Cerebellum tumors should be examined under two separate headings as adults and childhood.
Approximately 70-75% of adult brain tumors are located in the brain, while 60-70% of childhood brain tumors are located in the cerebellum. In other words, 2/3 of all adult brain tumors are seen in the brain, while 2/3 of childhood brain tumors are seen in the cerebellum.
While the most common brain tumor in adults is glial tumors (astrocytomas), the most common cerebellum tumor is hemangioblastomas, whose genetic transition is well known.
The most common type of tumor after childhood leukemia is cerebellum tumors. The most common among childhood cerebellum tumors (medulloblastoma, astrocytoma, epandioma, brain stem gliomas, dermoid and epidermoid cysts, etc.).
Among adult cerebellum tumors, the most common tumors (acoustic neuroma, meningioma, arachnoid and epidermoid cysts, plasmacytomas, glomus jugulare tumors, cerebellum metastases) are seen in the ponto-serbellar corner region in adults.
MENINGIOMAS
Ponto-cerebellar corner (PSA) is the petrous part of the temporal bone, the name given to the area between the internal acoustic canal and the pons. Pontocerebellar corner tumors are included in the cerebellum tumors.
Among the most common PSC tumors; There are 70-80% acoustic neuromas, 5-10% meningiomas and 5% epidermoid or dermoid cysts. Apart from these, aneurysms, arterio-venous malformations, cancer metastases, arachnoid cysts very rarely localize PSC. Apart from these, cerebellum or brain stem gliomas, pituitary adenomas, craniopharyngiomas, skull base tumors, glomus jugulare and choroid plexus papillomas can also be seen extending to the corner.
Meningiomas are benign encapsulated solitary tumors arising from the membranes of the brain or cerebellum. Menengiomas in the cerebellum; PSA can be seen in different regions such as petroclival region, foramen magnum, foramen jugulare and rarely ventricular meningiomas. Meningiomas were first described in 1614, but the definition of meningioma was used for the first time by Kuşig. Meningiomas constitute 25-30% of all brain tumors, they are seen in 90% brain and 10% cerebellum. Its incidence is 4.5/100 000, it is more common in women than in men. It is a middle-age disease and its incidence increases with increasing age. It is rarely seen in children, which is mostly malignant. Meningiomas are benign encapsulated slow-growing lesions. There are 3 types according to the WHO classification; Stage 1: typical meningioma, Stage II: atypical meningioma, Stage III malignant meningioma (malignant) type.
Risk factors
1. Head trauma, skull bone fractures
2. High-dose radiotherapy
3. Hormonal causes, common in women, hormone receptors are emphasized.
4. Viruses (Melnic virus)
Neurofibramatosis type II is an autosomal dominant genetic inherited and it is common to have meningioma together
Clinical complaints and findings,
Menengiomas of this region reach large diameters when diagnosed because they grow in very different directions towards regions such as the cerebellum and brainstem for the tumor to grow. In addition to the complaints and symptoms related to the pressure of both the cerebellum and the neighboring nerves in this region, signs of increased intracranial pressure are seen with the inhibition of CSF circulation. Headache, tinnitus, imbalance hearing loss are the leading complaints. As the tumor size grows, facial numbness and neuralgia-like facial pain continue insidiously with the suppression of neighboring nerves. In addition, when it reaches a certain volume, CIBA findings (headache, vomiting, diplopia, diplopia, papilledema) begin to be seen in the clinic. Generally, complaints of headache, vomiting and imbalance are the complaints of applying to a doctor in diseases of this region. Later, due to the suppression of the cerebellum, ataxia, nystagmus, deterioration of coordination movements and suppression of the neighboring nerves result in paralysis of the hearing and facial nerves, reaching larger volumes, and paralysis of the arm and leg on the same side, and paralysis of the swallowing nerve.
Diagnosis
The gold standard diagnostic method in patients with suspected cerebellar tumors is the medicated brain magnetig resonance (MR) technique. Brain MRI is used to distinguish whether it is present or not from other common tumors (acoustic neuroma, epidermoid, arachnoid cysts) seen in PSA. Because meningiomas have different radiological findings and features. In meningiomas, they are well-defined and round lesions with good contrast in the PSA region with Computed Tomography (CT) test. Also, the adjacent cerebellum called the tail is prominent and this feature is characteristic for meningiomas. Erosions, hyperostoses, and calcifications of meningiomas in bone are well-known radiological features of meningiomas. Edema around the tumor is common in some hormone-secreting types. Cerebrovascular angiography testing shows that some types (angioblastic) meningiomas have too many vascular nutrients. Knowing these feeding arteries well before the operation helps the surgeon to control early bleeding during the operation. Closing the tumor feeding arteries by embolization is not an accepted practice in the preoperative period. MR spectroscopy has little place in the diagnosis of meningioma. In addition, PET-CT has no place in the diagnosis of meningioma.
Treatment
The treatment of PSA corner meningiomas is surgery. Among other treatment options, radiotherapy and chemotherapy are applied only in malignant type meningiomas. Before the operation, information should be obtained about the origin of this tumor and its surrounding feeding arteries and adjacent drainage veins, as well as the normal arterial structure and vonous sinuses in the PSA region. This information will help to control tumor bleeding during surgery. The main goal should be to remove the entire tumor. Preparations should be made accordingly. Surgery mortality is very low in patients with good preoperative preparations. Mortality was not observed in the corner meningiomas that I did after 2000. These surgeries are performed very successfully in today’s high-tech hospitals. Meningiomas with postoperative pathology stage 1 do not require any additional treatment.
In conclusion
PSA meningiomas are the second most common benign corner tumor in this region. It is more common in women and is a middle-age disease. It is a well-circumscribed encapsulated extra-axial solitary tumor. Headache, imbalance, dizziness are the leading complaints. As the tumor grows in volume, complaints and findings related to both increased intracranial pressure and pressure from adjacent cranial nerves are observed. The diagnosis is made very easily and quickly today. Medicated brain MRI test is the gold standard in diagnosis. Its treatment is surgery. Surgical results are excellent.
