Adenoma
A usually benign tumor arising from a gland, such as a pituitary adenoma.

Adjunct or adjuvant treatment
One treatment given in addition to another. The treatments work together to make each more effective.

Aneurysm
A weak point in a blood vessel, such as an artery or vein, which may then blow up like a balloon. The danger is of the aneurysm bursting and bleeding into the brain, which causes a stroke.

Angiogram/Angiography
This procedure uses X-rays to produce pictures of arteries or veins by injecting a dye (contrast material) into the arteries or veins and "filming" it as it passes through the blood vessels.

Aphasia
Loss of ability to speak or write; loss of ability to understand speech or written words.

Arteriovenous malformation (AVMs)
A tangle of blood vessels in the brain.

Astrocytoma
A brain tumor arising in the supportive tissue of the brain. They are the most common primary CNS tumors, representing about half of all primary brain and spinal cord tumors.

Basal Ganglia
Masses of nerve cells deep within the brain at the base of cerebral hemispheres.

Benign
Not malignant, not cancerous.

Bilateral
Occurring on both sides of the body.

Blastoma
A tumor whose cells have embryonic characteristics, fast-growing and invasive.

Brachytherapy
In radiation therapy, the use of implants of radioactive material such as radium, iridium at the site or a short distance from the area being treated.

Brain Stem
The bottom-most portion of the brain connecting the cerebrum with the spinal cord. The midbrain, pons, medulla oblongata and reticular formation are all part of the brain stem.

Carcinoma
A malignant tumor that arises from skin or the lining of body organs. They often invade adjacent tissue and spread to distant organs, including the brain.

Central nervous system (CNS)
Pertaining to the brain, cranial nerves and spinal cord.

Cerebellopontine Angle
The angle between the cerebellum and the pons, a common site for the growth of acoustic neuromas (vestibular schwanomas).

Cerebellum
The second largest area of the brain, consisting of two hemispheres or halves and is connected to the brain stem.

Cerebral
Refers to the cerebrum or cerebral hemispheres.

Cerebral Edema
Swelling of the brain tissue due to an accumulation of fluid which may be caused by tumor, toxic chemicals or interaction.

Cerebrospinal Fluid
The clear fluid made in the ventricular cavities of the brain that bathes the brain and spinal cord.

Cerebrum
The largest area of the brain occupying the uppermost part of the skull. It consists of two halves called hemispheres. Each half of the cerebrum is further divided into four lobes: frontal, temporal, parietal, and occipital.

Chondroma
A rare, benign tumor arising at the base of the skull, especially in the area near the pituitary gland. It is very slow growing and might be present for a long time before causing any symptoms.

Chondrosarcoma
This very rare tumor arises from bone and is composed of cartilage. It is a locally invasive malignant tumor.

Chordoma
A rare, benign, slow growing tumor that occurs at the base of the skull in about 1/3 of patients or at the end of the spine.

Choroid Plexus
This is what produces spinal fluid, which flows through the ventricles and meninges surrounding the brain and spinal cord.

Circumscribed or encapsulated
Localized; having a border or being wholly confined to a specific area.

Conformal
Images in three dimensions to the shape of the tumor.

Congenital
Existing before or at birth.

Coronal
Circular In scans, an image from the top of a thin layer of the brain showing both the right and left sides.

Cranial Nerves
12 pairs of nerves having their origin in the brain.

Craniopharyngioma
A benign tumor arising from small nests of cells located near the pituitary stalk.

Craniotomy
Surgery involving the removal of skull bone to gain access to the brain and the bone is put back at the end of the operation.

CT
Computed Tomography. Also known as a "CAT scan". A sophisticated procedure using X-rays to produce computerized images through the body.

Cyst
A fluid-filled mass, usually enclosed by a membrane.

Diffuse
Lacking a distinct border, spread out, not localized.

Dosimetry
Measurement of doses.

Edema
Tissue swelling caused by the accumulation of fluid.

Efficacy
Able to achieve the desired results or produces beneficial results.

Encapsulated
Localized. Refers to a tumor that is wholly confined to a specific area, surrounded by a capsule.

Familial
Tending to occur repeatedly in family members, but is not genetic (inherited). Might indicate a susceptibility, or a common environmental influence.

Fractionated
The process of spreading the total required treatment dose over an extended period of time.

Focal
Limited to one specific area.

FSR or SRT (Fractionated Stereotactic Radiotherapy)
A moderately high dose radiation treatment usually received over three to eight sessions.

Ganglia
A mass of nerve tissue or a group of nerve cell bodies.

Glial Tissue/Cells
The supportive tissue of the brain. The most common cells are astrocytes and oligodendrocytes. Unlike nerves, glial can reproduce itself. Glial is the origin of the largest percentage of brain tumors.

Glioblastoma Multiforme (GBM)
A malignant tumor which commonly invades adjacent tissue and spreads throughout the CNS. This is usually a fast growing tumor containing a mixture of cell types.

Glioma
Any tumor arising from glial tissue of the brain, which provides energy, nutrients and other support for nerve cells in the brain.

Glomus Jugulare
A very rare, slow growing, benign tumor that invades the temporal bone.

Gy=Gray
A unit of absorbed radiation.

Hemangioblastoma
A benign tumor-like mass arising from blood vessels and is often cystic. It is often associated with von Hippel-Lindau disease.

Hemangiopericytoma
A rare tumor, grade II or grade III, different from the meningioma, although rising from the same cells.

Hemiparesis
Muscle weakness of one side of the body.

Hemiplegia
Complete paralysis of one side of the body.

Hereditary
Inherited or genetic; passed on from parent to child.

Hyperfractionation
An increased number of smaller dosage treatments of radiation therapy.

Hypothalamus
Part of the wall of the third ventricle and at the base of the optic chiasm.

Immunotherapy
Use of the body's immune system to fight tumors.

IMRT (Intensity Modulated Radiation Therapy)
The intensity of the radiation can be changed during treatment to spare adjoining normal tissue and increase the dose to the tumor.

Infiltrating
Penetrating normal, surrounding tissue.

Infratentorial
Below the tentorium, a flap of the membrane protecting the brain that separates the cerebral hemispheres from the brain structures in the posterior fossa.

Interstitial radiation
Implantation of radioactive seeds into a tumor.

Intracavity
Treatment delivered into the space created when the brain tumor was removed.

Intracerebral
Located within the cerebral hemispheres.

Intracranial
Within the skull.

Intraventricular
Injection into a ventricle. There are four ventricles or cavities in the brain, which are filled with cerebrospinal fluid and linked by ducts so the fluid can circulate.

Invasive
Refers to a tumor that invades healthy tissues; also called diffuse or infiltrating.

Irradiation
Radiation therapy; treatment by ionizing radiation.

Isodose
In radiation, to have equal doses of radiation in different areas.

Lesion
A change in tissue structure due to injury or disease.

Linac Radiosurgery
Radiosurgery given by a device producing powerful X-rays, which is normally used to give conventional radiotherapy. The unit is modified by bolting on a collimator which focuses the beam down to a few millimeters in width. Treatment with this equipment tends not to be as accurate as using the Gamma Knife, which is specifically designed for radiosurgery.

Lipoma
A rare, benign tumor composed of fat tissue, commonly located in the corpus callosum.

Local
In the area of the tumor; confined to one specific area.

Malignant
Cancerous or life-threatening, tending to become progressively worse.

Mass Effect
Damage to the brain due to the bulk of a tumor, the blockage of fluid, and/or excess accumulation of fluid within the skull.

Median Survival
Median means the middle value. An equal number of people live longer as die earlier than the median.

Medulloblastoma (MDL)
Fast-growing, invasive tumors located in the cerebellum that frequently spread to other parts of the central nervous system via the spinal fluid.

Membrane
Thin layer of tissue covering a surface, lining a body cavity, or dividing a space or organ.

Meninges
They are three, thin membranes that completely cover the brain and the spinal cord. Spinal fluid flows in the space between two of the membranes.

Meningioma
A brain tumor arising from the fibrous tissues that cover the brain's surface and spinal cord.

Metastasis
In cancer patients, the spreading of malignant cells.

Microsurgery
Delicate surgery involving the use of a special microscope and small instruments.

Morbidity
Complications directly resulting from treatment.

MRI Scan (Magnetic Resonance Imaging)
A scanning device that uses a magnetic field, radio waves, and a computer. Signals emitted by normal and diseased tissue during the scans are assembled into an image.

Necrosis
Dead cells.

Neoplasm
A tumor, either benign or malignant.

Nervous System
The entire integrated system of nerve tissue in the body: the brain, brain stem, spinal cord, nerves and ganglia.

Neuroectoderm
The region of the embryo that eventually develops into the nervous system.

Nuclear Medicine
The branch of medicine that deals with the use of radioisotopes in therapy and diagnosis.

Palliative Care
Caring for a patient by maintaining the best quality of remaining life.

Paresis
Weakness.

PET Scan (Positron Emission Tomography)
A special type of X-ray using a radioactive dye which shows areas of the brain that have a higher or lower metabolism than normal. It can sometimes be used when an MRI scan alone is inconclusive. This is a limited-use diagnostic tool.

Photodynamic Radiation Therapy (PRT)
A light sensitive drug is given through a vein and concentrates in the tumor. During a surgical procedure, a special light activates the drug which kills the tumor cells.

Pineal Gland
Lies below the corpus callosum that produces the hormone melatonin. Melatonin is believed to control the biological rhythms of the body.

Pituitary Gland
Composed of two lobes (anterior and posterior). Attached to and receives messages from the hypothalamus. Several hormones are produced by the pituitary including prolactin, corticotropin, and growth hormone.

Pons
Part of the brain stem, containing the origins of the 5th, 6th, 7th and 8th cranial nerves.

Primitive Neuroectodermal Tumor (PNET)
A tumor which appears identical under the microscope to the medulloblastoma, but occurs primarily in the cerebrum and most frequently occurs in very young children.

Protocol
An outline of care; a treatment plan.

Radiation Therapy
The use of radiation to destroy cancer or other abnormal cells in the body. During radiation therapy, a significant amount of healthy normal tissue is irradiated. To reduce the side effects caused by this, the radiation dose is split into a number of treatments, in theory enabling the normal healthy tissue to recover before the next treatment is given.

Radioresistant
Resistant to radiation therapy.

Radiosensitive
Responsive to radiation therapy.

Radiosurgery (stereotactic)
Use of a number of precisely aimed, highly focused beams of ionizing radiation to target a specific area.

Recurrence
The return of symptoms or the tumor itself.

Resection
Surgical removal of a tumor.

Residual tumor
Tumor remaining after surgery.

Sella
The saddle-shaped, hollowed extension of the sphenoid bone that contains the pituitary gland.

Sequela
The full disease process.

SRS (Stereotactic radiosurgery)
A one-session treatment with high dose focal radiation within the brain.

Stereotactic
A method of precisely locating areas in space utilizing 3-dimensional mapping, especially in the areas of the brain.

Steroids
Medications used to decrease swelling around tumors.

Tinnitus
Buzzing or ringing in the ear.

Trigeminal Neuralgia
An inflammatory or degenerative condition of the fifth cranial nerve characterized by severe pain in the face.

Toxoplasmosis
A generalized infection of the central nervous system caused by a small parasite.

Tumor
An abnormal growth.

Vascular
Relating to blood vessels.

Vascularity
The blood supply of a tumor.

Vertigo
Dizziness.

Vestibular Schwannoma
(also known as an acoustic tumor or neuromas) a benign tumor of the eighth cranial nerve, which supplies the ear.

XRT (Conventional external beam radiation therapy)
Small amounts of external beam radiation therapy given over an area to eliminate stray cells and future growth.