AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Low-grade astrocytomas are a heterogeneous group of intrinsic central nervous system (CNS) neoplasms that share certain similarities in their clinical presentation, radiologic appearance, prognosis, and treatment. The most common intrinsic brain tumor, glioblastoma multiforme (GBM), is high grade and malignant. This contrasts with low-grade astrocytomas, which are less common and therefore less familiar to practitioners. The strategies for diagnosis and treatment are also more controversial.

Improvements in neuroimaging permit the diagnosis of many low-grade astrocytomas that would not have been recognized previously. Low-grade astrocytomas are, by definition, slow growing, and patients survive much longer than those with high-grade gliomas. Proper management involves recognition, treatment of symptoms (eg, seizures), and surgery, with or without adjunctive therapy. Low-grade astrocytomas are found in both the brain and the spinal cord.

Pathophysiology

Low-grade astrocytomas are primary tumors (rather than extraaxial or metastatic tumors) of the brain. Astrocytomas are one type of glioma, a tumor that forms from neoplastic transformation of the so-called supporting cells of the brain, the glia or neuroglia. Gliomas arise from the glial cell lineage from which astrocytes, oligodendrocytes, and ependymal cells originate. The corresponding tumors are astrocytomas, oligodendrogliomas, and ependymomas. Grading of a glioma is based on the histopathologic evaluation of surgical specimens. Several classification schemes have been proposed.

The World Health Organization (WHO) scheme is based on the appearance of certain characteristics: atypia, mitoses, endothelial proliferation, and necrosis. These features reflect the malignant potential of the tumor in terms of invasion and growth rate. Tumors without any of these features are grade I, and those with one of these features (usually atypia) are grade II. Tumors with 2 criteria and tumors with 3 or 4 criteria are WHO grades III and IV, respectively. Thus, the low-grade group of astrocytomas are grades I and II.

A subset of astrocytomas, because of their distinctive pathology, preclude the use of the usual 4-featured grading system. These tumors may have endothelial proliferation and marked atypia; nevertheless, they are slow growing and well circumscribed. This subset comprises juvenile pilocytic astrocytoma (JPA) and its variant a juvenile pilomyxoid astrocytoma, pleomorphic xanthoastrocytoma (PXA), and subependymal giant-cell astrocytoma (SGCA). Low-grade astrocytomas generally cause symptoms by perturbing cerebral function (eg, seizures), elevating intracranial pressure (ICP) by either mass effect or obstructing cerebrospinal fluid (CSF) pathways (ie, hydrocephalus), or causing neurologic (and sometimes endocrine) abnormalities (eg, paralysis, sensory deficits, aberrant behavior, headaches).

Infiltrating low-grade astrocytomas tend to occur in the lobes of the cerebral hemispheres, especially in the frontal lobe. Pilocytic astrocytomas may occur in the frontal, temporal, and parietal lobes and cerebellum, but they are also common in locations closer to the midline, such as the hypothalamus, thalamus, optic chiasm, and brain stem. In children, pilocytic astrocytomas have a predilection for the mesial structures of the cerebellum. PXAs also are found most commonly in the hemispheres, particularly the temporal lobes. SGCAs are found most commonly in the lateral wall of the third ventricle and almost exclusively in patients with tuberous sclerosis.

Frequency

United States

The yearly incidence of gliomas in adults in the United States is approximately 5.4 cases per 100,000 population. Low-grade tumors make up approximately 10-20% of these tumors in adults and 25% in children. Thus, the incidence in adults of low-grade gliomas is about 0.8 case per 100,000 population. The incidence of gliomas in children is approximately 2.4 cases per 100,000 population, making the incidence of low-grade gliomas 0.6 case per 100,000 population.

Gliomas are associated with certain phakomatoses, especially neurofibromatosis type 1 (NF-1). Low-grade astrocytomas occur more commonly in these patients, particularly in the optic nerve and chiasm. Patients with tuberous sclerosis have a host of cerebral anomalies, accounting for the high incidence of mental retardation. SGCAs are found almost exclusively in patients with tuberous sclerosis.

International

The incidence of low-grade astrocytoma has not been shown to vary significantly with nationality. However, studies examining the incidence of malignant CNS tumors have shown some variation with national origin. Since some of these high-grade lesions arise from low-grade tumors, these trends are worth mentioning. Specifically, the incidence of CNS tumors in the United States, Israel, and the Nordic countries is relatively high, while Japan and Asian countries have a lower incidence. These differences probably reflect some biological differences as well as differences in pathologic diagnosis and reporting.

Mortality/Morbidity

Differences in patient populations, diagnostic methods, and reporting make defining the exact median survival duration for all patients with low-grade astrocytomas difficult. This is complicated by the fact that low-grade astrocytomas, as discussed already, are a heterogeneous group of tumors. However, the median survival duration of patients with low-grade astrocytomas is approximately 7.5 years.

• In a recent series, taking all patients, the 5-year survival rate ranged from 65-80%, while the 10-year survival rate varied from 20-45%. Several factors influence survival. For example, the histopathology of the tumor has a clear influence on prognosis. Patients with grade I lesions have better survival rates than those with grade II lesions. Younger age and better performance status at the time of diagnosis also have a positive influence on long-term survival.
• The type of therapy received also influences outcome. Total resection has been shown in numerous studies to be associated with better survival rates than other therapeutic modalities. This is partially due to the fact that complete resection is more easily accomplished in well-circumscribed, slower-growing tumors. However, sound oncologic principles also suggest that cytoreduction offers benefit. Radiation probably prolongs survival in patients whose tumors are resected incompletely. However, the survival advantage conferred by chemotherapy remains to be demonstrated clearly.
• Over periods of many years, these tumors frequently undergo dedifferentiation into higher-grade lesions. Such lesions then grow more rapidly and eventually become fatal. Progressive neurologic deficit is the norm as the tumor increases in size. Even lesions that do not dedifferentiate but continue to grow can cause death ultimately, primarily as a result of mass effect that may result in cerebral herniation and brainstem dysfunction.

Race

No clear evidence has been published in the literature that low-grade astrocytomas are more common in any racial or ethnic group. In the United States, malignant CNS tumors are slightly more common in whites than in blacks. Whether this applies to low-grade tumors as well remains to be shown.

Sex

In most series, a slight male predominance (55%-65%) has been noted, and this difference generally applies to gliomas of all types and grades.

Age

The median age of patients diagnosed with a low-grade astrocytoma, approximately 35 years, is younger than that of patients with more malignant gliomas. Juvenile pilocytic astrocytomas have a median age at diagnosis about a decade younger than other low-grade astrocytomas. This may account for the positive influence on survival duration in some series in which the pilocytic phenotype is associated with an improved outcome.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

No historical factors are pathognomonic for low-grade glioma. The history, however, should alert the clinician to the presence of a neurologic disorder and the need for an imaging study. Putting together the information from the history, the physical examination, and the imaging data will lead to a tentative diagnosis of low-grade glioma. The histories of patients with low-grade glioma are strangely similar. With low-grade astrocytomas, the most common complaints in the history are seizure and headache. Infiltrating low-grade astrocytomas can cause focal neurologic deficits (ie, weakness or numbness). Generally, these symptoms have a gradual onset.

• Pilocytic astrocytomas tend to be midline and may cause symptoms related to this location. A large cerebellar tumor can cause obstructive hydrocephalus, and the patient may present with headache and lethargy. These patients may also have a history of imbalance, falling, or incoordination. Pilocytic tumors in the brain stem cause neurologic deficits secondary to the involvement of brainstem nuclei, while hypothalamic tumors cause a variety of endocrine problems (eg, hypernatremia). Brainstem symptoms may include double vision or facial weakness. Persons with optic nerve tumors may present with visual deficits.
• SGCAs frequently cause obstructive hydrocephalus in patients with tuberous sclerosis. Headache is then secondary to hydrocephalus and elevated ICP.
• Patients with PXA frequently have long-standing histories of seizures in addition to the more general complaints already noted.
• A small percentage of low-grade astrocytomas present in the spinal cord of both children and adults. The history is characterized by a slow onset of back pain and neurologic deficits. The pain usually is localized over the region of the tumor, which is most common in the cervicothoracic area. Neurologic symptoms include paresthesias in the arms or legs. Weakness, objective numbness, and bowel or bladder symptoms also may be present.

Physical

A thorough neurologic examination is mandatory. Level of consciousness should be noted first. Lethargy is an important sign of elevated ICP. Examination of the cranial nerves may indicate involvement of the brain stem. Nystagmus is an important sign. Papilledema can be seen if ICP is elevated. The motor and sensory examination may show weakness or impairment of sensory discrimination if the motor or sensory pathways are involved with tumor, edema, or mass effect. Hemiparesis may be accompanied by increased deep tendon reflexes or an extensor plantar response (Babinski sign). Examining for cerebellar signs (eg, ataxia) is important if a tumor in that location is suspected.

• Since low-grade astrocytomas are associated with some genetic disorders, examining patients for these diseases is important. Patients with tuberous sclerosis have decreased intelligence and a characteristic skin lesion on the face (around the nose) called adenoma sebaceum, which is actually angiofibroma. Other cutaneous manifestations also may be present (eg, ash-leaf spots). Patients with NF-1 may have obvious cutaneous neurofibromas and/or café-au-lait spots.
• Low-grade astrocytomas that affect the spinal cord may result in various degrees of weakness and/or sensory change in the arms, legs, or sacral area. Myelopathy with increased deep tendon reflexes and/or positive Babinski sign may be present.

Causes

The etiology of low-grade gliomas is poorly understood. High-grade gliomas, which are much more common, have been studied in greater detail regarding possible environmental factors. Environmental factors that are linked with a higher incidence of high-grade gliomas include exposure to radiation or N-nitroso compounds. These factors have been verified in experimental models; however, the degree to which these factors play a role in the incidence of human tumors is unclear.

Neoplastic transformation is thought to be a genetic process, and deletions and mutations in certain genes are thought to play a role in the change of normal glial precursor cells to gliomas. For example, p53 mutations have been found in some, but not all, low-grade gliomas. Chromosomal analysis also has shown gain or loss of genetic material in certain low-grade gliomas, although as yet no consistent pattern has been appreciated. Patients with NF-1 are known to have an abnormality on chromosome 17, while the exact genetic defect in tuberous sclerosis still is being investigated.

In summary, the environmental or genetic factors that are involved in the generation of low-grade gliomas are unknown. As mentioned already, however, patients with NF-1 or tuberous sclerosis are at much higher risk of developing these tumors and should undergo surveillance imaging by MRI.

DIFFERENTIALS

Section 4 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Brainstem syndromes
Cerebritis or cerebral abscess
Cavernous angioma or arteriovenous malformation
Hamartoma
Stroke or infarct

WORKUP

Section 5 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• No specific laboratory test is available for low-grade glioma. If an endocrine abnormality is suggested, then the appropriate studies may be ordered, but laboratory tests are not indicated routinely for diagnosis of low-grade glioma.

Imaging Studies

• Both CT scan and MRI can aid in the diagnosis of low-grade glioma. Generally, MRI is considered the study of choice. However, in an emergency setting a noncontrast CT scan may be ordered first.
• Patients with new-onset headache, seizure, weakness, or numbness frequently undergo a CT scan first. Typical CT findings of a low-grade glioma show lower attenuation than the surrounding brain (see Image 1). A mild mass effect may be noted. Obstructive hydrocephalus can be confirmed. Low-grade gliomas also may show evidence of calcification. If a contrast CT scan is obtained, the tumor usually does not enhance.
• On MRI, low-grade gliomas show decreased signal relative to surrounding brain on T1 sequences (see Images 2-3, Images 6-8). On T2 sequences, higher signal reflects both the tumor and surrounding edema (see Images 4-5). Pilocytic astrocytomas often are associated with a cyst, which may be particularly prominent on T2-weighted sequences.
• MRI of the spinal cord is also the study of choice if an intramedullary low-grade astrocytoma is suspected. On MRI, widening of the spinal cord and frequently an associated cyst are noted. The tumor may show a variable degree of enhancement.

Other Tests

• Electroencephalography (EEG) may be performed on a patient with new-onset seizures; however, no EEG findings are specific to low-grade glioma. However, generalized, diffuse slowing and/or epileptogenic spikes can be seen over the area of the tumor.
• Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging sometimes are used to try to differentiate low-grade gliomas from either high-grade tumors or other types of pathology. Typically, low-grade gliomas show hypometabolism via PET or SPECT while high-grade gliomas are hypermetabolic. This information may be useful in guiding further therapy.

Procedures

• Lumbar puncture generally is contraindicated in patients with elevated ICP, which may occur in the setting of a brain tumor. Cerebrospinal fluid (CSF) studies do not aid in the diagnosis of low-grade glioma.

Histologic Findings

As briefly reviewed already, the histologic findings in low-grade astrocytomas depend on the type of tumor. Low-grade infiltrating astrocytomas are characterized by mild cellular proliferation and atypia. High-grade features, such necrosis or endothelial cell proliferation, are not present.

Pilocytic astrocytomas show piloid (hairlike) cells in 2 patterns: dense fascicles and loose arrangements. They also may show some degree of microvascular proliferation and necrosis, but these do not indicate malignant potential in these relatively well-circumscribed tumors. Pilocytic astrocytomas frequently are associated with a cyst.

PXA have a high degree of astrocytic pleomorphism as well as lipidized giant cells. Usually no necrosis or endothelial proliferation is noted. SGCAs demonstrate several types of cells, typically including small elongated cells as well as giant, multinucleated globoid cells.

TREATMENT

Section 6 of 11  

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• Introduction
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• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical Care

From the history, physical, and radiologic appearance of a tumor on CT scan or MRI, a presumptive diagnosis of a low-grade glioma can be made. The primary care physician should coordinate care with a neurologist, neurosurgeon, and oncologist. The initial treatment steps depend on patient presentation.

• If the patient presents with seizures, first-line therapy is to start the patient on phenytoin (Dilantin) or carbamazepine (Tegretol).
• If the patient presents with headache and has significant edema surrounding the tumor, dexamethasone (Decadron) therapy is appropriate in doses ranging from 2-4 mg every 6 hours. With dexamethasone, antiulcer medications (eg, antacid, H2 blocker) usually are prescribed. Corticosteroid therapy also may improve symptoms in patients who have low-grade astrocytomas of the spinal cord.
• If hydrocephalus is observed on CT scan or MRI and the patient is symptomatic, surgical placement of a ventricular drainage device may be appropriate. Either an external ventricular drain or a ventriculoperitoneal shunt may be inserted. The exact procedure depends on any further plans for surgery.

Surgical Care

Aside from the initial measures noted in Medical Care, the cornerstone of therapy for most low-grade gliomas is surgery.

• Of course, tumors in certain locations may be inoperable. However, most clinical series have shown that patients who undergo gross total resection have the longest survival durations. Even subtotal resection is of benefit if the tumor can be removed safely. Histologic diagnosis should be sought in every case (via biopsy or resection) if possible.
• Surgery is also the primary mode of treatment for low-grade astrocytomas of the spinal cord. Depending on the appearance of the tumor at surgery, a gross total resection, subtotal resection, or only biopsy may be possible. However, resection may lead to symptomatic and objective improvement in these patients. Furthermore, in low-grade astrocytomas, long-term remission (>10 y) and even cure are frequent in both children and adults.

Consultations

As already mentioned, patients in whom a low-grade glioma is suspected should consult with both a neurologist and a neurosurgeon.

• The neurologist's role is to document the neurologic examination and to correlate it with the imaging findings. The neurologist also may manage antiepileptic medication if the patient presents with seizures.
• The neurosurgeon needs to discuss the options for surgery. Particularly important is the need for ventricular drainage if hydrocephalus is present. Further surgery such as a resection or a biopsy also can be considered.
• In some centers, neurooncology specialists are available and may be consulted prior to surgery or after histologic diagnosis is obtained. In lieu of a coordinating neurooncologist, medical and radiation oncologists can provide a coordinated plan for adjunctive therapy.
• In refractory cases of epilepsy, a neurologist specializing in the treatment of epilepsy may be consulted.

Activity

In general, no restrictions are placed on activity of patients with low-grade glioma. However, patients' activity may relate to their overall neurologic status. The presence of seizures may prevent the patient from driving. Neurologic deficits such as hemiparesis may improve after treatment. Physical therapy is often beneficial.

MEDICATION

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• Follow-up
• Miscellaneous
• Multimedia
• References

No specific drugs are recommended for treatment of low-grade glioma; however, certain conditions (in the setting of low-grade astrocytoma) typically require treatment. For seizures, the patient usually is started on phenytoin or carbamazepine. Vasogenic edema around the tumor typically is treated with steroids. When administering steroids, typically some form of antiulcer agent is used.

Drug Category: Anticonvulsants

These agents are used to treat and prevent seizures.

Drug Name	Carbamazepine (Tegretol)
Description	Like phenytoin, acts by interacting with sodium channels and blocking repetitive neuronal firing. First-line drug in partial seizures and may be used for tonic-clonic seizures as well. Serum levels should be checked.
Adult Dose	Typical daily doses range from 200-600 mg PO tid/qid; extended release form available, which is given bid; serum levels should be in range of 4-8 µg/mL
Pediatric Dose	15-25 mg/kg/d PO divided tid/qid or bid if extended release form used
Contraindications	Documented hypersensitivity
Interactions	Phenytoin and phenobarbital may decrease levels by enzyme induction, while valproic acid may increase levels
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Hypersensitivity may manifest as skin rash or occasional hepatic dysfunction Leukopenia or aplastic anemia has been noted occasionally and requires careful monitoring; typically, anemia occurs within first few months after starting treatment and is more common in elderly Drug dosage should be watched closely; signs of toxicity include diplopia, ataxia, GI distress, and drowsiness; when these symptoms occur, serum drug levels should be checked; severe symptoms may necessitate discontinuing drug

Drug Category: Corticosteroids

These agents reduce edema around the tumor, frequently leading to symptomatic and objective improvement.

FOLLOW-UP

Section 8 of 11  

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• Follow-up
• Miscellaneous
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Further Inpatient Care

• Most experts agree that pilocytic astrocytomas are curable with gross total resection and no further therapy. Gross total resection is also a cure for patients with SGCA or PXA. If a subtotal resection is obtained and tumor regrowth occurs, radiation therapy can be considered.
• The treatment of most low-grade astrocytomas is far less straightforward. Every possible combination of treatments has its proponents. Some clinicians favor a "wait and see" approach with presumptive low-grade astrocytomas that show little or no mass effect and in patients whose seizures are well controlled on medications. Others have suggested that all patients should have a biopsy to confirm the diagnosis and then early local-field radiation. Finally, others maintain that the best treatment begins with the maximum possible resection followed by radiation. While some have suggested that biopsy and radiation is as effective as gross total resection and radiation, oncologic principles suggest that removing as much tumor as possible is beneficial even if all neoplastic cells cannot be removed owing to the infiltrating nature of gliomas. The role of adjuvant chemotherapy is also controversial.
• Radiation has been shown in a number of series to be of benefit in patients who previously underwent intracranial surgery for low-grade astrocytoma. Early radiation may be more appropriate for patients who have undergone subtotal resection, while watchful waiting may be more appropriate for patients who have undergone gross total resection. If the tumor recurs after gross total resection, further surgery and radiation should be considered. The role of chemotherapy in low-grade gliomas is less well understood. It may be an option for those patients who have regrowth of tumor after surgery and/or radiation. Standardized clinical trials in patients with low-grade glioma are lacking.
• The possible roles of radiation and chemotherapy in low-grade astrocytoma of the spinal cord are unknown since long-term remission is common following surgery alone.

Further Outpatient Care

• Upon discharge, these patients need to have regular follow-up with a qualified neurologist/neurooncologist and/or neurosurgeon to address the complex issues that arise in patients with low-grade gliomas. If the patient also has epilepsy, consultation with an epileptologist may be useful.
• Patients with low-grade lesions who present with symptomatic hydrocephalus, seizures, and/or mass effect need to be admitted. Patients with seizures need to be started on an anticonvulsant regimen, and an inpatient workup may include further imaging studies and EEG.
• Patients with hydrocephalus from obstruction of CSF pathways by tumor require admission and possibly surgery for placement of a shunt and/or tumor resection.
• Patients with symptoms and/or signs of elevated ICP due to mass effect from tumor and edema should be admitted and started on a regimen of dexamethasone while surgery is considered.
• Determination of the exact timing of surgery and the type of surgery requires consultation with a qualified neurosurgeon.

In/Out Patient Meds

• As described above, an anticonvulsant (if seizures are present) and dexamethasone (if edema is significant) are continued on an inpatient or outpatient basis. In addition, antiulcer medication is given with the corticosteroid for GI prophylaxis.

Transfer

• At some institutions, transferring the patient to another facility may be necessary if the proper consultations cannot be obtained. Particularly in patients with significant hydrocephalus, transfer to a facility with neurosurgical coverage is indicated. However, in patients with no hydrocephalus, surgery can be scheduled on an elective, but preferably urgent, basis.

Prognosis

• As already discussed, prognosis greatly depends on the pathology of the tumor. Taking many published series together, median survival duration is approximately 7.5 years. However, patients with pilocytic astrocytomas who undergo gross total resection can expect a cure. For low-grade astrocytomas that continue their relentless slow growth, progressive neurologic deficit may occur over a period of years.

MISCELLANEOUS

Section 9 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Potential medical pitfalls in the diagnosis and treatment of low-grade gliomas can be avoided if the clinician is familiar with their management. Recognition is the first key to success and involves perceiving that the patient's symptoms (eg, headache, seizure, personality change) represent an intracranial process. If an appropriate imaging study (CT scan or MRI) is ordered and interpreted by a qualified radiologist, most low-grade astrocytomas are recognized. A further pitfall is failure to recognize the necessity for expert consultation with a neurologist and/or neurosurgeon. The challenging nature of the treatment for these lesions necessitates expert consultation. Furthermore, patients with documented seizures benefit from initiation of antiepileptic medication. However, no evidence exists to support the use of prophylactic therapy in patients without a history of seizures. Patients with hydrocephalus need to be recognized (the imaging studies make this evident) and, inconsultationwithaneurosurgeon,admitted for treatment or transferred to an institution where therapy can begin.

MULTIMEDIA

Section 10 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  A 28-year-old male taxi driver presented to the emergency department after having a seizure. Noncontrast head CT scan was obtained showing the typical appearance of a low-grade astrocytoma. The lesion in the mesial left frontal lobe was hypodense on CT scan.
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Media type:  CT

Media file 2:  Preoperative MRI of the brain of a 28-year-old male taxi driver who presented to the emergency department after having a seizure. On T1-weighted sequences, the tumor does not enhance and shows decreased signal intensity compared to normal brain. These findings are consistent with low-grade astrocytoma.
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Media type:  MRI

Media file 3:  For tumors, MRI has the advantage of showing the lesion in multiple planes. This image, a T1-weighted sagittal image of the brain of a 28-year-old male taxi driver who presented to the emergency department after having a seizure, shows the tumor along the mesial aspect of the frontal lobe. Note that mass effect is minimal, typical of a low-grade lesion.
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Media type:  MRI

Media file 4:  T2-weighted sequences of an MRI of the brain of a 28-year-old male taxi driver who presented to the emergency department after having a seizure show increased signal intensity compared with normal brain. The radiologic appearance is typical of low-grade astrocytoma.
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Media type:  MRI

Media file 5:  A 9-year-old boy presented with headaches and gradual onset of right hemiparesis. MRI of the brain was obtained. The T2-weighted sequence in this MRI shows a tumor in the left thalamus, which is a typical location for a juvenile pilocytic astrocytoma. Note the relatively well-circumscribed nature of the lesion.
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Media type:  MRI

Media file 6:  Coronal T1-weighted gadolinium-enhanced MRI of the brain shows the tumor of a 9-year-old boy who presented with headaches and gradual onset of a right hemiparesis. Note the heterogeneous enhancement of the tumor.
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Media type:  MRI

Media file 7:  Sagittal T1-weighted MRI of the brain shows juvenile pilocytic astrocytoma of a 9-year-old boy who presented with headaches and gradual onset of right hemiparesis. Stereotactic surgery has made resection of these low-grade tumors in this deep location feasible.
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Media type:  MRI

Media file 8:  A 3-year-old boy presented with speech regression. MRI of the brain revealed a tumor in the left mesial temporal lobe. This T1-weighted gadolinium-enhanced image shows an enhancing tumor involving the hippocampus, uncus, and amygdala. The surgical pathologic studies revealed a low-grade mixed tumor of astrocytes and atypical neurons, a ganglioglioma.
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Media type:  MRI

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

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• McCormack BM, Miller DC, Budzilovich GN, et al. Treatment and survival of low-grade astrocytoma in adults--1977-1988. Neurosurgery. Oct 1992;31(4):636-42; discussion 642. [Medline].
• McCormick PC, Stein BM. Spinal cord tumors in adults. Neurological Surgery. 1996;4:3102-122. [Medline].
• Morantz R A. Low-grade astrocytomas. In: Kaye AH, Laws ER Jr, eds. Brain Tumors: An Encyclopedic Approach. New York: Churchill Livingstone; 1995:. 1995;433-48.
• Recht LD, Bernstein M. Low-grade gliomas. Neurol Clin. Nov 1995;13(4):847-59. [Medline].
• Salcman M. Radical surgery for low-grade glioma. Clin Neurosurg. 1990;36:353-66. [Medline].
• Vandenberg SR, Sampaio Lopes MB. Classification. In: Berger MS, Wilson CB, eds. The Gliomas. Philadelphia: WB Saunders; 1999:. 172-91.

Article Last Updated: Jan 10, 2007