Glioma Brain Tumour
Gliomas are classified by celltype, by grade, and by location
By type of cell
Gliomas are named according tothe specific type of cell they share histological features with, but notnecessarily originate from. The main types of gliomas are:
Gliomas are further categorizedaccording to their grade,which is determined by pathologic evaluation of the tumor.
- Low-grade gliomas [WHOgrade II] are well-differentiated (not anaplastic);these are not benign but stillportend a better prognosis for the patient.
- High-grade [WHO gradeIII-IV] gliomas are undifferentiated or anaplastic;these are malignant and carry a worse prognosis.
Of numerous grading systems inuse, the most common is the World Health Organization (WHO) gradingsystem for astrocytoma, under which tumors are graded from I (least advanced disease - best prognosis) to IV (most advanced disease - worst prognosis).
Gliomas can be classifiedaccording to whether they are above or below a membrane in the brain called the tentorium. The tentorium separates the cerebrum (above) from the cerebellum (below).
- supratentorial:above the tentorium, in the cerebrum, mostly found in adults (70%).
- infratentorial:below the tentorium, in the cerebellum, mostly found in children (70%).
- pontine: located in the pons of thebrainstem. The brainstem has three parts (pons, midbrain and medulla); the ponscontrols critical functions such as breathing, making surgery on theseextremely dangerous.
Symptoms of gliomas depend onwhich part of the central nervous system is affected. A brainglioma can cause headaches, nausea and vomiting, seizures,and cranialnerve disorders as a result of increased intracranialpressure. A glioma of the optic nerve can cause visual loss. Spinal cord gliomas can cause pain, weakness,or numbness inthe extremities. Gliomas do not metastasize bythe bloodstream, but they can spread via the cerebrospinal fluid and cause "dropmetastases" to the spinal cord.
The exact causes of gliomas arenot known. Hereditary genetic disorders such as neurofibromatoses (type 1 and type 2) and tuberous sclerosis complex are known topredispose to their development. Gliomas have been correlated tothe electromagnetic radiation from cellphones, and a link between the cancer and cell phoneusage is considered plausible, though there is no conclusive evidence. Mostglioblastomas are infected with cytomegalovirus,however the significance of this is not known. Pathophysiology High-grade gliomas are highly-vascular tumors and have a tendency toinfiltrate. They have extensive areas of necrosis and hypoxia.Often tumor growth causes a breakdown of the blood-brain barrier in the vicinity of the tumor. Asa rule, high-grade gliomas almost always grow back even after complete surgicalexcision, and so are commonly called recurrent cancer of the brain.
Gliomas are rarely curable. Theprognosis for patients with high-grade gliomas is generally poor, and isespecially so for older patients. Of 10,000 Americans diagnosed each year withmalignant gliomas, about half are alive 1 year after diagnosis, and 25% aftertwo years. Those with anaplastic astrocytoma survive about three years.Glioblastoma multiforme has a worse prognosis with less than a 12-month averagesurvival after diagnosis, though this has extended to 14 months with morerecent treatments. For low-grade tumors, theprognosis is somewhat more optimistic. One study reported that low-grade oligodendroglioma patients have a median survival of 11.6 years another reported a mediansurvival of 16.7 years.
Treatment for braingliomas depends on the location, the cell type and thegrade of malignancy.
Often, treatment is a combinedapproach, using surgery, radiation therapy,and chemotherapy.The radiation therapy is in the form of external beam radiation or the stereotactic approach using radiosurgery. Temozolomide isa chemotherapeutic drug that is able to cross the blood-brain barrier effectively and is currentlybeing used in therapy for high-grade tumors.
Diagnosing aglioma usually begins with a medical history review and exam by a braindisorder specialist (neurosurgeon), which includes checking your vision,hearing, balance, coordination and reflexes. Depending on thoseresults, your doctor may request one or more of the tests described below. All of your diagnostic testing can becompleted in a few days rather than in several weeks or months.
High-qualityimaging and rapid test results are required. Radiologists whospecialize in imaging the brain and nervous system perform and interpret eachexamination to the highest standard of quality.
Imaging scans helpgauge the tumour’s effect on your brain activity and function, and blood flow.
If a brain scan detects a tumour, especially multiple tumours, your doctor maytest for cancer elsewhere in your body. Imaging tests may include:
- Computerized tomography(CT) scan.A CT scan uses a sophisticated X-ray machine linked to a computer to producedetailed, two-dimensional images of the brain. A CT scan can help identifycertain types of tumors, especially those close to or involving bone.
- Magnetic resonanceimaging (MRI) scan.MRI uses a magnetic field and radio waves to create detailed images of thebrain. Sometimes a special dye is injected into the bloodstream to make tumorsappear different from healthy tissue (MR angiography). Perfusion, functionaland intraoperative MRI scans may be done to identify blood flow andvolume, critical brain areas involved in speech and motor activity, and thetumor's precise location.
- Other brain scans. Other tests — such asmagnetic resonance spectroscopy (MRS), single-photon emission computerizedtomography (SPECT) or positronemission tomography (PET)scanning — help doctors gauge brain tumor activity and blood flow.
- Angiogram. A special dye is injectedinto the arteries that feed the brain, making the blood vessels visible onX-ray. This test helps locate blood vessels in and around a brain tumor.
Your surgeon willtypically do a biopsy to diagnose a brain tumour and confirm its type. A biopsyinvolves removing a tiny piece of tumour tissue for examination under amicroscope as part of the surgery to remove the tumour. The sample isexamined instantly by a specialist in assessing brain tissue tumours (neuropathologist)to identify the kind of tumour, which is critical in determining theappropriate treatment for you. Studies show thatthe diagnosis may change substantially for at least one-fourth of people whenan experienced neuropathologist does the analysis
A neurosurgeonwith expertise in brain cancers usually serves as the team lead.
Neurosurgeons havesignificant expertise and experience in performing traditional and advancedglioma tumour removal surgeries.
When possible, yougenerally can be scheduled for surge.
Advances inneurosurgery offers the latest surgical options, technologies and techniques,including:
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