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Brain Tumor

(Primary)

--An expanding, intracranial lesion that may be either benign or malignant. However, since both types can be lethal if inaccessible or left untreated, and since malignant tumors rarely metastasize beyond the central nervous system, the distinction serves mainly to describe the rate of growth and invasiveness. Tumors are divided into six classes, according to their origin: (1) skull, (2) meninges, (3) cranial nerves, (4) neuroglia, (5) pituitary/pineal body, and (6) congenital.

Causes and Incidence The etiology is unknown. Brain tumors are diagnosed in about 10,000 people a year in the United States. Undiagnosed brain tumors are found in about 2% of all routine autopsies. They can occur at any age but are most prevalent between 30 and 50 years of age. The overall occurrence is evenly divided between the sexes. Common childhood tumors include cerebellar astrocytomas, medulloblastomas, gliomas, ependymomas, and assorted congenital tumors. Common adult tumors include meningiomas, schwannomas, and cerebral astrocytomas.

Disease Process As the tumor grows, the surrounding brain tissue is compressed or infiltrated (or both), causing focal disturbances. The flow and absorption of cerebrospinal fluid are altered and/or obstructed, causing increased intracranial pressure. Blood vessels are compressed, altering or obstructing blood flow and resulting in tissue necrosis and seizures. If tumors arise in certain locations, brain tissue can shift, leading to herniation, infarction, and hemorrhage in the pons and midbrain.

Symptoms The signs and symptoms depend heavily on the tumor's location, size, and rate of growth. Slow-growing tumors are often asymptomatic until they have grown quite large.

General

Headache, nausea, vomiting, impulsivity, diminished judgment, memory impairment, depression, seizures, drowsiness, lethargy, psychotic episodes, papilledema

Focal

Frontal lobe: hemiplegia, expressive aphasia, ataxia, visual field defects, focal seizures Parietal lobe: focal sensory seizures, impaired position sense and two-point discrimination, hemianopsia, apraxia, anosognosia, speech disturbances, denial of illness Temporal lobe: convulsions, aphasia/dysphasia, olfactory aura preceding seizures Occipital lobe: hemianopsia, flashing light aura preceding seizures Brainstem: hemiplegia, hemianesthesia

Potential Complications Herniation of the brain can occur when intracranial pressure is expanded beyond compensatory levels. Prompt intervention is required, or the individual will die. Benign tumors that cannot be excised because of their size or location (or both) are generally fatal.

Diagnostic Tests

Clinical evaluation

Any of above manifestations, particularly headaches and recent onset of seizure activity

Neurologic examination

Focal manifestations, impairment of mental status

Computed tomography, magnetic resonance imaging, positron emission tomography

To detect tumor, midline shifts, and changes in ventricle size

Eye examination

To test visual fields and acuity and detect papilledema

Audiometry

To test hearing

Treatments

Surgery

Tumor excision, shunting

Drugs

Corticosteroids to reduce cerebral edema; anticonvulsants to control seizure activity; chemotherapeutic agents as adjunctive therapy or to treat recurrence

General

Radiation for tumor or residual tumor; rehabilitation for neurologic sequelae