Tumors of Brain
B. H&P
C. DDx of brain tumor
Abscess, bleed, infarct, demyelination, radiation necrosis….
D. Tests
MRI + contrast, or CT + contrast if pt unstable or question of hemorrhage. See imaging of tumor, p. 182. Brain biopsy vs. resection. Consider workup for unknown primary tumor (usually CXR, mammogram, chest/abdominal CT), LP to rule out leptomeningeal spread.
E. Rx of brain tumor
See also specific tumor types, below.
1. Treat edema: Consider one or more of the following:
a. Dexamethasone: Bolus 10 mg IV, then 4 mg q6h. Taper after radiation therapy. If you suspect CNS lymphoma, try to withhold steroids until biopsy.
b. Fluid restrict: 1200 cc qd, no free water.
c. Mannitol: 50-100 g IV, then 25-50 g q6h to keep osmolality 305-310.
2. Neurosurgery:
a. Resection: Unless inaccessible, multiple foci, or very radiosensitive. Consider surgery for all posterior fossa tumors >3 cm even if there are other metastases.
b. Biopsy: In situations where full resection is inadvisable but a tissue diagnosis is necessary.
c. CSF access procedures: see p. 85. E.g., EVD or VP shunt for hydrocephalus, Ommaya reservoir for intraventricular chemotherapy.
3. Radiation therapy: Consider 2-3 d of steroids before beginning XRT to decrease swelling, especially in posterior fossa lesions.
4. Chemotherapy: Regimens vary. see p. 166 for side effects.
5. Seizure prophylaxis: No need to provide prophylaxis to pts who have never seized, except if there is a risk of herniation. Metastases in the cerebellum or deep subcortical areas rarely cause seizures.
F. Prevalence
1. Metastases: 30%-50% of all brain tumors. Presenting complaint is from a brain met in 15% of all cancer pts. 10% present with seizures.
2. Primary intracranial tumors: Astrocytomas (including GBM) 38%, meningiomas 18%, acoustic schwannomas 8%, oligodendrogliomas 4%, lymphomas 4%, craniopharyngiomas 1%.
G. Metastases
to CNS:
1. Most common source: Usually carcinoma ≫ sarcoma or lymphoma.
a. Intracranial metastases: Lung > breast > melanoma > renal, colorectal, lymphoma, and unknown primary. Prostate is very rare.
b. Dural, epidural, skull metastases: Breast, prostate.
c. Leptomeningeal metastases: see p. 124.
2. Tumors most likely to have brain metastases: Melanoma (40%).
3. Metastases likely to bleed: Renal, papillary thyroid, melanoma, choriocarcinoma, lung.
4. Number: On MRI, only 20%-30% of mets are solitary.
a. Solitary metastases: Resection is usually offered. If cannot resect, consider biopsy because 10% turn out not to be mets even if the pt has another known primary.
b. Multiple metastases: Consider resection of the dominant, symptomatic lesion. Stereotactic radiosurgery may help small lesions.
5. Location: 80% are supratentorial, 15% cerebellar (50% of cerebellar metastases are pelvic/GI).
6. Prognosis for brain metastases:
a. No rx: 4-wk survival.
b. Steroids aloneRelated posts:
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