This document summarizes information about intracranial tumors. It discusses their etiology, clinical features, classification, diagnosis and treatment. The major types of tumors covered include gliomas, meningiomas, acoustic neuromas, metastatic tumors and pituitary tumors. Gliomas form about 50% of adult primary intracranial tumors and arise from glial cells. Meningiomas are most often benign and originate from the meningothelial cells of the arachnoid villi. Acoustic neuromas arise from Schwann cells of the 8th cranial nerve. Metastatic tumors commonly originate from the lung, breast and kidney and are diagnosed via imaging. Pituitary tumors account for about 8%

1. Intracranial Tumors Dr. Khalid S. Mahmood F.I.C.M.S. (Neurosurgery)

2. Any mass lesion within the skull is a threat to the integrity of brain function and therefore even histologically benign tumours can threaten life. The incidence varies with age. The classification of brain tumors is determined by their cell of origin.

3. Etiology • The etiology of brain tumors is still not clearly understood. Chromosomal abnormalities: this is noted in many CNS tumors. Oncogenesisinvolves both the addition of oncogene to the genome and the loss of normally occurring tumor suppressor genes. Immunosuppression Chemicals Radiation Occupation Mobile phones Diet

4. Clinical Features There will be different combination of the followings: •Features of raised ICP • Focal neurological signs Motor and sensory area Dominant hemisphere near the speech area Optic pathways posterior to the chiasm Anterior frontal lobe Sellar tumors Tumors in relation to the CSF pathways Cerebellarvermis Cerebellar hemisphere • Seizures Late-onset epilepsy, particularly over the age of 25, should prompt investigation to exclude an intracranial neoplasm. Endocrine dysfunction

7. Gliomas Gliomas form about 50% of adult primary intracranial tumors. They are usually supratentorial. They arise from the glial cells of which there are four types: astrocytes, oligodendrocytes, ependymal, and microglial cells. The most common primary CNS tumor is astrocytoma. Diagnosis • CT scan with and without contrast. • MRI will show more details and in multiplanar views. Treatment • Dexamethasone • Surgery: its aim is to obtain pathological diagnosis and grading, and to debulk the tumor. • Radiotherapy: • External beam • Stereotactic focal irradiation [Gamma Knife (GK)] • Brachytherapy (implantation of radioactive source) • Chemotherapy

11. Meningiomas Most of them are benign. They are uncommon in children. There is slight female predominance, and their incidence peaks in middle age. They originate from the meningothelial cells of arachnoidvilli. They classically arise from a broad base along the dura and may invade the bone. Diagnosis CT scan and MRI. Treatment • Total surgical excision wherever possible with trying to preserve neurological function. Total resection of the tumor with its dural attachment is usually curative. • Perioperativedexamethasone. • Radiotherapy is reserved for aggressive tumors, recurrent tumors or subtotally removed tumors.

14. Acoustic Neuromas They are benign nerve sheath tumors arising from Schwann cells of the 8th cranial nerve within the internal acoustic meatus. As the tumor grows, it will extend into the cerebellopontine angle (CPA) compressing the pons, cerebellum, and cranial nerves. Bilateral acoustic schwannomas are diagnostic of Neurofibromatosis type 2. Unilateral hearing loss occurs early. CT and MRI will provide the diagnosis. Treatment Total surgical removal is usually aimed. Patients may sustain postoperative 7th nerve palsy. GK radiosurgery is recently used for small tumors.

16. Metastatic tumors Of those who die with cancer, 25% have brain metastases at autopsy. Origin of cerebral metastasis: Lung: 40%; Breast: 20%; Kidney: 11%; Melanoma: 11%; Colon: 8%; unknown primary: 5% It's diagnosed by CT scan and MRI General investigation must be done searching for the primary tumor (chest radiography, ultrasound, ESR, etc.) Treatment • Steroids • anticonvulsant • Surgery • Radiotherapy. More recently, GK.

18. Pituitary Tumors They account for about 8% of all brain tumors. Classified as the following: • According the size: microadenomas (<10 mm) mesoadenomas (10-20 mm) macroadenomas (>20 mm) • According to the hormone secreted by the adenoma: Growth hormone (GH) Adrenocorticotrophic hormone (ACTH) Prolactin (PRL), prolactinoma Thyroid-stimulating hormone (TSH) Non-functioning adenomas

20. Gigantism in children.pituitary apoplexy Diabetes insipidus

22. Investigations Neuroradiological imaging: MRI and CT scan Hormonal assessment Visual assessment: VA and VF (visual acuity and field) Treatment Conservative: in prolactinomas, bromocriptine(a dopamine agonist) or octreotide are useful. Surgical: either through trans-sphenoidal approach to the sellaturcica, or transcranial (subfrontal) approach. Surgery is indicated in: Lesions compressing the surrounding structures Inappropriate hormone production, which cannot be controlled by the drugs Replacement of the pituitary hormones is usually needed postoperatively. Radiotherapyis used for subtotal resection and for persistent hypersecretion of pituitary hormones.

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