine the relationship between the lesion and the adjacent structure. MRI can accurately display the lesion. The scope and relationship with adjacent structures, especially for optic canal and optic chiasm or glioma, show a reliable basis for clinical surgery, MRI is the best method for examination of this disease, B-ultrasound, CT can be used as an auxiliary examination method .
Differential diagnosis
Imaging differential diagnosis: 1 optic nerve meningioma: occurs in adult women, visual impairment, mostly after eyeball protrusion, optic nerve sheath meningiomas can be eccentric, CT value is high, may be accompanied by spots, ring or irregular calcification MRI examination of T1WI, T2WI showed moderate signal, CT or MRI enhanced "orbital sign"; 2 optic neuritis: clinically showed a sharp decline in visual acuity, may be accompanied by pain in the eyeball rotation and deep eyelid pain, MRI performance For diffuse thickening of the optic nerve, soft tissue mass is not formed, T1WI optic nerve signal is reduced, T2WI signal is increased, STIR is high signal, and enhanced after enhancement, the enhanced scan combined with fat suppression sequence shows the best, which can be multiple sclerosis. A change, MRI shows hardening plaque around the ventricles, then the disease can be identified.
In addition, mainly and some diseases that can cause optic nerve thickening, such as: inflammatory pseudotumor, meningioma, etc., inflammatory pseudotumor often has inflammation, and the shape of the optic nerve is often irregularly thickened, so with Glioma is easy to identify. Meningioma is more common in adults. The shape of the optic nerve is different, the border is irregular, and biopsy should be confirmed when clinical identification is difficult.
