Surgery 5th year, 1st lecture/part one (Dr. Khalid Shokor Mahmood)

Dr. Khalid S. MahmoodF.I.C.M.S. (Neurosurgery)

Intracranial Tumors

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.

• The etiology of brain tumors is still not clearly understood. Chromosomal abnormalities: this is noted in

many CNS tumors. Oncogenesis involves both the addition of oncogene to the genome and the loss of normally occurring tumor suppressor genes.

Immunosuppression Chemicals Radiation Occupation Mobile phones Diet

Etiology

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 Cerebellar vermis Cerebellar hemisphere

• Seizures Late-onset epilepsy, particularly over the age of 25,

should prompt investigation to exclude an intracranial neoplasm.

Endocrine dysfunction

Clinical Features

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

Gliomas

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 arachnoid villi.

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.

• Perioperative dexamethasone. • Radiotherapy is reserved for aggressive tumors,

recurrent tumors or subtotally removed tumors.

Meningiomas

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.

Acoustic Neuromas

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 MRIGeneral investigation must be done

searching for the primary tumor (chest radiography, ultrasound, ESR, etc.)

Treatment

• Steroids• anticonvulsant• Surgery• Radiotherapy. More recently, GK.

Metastatic 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

Pituitary Tumors

Clinical features Pituitary tumors arise in the sella turcica and can

compress the optic chiasm resulting in visual field defects

They may invade laterally into the cavernous sinuses compressing the 3rd to 6th cranial nerves.

Endocrine disturbance is due to either hypopituitarism or excess secretion of a particular pituitary hormone: Prolactinomas: usually in younger women and cause loss

of libido, infertility, amenorrhea, and galactorrhea. ACTH secreting adenomas: cause Cushing's disease. GH secreting adenomas: cause:

Acromegaly in adults. Gigantism in children.

pituitary apoplexyDiabetes insipidus

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 sella turcica, 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. Radiotherapy is used for subtotal resection and for

persistent hypersecretion of pituitary hormones.

Thank you