Meningiomas are common and are derivatives of the meninges and interstitial meninges, accounting for 19.2% of intracranial tumors and ranking second only to gliomas. Meningiomas originate from the arachnoid endothelium, and all intracranial areas rich in arachnoid granules and arachnoid villi are good sites for meningiomas. Meningiomas are more common in the parsagittal sinus, cerebral convexity, and pars falciformis, followed by the pterygoid crest, saddle node, bromic sulcus, cerebellopontine angle, and cerebellar curtain, etc. Meningiomas growing in the ventricles are rare, but there are also ectopic meningiomas, occasionally in the cranial plate, frontal sinus, nasal cavity, subscalp, or neck, which come from ectopic arachnoid tissue, not metastasis. Etiology: The occurrence of meningioma may be related to certain internal environmental changes and genetic variants, and is not caused by a single factor. Preferred sites: ① parsagittal sinus, about 50% of the convex surface of the brain, ② saddle node, ③ septal sinus, ④ cavernous sinus, ⑤ pontocerebellar horn, ⑥ cerebellar curtain, etc. Classification: According to the pathological characteristics, they are divided into: endothelial or fibrous type, vascular type, grit type, mixed type or migratory, malignant meningioma, and meningeal sarcoma. The first 5 types are generally classified as benign meningiomas, while malignant changes occur most frequently in angiogenic meningiomas and should be considered in cases of multiple recurrences. Clinical manifestations Benign meningioma grows slowly and has a long course, with early symptoms lasting about 2.5 years on average and up to 6 years in the long run. In elderly patients, epilepsy is the first symptom. Malignant meningioma, meningeal sarcoma, has rapid development, infiltrative growth, irregular shape and unclear boundary, rapid development after surgery, and distant metastasis. Meningiomas have different clinical manifestations depending on the location, which are briefly described below: Meningioma of the convex surface of the brain, which generally has a long history, mainly manifests with varying degrees of headache, mental disorders, limb movement disorders and changes in vision and visual field, and about 60% of patients can develop symptoms of increased cranial pressure after six months. Parasagittal sinus meningioma tumor grows slowly, usually the tumor is already very large when the patient develops symptoms, epilepsy is the first symptom of the disease, localized or grand mal seizures, mental disorders manifested as dementia, emotional indifference or euphoria, patients appear personality changes, parasagittal sinus meningioma located in occipital lobe may appear visual field disorders. Pterygoid crest meningioma: the tumor originates from the anterior bed projection and may present with vision loss or even blindness; invasion to the orbit or supraorbital area may present with eye protrusion, eye movement disorder, pupil dilatation; epilepsy, psychiatric symptoms, and olfactory disturbance. Meningioma of the saddle node: More than 80% of patients have visual impairment as the first symptom; headache, a few patients may develop drowsiness, memory loss, anxiety and other psychiatric symptoms; some patients may develop endocrine dysfunction, such as loss of libido, impotence, amenorrhea, etc.; some patients also present with loss of smell, epilepsy, and actinic nerve palsy as the first symptom. Parafalcine meningioma: The movement disorder starts from the foot, gradually goes to the lower extremity, followed by upper extremity muscle strength disorder, and finally spreads to the head and face. If the tumor grows to both sides, bilateral limb muscle strength and urinary disorder, epilepsy, and intracranial pressure increase symptoms may appear. Meningioma of olfactory sulcus: early symptoms include gradual loss of smell, increased intracranial pressure may cause visual impairment, excitement, hallucination, delusion, retardation, mental indifference when tumor affects frontal lobe function, and epilepsy in a few patients. Pontocerebellar horn meningioma: This part of the tumor is more common with auditory neuroma, which accounts for 70-80% of meningioma, only 6-8%, and cholesteatoma 4-5%. Clinical manifestations are hearing loss, tinnitus, facial numbness, and sensory loss. Damage is manifested by unsteady walking, gross horizontal tremor, and ataxia of the affected side. Rock-slope meningioma; often manifests as headache, but often goes unnoticed, with significant symptoms of III-X cranial nerve damage. Intracerebroventricular meningioma: Because of intracerebroventricular growth, early neurological impairment is not obvious, but the tumor is usually large by the time of consultation. It often presents with headache, optic papilledema, epilepsy, isotropic hemianopia, and contralateral limb hemiparesis. Meningioma of the middle cranial fossa: manifesting as trigeminal neuralgia, eye movement disorder, eyelid ptosis, diplopia, decreased visual acuity, isotropic hemianopia, etc. Meningioma of the cerebellar curtain: coarse horizontal tremor and ataxia on the affected side, visual field disorders, etc. Paraneoplastic meningioma of the spongy sinus: manifesting as headache, visual field changes, eye muscle paralysis, and pain in the area of distribution of one or two branches of the trigeminal nerve. Meningioma of the greater occipital foramen presents early with neck pain, numbness of the hands and upper extremities, and is easily misdiagnosed. Orbital and cranio-orbital communicating meningioma: protrusion of the eye, eye movement disorders, and loss of vision. Diagnosis The clinical features of meningioma are slow onset and long course. Meningioma may have different clinical manifestations in different parts of the body. Because of the high incidence in adults, the possibility of meningioma should be considered when adults have chronic headache, mental changes, epilepsy, loss of vision on one or both sides or even blindness, ataxia or limited cranial masses, especially when accompanied by symptoms of progressively increasing intracranial pressure. Funduscopic examination often reveals chronic optic nerve papillary edema or has shown secondary atrophy. Confirmation of tumor diagnosis also relies on ancillary diagnostic tests. Mainly CT, MRI scan plus enhancement. Not only can localization be achieved, but also the size and characterization of the tumor can be understood. Meningioma has its own specific signs, showing a limited circular contrast-enhanced image with uniform density in the skull, and meningeal tail sign. It may be accompanied by osteophytes, a band of hypodense cerebral edema around the tumor, corresponding brain displacement, and signs of hydrocephalus due to cerebrospinal fluid circulation obstruction. The treatment of meningioma is based on surgical resection. In principle, complete resection and removal of the meninges and bone invaded by the tumor should be pursued in order to achieve radical treatment. Meningioma is an extra-parenchymal growth tumor and most of them are benign. If early diagnosis is made and surgery is performed before the tumor damages the surrounding brain tissue, important cranial nerves and blood vessels, total resection should be achieved. However, there are some advanced tumors, especially deep meningioma, which are huge and adhere to the nerves, blood vessels, brainstem and lower thalamus, or the nerves and blood vessels are not easy to be separated, in this case, total resection should not be performed reluctantly, so as not to aggravate the damage of brain and cranial nerves and cause the risk of intraoperative hemorrhage, or even cause death or serious disability. It is advisable to limit to subtotal resection of tumor, reduce the volume of tumor, and supplement with decompression surgery to reduce the pressure of tumor on brain, relieve intracranial pressure and protect vision. Malignant cases can be supplemented with radiotherapy.