Olfactory groove meningioma

Introduction to olfactory meningioma The adhesion of the olfactory sulcus meningioma to the dura mater is located in the anterior cranial fossa and the posterior cranial fossa. The olfactory sulcus meningioma can be divided into unilateral or bilateral, more common on one side, and the tumor can also extend to the other side. . basic knowledge Sickness ratio: 0.001%-0.002% Susceptible people: no special people Mode of infection: non-infectious Complications: cerebral edema, coma

The cause of olfactory meningioma

(1) Causes of the disease

The cause of this disease is still unclear. Its occurrence may be related to certain internal environmental changes and genetic variation, not caused by a single factor. May be related to craniocerebral trauma, radiation exposure, viral infection, and bilateral auditory neuroma. A common feature of these pathological factors is that they may mutate the cell chromosome or increase the rate of cell division. It is generally believed that the cell division of arachnoid cells is very slow, and the above factors accelerate the rate of cell division, which may be an important stage leading to early cell degeneration. Meningeal tumors include meningeal endothelial cell tumors, mesenchymal non-meningeal endothelial tumors, primary melanocyte lesions, and tumors of unknown tissue origin.

(two) pathogenesis

Olfactory meningioma belongs to meningeal endothelial cell tumors and may be derived from arachnoid villi or embryonic remnants. Including 11 types, meningeal endothelial, fibrous, mixed, grit, vascular, microcapsule, secretory, clear cell type, chordate-like, lymphoplasmic cell type, metaplastic type. The most common of these is the meningeal endothelial type, accounting for 53.5% of the olfactory meningioma.

The olfactory meningioma has both spherical and flat shapes. The spherical shape is more common, the surface is intact or nodular, colored film, often has a "umbilical" connected with the dura mater; flat thickness often does not exceed 1cm, widely distributed on the dura mater, more common at the bottom of the skull. The olfactory sulcus meningioma is rich in blood vessels, and is mainly supplied by the external neck and the intracervical (or vertebral basal) arteries. The cut surface of the tumor is dark red, and there may be a milky yellow area with flaky lipid deposition. The woven structure is common, sometimes calcified sand is seen, and a few have cystic changes. The tissue morphology of olfactory meningioma has many manifestations, but each type has the basic structure of olfactory meningioma, containing meningeal endothelial cells, and the cell arrangement often retains some characteristics of arachnoid villi and arachnoid granules. It is concentric or concentric, and the middle of these concentric circles is prone to hyaline degeneration or calcification. Fibrous tissue, vascular tissue, fat, bone or cartilage, and melanin can be seen in the tumor tissue. The tumor malignancy is grade I.

Olfactory sulcus meningioma prevention

Some related factors of the disease are prevented before the onset of the disease. Many tumors are preventable before they are formed. A US report in 1988 compared the international malignant tumors in detail, suggesting that many of the known malignancies are preventable in principle, that is, about 80% of malignant tumors can be changed through simple lifestyles. prevention. Continuing with the retrospective, a study by Dr. Higginson in 1969 concluded that 90% of malignant tumors are caused by environmental factors. Environmental factors and lifestyle refer to the air that breathes, the water that is drunk, the food that is selected for production, the habits of activities, and social relationships.

Olfactory sulcus meningioma complications Complications, brain edema, coma

If surgery is performed, the following complications may occur:

1. Loss of olfactory: Loss of inevitable loss after bilateral olfactory surgery, but does not cause serious obstacles.

2. Cerebral anterior artery blood supply disorder: Injury of the anterior cerebral artery during operation and cerebral edema, brain swelling, and even ischemic necrosis after frontal lobe surgery.

3. Inferior thalamic injury: The patient developed persistent coma and central hyperthermia after surgery.

4. Optic nerve, anterior cerebral artery and its branch damage: only seen in the larger volume of the tumor, the posterior pole is extended to the saddle, and careful separation of the tumor can be avoided.

5. Cerebrospinal fluid rhinorrhea: mostly due to the removal of the dura mater of the basal stenosis of the tumor, it can also be the result of open frontal sinus and improper treatment during craniotomy.

Symptoms of meningioma of the olfactory groove Common symptoms Increased intracranial pressure, visual impairment, dysfunction of the olfactory side, nipple atrophy,... Olfactory loss hemianopia illusion

The early symptoms of olfactory meningioma are gradually lost. When the tumor is on one side, the olfactory loss is unilateral, which is meaningful for localization diagnosis. However, if it is bilaterally lost, it is often confused with rhinitis. Although olfactory disorders are more common, patients often ignore them. Many patients are confirmed when they are examined in the hospital. This is because the unilateral olfactory disturbance can be compensated by the contralateral side, and the patient is not easy to detect. In addition, the olfactory sulcus meningioma is caused. The loss of olfaction is different from the scent of scent caused by temporal lobe lesions. It should be noted that because early olfactory disorders are often ignored by patients, tumors are not detected for a long time. The tumors have grown very large during clinical diagnosis. Symptoms of increased intracranial pressure.

Visual impairment is also more common, causing vision loss due to increased intracranial pressure, optic disc edema and secondary atrophy, another cause of vision loss is the tumor backward development directly oppresses the optic nerve, individual patients may appear double or single Lateral temporal hemianopia, the literature reported that about a quarter of patients constitute Foster-Kennedy syndrome.

Tumor affects frontal lobe function, can cause mental symptoms, patients with excitement, hallucinations and delusions, but also due to increased intracranial pressure and unresponsiveness and mental apathy, a small number of patients may have seizures, pyramidal tract signs appear in late tumors or Limb tremor is the manifestation of tumor compression of the internal capsule or basal ganglia.

Examination of olfactory meningioma

1. Skull plain film: often shows the anterior cranial fossa bottom including sieve plate, the bone of the dome is thinned or damaged, and the outline is fuzzy. It can also be the bone plate and the dome bone hyperplasia. The calcification of the granules in the tumor can occur. The uniform density increases the block shadow and covers the anterior cranial fossa of the bone erosion.

2. Cerebral angiography: the lateral phase of the anterior cerebral artery is curved backwards. Most of the diseased side of the ocular artery is thickened, and the distal branch is increased or fenced to lead the blood supply to the front cranial fossa. At the same time, individual cases can also be used. There is a middle meningeal artery that supplies blood to the tumor.

3. CT and MRI scan: showing a circular tumor image on one side or both sides of the anterior cranial fossa, with a diameter of 2.0-6.0 cm, clear boundary, high-density shadow can be seen by CT scan, and tumor density is increased after contrast enhancement. The posterior aspect of the tumor can compress the frontal ventricle of the ventricle. The relationship between the tumor and the internal carotid artery can be seen on the MRI image.

Diagnosis and differentiation of olfactory sulcus meningioma

In the differential diagnosis of glioma, the age of onset and the shape of optic nerve thickening are better identified. It is easy to be confused with the irregular shape of the tumor inside the muscle cone. Because the density is close, it is not easy to identify on CT. Therefore, it is often necessary to rely on other clinical methods such as ultrasound to identify. Clinically, inflammatory pseudotumor around the optic nerve can be seen. The symptoms are similar to those of the optic nerve sheath olfactory sulcus meningioma. The imaging examinations have similarities. At this time, the symptoms and signs of clinical inflammation are very helpful in differential diagnosis. However, bilateral optic nerve sheath olfactory meningioma can be seen clinically, and should be noted in differential diagnosis. According to statistics, bilateral optic nerve meningioma accounts for 9% to 23% of olfactory meningioma.

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