| Patient Education |
|
Click here for patient education.
|
|
You are in: eMedicine Specialties >
Neurosurgery > Neoplasm
Posterior Fossa Tumors
Article Last Updated: Feb 5, 2008
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Hassan Ahmad Hassan Al-Shatoury, MD, PhD, MHPE, Assistant Professor, Department of Neurosurgery, Suez Canal University; Co-Director, Center of Research and Development in Medical Education and Health Services Suez Canal University Hospital
Coauthor(s):
Ayman Ali Galhom, MD, PhD, Fellow, Department of Neurosurgery, University of Mississippi Medical Center;
Herbert H Engelhard III, MD, PhD, Director, UIC Neuro-Oncology Program, Chief, Division of Neuro-Oncology, Associate Professor, Department of Neurosurgery, University of Illinois at Chicago
Editors: Michael G Nosko, MD, PhD, Chief, Division of Neurosurgery, Director of Neurovascular Surgery, Medical Director of Neuroscience Unit, Associate Professor, Department of Surgery, University of Medicine and Dentistry at New Jersey; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Allen R Wyler, MD, Former Medical Director, Northstar Neuroscience, Inc; Paolo Zamboni, MD, Professor of Surgery, Chief of Day Surgery Unit, Chair of Vascular Diseases Center, University of Ferrara, Italy; Allen R Wyler, MD, Former Medical Director, Northstar Neuroscience, Inc
Author and Editor Disclosure
Synonyms and related keywords:
posterior fossa tumors, infratentorial tumors, brain stem tumors, cerebellar tumors, cerebellar medulloblastoma, medulloblastoma, pineoblastoma, ependymomas, primitive neuroectodermal tumors, PNETs, astrocytomas, glial tumors
A brain tumor is one of the most devastating forms of human illness, especially when occurring in the posterior fossa. Brainstem compression, herniation, and death are all risks in tumors which occur in this critical location.
History of the Procedure
Hippocrates, who likely performed it for headache, epilepsy, fractures, and blindness, first described trephination. Cushing probably was the first to report a large series of posterior fossa tumors. He published information about 61 patients with cerebellar medulloblastoma with mostly fatal outcome.1 Advances in brain surgery for tumors primarily were due to discovery of anesthesia, asepsis, neurological localization, and the ability to achieve hemostasis.
Problem
Tumors in the posterior fossa are considered critical brain lesions. This is, primarily, because of the limited space within the posterior fossa and the potential involvement of vital brain stem nuclei.
Some patients should undergo an emergency operation, especially if they present with acute symptoms of brain stem involvement or herniation.
Frequency
- Posterior fossa tumors are more common in children than the adults.
- Between 54% and 70% of all childhood brain tumors originate in the posterior fossa.
- About 15-20% of brain tumors in adults occur in the posterior fossa.
- Certain types of posterior fossa tumors, such as medulloblastoma, pineoblastoma, ependymomas, primitive neuroectodermal tumors (PNETs), and astrocytomas of the cerebellum and brain stem, occur more frequently in children.
- Some glial tumors, such as mixed gliomas, are unique to children. They are located more frequently in the cerebellum (67%) and are usually benign.
Etiology
No specific causes for posterior fossa tumors exist. However, genetic factors, such as dysfunction of some tumor suppressor genes (p53 gene) and activation of some oncogenes, may play a role in their development.2 Environmental factors such as irradiation and toxins may also play a role.
Pathophysiology
Common types of posterior fossa tumors include the following:
Cerebellar astrocytoma
Cystic cerebellar astrocytoma comprises about 33% of all posterior fossa tumors in children. It represents 25% of all pediatric tumors. Average age at presentation is 9 years. Typically, cerebellar astrocytoma presents as a laterally located cyst with a well-defined solid component. The tumor may be solid or cystic and may be located medially in the vermis or laterally in the cerebellar hemisphere.
Primary neuroectodermal tumors
PNETs include medulloblastomas, medulloepitheliomas, pigmented medulloblastomas, ependymoblastomas, pineoblastomas, and cerebral neuroblastomas. These tumors originate from undifferentiated cells in the subependymal region in the fetal brain. PNETs are second to the cerebellar astrocytoma in frequency, comprising 25% of intracranial tumors in children.
Medulloblastoma
Medulloblastoma initially arises in the inferior medullary velum and grow to fill the fourth ventricle, infiltrating the surrounding structures. Some erroneously thought it arose from medulloblast cells, which do not exist. It is better included in the family of PNETs.
Ependymoma and ependymoblastoma
Ependymomas are derived from ependymal cells. They occur more frequently in females, with 50% presenting in children younger than 3 years. An ependymoma has a much better prognosis than an anaplastic ependymomas (ependymoblastoma). Plastic ependymoma can mold itself to the available spaces inside or outside the ventricle without adhering to the ventricle.
Choroid plexus papilloma and carcinoma
Choroid plexus papilloma and carcinoma represent 0.4-0.6% of all intracranial tumors. They are more frequent in children than in adults (3% of childhood brain tumors). Sixty percent occur in the lateral ventricle and 30% in the fourth ventricle. The third ventricle and cerebellopontine angle are rare locations for this tumor. Cerebrospinal fluid (CSF) overproduction may occur, sometimes reaching more than 4 times normal volumes. In most of cases, CSF analysis demonstrates increased protein, xanthochromia, or both.
Dermoid tumors
Dermoid tumors arise from incomplete separation of epithelial ectoderm from neuroectoderm at the region of the anterior neuropore; this usually occurs during the fourth week of gestation. The cyst wall often includes hair follicles, sweat glands, and sebaceous glands. The cyst grows slowly and gradually becomes filled by desquamated epithelium, sweat, and sebaceous materials. Aseptic meningitis is a sequela of cyst rupture. More commonly, the cyst occurs in the posterior fossa, at or near the midline. It may be extradural, vermian, or intraventricular. A dermal sinus may be connected to the mass. It may be detected clinically or by MRI.
Hemangioblastoma
Hemangioblastoma represents about 7-12% of all posterior fossa tumors. About 70% of hemangioblastomas occurring in the cerebellum are cystic. Age of presentation is 30-40 years old. Hemangioblastomas are more common in males. Hemangioblastoma may be associated with von Hippel-Lindau disease.
Metastatic tumors
Three percent of all cranial metastatic lesions occur in the brainstem and 18% occur in the cerebellum. Originating sites include breast, lung, skin, and kidney. Solitary metastasis is better treated by surgical removal before radiation therapy. Surgery also should be considered in case of radiosensitive original tumors or when the primary source is unknown.
Brainstem gliomas
Brainstem gliomas constitute 15% of all brain tumors. In children, brainstem glioma represents 25-30% of all brain tumors. Most brainstem gliomas are low-grade astrocytoma.
Clinical
The clinical presentation depends on the site of the tumor, biological behavior and aggressiveness of the tumor, and the rate of growth. At the time of presentation, the patient may be very ill from severe headache or frequent vomiting due to associated hydrocephalus. Symptoms may be caused by focal compression of the cerebellum or brain stem centers and increased intracranial pressure. Symptoms due to focal brainstem compression include cranial nerve dysfunction. This commonly involves the nuclei or tracts of the third, fourth, or sixth cranial nerves, resulting in ocular palsies and diplopia and long tract signs (hemiparesis). Symptoms due to focal compression of the cerebellum include characteristic eye findings and vermian syndrome. Truncal ataxia is a common finding in midline tumors, such as medulloblastomas, ependymomas, and vermian astrocytomas. It is manifested by a tendency to fall frequently and a widely based gait. Hemi-cerebellar syndrome involves limb ataxia, nystagmus, and dysmetria. Tumors that occur in the cerebellar hemisphere, such as metastases, cerebellar astrocytomas, or cystic hemangioblastomas, may present by ataxia of the contralateral limbs. Nystagmus usually occurs late in the disease. Vertical nystagmus suggests a lesion in the anterior vermis, periaqueductal region, or craniocervical junction. Horizontal nystagmus implies involvement of the cerebellar hemisphere. Intracranial hypertension causes the following 8 symptoms:
- Headache: This is the most common symptom in patients with posterior fossa tumors. Associated neck pain, stiffness, or head tilt suggest tonsillar herniation into the foramen magnum. Headache is insidious and intermittent. It is most severe in the morning or after a nap because of increased intracranial pressure from recumbency and hypoventilation during sleep. Headache manifests in children as irritability and difficulty to be handled.
- Vomiting: It may be due to generalized intracranial hypertension or irritation of the vagal nuclei in the medulla oblongata or area postrema of the fourth ventricle. Vomiting (including projectile vomiting) may occur, usually in the morning. Vomiting sometimes relieves headache.
- Strabismus: It is secondary to sixth nerve palsies from intracranial hypertension. Third nerve palsies may also occur.
- Blurring of vision due to papilledema
- Meningismus
- Dizziness
- Macrocephaly in children
- Hydrocephalus
Patients who present with posterior fossa tumors undergo surgery for the following goals:
- To decompress the posterior fossa for the purpose of relieving pressure on the brain stem and/or to release intracranial pressure and avert the risk of herniation
- To diagnose the tumor based on histopathology
- To determine further plan of management depending on the nature of the tumor
- When indicated, to treat hydrocephalus by shunting cerebrospinal fluid (CSF) to the peritoneal cavity (External CSF drainage or even no drainage is considered in some cases. Still, many disagree regarding the ideal shunting procedure.)3
Posterior cranial fossa: It is the deepest and most capacious of the 3 cranial fossae. It contains the cerebellum, pons, and medulla oblongata. The foramen magnum is located centrally and inferiorly in the posterior fossa. The posterior fossa is surrounded by deep grooves containing the transverse sinuses and sigmoid sinuses.
Brainstem: It is the portion of the brain connecting the cerebral hemispheres with the spinal cord. It contains the midbrain, pons, and medulla oblongata. The brainstem is partially obscured by the cerebral hemispheres and cerebellum. The gray matter in the brainstem is scattered into numerous small masses called nuclei, many of which are motor or sensory nuclei of the cranial nerves.
Midbrain: The midbrain is the portion of the brain that connects the pons and the cerebral hemispheres. The dorsal segment of the midbrain is called the tectum; the more central and ventral portion is called the tegmentum.
Pons: The pons lies anterior to the cerebellum and superior to the medulla, from which it is separated by a groove through which the abducens, facial, and acoustic nerves emerge.
Medulla oblongata: It is the pyramid-shaped segment of brainstem between spinal cord and pons. The lower half contains the remnants of the central canal; the posterior portion of the superior half forms the floor of the body of the fourth ventricle.
Cerebellum: The cerebellum is located in the posterior fossa of the skull, dorsal to the pons and medulla. It is separated from the overlying cerebrum by an extension of dura mater, the tentorium cerebelli. It is oval in form, with its widest diameter along the transverse axis. It is composed of a small, unpaired central portion—the vermis—and 2 large lateral masses—the cerebellar hemispheres.
Performing a lumbar puncture in patients with suspected posterior fossa tumors is contraindicated. A risk of central herniation exists even with a very small amount of CSF drainage. To avoid this catastrophe, a thorough clinical examination, including funduscopy and a CT scan of the brain should be performed before lumbar puncture.
Lab Studies
- Complete blood profile: Used for preoperative preparation, and as a diagnostic tool in some patients. In cases of hemangioblastoma, erythrocytosis may be found, presumably from erythropoietic factors secreted by the tumor.
- Coagulation profile
- Blood grouping
- Renal function tests
- Liver function tests
- Tumor markers
- A tumor marker is any substance that makes possible either a qualitative diagnosis of neoplasm or a quantitative estimate of tumor burden.
- They are used for screening, for staging, and for evaluation of response to therapy and detection of early tumor recurrence.
- Three examples of tumor markers include (1) carcinoembryonic antigen (CEA), (2) alpha-fetoprotein (AFP), and (3) placental proteins.
- The diagnostic role of tumor markers is less crucial in the posterior cranial fossa than in other regions of the body because of the ability of MRI to clearly visualize distinctive characteristics, such as cysts.
Imaging Studies
- Plain x-ray skull
- It may show signs of chronic intracranial hypertension.
- It may show calcification.
- In case of a dermoid cyst, a bone defect with sclerotic margins may be detected.
- CT scanning: CT scan of the posterior fossa is inferior to MRI in diagnostic value because of the artifact produced from the surrounding thick bone. However, CT scan is helpful for postoperative follow-up.
- Cerebral angiography
- Cerebral angiography is useful to assess the vascular supply of the tumor.
- With the wide availability of MRI, cerebral angiography is no longer used as the first option in brain tumor assessment.
- Magnetic resonance imaging
- MRI appearance of cerebellar astrocytoma
- Intra-axial, either midline or hemispheric, mass
- Prominent cystic component that is hypointense in T1-weighted images and slightly hyperintense in T2-weighted images (more protein content)
- Mural nodule, usually enhanced in T2 images
- Displacement of effacement of the fourth ventricle
- Hydrocephalic changes due to obstruction of the CSF pathway
- Nodule that usually is enhanced with contrast
- Cystic wall that may or may not enhance
- Heterogenicity and calcification, rarely found
- MRI appearance of PNET
- Intraventricular midline or paramedian mass that is isointense in T1 images
- Prominent enhancement with intravenous contrast
- May appear heterogeneous on MRI, with areas of cystic degeneration and central necrosis
- Infrequently, calcification, eccentric location, and lack of enhancement
- MRI appearance of ependymomas
- Commonly found intraventricularly
- Calcification found in 45% of cases
- Plastic ependymomas that can extend through the foramina of Magendie and Luschka to compress the craniocervical junction and/or the brain stem
- Extension to the cerebellopontine angle that is pathognomonic of ependymomas
- Enhance with intravenous contrast
- May be heterogeneous in character
- MRI appearance of posterior fossa hemangioblastoma
- Appears as a cystic mass with pial-based mural nodule that is slightly hyperintense and enhanced prominently with intravenous contrast
- Appearing as regions of signal void on spin-echo images, abnormal vessels that may be found adjacent or within the tumor
- Cyst that may be isointense or hyperintense on T1- and T2-weighted images
- Cyst wall that often is sharply delimited
- Variation of MRI appearance, including presence of hemorrhage in the cyst, solid rather than cystic mass, multiple lesions, and associated syrinx cavity
- MRI appearance of posterior fossa choroids plexus papilloma
- Intraventricular mass with lobulated margin
- Hypointense on T1 images
- Patchy regions of hypointensity that express calcification and hypervascularity
- Region of hyperintensity on T2 images (calcification and old hemorrhage)
- Prominent enhancement with intravenous contrast
- Tumor extension through foramina of Luschka or Magendie into the basal cisterns
- Commonly, hydrocephalic changes
- MRI appearance of posterior fossa dermoid cyst
- Hyperintense on T1 images and hypointense on T2 images
- Midline mass
Other Tests
- Brainstem auditory evoked response
- Brainstem auditory evoked response (BAER) specifically is helpful as an intraoperative monitor of brainstem function.
- Abnormal response alerts the surgeon about potential danger that, in most cases, can be reversed early.
Histologic Findings
- Cerebellar astrocytoma
- Pilocytic subtype (61%): Most astrocytes found in the tumor are fibrillary, with round-to-oval nuclei with some cytoplasmic pleomorphism and Rosenthal fibers. A honeycomb pattern (area with densely and areas with loosely cellular appearance) is present. Malignant transformation is uncommon.
- Infiltrative fibrillary type (28%): It usually occurs in adults. It displays the histological features of anaplasia.
- Anaplastic astrocytoma (11%): More anaplastic features are present.
- Medulloblastoma
- Grossly, it appears as a soft and friable mass. Area of necrosis and focal hemorrhage may be present.
- Calcification is uncommon.
- The tumor may infiltrate the brainstem and adjacent cerebellar structures in 30% of patients.
- Dissemination through the subarachnoid space is common. Metastatic lesions are present in 50% of patients at autopsy.
- The tumor appears highly cellular with round-to-oval cells.
- Cytoplasm is scant, and hyperchromic nuclei are present. With hematoxylin and eosin staining, it appears as a blue tumor.
- Homer-Wright rosettes and pseudorosettes are commonly present, suggesting neuronal differentiation.
- Ependymomas (3 classic histological features)
- Uniform-appearing cells are arranged around a vessel, forming perivascular pseudorosettes.
- A true ependymal rosette is present.
- Cells contain blepharoplasts (basal bodies of cilia).
- Ependymoblastoma (histological features of malignancy)
- Cytoplasmic and nuclear pleomorphisms are present.
- Nuclear hyperchromatism occurs.
- Excessive mitosis occurs.
- Necrosis is present.
- Cytoarchitectural disorganization is present.
- Choroid plexus papilloma
- Gross picture: It is a reddish mass with an irregular surface.
- Microscopic picture:
- Cuboidal epithelial cells similar to the normal choroids plexus are present.
- Hemangioblastoma
- Macroscopic picture: It is yellow to pink in color. The mural nodule is found touching the pial surface of the cerebellum. In 20% of cases, the dura is involved. The cystic wall and its contents may be yellow or white.
- Microscopic picture: Benign cellular proliferation, with formation of vascular channels, occurs. Reticulin-rich stromal network and (fat-laden) cells are characteristic.
Medical therapy
No primary medical therapy exists for posterior fossa brain tumors. Medications, such as Lasix and corticosteroids, are administered before surgery to reduce the effect of edema on the surrounding structures.
Preoperative details
- Assessment of the general condition of the patient
- Preoperative clearance, including cardiovascular assessment, pulmonary assessment, renal assessment, metabolic assessment, and hematologic assessment
- Management of the secondary effects of tumor and intracranial hypertension, such as headache, vomiting, and dehydration
- Reservation of at least 3 units of fresh blood in case of intraoperative need
- Managing symptomatic obstructive hydrocephalus before surgical removal of the tumor (2 schools of thought)
- CSF shunting, either internal or external (may expose the patient to the additional inherent shunt risks as well as infection or other surgical complications)
- Medical management - Decreasing the intracranial pressure by administering glucocorticoids, such as dexamethasone in a dose of 1 mg/kg/d
- Neurological deterioration - Possible emergent operation for tumor removal
Intraoperative details
- Operative position
- Prone is comfortable for the surgeon. The head is fixed in 3-point head fixation if the patient is older than 2 years.
- The sitting position carries the risk of air embolism. It is less comfortable for the surgeon. The field is much clearer because drainage is easier. In children younger than 2 years, a Mayfield headrest is used. The head is flexed slightly, without compressing the neck vessels.
- Safety burr hole
- A safety burr hole is placed in the occipital area. This could be used in case of acute hydrocephalus requiring ventricular drainage.
- In patients with hydrocephalus, the ventricle is cannulated through this burr hole. The catheter is tunneled subcutaneously and connected to an external ventricular drainage system for subsequent management.
- Approaches: The most common approaches to the posterior fossa tumors are midline, paramedian, or retromastoid.
- General operative principles
- Midline incision extends from the inion to the upper cervical vertebra.
- The paracervical and suboccipital muscles are separated by diathermy.
- Craniectomy is performed according to the site and size of the tumor.
- The foramen magnum is opened, and the C1 arch may be removed, especially in tumors extending to, or beyond, the craniocervical junction.
- The dura is opened in Y-shape, with the base upward.
- Bipolar and self-retaining retractors are used for cerebellar cortical incision to expose the tumor.
- Tumors are removed using gentle suction, ultrasonic surgical aspirator, or carbon dioxide laser. The last method is used only infrequently.
- The extent of tumor removal should be weighed with the possible risk of complication, especially with tumors adherent to the brainstem.
- The dura is closed in a watertight fashion. Dural grafting may be needed for complete closure.
- Special concerns
- Choroid plexus papilloma should be removed totally because it is a benign tumor that does not invade the brain.
- If a dermoid cyst is associated with a sinus, the sinus should be removed completely.
Postoperative details
- Early postoperative care
- Increased ataxia
- Increased lower cranial nerve dysfunction
- Apnea, or respiratory abnormalities
- Late postoperative care
Follow-up
- MRI is a helpful postoperative tool to detect early recurrence before it is manifested clinically.
- The interval of MRI scanning depends on the tumor histology and postoperative course.
- Patients receiving chemotherapy for a malignant lesion also should be studied between chemotherapy cycles to assess response.
- The presence of residual or recurrent contrast enhancement 2 months after surgery suggests recurrence.
- Postirradiation changes may mimic recurrence, requiring follow-up after few weeks.
Possible complications of posterior fossa tumor surgery include the following:
- Lower cranial nerve dysfunction
- Facial nerve palsy
- Deafness
- Long tract deficits
- Hemiplegia
- Hemiparesis
- Sensory abnormalities
- Other postoperative complications
- Infection
- Prolonged coma
- Shunt obstruction or malfunction
- Chest infection
- Deep venous thrombosis
- Pulmonary embolism
- Cerebrospinal fluid leak
- The 5-year survival rates exceed 60% for all patients and 80% for certain good-risk individuals with posterior fossa tumors.
- In cases of pilocytic cerebellar astrocytoma, the 25-year survival rate exceeds 94%.6
- Patients with medulloblastoma are classified into good-risk and bad-risk categories based on the following:
- Age of presentation
- Extension of surgical resection
- Leptomeningeal dissemination or metastasis
- Prognosis in medulloblastoma is worse for children younger than 2 years, for patients with subtotal resection (80%), and for those with subarachnoid metastasis or positive results on CSF cytology more than 2 weeks after surgery.
- In patients with ependymomas, the 5-year survival rate is 20%.
- In ependymoblastoma, the 5-year survival rate is only 6%.
- Choroid plexus papilloma has excellent prognosis, as high as 100% survival rate.
- Choroid plexus carcinoma has poor prognosis.
Future management
- Stereotactic radiosurgery utilizes only the physical properties of the irradiation to deliver deadly radiation doses to the tumor.
- Stereotactic radiotherapy benefits from the differences in radiobiological properties between normal and pathological tissue.
- In interstitial brachytherapy, a radioactive material is implanted into the tumor bed at the time of surgery to deliver a continuous, localized dose of irradiation.
- Chemotherapy with new therapeutic medications may have a role in the treatment of residual tumors after surgery.
- Immunotherapy aims at activation of cell-mediated cytotoxic responses and humorally mediated cytotoxic response against the tumor cells. This is still investigational.
Special issues
An informed consent must be obtained from the patient if his or her general condition permits understanding the risks and potential benefits of surgery; otherwise, it must be obtained from relatives. The discussion related to the informed consent should include the following:
- Summary of the nature of the condition and its presumed course without treatment
- Description of the proposed surgical treatment
- Possible complications that can occur as a result of surgery
- Review of alternative treatment modalities, including a brief discussion of the pros and cons of each treatment
- A statement that the operation is not guaranteed to improve the patient's condition
- Cushing H. Experience with the cerebellar medulloblastoma: critical review. Acta Pathol Microbiol Immunol Scand. 1930;7:1-86.
- Badhe PB, Chauhan PP, Mehta NK. Brainstem gliomas--a clinicopathological study of 45 cases with p53 immunohistochemistry. Indian J Cancer. Oct-Dec 2004;41(4):170-4. [Medline].
- Arriada N, Sotelo J. Continuous-flow shunt for treatment of hydrocephalus due to lesions of the posterior fossa. J Neurosurg. Nov 2004;101(5):762-6. [Medline].
- Abe M, Tokumaru S, Tabuchi K, Kida Y, Takagi M, Imamura J. Stereotactic radiation therapy with chemotherapy in the management of recurrent medulloblastomas. Pediatr Neurosurg. 2006;42(2):81-8. [Medline].
- Levin VA, Edwards MS, Gutin PH, et al. Phase II evaluation of dibromodulcitol in the treatment of recurrent medulloblastoma, ependymoma, and malignant astrocytoma. J Neurosurg. Dec 1984;61(6):1063-8. [Medline].
- Gjerris F, Klinken L. Long-term prognosis in children with benign cerebellar astrocytoma. J Neurosurg. Aug 1978;49(2):179-84. [Medline].
- Akay KM, Izci Y, Baysefer A, et al. Surgical outcomes of cerebellar tumors in children. Pediatr Neurosurg. Sep-Oct 2004;40(5):220-5. [Medline].
- DeAngelis LM. Chemotherapy for brain tumors--a new beginning. N Engl J Med. Mar 10 2005;352(10):1036-8. [Medline].
- Edwards M, Hudgins R. Medulloblastomas and primitive neuroectodermal tumors of the posterior fossa. In: Mclaurin R, Schut L, Venes J, et al, eds. Pediatric Neurosurgery: Surgery of the developing nervous system. Philadelphia, Pa:. WB Saunders Co;1989:347-356.
- Gottardo NG, Gajjar A. Current Therapy for Medulloblastoma. Curr Treat Options Neurol. Jul 2006;8(4):319-334. [Medline].
- Hawkins JC 3d. Treatment of choroid plexus papillomas in children: a brief analysis of twenty years'' experience. Neurosurgery. Apr 1980;6(4):380-4. [Medline].
- Hendrick E, Raffel C. Tumors of the fourth ventricle: ependymomas, choroid plexus papillomas, and dermoid cysts. In: McLaurin R, Schut L, Venes J, et al, eds. Pediatric neurosurgery: Surgery of the developing nervous system. Philadelphia, Pa:. WB Saunders Co;1989:366-372.
- Hoffman HJ, Becker L, Craven MA. A clinically and pathologically distinct group of benign brain stem gliomas. Neurosurgery. Sep 1980;7(3):243-8. [Medline].
- Jones B. Posterior fossa treatment. Br J Radiol. Mar 2005;78(927):285; author reply 285. [Medline].
- May PL, Blaser SI, Hoffman HJ, et al. Benign intrinsic tectal "tumors" in children. J Neurosurg. Jun 1991;74(6):867-71. [Medline].
- Morawski KF, Niemczyk K, Bohorquez J, Marchel A, Delgado RE, Ozdamar O. Intraoperative monitoring of hearing during cerebellopontine angle tumor surgery using transtympanic electrocochleography. Otol Neurotol. Jun 2007;28(4):541-5. [Medline].
- Padovani L, Sunyach MP, Perol D, Mercier C, Alapetite C, Haie-Meder C. Common strategy for adult and pediatric medulloblastoma: a multicenter series of 253 adults. Int J Radiat Oncol Biol Phys. Jun 1 2007;68(2):433-40. [Medline].
- Park TS, Hoffman HJ, Hendrick EB, et al. Medulloblastoma: clinical presentation and management. Experience at the hospital for sick children, toronto, 1950-1980. J Neurosurg. Apr 1983;58(4):543-52. [Medline].
- Pierre-Kahn A, Hirsch JF, Roux FX, et al. Intracranial ependymomas in childhood. Survival and functional results of 47 cases. Childs Brain. 1983;10(3):145-56. [Medline].
- Raffel C. Medulloblastoma: molecular genetics and animal models. Neoplasia. Jul-Aug 2004;6(4):310-22. [Medline].
- Rath GP, Bithal PK, Chaturvedi A, Dash HH. Complications related to positioning in posterior fossa craniectomy. J Clin Neurosci. Jun 2007;14(6):520-5. [Medline].
- Rogers L, Pueschel J, Spetzler R, et al. Is gross-total resection sufficient treatment for posterior fossa ependymomas?. J Neurosurg. Apr 2005;102(4):629-36. [Medline].
- Rorke L, Schut L. Introductory survey of pediatric brain tumors. In: McLaurin R, Schut L, Venes J, et al, eds. Pediatric Neurosurgery: Surgery of the developing nervous system. Philadelphia, Pa:. WB Saunders Co;1989:335-337.
- Rorke LB. The cerebellar medulloblastoma and its relationship to primitive neuroectodermal tumors. J Neuropathol Exp Neurol. Jan 1983;42(1):1-15. [Medline].
- Schijman E, Peter JC, Rekate HL, et al. Management of hydrocephalus in posterior fossa tumors: how, what, when?. Childs Nerv Syst. Mar 2004;20(3):192-4. [Medline].
- Schumacher M, Schulte-Mönting J, Stoeter P, Warmuth-Metz M, Solymosi L. Magnetic resonance imaging compared with biopsy in the diagnosis of brainstem diseases of childhood: a multicenter review. J Neurosurg. Feb 2007;106(2 Suppl):111-9. [Medline].
- Smith RR, Zimmerman RA, Packer RJ, et al. Pediatric brainstem glioma. Post-radiation clinical and MR follow-up. Neuroradiology. 1990;32(4):265-71. [Medline].
- Sutton L, Schut L. Cerebellar astrocytomas. In: McLaurin R, Schut L, Venes J, et al, eds. Pediatric Neurosurgery: Surgery of the developing nervous system. Philadelphia, Pa:. WB Saunders Co;1989:338-346.
- Wilne S, Collier J, Kennedy C, Koller K, Grundy R, Walker D. Presentation of childhood CNS tumours: a systematic review and meta-analysis. Lancet Oncol. Aug 2007;8(8):685-95. [Medline].
- Zabek M. Primary posterior fossa tumours in adult patients. Folia Neuropathol. 2003;41(4):231-6. [Medline].
- Zhou LF, Du G, Mao Y, Zhang R. Diagnosis and surgical treatment of brainstem hemangioblastomas. Surg Neurol. Apr 2005;63(4):307-15; discussion 315-6. [Medline].
Posterior Fossa Tumors excerpt Article Last Updated: Feb 5, 2008
|
