eMedicine Specialties > Emergency Medicine > Hematology & Oncology

Neoplasms, Brain

Author: J Stephen Huff, MD, Associate Professor, Emergency Medicine and Neurology, Department of Emergency Medicine, University of Virginia Health Sciences Center
Contributor Information and Disclosures

Updated: Aug 26, 2009

Introduction

Background

Brain tumors may originate from neural elements within the brain, or they may represent spread of distant cancers. Primary brain tumors arise from CNS tissue and account for roughly half of all cases of intracranial neoplasms. The remainder of brain neoplasms are caused by metastatic lesions. In adults, two thirds of primary brain tumors arise from structures above the tentorium (supratentorial), whereas in children, two thirds of brain tumors arise from structures below the tentorium (infratentorial). Gliomas, metastases, meningiomas, pituitary adenomas, and acoustic neuromas account for 95% of all brain tumors. Classification by tumor cell type is irrelevant to the emergency physician because emergent treatment is the same regardless of the tumor type.

Pathophysiology

Tumors of the brain produce neurologic manifestations through a number of mechanisms. Small, strategically located tumors may damage specific neural pathways traversing the brain. Tumors can invade, infiltrate, and supplant normal parenchymal tissue, disrupting normal function. Because the brain dwells in the relatively restricted repository of the cranial vault, growth of intracranial tumors with accompanying edema may compress normal tissue and impair function. Tumors proximal to the third and fourth ventricles may obstruct the flow of cerebrospinal fluid, leading to hydrocephalus. In addition, tumors generate new blood vessels (ie, angiogenesis), disrupting the normal blood-brain barrier and promoting edema.

The cumulative effects of tumor invasion, edema, and hydrocephalus may elevate the intracranial pressure (ICP) and impair cerebral perfusion. Intracranial compartmental rise in ICP may provoke shifting or herniation of tissue under the falx cerebri, through the tentorium cerebelli, or through the foramen magnum.

Slow-growing tumors, particularly tumors expanding in the so-called silent areas of the brain, such as the frontal lobe, may be associated with a more insidious course. These tumors tend to be larger at detection.

Most primary brain tumors do not metastasize. Of those neural element tumors that do, intraparenchymal metastasis generally precedes distant hematogenous dissemination via the arterial system.

Metastatic brain tumors from non-CNS primary tumors may be the first sign of malignancy, or they may herald a relapse. Nonetheless, the signs and symptoms of brain metastases simulate those of primary brain tumors.

Frequency

United States

Estimates of the annual incidence rate of primary brain tumors range from 7-19.1 cases per 100,000 population.^1,2 Metastatic tumors to the brain are more common with more than 100,000 patients per year in the United States dying with symptomatic intracranial metastases.²  An increase in the prevalence of HIV infection corresponds to an increase in the occurrence of primary CNS lymphoma. Pituitary adenomas are exceptionally common, and they are frequent incidental findings on autopsy. Autopsy series of patients with systemic cancer show that intracranial metastases are present in 18-24% of patients.³

International

The international incidence is not known, but it is thought to parallel that of the United States.

Mortality/Morbidity

• In the United States in 1999, primary cancers of the central nervous system were the cause of death in approximately 13,100 people.²
• Brain tumors are the second most common cancer in children, comprising 15-25% of all pediatric malignancies.¹  
• Perhaps no other cancer is as feared as brain tumor since severe disability, including paralysis, seizures, gait disturbances, and impairment of intellectual capacity may occur.

Race

Differences are seen between ethnic groups within the same country, and a 3-fold difference in incidence has been reported between countries worldwide. Developed countries appear to have the highest rates, but this may reflect better registration systems.¹

Sex

• Meningiomas and pituitary adenomas are slightly more common in women than in men.
• Males are more likely to be diagnosed with brain tumors than females, with a male-to-female ratio of 1.5:1.¹

Age

• Tumors in the posterior fossa predominate in preadolescent children, with the incidence of supratentorial tumors increasing from adolescence to adulthood.
• Low-grade gliomas, such as astrocytomas, are more common in younger people than in older people. High-grade gliomas, such as anaplastic astrocytoma and glioblastoma multiforme, tend to originate in the fourth or fifth decade or beyond.
• In children, brain tumors are the most prevalent solid tumor, second only to leukemia as a cause of pediatric cancer. The incidence rate of primary CNS neoplasms is 3.6 cases per 100,000 children each year. 

Clinical

History

Presenting complaints of patients with an intracranial neoplasm tend to be similar for primary brain tumors and intracranial metastases. Manifestations depend on the cause of the symptoms: an increase in ICP, direct compression of essential gray or white matter, shifting of intracranial contents, or secondary cerebral ischemia.

Symptoms may be nonspecific and include headache, altered mental status, ataxia, nausea, vomiting, weakness, and gait disturbance. CNS neoplasms also may manifest as focal seizures, fixed visual changes, speech deficits, or focused sensory abnormalities. The onset of symptoms usually is insidious, but an acute episode may occur with bleeding into the tumor, or when an intraventricular tumor suddenly occludes the third ventricle.

• Although headache is the symptom customarily associated with an intracranial neoplasm, it often is a late complaint. Usually, headache is not an isolated finding.
  • Headache is the worst symptom in only one half of patients.
  • Most headaches in patients with brain tumors are nonspecific and resemble tension-type headaches.⁸
  • A change in any patient's headache pattern may be cause for concern.
  • New onset of headaches in middle-aged or older patients is worrisome.
  • The location of the headache reliably indicates the side of the head affected, but it does not indicate the precise site of the tumor.
  • Headaches are more common with posterior fossa tumors.
  • Headache is a more frequent symptom of intracranial tumor in pediatric patients.
  • Prevailing inaccurate portrayals of a tumor headache include pain that is worse in the early morning than at other times; vomiting (with or without nausea); and exacerbation with Valsalva maneuvers, bending over, or rising from a recumbent position.
• Mental status changes, especially memory loss and decreased alertness, may be subtle clues of a frontal lobe tumor. Complaints may be as mundane as sleeping longer, appearing preoccupied while awake, and apathy.
  • Temporal lobe neoplasms may lead to depersonalization, emotional changes, and behavioral disturbances.
  • Vision, smell, and other sensory disturbances may be caused by a brain tumor.
  • An acoustic neuroma may present as intermittent (then progressive) hearing loss, disequilibrium, and tinnitus.
  • Symptoms of pediatric posterior fossa tumors include increased irritability, unsteadiness, ataxia, headache, vomiting, and progressive obtundation.
  • Supratentorial tumors in children are more commonly associated with seizures, hemiparesis, visual field cuts, speech difficulties, and intellectual disturbance.
  • Pituitary adenomas may be divided into 2 broad categories: nonfunctional and hypersecretory. Nonfunctional pituitary adenomas remain asymptomatic until they are large enough to encroach the optic chiasm and disturb normal vision. Most hypersecretory pituitary adenomas secrete prolactin, with affected women noting an amenorrhea-galactorrhea syndrome. Men with prolactin pituitary adenomas more commonly complain of headache, visual problems, and impotence.
• Seizures, focal or generalized, may be the earliest expression of a brain tumor.
  • A Jacksonian pattern, ie, one in which a focal seizure begins in one extremity and then progresses until it becomes generalized, is distinctive in suggesting a focal structural lesion of the cortex.
  • Depending on the rate of growth of the tumor, seizures may be present for months to years before a brain tumor is diagnosed.
  • Any middle-aged or elderly patients presenting with a first seizure should have CNS tumor high in the differential diagnosis.
  • Patients with a brain tumor may present with acute neurologic changes mimicking those associated with stroke.

Physical

No physical finding or pattern of findings unmistakably identifies a patient with a CNS neoplasm.

• Based on their location, intracranial tumors may produce a focal or generalized deficit, but signs may be lacking (especially if the tumor is confined to the frontal lobe) or even falsely localizing.
• Papilledema, which is more prevalent with pediatric brain tumors, reflects an increase in ICP of several days or longer. Papilledema usually does not cause visual loss. Not all patients with CNS tumors develop papilledema. 
• Diplopia may result from displacement or compression of the sixth cranial nerve at the base of the brain.
• Impaired upward gaze, called Parinaud syndrome, may occur with pineal tumors.
• Tumors of the occipital lobe specifically may produce homonymous hemianopia or partial visual field deficits.

• Anosmia may occur with frontal lobe tumors.
• Brainstem and cerebellar tumors induce cranial nerve palsies, ataxia, incoordination, nystagmus, pyramidal signs, and sensory deficits on one or both sides of the body. 
  • Three cranial nerves run through the cerebellopontine angle: facial, cochlear, and vestibular. Masses in these regions may impair the functions of these nerves.
  • Acoustic neuromas most commonly originate from the vestibular nerve (part of cranial nerve VIII).

Causes

Although few factors are unequivocally associated with an increased risk of brain cancer, some are consequential.

• Most CNS neoplasms are thought to arise from individual cell mutations.
• A prior history of irradiation to the head for reasons other than treatment of the present tumor may increase the chance of primary brain tumor.
• A few inherited diseases, such as neurofibromatosis, tuberous sclerosis, multiple endocrine neoplasia (type 1), and retinoblastoma, increase the predilection to develop CNS tumors.
• The most common tumors originating from the cerebellopontine angle are acoustic neuroma and meningioma.
• Primary CNS lymphoma is a relatively frequent occurrence in HIV patients.
• Metastatic tumors reach the brain via hematogenous dissemination through the arterial system.
  • Lung cancer is by far the most common solid tumor disseminating to the brain, followed by breast, melanoma, and colon cancer.³
  • Less common sources of metastasis are malignant melanoma, testicular cancer, and renal cell cancer.
  • Prostate, uterine, and ovarian cancers are unlikely sources of brain metastasis.

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