Glossary of Terms

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accessible tumors which can be approached by a surgical procedure, not deep in the brain or beneath vital structures.
acoustic nerve the eighth nerve within the skull; it is concerned with hearing and balance.
agnosia loss of ability to recognize objects, people, sounds, shapes, or smells. Common to tumors of the parietal lobe of the cerebral hemispheres.
agraphia loss of ability to write (a form of aphasia). Symptom common to tumors of the parietal lobe of the dominant cerebral hemisphere.
alopecia loss of hair; baldness in areas where hair is usually present. A common side effect of radiation therapy to the brain and some chemical therapies.
amplitude the height of a single sound wave as seen on an ocsilliscope. It is associated with the loudness of a sound.
ampulla the swelling at the base of each semicircular canal; it contains sensory cells which detect movement of the fluid within the canals.
anaplasia characteristics of a cell identifies it as a cancer cell. Malignant.
angiogram a diagnostic procedure done in the x-ray department to visualize blood vessels following introduction of a contrast material into an artery.
anosmia absence of the sense of smell. Symptom common to tumors of the frontal lobe of the cerebral hemispheres.
anvil one of three bones of hearing in the middle ear that help transmit sound waves from the outer ear to the cochlea. Also called incus.
aphasia loss of ability to speak or write; loss of ability to understand speech or written words.
assistive device any device other than a hearing aid which helps the hearing impaired.
ataxic gait walking that is clumsy, uncoordinated.
audiogram a graph depicting one’s ability to hear sounds at different frequencies.
audiologist a person trained in the science of hearing and hearing impairments; they can administer tests and help in the rehabilitation of hearing-impaired people.
audiometry the measurement of hearing acuity.
auditory nerve the nerve which carries electrical signals from the inner ear to the base of the brain.
auricle outer flap of the ear. Also called pinna.


basilar membrane thin membrane which vibrates in response to movements of the liquid that fills the cochlea.
benign not malignant.
biopsy examination of a small amount of tissue taken from the patient’s body to make a diagnosis.
bone conduction the conduction of sound waves to the inner ear through reverberations of the mastoid bone.
bony labyrinth the cavity in the skull which contains the inner ear mechanism.
brainstem testing measures hearing sensitivity without requiring responses from infants or persons who are unable to communicate about their hearing tests.


cancer malignant tissue that is invasive, destroys healthy tissue, and tends to spread to distant locations.
carcinoma a malignant tumor that arises from epithelium, found in skin and the lining of body organs; for example, breast, prostate, lung, stomach or bowel. Carcinomas tend to infiltrate into adjacent tissue and spread (metastasize) to distant organs, such as bone, liver, lung, or the brain.
catheter a flexible, tubular instrument, used for the removal or insertion of fluids.
CC (closed captioned) a broadcast television program that includes a signal which produces descriptive subtitles on the screen. Requires CC converter in the TV set.
cerebral referring to the cerebrum, part of the brain.
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, the cerebrum occupies 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.
cerumen ear wax.
chemotherapy the use of chemical agents to treat brain tumors.
circumscribed having a border, localized. Often associated with a capsule and benign tumors of the brain: meningiomas, pituitary adenomas and acoustic neuromas.
cochlea shaped like a snail’s shell, this organ of the inner ear contains the organ of Corti, from which the eighth nerve fibers send electric impulses, hearing signals, to the brain.
cochlear implant replacement of part or all of the function of the inner ear.
conductive hearing loss hearing loss caused by a problem of the outer or middle ear, resulting in the inability of sound to be conducted to the inner ear.
congenital existing before or at birth.
congenital hearing loss hearing loss that is present from birth which may or may not be hereditary.
contralateral affecting the opposite side.
cortex that surface of the brain where sensory information is processed.
cranial cavity the skull.
craniectomy surgery performed on the skull where pieces of bone are removed to gain access to the brain, and the bone pieces are NOT replaced.
craniotomy surgery performed on the skull where a portion of bone is removed to gain access to the brain, and the bone is PUT BACK in its place.
crista sensory cells within the semicircular canals which detect fluid movement.
CT or CAT scan (Computerized Axial Tomography) – an x-ray device linked to a computer that produces an image of a predetermined cross-section of the brain. A special dye material may be injected into the patient’s vein prior to the scan to help make any abnormal tissue more evident.
cupola jelly-like covering of the sensory hairs in the ampullae of the semicircular canals. This responds to movement in the surrounding fluid and assists in maintaining balance.
cycles (per second) arithmetic measurement of frequency, or a sound’s pitch. (The higher the number, the higher the pitch of the sound.)
cyst a fluid filled mass. Usually enclosed by a membrane.


debulk a surgical procedure to decrease swelling by removing a portion of a tumor or dead tissue.
Decadron (R) Dexamethasone. A glucocorticosteroid medication used to reduce brain tissue swelling.
decibel arithmetic scale used as a measurement of the volume or loudness of sound.
decompressive surgical procedure during which bone, tissue, or tumor is removed to lessen intracranial pressure.
diabetes insipidus a problem with water balance in the body causing excess urine production and great thirst, due to pituitary-hypothalamic damage in the brain. Ordinary diabetes, which has the same symptoms, is due to insufficient insulin production by the pancreas.
diplopia double vision.
distal located far from the reference point.
dura mater the outermost, toughest, and most fibrous of the three membranes (meninges) that cover the brain and spinal cord.
dysarthria impairment of speech caused by damage or disorder of the tongue or speech muscles. Symptom may indicate pressure on the brain stem or elsewhere.
dysphagia difficulty in swallowing or inability to swallow. Symptom usually indicates tumors involving the lower brain stem.
dysphasia language disorder. Inability to speak words which one has in mind or to think of correct words; or inability to understand spoken or written words. Symptom common to tumors of the dominant cerebral hemisphere, particularly the frontal, temporal, and parietal lobes.


ear canal the short tube which connects sound from the outer ear to the ear drum.
ear drum membrane separating outer ear from the middle ear; the tympanum.
edema swelling due to an excess of water.
encapsulated tumor that is wholly confined to a specific area, surrounded by a capsule. Localized.
etiology the study of the cause of a disease.
eustachian tube tube running from the nasal cavity to the middle ear. Helps maintain sinus and middle ear pressure, protecting the ear drum.
evoked potentials the use of electrodes to measure the electrical activity of nerves. May be used as a guide during the removal of tumors growing around the important nerves.
extracerebral located outside the cerebral hemispheres.
extradural located outside the dura mater.


frequency the number of vibrations per second of a sound. (See cycles.)


gait pattern of walking.
ganglia a mass of nerve tissue (gray matter) or a group of nerve cell bodies. Also refers to specific groups within the brain or spinal cord (as basal ganglia). Ganglion is the singular of ganglia.
GFAP Glial Fibrillary Acidic Protein – this protein, found in microfilaments of glial cells, helps distinguish glial from non-glial tumors. A laboratory stain is used to test for its presence.
gland an organ of the body that produces materials (hormones) released into the bloodstream, such as the pituitary or pineal gland. Hormones influence metabolism and other body functions.
glia (neuroglia) supportive tissue of the brain. There are three types of glial tissue: astrocytes, oligodendrocytes and microglia. Glial cells do not conduct electrical impulses, as opposed to neurons.
glioma any tumor arising from glial tissue.
glucocorticosteroids medications used to decrease swelling around tumors.
gray matter the “thinking brain” appears gray because it is composed of numerous nerve cells and blood vessels. The outer layer of the cerebrum – the cerebral cortex, and areas deep within the brain – the basal ganglia, are made up of gray matter.
growth factor a naturally occurring protein chemical that stimulates cell division and proliferation. It is produced by normal cells during embryonic development, tissue growth, and wound healing. Tumors, however, produce large amounts of growth factors.


hammer another of the three bones of hearing in the middle ear which helps transmit sound waves from the outer ear to the cochlea. Also called malleus.
hemianopsia loss of one half of the field of vision (the area that can be seen by each eye when staring straight ahead).
hemiplegia complete paralysis of one side of the body.
herniation bulging of tissue through an opening in a membrane, muscle or bone.
heterogeneous composed of various cell types.
homogeneous composed of identical cell types.
hydrocephalus Hydro = water, cephalo = head. Excess water in the brain due to blockage of cerebrospinal fluid flow, increased production, or decreased absorption.
hyperfractionation an increased number of smaller dosage treatments of radiation.
hyperthermia the use of heat to kill tumor cells.
hypophysis pituitary gland.
hypotonicity diminished muscle tone; limp muscles.


ICP IntraCranial Pressure – harmful when increased.
IICP Increased IntraCranial Pressure
immunotherapy use of the body’s immune system to fight tumors.
impedance audiometry test for measuring the ability to hear sound waves transmitted through the bones.
incus one of three bones of hearing in the middle ear that help transmit sound waves from the outer ear to the cochlea. Also called the anvil.
infiltrating tumor that penetrates the normal, surrounding tissue.
informed consent the right to have information explained to you so that you fully understand and agree to the nature of the proposed treatment.
inner ear the portion of the ear, beginning at the oval window, which transmits electric impulses, sound signals, to the brain. It helps maintain balance. It consists of the cochlea and vestibular apparatus.
interstitial radiation therapy the implantation of radioactive seeds directly into a tumor.
intra-arterial injection into an artery (that may supply a tumor).
intracerebral located within the cerebral hemispheres (cerebrum).
intracranial within the skull.
intradural beneath the dura mater.
intramuscular into a muscle.
intrathecal injection into the sub-arachnoid space of the meninges. Usually done by lumbar puncture.
intratumoral injection into a tumor (usually performed during surgery).
intravenous injection into a vein.
intraventricular injection into a ventricle.
invasive refers to a tumor that invades healthy tissues. The opposite of encapsulated. Also called diffuse or infiltrating.
ipsilateral affecting the same side.
irradiation treatment by ionizing radiation, such as x-rays, or radioactive sources such as radioactive iodine seeds.


labyrinthitis a viral infection in the vestibular canal which may cause vertigo.
laser an acronym for light amplification by stimulated emission of radiation. A surgical tool that creates intense heat and power when focused at close range, destroying cells by vaporizing them.
local in the area of the tumor, confined to one specific area.
lumbar puncture spinal tap. Needle penetration into the subarachnoid space of the lumbar spine. Used to withdraw a sample of spinal fluid for examination. Also used to inject a dye into the spine prior to a myelogram.


macula within the organs of balance, area containing sensory cells which measure head position.
malignant cancerous or life-threatening, tending to become progressively worse.
malleus one of three bones of hearing in the middle ear that helps transmit sound waves from the outer ear to the cochlea. Also called the hammer.
Mannitol a medication given to reduce brain swelling and elevated intracranial pressure. Also used to temporarily disrupt the blood barrier prior to some forms of chemotherapy.
mass effect damage to the brain due to the bulk effect of a tumor, the blockage of fluid, or excess accumulation of fluid within the skull.
mastoid the bone in which the entire ear mechanism is housed. Part of the larger temporal bone.
membrane thin layer of tissue covering a surface, lining a body cavity, or dividing a space or organ.
Meniere’s Disease a condition resulting from fluid buildup in the inner ear, leading to episodes of hearing loss, tinnitus, and vertigo.
metastisize to spread to another part of the body, usually through the blood vessels, lymph channels, or spinal fluid.
middle ear the portion of the ear between the ear drum and the oval window which transmits sound to the inner ear. Consists of the hammer, anvil and stirrup, the three bones of hearing.
monoclonal antibodies (MAB)- a biological response modifier with unique “homing device” properties. Chemicals or radiation tagged to the MAB may be delivered directly to tumor cells. Or, the MAB itself may be capable of tumor cell destruction.
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 scan are assembled into an image.
mutate change in the genetic material (DNA) inside the cell.


necrosis dead cells. A common feature of glioblastoma multiforme and other malignant tumors, including metastatic cancer to the brain. Caused by either lack of blood supply or irradiation.
neoplasm a tumor, either benign or malignant.
nerve loss deafness a term used to differentiate inner ear problems from those of the middle ear.
nervous system the entire integrated system of nerve tissue in the body: the brain, brain stem, spinal cord, nerves and ganglia.
neuroectoder the region of the embryo that eventually develops into the nervous system.
neuron nerve cell; conducts electrical signals.
nuclear medicine the branch of medicine that deals with the use of radioisotopes in therapy and diagnosis.
nucleus the center of the cell containing the genetic information (genes, chromosomes, DNA, etc.) The appearance of the nucleus is used as a criterion to determine the malignant potential of a cell of tissue.
nystagmus rapid movement of the eyeballs.


Ommaya reservoir a device with a fluid reservoir implanted under the scalp with a catheter to a ventricle. It allows for medication to be given directly to the CSF (cerebrospinal fluid) and into the brain.
oncogene fragments of genetic material (DNA) that carry the potential to cause cancer (transform normal cells into malignant cells).
oncogenesis the causation or production of tumors.
Organ of Corti This organ is located in the cochlea; it contains the hair cells that actually transmit sound waves from the ear through the auditory nerve to the brain as electric impulses.
ossicles collective name for the three bones of hearing of the middle ear: hammer, anvil and stirrup.
otitis media infection of the middle ear.
otoliths stone-like particles in the macula which aid in our awareness of gravity and movement.
otology branch of medicine concentrating on diseases of the ear.
otosclerosis a conductive hearing loss caused when the middle ear no longer transmits sound properly from the eardrum to the inner ear.
outer ear the external portion of the ear which collects sound waves and directs them into the ear. It consists of the pinna (auricle) and the ear canal and is separated from the middle ear by the eardrum.
oval window membrane which vibrates, transmitting sound into the cochlea. It separates the middle ear from the inner ear.


palsyB> complete paralysis.
papilledema swelling of the optic nerve. Indicates increased intracranial pressure on the optic nerve. Also called choked disc.
paresis weakness.
paresthesia abnormal sensations, such as burning, prickling.
perilymph watery liquid that fills the outer tubes running through the cochlea.
PET scan Positron Emission Tomography – a scanning device which uses low-dose radioactive sugar to measure brain activity. This is a limited-use diagnostic tool.
Phenobarbital (R) a sedating medication used to control seizures.
photodynamic radiation therapy a light sensitive drug which is given through a vein and concentrates in the tumor. Then, during a surgical procedure, a special light activates the drug. The activated drug kills the tumor cells.
pinna the outer, visible part of the ear, also called the auricle.
PNET Primitive NeuroEctodermal Tumor.
presbycusis a hereditary sensory-neural hearing loss that comes with aging.
primary brain tumor original source of tumor which is the brain rather than other areas of the body.
primitive undeveloped or in early stages of development, undifferentiated.
prognosis a forecast as to probable outcome.
proto-oncogenesdt> fragments of genetic material (DNA), related to oncogenes, but are the normal “switches” used to control growth and tissue repair.
proximal located closest to the reference point.


radiation therapy the use of radiation energy to interfere with tumor growth.
radioresistant resistant to radiation therapy.
radiosensitive responsive to radiation therapy.
recurrence the return of symptoms or the tumor itself, as opposed to a remission.
remission the disappearance of symptoms; the disappearance of the tumor.
resection surgical removal of a tumor.
residual remaining tumor.
respiration breathing. To inhale and exhale.


saccule inner ear area which contains some of the organs that measure position and gravitational field.
seizure convulsions, epilepsy, due to temporary disruption in electrical activity of the brain.
semicircular canal curved tubes containing fluid, movement of which makes us aware of turning sensations as the head moves.
sensorineaural hearing loss hearing loss resulting from an inner ear problem.
shunt a drainage system. Spinal fluid flows from a ventricle into a body cavity via a tube. Used to relieve increased intracranial pressure caused by brain tumors that block the flow of spinal fluid.
shunt (VA) ventriculo-atrial – the tube empties into the right atrium of the heart.
shunt (VP) ventriculo-peritoneal – the tube empties into the stomach.
sound wave alternating low and high pressure areas, moving through the air which are interpreted as sound when collected in the ear.
spasticity increased involuntary muscle contraction (the opposite of hypotonicity).
stalk a stem. Usually refers to the pituitary stalk that connects the pituitary gland to the hypothalamus.
stapes last of the three bones of hearing in the middle ear that help transmit sound waves from the outer ear to the cochlea. Also called the stirrup.
stereotactic precise positioning in three dimensional space. Refers to surgery or radiation therapy directed by scanning devices.
stereotactic radiosurgery a radiation therapy technique that uses a large number of narrow, precisely aimed, highly focused beams of ionizing radiation. The beams are aimed from many directions circling the head, and meet at a specific point, the tumor.
stirrup last of the three bones of hearing in tne middle ear that help transmit sound waves from the outer ear to the cochlea. Also called the stapes.
strabismus imperfect eye coordination (crossed eyes).
subcutaneous beneath the skin.
systemic circulating throughout the body.


tectorial membrane this thin strip of membrane is in contact with sensory hairs whose sound vibrations move, producing nerve impulses as electric impulses in the Corti.
Tegretol (R) carbamazepine. A medication given to control seizures; also used for pain relief in patients who have trigeminal neuralgia.
tinnitus buzzing or ringing in the ear. Symptom common to tumors of the acoustic nerve.
TTY a phone device. Dialogue is achieved at any distance, as words are typed into a TTY, converted to phone signals and appear, or are printed, as words on a receiving TTY machine.
tumor marker substances found in blood or other fluids that identify the presence of a tumor, and/or the tumor type.
tympanum membrane separating outer ear from middle ear: the eardrum.


ultrasound visualization of structures in the body by recording the reflections of sound waves directed into tissues. May be used during surgery.


vascular relating to blood vessels.
vascularity the blood supply of a tumor.
vertigo the sensation of moving or spinning while actually sitting or lying still. Symptom common to tumors of the acoustic nerve.
vestibular apparatus part of the cochlea concerned with maintaining balance.


wave length distance between the peaks of successive sound waves, as seen on an oscilliscope.
white matter brain tissue composed of myelin-coated nerve cell fibers. White matter carries information between the nerve cells in the brain and the spinal cord. The inner portion of the cerebrum is composed of white matter.
white noise a sound, such as running water, which masks all speech sounds.