brain tumor brain tumor a brain tumor occurs when abnormal cells form within the brain. there are two main types of tumors: malignant tumors and benign (non-cancerous) tumors. these can be further classified as primary tumors, which start within the brain, and secondary tumors, which most commonly have spread from tumors located outside the brain, known as brain metastasis tumors. all types of brain tumors may produce symptoms that vary depending on the size of the tumor and the part of the brain that is involved. where symptoms exist, they may include headaches, seizures, problems with vision, vomiting and mental changes. other symptoms may include difficulty walking, speaking, with sensations, or unconsciousness. brain tumorother namesintracranial neoplasm, brain tumourbrain metastasis in the right cerebral hemisphere from lung cancer, shown on magnetic resonance imagingspecialtyneurosurgery, neuro-oncologysymptomsvary depending on the part of the brain involved, headaches, seizures, problem with vision, vomiting, mental changestypesmalignant, benigncausesusually unknownrisk factorsneurofibromatosis, exposure to vinyl chloride, epstein–barr virus, ionizing radiationdiagnostic methodcomputed tomography, magnetic resonance imaging, tissue biopsytreatmentsurgery, radiation therapy, chemotherapymedicationanticonvulsants, dexamethasone, furosemideprognosisaverage five-year survival rate 33% (us)frequency1.2 million nervous system cancers (2015)deaths228,800 (worldwide, 2015) the cause of most brain tumors is unknown. uncommon risk factors include exposure to vinyl chloride, epstein–barr virus, ionizing radiation, and inherited syndromes such as neurofibromatosis, tuberous sclerosis, and von hippel-lindau disease. studies on mobile phone exposure have not shown a clear risk. the most common types of primary tumors in adults are meningiomas (usually benign) and astrocytomas such as glioblastomas. in children, the most common type is a malignant medulloblastoma. diagnosis is usually by medical examination along with computed tomography (ct) or magnetic resonance imaging (mri). the result is then often confirmed by a biopsy. based on the findings, the tumors are divided into different grades of severity. treatment may include some combination of surgery, radiation therapy and chemotherapy. if seizures occur, anticonvulsant medication may be needed. dexamethasone and furosemide are medications that may be used to decrease swelling around the tumor. some tumors grow gradually, requiring only monitoring and possibly needing no further intervention. treatments that use a person's immune system are being studied. outcomes for malignant tumors vary considerably depending on the type of tumor and how far it has spread at diagnosis. although benign tumors only grow in one area, they may still be life-threatening depending on their size and location. malignant glioblastomas usually have very poor outcomes, while benign meningiomas usually have good outcomes. the average five-year survival rate for all (malignant) brain cancers in the united states is 33%. secondary, or metastatic, brain tumors are about four times as common as primary brain tumors, with about half of metastases coming from lung cancer. primary brain tumors occur in around 250,000 people a year globally, and make up less than 2% of cancers. in children younger than 15, brain tumors are second only to acute lymphoblastic leukemia as the most common form of cancer. in nsw australia in 2005, the average lifetime economic cost of a case of brain cancer was au$1.9 million, the greatest of any type of cancer. signs and symptoms the signs and symptoms of brain tumors are broad. people may experience symptoms regardless of whether the tumor is benign (not cancerous) or cancerous. primary and secondary brain tumors present with similar symptoms, depending on the location, size, and rate of growth of the tumor. for example, larger tumors in the frontal lobe can cause changes in the ability to think. however, a smaller tumor in an area such as wernicke's area (small area responsible for language comprehension) can result in a greater loss of function. headaches headaches as a result of raised intracranial pressure can be an early symptom of brain cancer. however, isolated headache without other symptoms is rare, and other symptoms including visual abnormalities may occur before headaches become common. certain warning signs for headache exist which make the headache more likely to be associated with brain cancer. these are, as defined by the american academy of neurology: "abnormal neurological examination, headache worsened by valsalva maneuver, headache causing awakening from sleep, new headache in the older population, progressively worsening headache, atypical headache features, or patients who do not fulfill the strict definition of migraine". other associated signs are headaches that are worse in the morning or that subside after vomiting. location-specific symptoms the main areas of the brain and limbic system the brain is divided into lobes and each lobe or area has its own function. a tumor in any of these lobes may affect the area's performance. the symptoms experienced are often linked to the location of the tumor, but each person may experience something different. frontal lobe: tumors may contribute to poor reasoning, inappropriate social behavior, personality changes, poor planning, lower inhibition, and decreased production of speech (broca's area). temporal lobe: tumors in this lobe may contribute to poor memory, loss of hearing, and difficulty in language comprehension (wernicke's area is located in this lobe). parietal lobe: tumors here may result in poor interpretation of languages, difficulty with speaking, writing, drawing, naming, and recognizing, and poor spatial and visual perception. occipital lobe: damage to this lobe may result in poor vision or loss of vision. cerebellum: tumors in this area may cause poor balance, muscle movement, and posture. brain stem: tumors on the brainstem can cause seizures, endocrine problems, respiratory changes, visual changes, headaches and partial paralysis. behavior changes a person's personality may be altered due to the tumor damaging lobes of the brain. since the frontal, temporal, and parietal lobes control inhibition, emotions, mood, judgement, reasoning, and behavior, a tumor in those regions can cause inappropriate social behavior, temper tantrums, laughing at things which merit no laughter, and even psychological symptoms such as depression and anxiety. more research is needed into the effectiveness and safety of medication for depression in people with brain tumors. personality changes can have damaging effects such as unemployment, unstable relationships, and a lack of control. cause epidemiological studies are required to determine risk factors. aside from exposure to vinyl chloride or ionizing radiation, there are no known environmental factors associated with brain tumors. mutations and deletions of tumor suppressor genes, such as p53, are thought to be the cause of some forms of brain tumor. inherited conditions, such as von hippel–lindau disease, tuberous sclerosis, multiple endocrine neoplasia, and neurofibromatosis type 2 carry a high risk for the development of brain tumors. people with celiac disease have a slightly increased risk of developing brain tumors. smoking has been suggested to increase the risk but evidence remains unclear. although studies have not shown any link between cell phone or mobile phone radiation and the occurrence of brain tumors, the world health organization has classified mobile phone radiation on the iarc scale into group 2b – possibly carcinogenic. the claim that cell phone usage may cause brain cancer is likely based on epidemiological studies which observed a slight increase in glioma risk among heavy users of wireless phones. when those studies were conducted, gsm (2g) phones were in use. modern, third-generation (3g) phones emit, on average, about 1% of the energy emitted by those gsm (2g) phones, and therefore the finding of an association between cell phone usage and increased risk of brain cancer is not based upon current phone usage. pathophysiology meninges the meninges lie between the skull and brain matter. tumors originating from the meninges are meningiomas. human brains are surrounded by a system of connective tissue membranes called meninges that separate the brain from the skull. this three-layered covering is composed of (from the outside in) the dura mater, arachnoid mater, and pia mater. the arachnoid and pia are physically connected and thus often considered as a single layer, the leptomeninges. between the arachnoid mater and the pia mater is the subarachnoid space which contains cerebrospinal fluid (csf). this fluid circulates in the narrow spaces between cells and through the cavities in the brain called ventricles, to support and protect the brain tissue. blood vessels enter the central nervous system through the perivascular space above the pia mater. the cells in the blood vessel walls are joined tightly, forming the blood–brain barrier which protects the brain from toxins that might enter through the blood. tumors of the meninges are meningiomas and are often benign. though not technically a tumor of brain tissue, they are often considered brain tumors since they protrude into the space where the brain is, causing symptoms. since they are usually slow-growing tumors, meningiomas can be quite large by the time symptoms appear. brain matter the brains of humans and other vertebrates are composed of very soft tissue and have a gelatin-like texture. living brain tissue has a pink tint in color on the outside (gray matter), and nearly complete white on the inside (white matter), with subtle variations in color. the three largest divisions of the brain are: cerebral cortex brainstem cerebellum these areas are composed of two broad classes of cells: neurons and glia. these two types are equally numerous in the brain as a whole, although glial cells outnumber neurons roughly 4 to 1 in the cerebral cortex. glia come in several types, which perform a number of critical functions, including structural support, metabolic support, insulation, and guidance of development. primary tumors of the glial cells are called gliomas and often are malignant by the time they are diagnosed. the thalamus and hypothalamus are major divisions of the diencephalon, with the pituitary gland and pineal gland attached at the bottom; tumors of the pituitary and pineal gland are often benign. the brainstem lies between the large cerebral cortex and the spinal cord. it is divided into the midbrain, pons, and medulla oblongata. spinal cord the spinal cord is considered a part of the central nervous system. it is made up of the same cells as the brain: neurons and glial cells. diagnosis a posterior fossa tumor leading to mass effect and midline shift although there is no specific or singular symptom or sign, the presence of a combination of symptoms and the lack of corresponding indications of other causes can be an indicator for investigation towards the possibility of a brain tumor. brain tumors have similar characteristics and obstacles when it comes to diagnosis and therapy with tumors located elsewhere in the body. however, they create specific issues that follow closely to the properties of the organ they are in. the diagnosis will often start by taking a medical history noting medical antecedents, and current symptoms. clinical and laboratory investigations will serve to exclude infections as the cause of the symptoms. examinations in this stage may include the eyes, otolaryngological (or ent) and electrophysiological exams. the use of electroencephalography (eeg) often plays a role in the diagnosis of brain tumors. brain tumors, when compared to tumors in other areas of the body, pose a challenge for diagnosis. commonly, radioactive tracers are uptaken in large volumes in tumors due to the high activity of tumor cells, allowing for radioactive imaging of the tumor. however, most of the brain is separated from the blood by the blood–brain barrier (bbb), a membrane that exerts a strict control over what substances are allowed to pass into the brain. therefore, many tracers that may reach tumors in other areas of the body easily would be unable to reach brain tumors until there was a disruption of the bbb by the tumor. disruption of the bbb is well imaged via mri or ct scan, and is therefore regarded as the main diagnostic indicator for malignant gliomas, meningiomas, and brain metastases. swelling or obstruction of the passage of cerebrospinal fluid (csf) from the brain may cause (early) signs of increased intracranial pressure which translates clinically into headaches, vomiting, or an altered state of consciousness, and in children changes to the diameter of the skull and bulging of the fontanelles. more complex symptoms such as endocrine dysfunctions should alarm doctors not to exclude brain tumors. a bilateral temporal visual field defect (due to compression of the optic chiasm) or dilation of the pupil, and the occurrence of either slowly evolving or the sudden onset of focal neurologic symptoms, such as cognitive and behavioral impairment (including impaired judgment, memory loss, lack of recognition, spatial orientation disorders), personality or emotional changes, hemiparesis, hypoesthesia, aphasia, ataxia, visual field impairment, impaired