Neurosurgery

Question 1

Brain Tumors

Answer 1

• Because the brain is encased in a nonexpandable bony

skull, both benign and malignant brain tumors can cause

death if not appropriately diagnosed and treated. Brain

tumors cause elevated intracranial pressure (ICP) by

occupying space, producing cerebral edema, interfering

with the normal flow of cerebrospinal fluid, or impair-

ing venous drainage (Fig. 20-1). Patients may present

with progressive neurologic deficits owing to increasing

ICP, tumor invasion, or brain compression. Alternatively,

they can present with headache or seizures.

Question 2

Brain Tumors: Pathology

Answer 2

• Intracranial tumors can be classified as either intra-

cerebral or extracerebral (Table 20-1). Intracerebral

tumors include glial cell tumors (astrocytomas, oligo-

dendrogliomas, ependymomas, primitive neuroecto-

dermal tumors), metastatic tumors (lung, breast, skin

[melanoma], kidney, colon), pineal gland tumors, and

papillomas of the choroid plexus. Extracerebral tumors

arise from extracerebral structures and include menin-

giomas, acoustic neuromas, pituitary adenomas, and

craniopharyngiomas.

Glial cell tumors and metastatic tumors are the

most common central nervous system (CNS) tumors

seen in adults. Children have a higher proportion of

posterior fossa tumors.

Question 3

Glial Cell Tumors (Part 1)

Answer 3

• Glial cells account for approximately 50% of CNS

tumors in adults. Different glial cell types (astrocytes,

oligodendrocytes, ependymal cells, and neuroglial pre-

cursors) give rise to various histologic types of tumors.

Although the term “glioma” can be used to describe

he above glial tumor types, its common use refers

only to astrocytic tumors.

Question 4

Glial Cell Tumors (Part 2)

Answer 4

• Astrocytic tumors are graded I to IV based on his-

tologic evidence of malignancy; grade I and II tumors

are slow-growing malignancies. In children, astrocy-

tomas located in the posterior fossa (cerebellum)

usually have cystic morphologies (pilocystic astrocy-

toma). Grade III tumors are the more aggressive

anaplastic astrocytomas. The most common as well as

the most malignant astrocytoma is the grade IV

glioblastoma multiforme. Glioblastoma multiforme

tumors often track through the white matter, crossing

the midline via the corpus callosum, resulting in the

so-called butterfly glioma on computed tomography

(CT). Median survival is 1 year.

Question 5

Glial Cell Tumors (Part 3)

Answer 5

• Oligodendrogliomas are slow-growing calcified

tumors, often seen in the frontal lobes. They are most

common in adults and are often associated with seizures.

Ependymomas arise from cells that line the ven-

tricular walls and central canal. Clinical signs and

symptoms of elevated ICP are the main features of

presentation. Ependymomas are mostly seen in chil-

dren and usually arise in the fourth ventricle.

Classified by location, infratentorial posterior fossa

tumors make up most of the lesions seen in child-

hood. These are most commonly cystic cerebellar

astrocytomas, ependymomas, and medulloblastomas.

Highly malignant medulloblastomas typically occur

in the vermis in children and in the cerebellar hemi-

spheres in young adults.