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.
ACOUSTIC NEURINOMS
Pontocerebellar corner (PSA) is the petrous part of the temporal bone, the area between the internal acoustic canal and the pons. The most common tumors in this region are; schwannomas (acoustic neuromas), meningiomas, hemangioblastomas (VHL complex), arachnoid cysts, epidermoid cysts and sometimes cerebellum metastases.
Acoustic neuromas; Approximately 8-10% of all brain tumors are intracranial neuromas. The most common location of neuromas is the PSA region. Acoustic neuromas are the most common cerebellum tumors located in the PSA region. In other words, approximately 80-90% of tumors located in the PSA are acoustic neuromas.
They are generally benign lesions. Slow-onset, originate from the ear nerve (vestibular schanoma), rarely have malignant types. It is a middle-aged disease and although it is more common in the 30s, it can rarely be seen at any age. These tumors are slow growing lesions. Annual growth rates of 1-10 mm are reported in the literature. It is generally more common in women. In this regard, estrogen receptors are held responsible. Acoustic neuromas are usually unilateral, and bilateral ones are more commonly called neurofibramatosis type II.
Clinical complaints and findings;
Since this disease originates from the ear nerve, its leading complaints are tinnitus, imbalance and hearing loss. Therefore, cases primarily apply to ENT polyclinics. Hearing tests performed in these polyclinics also detect sensori-neural hearing loss. These tumors cause additional neurological complaints and findings due to their slow growth and as the tumor expands. If the tumor reaches larger volumes, balance and coordination disorders (ataxia nystagmus), swallowing difficulties, hoarseness are seen. In very large volumes, CIBA findings (papilledema, headache, vomiting, diplopia) and lower cranial nerve paralysis are seen after cerebrospinal water (CSF) obstruction.
Diagnosis;
The gold standard diagnostic method in patients with suspected cerebellar tumors is medicated brain magnetig resonance technique (MR). With the MR technique, PSA is distinguished from other common tumors (meningiomas). Because meningiomas have different radiological findings and features. In acoustic neuromas, temporal bone Computed Tomography (CT) test reveals enlargement in the internal acoustic canal and erosions in the bone.
Different clinical classifications of acoustic neuromas have been made in the literature according to their volume. Tumors less than 20×30 mm in diameter were classified as small, and those larger than 20×30 mm were classified as large-diameter acoustic norinoma.
Treatment;
1.Follow-up
2.Surgery
3.Radiosurgery
First of all, the decision on which treatment will be made with the cooperation of the patient and the doctor who will perform the surgery. In very small tumors and elderly individuals, only follow-up examinations of patients with established hearing should monitor tumor growth rates. Tumors larger than 2 cm should be operated and the tumor removed. Surgical mortality in the surgical treatment of these tumors is currently below 1%. Complication rates of the surgery are closely related to the diameter of the tumor. The most important question here is to preserve the anatomical integrity of this nerve during surgery in patients with hearing loss but without 7 nerve palsy. For example, it has been reported that in tumors smaller than 1 cm, 95-100% for the facial nerve and 50% for the auditory nerve are preserved. The rate of preservation of nerves in surgery decreases especially as the tumor diameter increases. The most important issue here is the experience of the surgeon performing this surgery and the technologies he uses. There are surgeons who recommend two-stage surgeries or post-operative radiosurgery for very large tumors.
In general, if there is no facial paralysis in patients with a diameter of 2.5-3 cm, radiosurgery is an alternative treatment. This form of treatment has been practiced since the 1950s. In particular, high-dose radiation (18-25 Gy) is given to the tumor in a single session. It is generally applied to tumors smaller than 3 cm. It has been reported that after radiosurgery, tumor volume shrinks in 40-50% of patients, 32-42% stays in the same volume, and increases in volume at a rate of 9-15%. In addition, the radaysurgery method does not immediately remove the tumor like microsurgery, but has a treatment period of 1-2 years. In the decision of radiotherapy option; Issues such as the general condition of the patient, the size of the tumor, and its bilateral nature are important.
As a result;
Acoustic neuromas are the most common benign tumors of PSA. These tumors are more common in young adults and women. The diagnosis is made very easily and quickly thanks to MR, one of today’s advanced technologies. There are 3 different options for treatment. Each treatment option has advantages and disadvantages. Whatever treatment is done, it is a benign disease after all. Today, very successful and excellent results are obtained in the treatment of these tumors with very low mortality rates (less than 1%), and low complications, thanks to experienced microsurgeons.
