Supratentorial Brain Tumors

Highest incidence age is 3–12 y and 55–65 y.

Account for 80% of adult CNS tumors; incidence of primary tumor is ∼15–20:100,000 per y.

Account for one-third of childhood CNS tumors.

Increased ICP: Headache, seizures, neurologic deficit/dementia, visual and hearing changes, focal neurologic changes (hemiparesis, numbness, ataxia), and/or visual deficits if pituitary tumor present

Endocrinopathy, fluid, and electrolyte imbalance

AEDs: Dilantin, keppra, tegretol. Adequate levels needed to avoid postop seizures.

Raised ICP and brain edema: May lead to herniation (transtentorial [dilate ipsilateral] pupil), subfalcine (leg weakness), tonsillar (neck stiffness, spasticity, extensor-plantar response), and upward transtentorial (small pupils, extensor rigidity).

Dexamethasone Rx may lead to hyperglycemia.

Hyperglycemia may cause more retractor-induced ischemic injury to adjacent brain tissues.

Endocrinopathy, particularly diabetes insipidus, if near pituitary.

Portion of brain superior to tentorium cerebella.

13,000 deaths per y; third leading cause of death in pts 15–34 y of age.

Brain edema surrounding malignant tumors causes initial Sx; often improve initially after corticosteroids.

Seizures due to local neuronal irritation; 30–70% incidence related to tumor type.

Obstructive hydrocephalus if the tumor is near third ventricle or foramen of Monro.

In adults, 85% of primary tumors occur in anterior two-thirds of cortex (most benign): glioma (45–50%), medulloblastoma, ependymoma, low-grade lymphoma (children: astrocytoma, medulloblastoma). 15% are meningiomas. Common presentation age is 55–65 y (1% of all cancers).

Many supratentorial tumors are metastases (20–30%): Melanoma, breast cancer, small-cell lung, non-Hodgkin’s lymphoma, colon, renal, nasal/throat. 50% have multiple metastases (25% of all pts with cancer have brain metastases), usually located at white-gray border.

Associated Dx includes neurofibromatosis and von Hippel-Lindau syndrome.

Brain tumors rarely metastasize outside the brain.

Pediatric (uncommon >age 2) <1 y present when large (pliable skull, glioma 50%; (astrocytoma). Most are low-grade and deep midline; others are ependymoma, medulloblastoma, and PNET (primitive neuroectodermal tumors).