Chapter 28 - Mass lesions - Neoplasm

When an intracranial mass lesion is observed on imaging studies there are several potential causes to consider in the differential diagnosis. Frequently symptoms are non-specific to the cause of the mass as they are simply the manifestation of tissue dysfunction and pressure exerted by the mass on normal structures. In some instances, however, the symptoms are specific to the etiology. Hemorrhage, which can be parenchymal or extra-axial is the most common cause of intracranial mass lesions and is discussed in Chapter 27 . Tumors, both malignant and benign, are the most common mass lesions affecting the intracranial and intraspinal contents. Less common mass lesions include inflammatory masses (i.e., granuloma, abscess, and rarely, localized hemorrhagic viral encephalitis) and on occasion demyelinating plaques of multiple sclerosis (tumefactive plaque). They are expanding mass lesions and therefore their clinical presentation is much the same as that of neoplasms, except that the inflammatory lesions are frequently associated with some systemic manifestations of infection or there is a history of a previous episode of neurologic dysfunction that improved spontaneously in the case of multiple sclerosis.

We will consider neoplasms as our model in this chapter since many of the principles concerning their effects also hold for other categories of mass lesions. The specific causes and effects of abscesses are considered further in Chapter 25, the causes and clinical presentation of hemorrhage are discussed in Chapter 27 and the traumatic hematomas are considered in Chapter 29.

Neoplasms

Intracranial tumors or neoplasms are classified according to the cell of origin. Table 28-1 lists the types that most commonly affect the brain and spinal cord. Central nervous system (CNS) neoplasms are seen in all age groups, but the frequency of specific types varies with age. Posterior cranial fossa and spinal cord neoplasms predominate in children, whereas middle and anterior cranial fossa tumors are most common in adults. Metastatic neoplasms are common in adults and unusual in children. Breast and lung carcinomas are the most common systemic cancers that metastasize to the CNS and they do so in about one quarter of patients who have these malignancies. The most frequent primary intracranial tumors are gliomas, and the most aggressive astrocytoma (glioblastoma multiforme) leads the list. Meningiomas, extra-axial tumors of the meninges, follow in frequency.

The cause of brain tumors is unknown although there are hereditary syndromes in which a predisposition to develop CNS neoplasms has been observed. For example, individuals with neurofibromatosis have a relatively high incidence of acoustic and other cranial nerve neurilemomas, glial neoplasms, and meningiomas. A similar predisposition is seen in persons with tuberous sclerosis and several other rare conditions. In addition, children who received radiation therapy for a fungal infection of the scalp (tinea capitis) also have a higher incidence of brain tumors as adults.

Symptoms

The manifestations of CNS neoplasms depend on a variety of factors, The most relevant of these factors are location, growth rate, amount of edema and intratumoral bleeding. To some extent, the dysfunction of the surrounding brain tissue depends on the rate of development of pressure and, therefore, on the rate of tumor growth. Slow-growing neoplasms such as meningiomas and neurilemmomas cause relatively little dysfunction until very late in the course of the disease because of the ability of the brain (and to lesser degree the spinal cord) to accommodate and compensate in pace with the expanding, compressive process. Rapidly enlarging neoplasms such as metastatic tumors and glioblastomas cause progressive loss of function over a short interval of time (weeks to months). Occasionally, a rapidly growing neoplasm causes sudden loss of function clinically suggestive of a stroke. This is usually the result of hemorrhage or infarction in the core of the neoplasm, which may become necrotic due to outstripping its blood supply. Also, edema may appear in and around certain neoplasms (most notably metastatic tumors) and cause the rapid appearance of symptoms and signs. Though dysfunction appears rapidly with glioblastomas, it is frequently less than the tumor size would predict because the tumor infiltrates nervous tissue and leaves many neurons functional. Therefore surgical removal of gliomas may increase a patient's neurologic impairment, although usually the deterioration is transitory.

The intracranial space is a closed chamber, with one outlet (the foramen magnum) and stiff dural membranes (the falx cerebri and the tentorium cerebelli) that divide the space into compartments. Depending on where they are located (supratentorial or infratentorial), expanding masses create vectors of force that are directed toward the paths that connect these intracranial compartments (for example, the subfalcine passage that connects one hemisphere region to the other, the tentorial notch that connects the supratentorial and infratentorial compartments and the foramen magnum that connects with the vertebral canal). This gives rise to a potentially lethal complication of mass lesions, herniation of brain tissue into another compartment. As herniation progresses there is a pattern of rostro-caudal deterioration of neural functions, which is discussed further in the chapter on stupor and coma (Chapter 17). Infants whose cranial sutures are not closed do not show rostro-caudal deterioration until quite late because the cranial cavity can enlarge progressively with widening of the sutures. Papilledema, swelling of the optic nerve head caused by increased intracranial pressure, is also late in developing or absent in infants with expansion of the intracranial contents for the same reasons.

The tumor's location can often predict the severity of symptoms and degree of loss of function. Brain regions having redundant functions are less likely to be recognized early in the course. For example, frontal-pole tumors produce few, if any, deficits until they are very large (we have on record a frontal-pole meningioma that was the size of an orange and produced no noticeable loss of function). At the other extreme, even very small tumors involving the primary motor or sensory cortex, the brain stem or the spinal cord may cause early severe impairment. In addition to producing dysfunction by direct pressure, intracranial tumors can produce focal defects by edema within nervous tissue in and around the mass (which on occasion can be massive), and by ischemia caused by compressing of blood vessels supplying the surrounding brain. Some rapidly growing and very vascular neoplasms may cause ischemic injury by stealing the blood flow from adjacent normal brain tissue.

The symptoms and signs resulting from intracranial neoplasms can be divided into non-localizing, localizing, and seizures.

Non-localizing clinical manifestations

Increased intracranial pressure

Increased intracranial pressure is characteristic of many intracranial masses and it is related to tumor size, edema, rapidity of growth, ventricular system obstruction (i.e., hydrocephalus), rate of cerebrospinal fluid absorption relative to production, venous obstruction, presence or absence of closed cranial sutures, and other unknown factors.

Headache is the most common symptom associated with increased intracranial pressure, occurs in a high proportion of persons with rapidly expanding masses, less often with slow-growing tumors. Strictly speaking, however, increased intracranial pressure alone does not necessarily cause headache. It is usually the process that has caused the increased pressure that also causes the headache by involving or displacing pain-sensitive intracranial structures such as superficial cerebral blood vessels, meninges, and some cranial and upper spinal nerves (see Chapter 18 ).

The pain location is not usually useful for location of the tumor since the pain can be referred. The headache is frequently worse in the mornings after the subject has been horizontal through the night, which presumably is the result of increased pressure-induced peri- and intratumor edema with accentuation of the tumor's size and traction effects. Nausea and vomiting are also relatively common and considered secondary to traction on lower brain stem emetic centers or a reflection of increased autonomic afferent bombardment of the brain stem caused by traction of blood vessels and meningeal structures.

The most easily observed and most telling sign of increased intracranial pressure on examination is papilledema, swelling of the optic nerve head, which is associated with a loss of retinal venous pulsations and enlargement of the blind spot on visual field testing (see the section on papilledema in Chapter 1). As mentioned, papilledema may not be manifested in infants whose cranial sutures have not yet closed. Also, older patients who have increased intraocular pressure (glaucoma) do not readily develop papilledema.

A rising or, less commonly, a slowed pulse rate and elevation of blood pressure are occasional and ominous signs of increasing intracranial pressure and imminent or ongoing rostrocaudal deterioration. It is hypothesized by some that rising pulse rate and blood pressure are compensatory autoregulating responses to the decreased cerebral blood flow caused by the raised intracranial pressure. The slowed pulse, when it occurs, appears to be a vagal excitation or release phenomenon. It may be a response of the carotid sinus to the acute rise in blood pressure or a release of the medulla and vagal outflow from diencephalic sympathetic counter forces.

Other non-localizing manifestations

Other non-localizing, also called false localizing, manifestations are abnormalities found on neurologic examination that are distant from the tumor locations and frequently misleading secondary effects of tumor enlargement. The most common are related to expanding supratentorial masses and are: (1) unilateral or bilateral sixth-nerve palsies caused by rostrocaudal displacement of the brain stem with stretching of the already taut abducens nerves; (2) third-nerve dysfunction from compression by herniating temporal lobe where the nerve passes forward at the edge of the tentorium; (3) compression of the contralateral cerebral peduncle against the edge of the tentorium, causing an ipsilateral to mass hemiparesis; (4) posterior cerebral artery compression against the edge of the ipsilateral to mass tentorium, causing ischemia-infarction of the occipital cortex and a contralateral homonymous hemianopsia; and (5) hydrocephalus secondary to tumor compression and occlusion of fourth ventricle, aqueduct of Sylvius, third ventricle, or foramen of Monro, which causes diffuse hemispheric dysfunction (i.e., dementia) that may obscure the local compressive and destructive signs of the mass itself.

Isolated personality and behavioral changes may be the initial manifestations of an intracranial mass, although usually by the time of presentation there are other associated signs and symptoms. A gait disorder is another non-localizing syndrome that may result from a brain tumor.

Localizing clinical manifestations

Focal neurological symptoms and findings caused by cortical tumors correlate with the location of the mass and the surrounding edema. If the lesion affects the motor frontal cortex there is going to be a contralateral hemiparesis. Likewise tumors in the speech area will result in aphasia. Pattern of visual field defect found on examination will help in localizing where the tumor is affecting the visual pathway (i.e. bitemporal hemianopia from a suprasellar mass compressing the chiasm).

Seizures

Seizures are the initial manifestation of approximately one quarter of adults with neoplasms and localize the tumor to the cerebral hemispheres. If focal, the seizures may localize the tumor precisely. Any adult who has a recent onset of seizures, particularly focal seizures, is considered a tumor suspect until adequate neurologic workup proves otherwise.

Specific Tumor Types

There are many types of tumors that develop intracranially. Primary tumors of the brain can derive from any of the common tissue types that are normally present (see Table 28-1). Additionally, most tumors that metastasize can spread to the brain (although some common tumors, such as prostate and colon cancer, are less likely to). Finally, the nervous system can be affected by invasion from tumors in adjacent regions such as the skull and spinal cord.

Meningiomas

Meningiomas are almost always benign and very slowly growing tumors. They may be very large because their slow growth allows the brain to adapt. Most meningiomas these days are found on scans done for other reasons and are asymptomatic. These are tumors that develop from the dura and have some attachment to the dura. They are typically quite hard and may calcify.

The damage that is done is due to pressure. Meningiomas in very delicate areas (such as where there are many cranial nerves, for example, the sphenoid wing), may produce severe symptoms. However, when they occur over the hemispheres they can be large without any symptoms at all. Meningiomas may irritate surrounding tissue and result in seizures.

There are some classic presentations for meningioma. Large meningiomas may develop inferior to the frontal lobe ("olfactory groove" meningiomas). By pushing up on the frontal lobes there may be personality changes (usually with loss of the sense of smell). Sphenoid wing meningiomas often damage the optic nerve or the extraocular nerves. Meningiomas at the foramen magnum may produce a very high cervical myelopathy. Unfortunately, CT scans are often not very good at the base of the skull (due to artifact) and, therefore, these may be overlooked even if the head is imaged with CT.

Most meningiomas are surgically resectable if they are producing symptoms. They may shrink slightly with radiation therapy. Most often these tumors can be watched since they are very slowly growing and since they very rarely undergo malignant transformation.

Glioma

The support cells of the nervous system are called glia (oligodendroglia, astroglia and ependymal cells). Gliomas are tumors that derive from these supportive cells. These are the most common intra-axial primary brain tumors. Astrocytomas are more common than oligodendrogliomas.
Astrocytomas are tumors of the astrocytes. They invade adjacent normal brain tissue and, invariably, the tumor is much larger than is visible by imaging. Also, it usually produces fewer symptoms than would be anticipated by size because it invades brain tissue and coexists with normally functioning neurons. This makes it very difficult to remove these tumors completely.

Astrocytomas are tumors of the astrocytes. They invade adjacent normal brain tissue and, invariably, the tumor is much larger than is visible by imaging. Also, it usually produces fewer symptoms than would be anticipated by size because it invades brain tissue and coexists with normally functioning neurons. This makes it very difficult to remove these tumors completely.

There are several grades of gliomas. The most malignant (and most common) is the glioblastoma multiforme, where there are pathologic features of necrosis (due to outgrowing blood supply), pseudopalisading of cells and proliferation of endothelial cells. While most of the primary nervous system tumors don't metastasize, this one can (usually by spreading in the CSF). Lower grade gliomas tend to grow quite slowly, though they can degenerate into glioblastoma multiforme.

Oligodendrogliomas are typically somewhat less aggressive. They often present with seizures rather than specifically with mass effect. As with many slowly growing tumors, they can calcify. These have a somewhat better prognosis with chemotherapy and radiation therapy. However, they are often not completely curable.

Unfortunately, there is rarely a definitive cure for glial tumors. They tend to infiltrate into surrounding normal brain, and therefore usually are not totally respectable unless they are very small and in areas of brain where very large resections can be made. Occasionally, a very low-grade glioma can be cured by less radical resections. Radiation therapy can decrease growth (and can cause some regression in size), but is also not curative. There are newer forms of chemotherapy that are being developed that are somewhat better than older versions. However, cures are quite rare with this kind of tumor.

Neurolemoma

Neurolemomas derived from the coverings of nerves. By far the most common of these tumors is an acoustic neuroma. This is a bit of a misnomer since usually this tumor arises from the vestibular nerve. The slow growth of this tumor often impinges upon the acoustic nerve with gradual hearing loss. It may affect the facial nerve as well with facial weakness. It is quite rare that it actually produces vertigo because the slow growth permits ample time for compensation. These tumors are resectable, though larger tumors may leave residual deficit.

Ependymoma

Ependymomas derive from the lining tissue of the ventricles and the central canal of the spinal cord. These have a tendency to be seen in younger individuals and often focus on the fourth ventricle or spinal cord region. These tumors can exceed the ventricular system and even subarachnoid space and so-called drop metastases are possible. Some of these tumors are completely resectable but most require adjuvant treatment. Deficits may result from pressure and local invasion or from the effects of treatment. These tumors often recur after attempted treatment, however.

Primitive neuroectodermal tumors

Primitive neuroectodermal tumors are most often seen in children and young adults. They are often midline tumors and are particularly common in the posterior fossa (especially in the area of the cerebellum/fourth ventricle and the area of the tectum. These cells these tumors are often called "small blue tumors", because they have a heavy concentration of nuclei on pathologic specimens, giving a strong basophilic appearance of a sea of blue dots. They are sensitive to chemotherapy and radiation but are not completely curable in most cases. These tumors can also spread to other areas of the brain and spinal cord through the spinal fluid. Some of the particular types of tumors in this category include pineal tumors and medulloblastomas.

Metastasis

There are many tumors that metastasize to the brain and spine. Most of these represent the common tumor types seen in adults. These include lung cancer, breast cancer and colon cancer. Some uncommon tumor types have a tendency to metastasize to the brain disproportionately, including renal cancer, while some common tumors rarely metastasize to the brain (such as prostate cancer). Ovarian cancer and melanoma also commonly metastasize to the brain.

Although solitary brain metastases may be surgically removed with improvement in outcome, multiple metastases represent a more difficult issue. Newer stereotactic radiation procedures may be quite helpful but are usually only palliative. Of course, the prognosis of the condition is heavily influenced by the primary tumor. Nonetheless, metastasis to the brain or spinal cord may represent an important source of morbidity.

Lymphoma is a form of cancer that can either develop in the brain (primary) or spread to the brain. Patients with severe immunosuppression, such as with HIV, are at particular risk for primary CNS lymphoma and this can often mimic other neurologic conditions, such as demyelinating disease. In the case of secondary spread of lymphoma to the nervous system, involvement of nerve roots and the meninges (carcinomatous meningitis) is a common presentation.

Spinal

There are many tumors that affect the spine and spinal cord. Most are metastatic (see above), however, there are some primary tumors as well. Some of these primary tumors affect the vertebra (such as multiple myeloma). Spinal tumors often result in expanding extradural masses, which can compress the cord or nerve roots. There are intradural but extramedullary tumors, such as neurofibromas, meningiomas or Schwanomas, and there are intramedullary spinal cord tumors such as gliomas or ependymomas. Additionally, these latter two tumors can metastasize in the spinal fluid and result in extra-axial masses. The key to diagnosis of spinal tumors is recognizing unusual types and locations of radicular pain as well as properly investigating progressive myelopathy.

A particular concern is spinal epidural metastasis with resultant spinal cord compression. Such a condition can produce major morbidity. The earliest symptom in most cases is back pain. This makes diagnosis difficult since back pain is common in the general population. However, back pain in a patient with a history of cancer, a new type of back pain in an older individual, back pain that does not seem responsive to specific positions or motions, back pain that awakens the patient from a sound sleep or back pain that is unresponsive to normal treatments should be viewed with high suspicion. When a patient is identified with epidural spinal cord compression, rapid administration of steroids and treatment with surgery or radiation may has a high potential for preserving function (though outcomes are highly dependent on the degree of disability at the time of initiating therapy).

Cerebellar tumors

Cerebellar tumors in children represent a particularly important clinical phenomena. Children have a higher predilection for posterior fossa tumors than adults (where tumors tend to be supratentorial). The most common of these is cerebellar astrocytoma. As opposed to adult astrocytomas, these are often surgically curable. Children may develop similar astrocytomas in the pons. However, in this location they are not curable due to the fact that large surgical procedures in the pons usually produce intolerable deficits. In addition to astrocytomas, medulloblastoma (as described above) can represent a severe and devastating form of cancer that usually develops in the cerebellar region of children. This may occasionally respond to chemotherapy and radiation, but is typically progressive and fatal.

Cerebellar tumors are relatively rare in adults. However, hemangioblastoma represents one type of tumor that may be seen (usually as a cystic mass) in the cerebellum of adults.

Pituitary tumors

Neoplasms involving the pituitary gland, hypothalamus, or both most commonly give rise to loss of function, often with systemic metabolic or endocrinologic effects. Combinations of loss of posterior pituitary function (diabetes insipidus) and anterior pituitary function (hypogonadism, hypoadrenalism, hypothyroidism, and insufficient growth) may be seen. Hypothalamic involvement may also cause changes in behavior (hypophagia, hyperphagia, placidity, sedation, low threshold for rage reactions) and autonomic function disorders (Horner's syndrome, disordered temperature regulation with hypothermia from posterior involvement or hyperthermia from anterior involvement). Encroachment on the neighboring optic chiasm leads to visual field defects, classically bitemporal hemianopia (see Chapter 3). This can also be seen with craniopharyngioma, a benign, cystic tumor that derives from remnants of Rathke's pouch.

Anterior pituitary tumors may produce positive humoral effects via increased secretion of pituitary hormones. Eosinophilic adenomas secreting growth hormone are associated with gigantism in children or acromegaly in adults, whereas basophilic adenomas are associated with Cushing's hyperadrenal syndrome. Anterior pituitary adenomas are frequently associated with excess prolactin production and galactorrhea (often accompanies by amenorrhea and infertility).

A more bizarre positive humoral affect is seen with some hemangioblastomas of the cerebellum. An erythroprotein-like substance is secreted, causing polycythemia.

Clinical course

It is typical for a person with a neoplasm to have a downhill course interrupted by periods of some improvement. There is no proven explanation for these periods of improvement; however, it is speculated that changing levels of edema and vascular integrity around the tumor are important and that circadian changes in circulating cortisol levels may bring about these changes. Variations in absorption and production of cerebrospinal fluid in response to the mass and increased intracranial pressure may also play a role.

In summary, the typical patient afflicted with a rapidly growing brain tumor has a progressive focal loss of neurologic function, with or without seizure activity. S/he complains of headache, which is frequently worse in the morning and associated with nausea, less often vomiting, and may be generalized or focal. On examination, early or well-developed papilledema may be present and focal signs of neurologic dysfunction are elicited.

In contrast, the person with a slowly growing neoplasm (e.g., meningioma) may develop very little abnormality until the tumor has become very large (may take many years) and accommodation is no longer possible, at which time a relatively acute decompensation may occur.

With spinal cord neoplasm, extrinsic or intrinsic, progressive segmental and long-tract motor and sensory deficits are typical. Focal back, neck, or limb pain is most common, with extramedullary masses affecting spinal roots and the bony encasement.

Diagnostic testing

A thorough neurologic examination utilizing the patient's story to assess the problem usually localizes the neoplasm. This may be supplemented by specialized imaging techniques.

Imaging

Imaging with CT scan or MRI is the routine diagnostic procedure to be carried out on all persons suspected of having an intracranial tumor. However, MRI is more sensitive since intracranial lesions that are of the same radiographic density as brain can be missed with unenhanced CT scans. Where density differences are too small for visualization, enhancement procedures may be effective. Magnetic resonance imaging (MRI) essentially detects hydrogen and therefore water, in differential concentrations. Neoplasms, hemorrhages, infarctions, demyelinated plaque, and other structural abnormalities are readily visible (see Chapter 23). The injection of intravascular contrast often helps to clarify the lesion since many tumors have blood vessels that do not have normal blood-brain barrier. Therefore, while the contrast is excluded from normal brain, it often "enhances" the appearance of the tumor.

Magnetic resonance spectroscopy, which can evaluate the chemical constituents of a mass, may be used to distinguish tumors from other enhancing masses, such as abscesses. Further, positron emissions tomography may be used to show the relatively high metabolic activity in the tumor.

Opacification of the cerebral arteries and veins (angiography) may define the arterial supply of the tumor and aid resection (and, occasionally, diagnosis). Abnormal tumor vessels can be delineated with arteriography in some neoplasms. Arteriovenous malformations and giant aneurysms may present clinically as mass lesions and are best delineated by angiography.

Lumbar puncture

Lumbar puncture is carried out to study the cerebrospinal fluid after results of the routine diagnostic procedures have proved negative. If preliminary observations indicate a mass lesion or suggest increased intracranial pressure, a lumbar puncture should not be done because of the chance of precipitating rostrocaudal deterioration by the rapid and possibly differential lowering of the CSF pressure in the lumbar subarachnoid space. A lumbar puncture is carried out as a preliminary examination only when (1) CNS infection (in particular, meningitis) is suspected, and (2) a patient has severe acute headache or other symptoms or a history that suggests subarachnoid hemorrhage in the absence of focal neurologic deficit and a CT scan is negative. CT scans can miss small subarachnoid hemorrhages. If this is a focal deficit, hospital admission is necessary for comprehensive study including CT scan or MRI and arteriography prior to considering lumbar puncture. With neoplasm, elevation of the level of protein in the CSF is the major finding sought, and it is nonspecific ally elevated in a majority of persons. Occasionally neoplastic cells are shed into the CSF and can be identified by cytologic techniques; tumor typing may also be possible. Both metastatic and primary malignant neoplasms are likely to shed malignant cells into the CSF, particularly those tumors located near the subarachnoid or ventricular surface of the brain. Rarely, a meningeal inflammatory response occurs with superficial and especially necrotic tumors. The CSF is infiltrated with predominantly mononuclear white cells. A polymorphonuclear cell predominance may occur, and there may be an acute, full-blown clinical picture of meningitis.

Seeding of the meninges by metastatic tumor cells in the absence of any metastatic CNS mass lesions may occur and present as a chronic meningitis. As a rule, CSF cytology readily diagnoses leukemic infiltration while multiple CSF samples may be needed to determine the presence of carcinoma cells.

Spine imaging

Spine films are routine for persons suspected of harboring spinal neoplasm. Progressive para- or quadriparesis is characteristic of spinal tumor and is a major neurologic emergency. MRI with and without enhancement is the procedure of choice in the emergency situation. If MRI is unavailable, a CT scan or CT-myelogram should be carried out (see Chapter 11).

Treatment

Treatment of CNS neoplasms is either palliative (surgical decompression, chemotherapy and radiotherapy, and corticosteroid and hyperosmotic agent decrease of edema) or curative (surgical removal, occasionally radiotherapy and rarely chemotherapy). Palliative therapy is used most for malignant tumors or tumors that are not removable because of proximity to or presence within vital centers. Curative therapy is most often for benign, accessible tumors and occasionally for isolated, single metastases.

References

Questions

Define the following terms:

metastasis, primary brain tumor, meningioma, glioma, oligodendroglioma, astrocytoma, anaplastic astrocytoma, glioblastoma multiforme, medulloblastoma, ependymoma, drop metastasis, sensory level, myelopathy, radiculopathy, non-metastatic complications of cancer, paraneoplastic syndrome.
Metastasis is the spread of a malignant tumor to a remote part of the body.
A primary brain tumor is a tumor that develops from normal tisses of the brain.
A meningioma is a (usually benign) tumor that develops from coverings of the brian.
A glioma is a tumor that develops from glial cells.
An oligodendroglioma is a glial tumor that develops from glial cells.
An astrocytoma is a glial tumor that develops from astrocytes.
An anaplastic astrocytoma is a high grade glial tumor that develops from astrocytes.
A glioblastoma multiforme is a malignant glial tumor that develops from astrocytes.
A medulloblastoma is a tumor that develops from primative neuroectodermal cells (usually in children).
An ependymoma is a glial tumor that develops from ependymal cells.
A drop metastasis is a metastasis, usually from glioblatomas or ependymomas, that occurs through the cerebrospinal system. it typically occurs around the lumbar nerve roots or the lower spinal cord.
A sensory level is a line on the trunk below which sensation is lost.
A myelopathy is damage to the spinal cord.
A radiculopathy is damage to a nerve root.
Non-metastatic complications of cancer are those that don't result from direct involvement by the tumor.
A paraneoplastic syndrome is a syndrome, usually from development of an autoimmune reaction, where there is damage to neural structures.


28-1. How are tumors localized?

Answer 28-1. Tumors are localized by their focal effects on the brain.

28-2. What are the signs that localize tumors?

Answer 28-2. There are several signs that localize tumors:

Cortical signs - aphasia, hemiparesis, hemianopsia/quadrantanopsia, sensory loss, parietal lobe symptoms (neglect, agnosia), frontal lobe signs (dysinhibition, apathy personality change)

Cerebellar - incoordination, ataxia

Lateral brain stem - unilateral loss of pin and temperature sense on face

Brain stem - cranial nerve palsy

Loss of upgaze - dorsal brain stem, pineal region

Bitemporal hemianopsia - pituitary region

Spinal cord - saddle anesthesia, paraplegia, sphincter dysfunction

28-3. What are some irritative signs of tumors of the nervous system?

Answer 28-3. Radiculopathy is due to irritation of the nerve roots. A significant percentage of brain tumors present with seizure when they irritate the cerebral cortex.

28-4. What are the signs and symptoms of increased intracranial pressure that can be found in brain tumors?

Answer 28-4. The patient with increased intracranial pressure may be awakened from sleep by headache. Papilledema or loss of venous pulsations in fundus of eye may be observed. Cushing response (increase BP with decrease pulse) occurs in a small number of cases. There may be signs of herniation (there are several types: subfalcine/cingulate, transtentorial, cerebellar). Transtentorial herniation is most common, often resulting in a dilating pupil (usually ipsilateral) and hemiparesis (usually contralateral).

28-5. What signs and symptoms are common in tumors of the pituitary region?

Answer 28-5. Endocrine problems or bitemporal hemianopsia are common with tumors of the pituitary region.

28-6. What signs and symptoms are common in tumors of the pineal region?

Answer 28-6. Failure of upgaze (Parenaud's syndrome) may be seen with pineal/tectal region neoplasms.

28-7. Why do symptoms of brain tumors often respond to steroids?

Answer 28-7. Brain tumors, especially metastatic ones, often result in severe vasogenic edema. This type of tumor often responds to steroids with some inprovement in symptoms.

28-8. What are the types of primary brain tumors?

Answer 28-8. Most primary brain tumors are named according to their cell of origin: glioma, ependymoma, meningioma, lymphoma (either primary or spread from elsewhere), Schwanoma, pituitary adenoma, primitive neuroectodermal tumor and pinealoma. The gliomas may be subdivided into astrocytomas (4 grades, with glioblastoma multiforme being the worst) and oligodendrogliomas.

28-9. Why is it usually impossible to cure a glioma?

Answer 28-9. Gliomas often infiltrate the brain so complete resection is impossible.

28-10. What glioma is usually resectible?

Answer 28-10. Cerebellar astrocytoma (pilocytic astrocytoma) in children are usually benign and resectable if found early.

28-11. What tumors are primarily localized to the posterior fossa?

Answer 28-11. Meningioma, ependymoma, acoustic neuroma (Schwanoma), cerebellar hemangioblastoma are usually localized to the posterior fossa. Many childhood brain tumors (ependymoma, astrocytoma, medulloblastoma) are localized to the posterior fossa. The prognosis is highly variable: cerebellar astrocytoma has a good prognosis, pontine glioma has a bad prognosis because of location. Medulloblastoma also has a bad prognosis while the prognosis of ependymoma depends on location and the presence/absence of drop metastasis elsewhere in the subarachnoid space.

28-12. What are the treatments for brain tumors?

Answer 28-12. Surgical resection is possible for benign tumors like meningioma and sometimes for solitary metastasis (if the systemic cancer controllable). Chemotherapy is limited by the blood-brain barrier and only specific types can be used. Sometimes chemotherapeutic agents can be delivered to the intrathecal space. Radiation is often useful for treatment, but it can damage the brain, especially long-term. For example it may result in necrosis that looks like recurrent tumor. There are experimental approaches to block angiogenesis or immune targeting.

28-13. What are non-metastatic complications to systemic cancers?

Answer 28-13. Patients with systemic cancer may develop neurologic symptoms of several types even if the cancer does not metastasize to the brain, and the symptoms can be related to a stroke, an infection, side effects of treatment , paraneoplastic syndrome. There are several paraneoplastic syndromes due to autoantibodies. These can produce: a subacute cerebellar syndrome; polyneuropathy; myoneural junction disease (weakenss); or confusional state.

28-14. What is the most common cause of tumors of the spine?

Answer 28-14. Most tumors of the spine are metastatic.

28-15. What are the common signs and symptoms of metastatic tumors of the spine?

Answer 28-15. Metastatic tumor of the spine often result first in back pain (that may persist even at rest), with subsequent signs of acute or subacute myelopathy (initially flaccid weakness, upgoing toes, sensory level over the trunk, bladder and bowel dysfunction), possible radiculopathy at the level of the tumor. The level of back pain and the radiculopathy are the most predictive of the location of the tumor.

28-16. Why is it critical to identify malignant spinal cord compression early?

Answer 28-16. It is critical to identify malignant spinal cord compression early because the outcome of treatment depends on the severity of deficit at the beginning of therapy.

28-17. What is the standard therapy for spinal cord metastatic disease?

Answer 28-17. High-dose steroids are often helpful along with radiation therapy are the common initial measures. These may be used with or without surgery (usually depending on the stability of the spine).

28-18. What are the primary tumors of the spine?

Answer 28-18. There are rare primary tumors of nerve root (neurofibromas, Schwanomas), meningiomas, gliomas. Also, there are rare tumors inside the spinal cord, mainly ependymoma and glioma.

28-19. How can you evaluate possible metastatic disease affecting the nervous system?

Answer 28-19. MRI scans are much better than CT scans at detecting metastasis (especially small ones), and CT scans are not very effective (particularly in the spine and posterior fossa of the head) unless there is destruction of bone. Plain x-rays are useful when the metastasis involves bone. At the present time, tissue diagnosis is critical to determine the type of tumor. In the future MR spectroscopy holds promise for noninvasive diagnosis.
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