Oncologic Disorders of the Brain

8/3/2019 Oncologic Disorders of the Brain

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ONCOLOGIC

DISORDERS OF THEBRAIN


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BRAIN TUMORS

A brain tumor is a localized intracranial lesionthat occupies space within the skull.

Usually grow as a spherical mass, but they

can grow diffusely and infiltrate tissue.


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PRIMARY BRAIN TUMORS

Originate from cells and structures within thebrain.


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SECONDARY, OR METASTATIC,

BRAIN TUMORS

Develop from structures outside the brain.


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CAUSE OF BRAIN TUMORS

Unknown

The only known risk factor is exposure toionizing radiation.


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INCIDENCE

Have increased in the past few decades

The highest incidence of brain tumors in adultsoccurs in the fifth, sixth, and seventh decades,with a slightly higher incidence in men.

In adults, most brain tumors originate from glialcells (glial cells make up the structure and supportsystem of the brain and spinal cord) and aresupratentorial (located above the covering of thecerebellum). Neoplastic lesions in the brainultimately cause death by impairing vital functions,such as respiration, or by increasing intracranialpressure (ICP).


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PATHOPHYSIOLOGY

Brain tumors may be classified into severalgroups:

Those arising from the coverings of the brain

(eg, dural meningioma), those developing in oron the cranial nerves (eg, acoustic neuroma),those originating within brain tissue (eg,

gliomas), and metastatic lesions originatingelsewhere in the body.

Tumors of the pituitary and pineal glands andof cerebral blood vessels are also types of

brain tumors.


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GLIOMAS

Glial tumors, the most common type of brainneoplasm, are divided into many categories.

Astrocytomas are the most common type of

glioma.

Oligodendroglial tumors are another type ofglial tumor, representing 20% of gliomas


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MENINGIOMAS

Represent 20% of all primary brain tumors, arecommon benign encapsulated tumors ofarachnoid cells on the meninges.

They are slow-growing and occur most often inmiddle-aged adults (more often in women).

Most often occur in areas proximal to the venoussinuses.

Manifestations depend on the area involved andare the result of compression rather than invasionof brain tissue.

Standard treatment is surgery with completeremoval or artial dissection.


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ACOUSTIC NEUROMAS

Is a tumor of the eighth cranial nerve.

It usually arises just within the internal auditorymeatus, where it frequently expands before

filling the cerebellopontine recess.

May grow slowly and attain considerable sizebefore it is correctly diagnosed.

The patient usually experiences loss ofhearing, tinnitus, and episodes of vertigo andstaggering gait.


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PITUITARY ADENOMAS

Represent about 8% to 12% of all brain tumorsand cause symptoms as a result of pressureon adjacent structures or hormonal changes

(hyperfunction or hypofunction of the pituitary).


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Angiomas

Brain angiomas (masses composed largely of abnormalblood vessels) are found either in or on the surface of thebrain.

They occur in the cerebellum in 83% of cases.

Some persist throughout life without causing symptoms;others cause symptoms of a brain tumor.

Occasionally, the diagnosis is suggested by the presence ofanother angioma somewhere in the head or by a bruit (anabnormal sound) audible over the skull.

Because the walls of the blood vessels in angiomas are thin,these patients are at risk for a cerebral vascular accident(stroke). In fact, cerebral hemorrhage in people younger than40 years of age should suggest the possibility of an angioma.


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CLINICAL MANIFESTATIONS

Brain tumors can produce either focal orgeneralized neurologic signs and symptoms.

Generalized symptoms reflect increased ICP,

and the most common focal or specific signsand symptoms result from tumors interferingwith functions in specific brain regions.


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INCREASING ICP

EnlargingTumor

Disruption of the equilibrium that existsbetween the brain, the CSF, and the

cerebral blood, all located within theskull

As the tumor grows, compensatory

adjustments may occur.

Gradual compression of the

brain


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compression of intracranial

reduction of CSF volume (by increasedabsorption or decreased production

a modest decrease of cerebral bloodflow, and reduction of intracellular and

extracellular brain tissue mass.


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If compensatory mechanisms fail

Development of signs and symptoms

headache

Nauseaand

vomiting

6th

nervepalsy

Localize

dSympto

ms


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Headache

Not always present

Most common in the early morning and is madeworse by coughing, straining, or suddenmovement.

It is thought to be caused by the tumor invading,compressing, or distorting the pain-sensitivestructures or by edema that accompanies thetumor.

Headaches are usually described as deep orexpanding or as dull but unrelenting.

Frontal tumors usually produce a bilateral frontalheadache; pituitary gland tumors produce painradiating between the two temples (bitemporal); in

cerebellar tumors, the headache may be locatedin the subocci ital re ion at the back of the head.


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Vomiting

Seldom related to food intake

Usually due to irritation of the vagal centers inthe medulla.


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Visual Disturbances and

Papilledema

Present in 70% to 75% of patients

Is associated with visual disturbances such asdecreased visual acuity, diplopia (double

vision), and visual field deficits.


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Localized Symptoms

The most common focal or localizedsymptoms are hemiparesis, seizures, and

mental status changes When specific regions of the brain are

affected, additional local signs and symptoms

occur, such as sensory and motorabnormalities, visual alterations, alterations incognition, and language disturbances such asaphasia.


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A motor cortex tumor produces seizure-like movementslocalized on one side of the body, called Jacksonian seizures.

An occipital lobe tumor produces visual manifestations:

contralateral homonymous hemianopsia (visual loss in half ofthe visual field on the opposite side of the tumor) and visualhallucinations.

A cerebellar tumor causes dizziness, an ataxic or staggeringgait with a tendency to fall toward the side of the lesion, marked

muscle incoordination, and nystagmus (involuntary rhythmiceye movements), usually in the horizontal direction.


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A frontal lobe tumor frequently produces personality

disorders, changes in emotional state and behavior, and anuninterested mental attitude. The patient often becomesextremely untidy and careless and may use obscene

language.

A cerebellopontine angle tumor usually originates in thesheath of the acoustic nerve and gives rise to acharacteristic sequence of symptoms. Tinnitus and vertigo

appear first, soon followed by progressive nerve deafness(eighth cranial nerve dysfunction). Numbness and tinglingof the face and the tongue occur (due to involvement of thefifth cranial nerve). Later, weakness or paralysis of the face

develops(seventh cranial nerve involvement). Finally,because the enlarging tumor presses on the cerebellum,

ssessmen an agnos c


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ssessmen an agnos cFindings

NeurologicExamination

CT Scan

indicates the areas of the CNSinvolved

gives specific information concerningthe number, size, and density of thelesions and the extent of secondary

cerebral edema, CT scans canprovide information about theventricular system.


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MRI

- The most helpful diagnostic tool fordetecting brain tumors, particularlysmaller lesions A, and tumors in the

brain stem and pituitary regions,where bone interferes with CT.

- The appearance of a brain tumor

on an MRI is so characteristic that abiopsy is unnecessary, especiallywhen the tumor is located in a partof the brain that is difficult to biopsy.


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Positron

emissiontomography

(PET)

-It is used to supplement MRI.-On PET scans, low-grade tumors areassociated with hypometabolism andhigh-grade tumors show

hypermetabolism.


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Computer-

assistedstereotactic (3-dimensional)

biopsy

- Used to diagnose deep-seated braintumors and to provide a basis fortreatment and prognosis.


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CerebralAngiography

- Provides visualization of cerebralblood vessels and can localize mostcerebral tumors


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Electroencephalogram

- Can detect an abnormal brainwave in regions occupied by atumor and is used to evaluatetemporal lobe seizures and assist

in ruling out other disorders.


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Cytologic Studies ofthe CSF - Detect malignant cells


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Gerontologic Considerations

Produce personality changes, confusion,speech dysfunction, or disturbances ofgait.

The most frequent tumor types in theelderly are anaplastic astrocytoma,glioblastoma multiforme, and cerebral

metastases from other sites. The incidence of primary brain tumors and

the likelihood of malignancy increase with

age.


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Medical Management

Chemotherapy

External-beam radiation therapy

Surgical resection

Intravenous (IV) autologous bone marrowtransplantation

Gene-transfer therapy

Photodynamic therapy


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CHEMOTHERAPY

Antineoplastic agents

Oncologic Disorders of the Brain

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