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Astrocytomas:
These tumors, which develop from star-shaped glial cells
called astrocytes, range from slow growing and benign
to fast-growing and malignant. They are a type of glioma
(see below). Biopsy:
Removal of a small sample of a tumor for examination
by a pathologist.
Blood-Brain
Barrier: A wall of nerves and cells
surrounding the brain membrane. While this barrier has
a protective function, it also reduces the ability of
chemotherapeutic drugs to effectively reach some brain
tumors.
Brachytherapy:
Also called interstitial radiation. Stereotactic
techniques are used to implant radioactive "seeds"
directly into a tumor.
Brain
Neoplasm: Another name for a brain
tumor.
Brain
stem: The
brain stem, located at the front of the cerebellum,
links the cerebrum to the spinal cord and controls various
automatic as well as motor functions. It is composed
of the medulla oblongata, the pons, the midbrain, and
the reticular formation.
Brain
Stem Gliomas: These tumors are located
at the base of the brain and occur more frequently in
children than in adults.
Cerebrospinal
Fluid (CSF): This protective, clear
fluid circulates through the brain and the spinal canal.
When this flow is blocked–as may be the case with a
brain tumor–hydrocephalus, or water on the brain, occurs.
Cerebellum:
Located at the back of the brain, the cerebellum
controls body movement, i.e., balance, walking, etc.
Cerebrum:
The brain’s largest section can be divided into
two parts: the left and right cerebral hemispheres.
These hemispheres are joined by the corpus callosum,
which enables "messages" to be delivered between
the two halves. The right side of the brain controls
the left side of the body, and vice versa. Each hemisphere
also has four lobes that are responsible for different
functions: frontal (behavior, emotions, problem solving);
temporal ( short-term memory, identification of sound
and smell); parietal (touch, language comprehension),
and occipital (visual processing, shape and color identification).
Clinical
Trials: These studies involve
patients in the testing of new treatments and therapies
and are part of the drug approval process in America.
A clinical trial, which typically has three stages,
or phases, gauges a drug’s safety, effectiveness, dosage
requirements, and side effects. Patients must meet certain
criteria to be enrolled in a clinical trial (which is
determined for each individual study), and participation
in a study is voluntary. Clinical trials are sponsored
by pharmaceutical companies, government agencies, and
other healthcare-related organizations; many are based
at research universities or hospitals. A set of rules,
or protocol, is established for each trial.
Computed
Tomography (CT): This scanning tool
combines X-ray with a computer to produce detailed images
of the brain.
Cranial
nerves: Twelve pairs of nerves responsible
for various functions, including speech, hearing, taste,
facial sensation and facial expression, balance, and
smell.
Craniopharyngiomas:
These tumors of the pituitary gland most often affect
infants and children.
Cranium:
The bony covering that surrounds the brain. The
cranium and the facial bones comprise the skull.
"Eloquent"
Brain: Areas within the brain that
control the senses, motor functions, and speech.
Ependymomas:
Generally benign tumors that develop from cells that
line both the hollow cavities of the brain and the canal
containing the spinal cord. These tumors most commonly
occur in children.
Fractionated
Stereotaxis Radiotherapy: The process of
delivering doses of radiation in daily treatments in
order to increase the total amount of radiation directed
at a tumor site.
Frameless
Stereotactic Surgery: See "Stereotactic
Surgery."
Functional
Image-Guided Surgery (FIGS): A technique
that combines Functional MRI (fMRI) with frameless stereotactic
radiosurgery to optimize the safety and efficacy of
treatment for patients with tumors located in the cerebral
hemispheres.
Functional
MRI (fMRI): A technique that helps to pinpoint
functional areas of the brain. While the MRI is scanning,
the patient is asked to perform a series of activities
and movements, such as reading a list or tapping fingers.
The areas of the brain that correlate to these movements
and activities "light up" on the scan and create an
image. This information is used by surgical navigation
computers in the planning of incisions, skull openings
and tumor removal to minimize neurological deficits.
Gangliogliomas:
A rarely occurring and slow-growing form of glioma,
gangliogliomas can be found in the brain or spinal cord.
Glioblastoma
Multiforme: These tumors, sometimes called
high-grade or grade IV astrocytomas, grow rapidly, invade
nearby tissue, and contain cells that are very malignant.
Gliomas:
A large category of primary brain tumors that originate
from nerve cells called glial cells. There are
many specific types of gliomas; see Astrocytes; Glioglastoma
Multiforme; Mixed Gliomas; Optic Nerve Gliomas.
Grading:
Brain tumors can be categorized by grades. Grading occurs
after biopsy, when a pathologist examines the brain
tissue for breakdown of cell structure. While there
are different systems used to assign grades, in general,
they are as follows:
- Grade I tumors
are slow growing; their cells are near-normal in appearance;
and are not malignant.
- Grade II
tumors have cells that are slightly abnormal in appearance
and can spread to surrounding tissue.
- Grade III tumors
grow quickly, contain abnormal cells, and spread to
surrounding tissue.
- Grade IV tumors
contain aggressive, abnormal cells that reproduce
quickly. These are the most malignant of brain tumors.
Hypothalamus:
The part of the brain that acts as a messenger to
the pituitary gland; it also plays an integral role
in body temperature, sleep, appetite, and sexual behavior.
Intraoperative
MRI: MRI images obtained during surgery to
confirm the location of lesions, plan the operative
approach, and evaluate the margin of the lesion resection.
Left
Hemisphere: The half of the cerebrum
sometimes referred to as the "dominant" hemisphere.
It has primary responsibility for speech and language.
However, in some left-handed people, the right hemisphere
controls speech function.
Magnetic
Resonance Imaging (MRI): This equipment
uses a magnetic field to capture an image and can provide
a three-dimensional image of the brain.
Medulloblastomas:
These malignant tumors represent more than
one-fourth of all childhood brain tumors. Left untreated,
medulloblastomas can spread throughout the nervous system
and, sometimes, to other parts of the body
Medulla
oblongata: This section of the brain
stem connects the brain to the spinal cord. It is responsible
for involuntary functions such as breathing, heart rhythms,
and swallowing.
Meninges:
Protective layers of tissue that surround
the brain and the spinal cord.
Meningiomas:
Tumors that originate from the meninges, thin membranes
that cover the brain and the spinal cord. These slow-growing
tumors rarely become malignant or spread; malignancy
occasionally does occur.
Metastatic
Tumors:These are malignant tumors that have
spread from another part of the body.
Midbrain:
Part of the brain stem, it is the origin of the
third and fourth cranial nerves which control eye movement
and eyelid opening.
Mixed
Gliomas: These tumors contain more
than one type of glial cell, are often located near
the motor cortex, and most commonly occur in young men.
Neuroendoscopy:
The use of miniaturized, optically guided instruments
that can be navigated directly to the tumor site. Oligodendrogliomas:
Slow-growing, rare tumors that most commonly affect young
adults.
Optic
chiasm: The area in the front of the
brain where the optic nerves cross.
Optic
Nerve Gliomas: Tumors that are found
on or near the optic nerve. Untreated, they can interfere
with vision, causing "crossed" eyes, or strabismus;
bulging eyeballs; or loss of sight.
Pineal
Tumors: Tumors near the pineal gland, a small
structure deep within the brain that produces the hormone
melatonin. They can be of about 17 different types,
some malignant and some benign.
Pituitary
Adenomas: These tumors are located near the
pituitary gland, a small oval-shaped structure that
supplies hormones. Hormones are chemical messengers
that control many bodily processes, such as growth and
metabolism. Secreting tumors release unusually high
levels of pituitary hormones, which can result in a
variety of symptoms–from impotence to abnormal body
growth to hyperthyroidism–depending on the hormone involved.
Pons:
This part of the brain stem is the origin of four pairs
of cranial nerves: fifth (facial sensation); sixth (eye
movement); seventh (taste, facial expression, eyelid
closure); and eighth (hearing and balance).
Posterior
fossa: The part of the skull containing the
brain stem and the cerebellum.
Primary
Brain Tumors: Tumors that originate
from within the brain.
Primitive
Neuroectodermal Tumors: PNETs, which usually
affect children and young adults, originate from primitive
cells left over from early nervous system development.
PNETs are usually very malignant, growing rapidly and
spreading easily within the brain and spinal cord. In
rare cases, they spread outside the CNS.
Right
hemisphere: The half of the cerebrum
that processes visual information.
Schwannomas:
These tumors, while usually benign, can affect balance
and hearing, and may cause facial paralysis. They are
also known as vestibular schwannomas or acoustic neuromas
and may grow on one or both sides of the brain.
SPECT:
Single Photon Emission Computed Tomography, or SPECT,
is a scanner that measures a low-dose radioactive material
as it circulates through the brain. SPECT can be used
to differentiate between low and high grade tumors.
Stereotactic
Radiation Therapy: The use of frameless stereotaxis
to deliver small doses of radiation therapy to tumor
sites.
Stereotactic
Radiosurgery: A non-invasive modality
that precisely delivers focused, multiple beams of radiation
to areas where they’re needed–a single point on a tumor
site–while avoiding healthy tissue.
Stereotactic
Surgery: A sophisticated, computer-based
modality where a metal frame is attached to the patient's
skull to provide a fixed reference point. This point,
combined with a three-dimensional image of the brain
provided by a computer and MRI scanning, allows for
precise mapping and visualization of the tumor and surrounding
tissue. Precise navigation to the tumor site and optimal
tumor resection is possible using a variety of surgical
devices attached to the frame. Frameless
Stereotactic Surgery: provides the same precision
without the need to attach a heavy metal frame to the
patient's skull. Frameless systems substitute a reference
system created by "wands," plastic guides,
or infrared markers.
Thalamus:
A small area in the brain that relays information
to and from the cortex and translates impulses related
to pain, attention, and alertness.
Vascular
Tumors: These rare, benign tumors arise from
excess growth of blood vessels of the brain and the
spinal cord.
Ventricles:
Four small cavities within the brain; they contain the
choroid plexus, which produce cerebrospinal fluid.
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About
the Brain & Brain Tumors
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