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Nervous System
and often is worsened by coughing, bending, or sudden
movements of the head.
Vomiting occurs with or without nausea, may be pro-
jectile, and is a common symptom of increased ICP and
brain stem compression. Direct stimulation of the vomit-
ing center, which is located in the medulla, may contrib-
ute to the vomiting that occurs with brain tumors. The
vomiting is often associated with headache. Papilledema
(edema of the optic disk) results from increased ICP
and obstruction of the CSF pathways. It is associated
with decreased visual acuity, diplopia, and deficits in the
visual fields. Visual defects associated with papilledema
often are the reason that persons with a brain tumor
seek medical care.
Personality and mental changes such as depression are
common with brain tumors. Persons with brain tumors
often are irritable initially and later become quiet and
apathetic. They may become forgetful, seem preoccupied,
and appear to be psychologically depressed. Because of
the mental changes, a psychiatric consultation may be
sought before a diagnosis of brain tumor is made.
Focal signs and symptoms are determined by the loca-
tion of the tumor. Tumors arising in the frontal lobe may
grow to a large size, increase the ICP, and cause signs
of generalized brain dysfunction before focal signs are
recognized. Tumors that impinge on the visual system
cause visual loss or visual field defects long before gen-
eralized signs develop. Certain areas of the brain have
a relatively low threshold for seizure activity. Temporal
lobe tumors often produce seizures as their first symp-
tom. Hallucinations of smell or hearing and déjà vu
phenomena are common focal manifestations of tempo-
ral lobe tumors. Brain stem tumors commonly produce
upper and lower motor neuron signs, such as weakness
of facial muscles and ocular palsies that occur with or
without involvement of sensory or long motor tracts.
Cerebellar tumors often cause ataxia of gait.
Diagnosis andTreatment
The diagnosis of brain tumors relies mainly on MRI.
7,47,50
Gadolinium-enhanced MRI is the test of choice for iden-
tifying and localizing the presence and extent of tumor
involvement. Computed tomographic scans may fail to
reveal certain mass lesions such as low-grade tumors or
posterior fossa masses. Diagnostic maneuvers that suggest
a possible tumor and indicate the need for MRI include
physical and neurologic examinations, visual field and
funduscopic examination, and sometimes electroenceph-
alography (EEG). Approximately 75% of persons with a
brain tumor have an abnormal EEG, which can indicate
an underlying structural lesion warranting MRI. Cerebral
angiography can be used to visualize the tumor’s vascular
supply, information that is important when planning sur-
gery. MRI may be supplemented with positron emission
tomography to better characterize the metabolic proper-
ties of the tumor, which is useful in planning treatment.
54
Magnetic resonance angiography and CT angiography
can be used to distinguish vascular masses from tumors.
The three general methods for treatment of brain
tumors are surgery, irradiation, and chemotherapy.
Surgery is part of the initial management of virtually all
brain tumors; it establishes the diagnosis and achieves
tumor removal in many cases. However, the degree of
removal may be limited by the location of the tumor
and its invasiveness. Stereotactic surgery uses three-
dimensional coordinates and CT and MRI to precisely
localize a brain lesion. Ultrasonographic technology
has been used for localizing and removing tumors. The
ultrasonic aspirator, which combines a vibrating head
with suction, permits atraumatic removal of tumors
from cranial nerves and important cortical areas. An
important adjunct to some types of surgery is intraop-
erative monitoring of evoked potentials. For example,
evoked potentials can be used to monitor auditory,
visual, speech, or motor responses during surgery done
under local anesthesia.
Most malignant brain tumors respond to exter-
nal irradiation. Irradiation can increase longevity and
sometimes can allay symptoms when tumors recur. The
treatment dose depends on the tumor’s histologic type,
radioresponsiveness, and anatomic site and on the level
of tolerance of the surrounding tissue. A newer tech-
nique called
gamma knife
combines stereotactic local-
ization of the tumor with radiosurgery, allowing delivery
of high-dose radiation to deep tumors while sparing the
surrounding brain tissue. Radiation therapy is avoided
in children younger than 2 years of age because of the
long-term effects, which include developmental delay,
panhypopituitarism, and secondary tumors.
The use of chemotherapy for brain tumors is somewhat
limited by the blood–brain barrier. Chemotherapeutic
agents can be administered intravenously, intra-arterially,
intrathecally (i.e., into the spinal canal), as wafers impreg-
nated with a drug and implanted into the tumor at the
time of surgery.
SUMMARY CONCEPTS
■■
Brain tumors can be divided into primary
intracranial tumors of neuroepithelial tissue
(e.g., neuroglia, neurons), primary intracranial
tumors that originate in the skull cavity but are
not derived from the brain tissue itself (e.g.,
meninges, primary CNS lymphoma, pituitary
gland tumors), and metastatic tumors.
■■
The clinical manifestations of brain tumor depend
on the size and location of the tumor. Focal
disturbances result from brain compression, tumor
infiltration, disturbances in blood flow, and cerebral
edema. General signs and symptoms include
headache, nausea, vomiting, mental changes,
papilledema, visual disturbances, alterations in
motor and sensory function, and seizures.
■■
The three general methods for treatment of brain
tumors are surgery, irradiation, and chemotherapy.
