Glossary

A B C D E F G H I L M N O P R S T V X

A

Acoustic Neuroma Vestibular schwannomas are commonly known as acoustic neuromas. A benign tumor of the nerve of hearing (the 8th cranial nerve.) This tumor is usually very slow growing.

Ademoma A tumor usually benign 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.

Angiogram A diagnostic procedure to visualize blood vessels using a contrast material similar to a dye.

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

Arteriovenous Malformation (AVM) An AVM is an abnormal collection of blood vessels in the brain or spinal cord that is prone to bleed. Bleeding from an AVM can cause symptoms ranging from headaches and seizures to stroke, paralysis, and even death.

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.

B

Basal Ganglia Masses of nerve cells deep within the brain at the base of cerebral hemispheres. The basal ganglia is critical for coordinating motor function

Benign tumor A benign tumor is an abnormal growth of tissue not considered to be cancerous. However, these tumors may compress surrounding tissue as they grow causing serious symptoms such as headaches, seizures, stroke, paralysis and even death if not treated. In some cases, these tumors can also transform into cancerous tumors.

Bragg peak The Bragg peak is a pronounced peak on the Bragg curve which plots the energy loss of ionizing radiation during its travel through matter. For protons, alpha rays, and other ion rays, the peak occurs immediately before the particles come to rest. This is called Bragg peak, for William Henry Bragg who discovered it in 1903.

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. The brainstem controls vital functions such as respiration and cardiac function in addition to relaying commands from the brain to the spinal cord.

C

Cancerous Tumor A tumor in which abnormal cells divide without control and can invade nearby tissues. Cancerous tumors can also spread to other parts of the body through the blood and lymph systems. A cancerous tumor is also referred to as a malignant tumor.

Carcinoma A cancer that begins in the skin or in tissues that line or cover internal 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. The cerebellum mainly functions to control coordinated and fluid motor function.

Cerebrospinal Fluid The clear fluid made within 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.

Chemotherapy Chemotherapy is a treatment that destroys tumor cells through the use of chemicals that are injected into the body or taken orally over a period of time.

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, slow growing low grade malignant 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 structure 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.

Cold spots During certain types of radiation treatment, cold spots are areas on the target that receive underdosing. Consequently, tumor cells may not be fully destroyed.

Compton Scatter In physics, Compton scattering is a type of scattering that x-rays and gamma rays undergo as they course through matter. The scattering of photons in matter results in a decrease in energy (increase in wavelength) of an X-ray or gamma ray photon, called the Compton effect. Part of the energy of the X/gamma ray is transferred to a scattering electron, which recoils and is ejected from its atom (which becomes ionized), and the rest of the energy is taken by the scattered, “degraded” photon.

“Conformal” radiosurgery Conformal radiosurgery refers to the process of shaping the radiation beam to fit the tumor or malformation contours. Conformal radiosurgery maximizes radiation to the tumor or malformation and minimizes doses to surrounding healthy tissue.

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.

Critical structures Critical structures are areas within the brain that are responsible for such vital functions as memory, speech, hearing, sight, breathing, and movement. The spinal cord is an example of a critical structure contained within the spinal column.

CT (Computerized Tomography) A CT scan is a diagnostic imaging technique that uses a sophisticated x-ray machine to create a detailed internal picture of the body. Is is particularly useful for imaging bony structures. A dye, or contrast agent, may be injected into the patient to highlight abnormalities in tissue.

CyberKnife A robotic radiosurgery system that delivers multiple beams of radiation, used to treat benign and cancerous tumors as well as other medical conditions located anywhere in the body. It consists of a linear accelerator and a robotic arm.

CyberKnife Synchrony CyberKnife Synchrony is a technology developed in order to deliver dynamic radiosurgery to tumors that move with respiration. The Synchrony system precisely tracks tumors in or near the lungs as they move, enabling highly focused beams of radiation to destroy the tumors with minimal damage to adjacent normal tissue.

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

D

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

E

Edema Tissue swelling caused by the accumulation of fluid.

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

F

Fellowship A fellowship is an additional period of medical training that a physician may undertake usually after completing an internship and residency training program. During this time (usually 1-2 years), physicians focus their training to a specific subspecialty in their field. An example of this is a fellowship in complex and minimally invasive spine surgery or neurosurgical oncology and radiosurgery, both of which Dr. Lipani has competed to compliment his internship in general surgery and residency in neurosurgery.

Fiducials Fiducials are markings used as reference points to track a tumors location in space. They may be found on either a head frame or bite block apparatus used by some radiosurgery technologies. Alternatively, they may be surgically implanted to treat spine or other tumors such as lung or pancreas. Newer technologies use internal skeletal markings as stationary reference points to avoid the need for surgically implantable fiducial markers.

Focal Limited to one specific area.

Fractionation Fractionation, or staging, occurs when the total dose of radiation is divided into smaller doses over several consecutive days in order to give healthy tissue time to repair itself.

G

Gamma Knife The Gamma Knife uses older radiosurgery technology that is confined to treating tumors in the head and high cervical (neck) spine. The Gamma Knife uses ionizing radiation (gamma rays) produced by 201 cobalt-60 sources to target the tumor or abnormality. Gamma Knife radiosurgery like all radiosurgery is not a knife and is not surgery. Gamma Knife is a registered trademark of Elekta Instruments, Inc.

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

Gantry A frame housing the x-ray tube, collimators, and detectors in a CT machine, with a large opening into which the patient is inserted; a mechanical support for mounting a device to be moved in a circular path.

Glia The supportive tissue cells of the brain. The most common cells are astrocytes and oligodendrocytes. Unlike nerves, glia can reproduce. Glial cells are 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 aggressive tumor containing a mixture of cell types.

Glioma Gliomas, or tumors that arise from the supportive tissue of the brain, are the most common primary brain tumors. Astrocytomas, ependymomas, oligodendrogliomas and tumors with mixtures of two or more of these cell types are the most common gliomas.

Glomus Jugulare A very rare, slow growing, benign tumor that invades the temporal bone and surrounding neural and vascular structures.

H

Head frame The head frame is a metal halo that is fixed to the patient’s skull. It contains markings (fiducials), which are visualized on the CT and/or MRI image. Local anesthesia is used to secure the head frame into position with four micro-pins. Technologies such as the Gamma Knife use a head frame for targeting purposes.

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.

Hot spots During certain types of radiation treatment, hot spots are areas where radiation beams overlap, causing overdosing in some areas. Overdosing may increase the risk of complications as a result of excessive radiation exposure to normal tissue, including critical structures such as the highly radiosensitive optic chiasm and acoustic nerves.

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. The hypothalamus plays a critical role in regulating the autonomic nervous system, hormonal function, body temperature, and satiety.

I

Image guidance system An image guidance system is utilized by the CyberKnife Radiosurgery system that tracks and verifies tumor location to enable automatic compensation for patient movement during the procedure. The image guidance system’s sophisticated technology allows for 100% frameless treatments with the ability to achieve submillimeter accuracy without the use of a painful head frame.

IMRT (Intensity Modulated Radiation Therapy) IMRT is a form of three-dimensional conformal radiation therapy (3D-CRT) that that adjusts the intensity of the radiation during treatment to spare adjoining normal tissue and increase the dose to the tumor.

Inaccessible or inoperable tumor An inaccessible tumor cannot be removed surgically because it is located in an area that is difficult to access surgically without risk of permanent damage to brain or spine function.

Infiltrating Penetrating normal surrounding tissue.

Interstitial radiation Implantation of radioactive seeds into a tumor.

Intracerebral Located within the cerebral hemispheres.

Intracranial Located within the skull.

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

Invasive Refers to a tumor that invades healthy tissues; also called diffuse or infiltrating. Also, when describing a surgical approach, refers to the process by which a surgeon gains access to the target tissue by cutting through the skin and dissecting the underlying tissue until the target tissue is accessed.

Ionizing radiation A type of radiation produced by x-ray procedures, radioactive substances, rays that enter the Earth’s atmosphere from outer space (i.e. ultraviolet radiation), and other sources. At high doses, ionizing radiation can injure genetic material inside cells which can lead to health risks, including cancer.

Irradiation Radiation therapy; treatment by ionizing radiation.

Isocentric Treatment Planning Isocentric treatment, or multi-isocentric treatment, involves packing the lesion or target with a single (or multiple, overlapping) spherically shaped dose distributions. Depending on the shape of the target, this may result in hot and cold spots.

L

Lesion An area of abnormal tissue. A lesion may be benign (not cancer) or malignant (cancer).

Leukemia A cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood.

Linac Linac, or linear accelerator, delivers x-ray radiation treatment by moving in an arc around the patient’s head while delivering narrow beams of collimated radiation. The ability to reach some tumors may be difficult due to the restrictions of the arc, making it more challenging to treat some tumors.

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.

Lumbar puncture A lumbar puncture, or spinal tap, is a procedure used to withdraw a small sample of cerebrospinal fluid so that it can be examined for abnormal cells.

M

Malignant tumor A malignant tumor is cancerous and behaves in an aggressive manner.

Mass Effect Damage to the brain due to the bulk of a tumor that compresses adjacent tissue. Mass effect may also lead to 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 The 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 type of slow-growing usually benign tumor that forms in the meninges (thin layers of tissue that cover and protect the brain and spinal cord). Meningiomas usually occur in adults.

Metastatic tumor A metastatic tumor or “met” is caused by cancer cells that originate elsewhere in the body and travel to the current site through the bloodstream.

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

Minimally Invasive Surgery Surgery performed through a small opening in the skin and with minimal trauma to underlying tissues which often results in less blood loss. Patients who have minimally invasive procedures are often able to recover more quickly after surgery.

Morbidity Complications directly resulting from treatment.

MRI (Magnetic Resonance Imaging) MRI uses a magnetic field rather than x-rays (used by CT scans) to image body tissues. A contrast agent may be injected for better visualization of certain tumors. An MRI does not use ionizing radiation.

Multi-jointed robotic arm Utilized by the CyberKnife Radiosurgery system, the multi-jointed robotic arm enables access to previously unreachable tumors and reduces damage to surrounding critical structures.

N

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.

Neurosurgeon (AKA Neurological Surgeon) A physician who specializes in performing surgery on the brain, spine and peripheral nerves. Neurosurgeons are often referred to as brain surgeons, even though they are trained to perform surgery on the brain, spine and peripheral nerves.

Neurosurgery (AKA Neurological Surgery) The field of medicine that specializes in surgery on the brain, spine, and other parts of the nervous system.

Non-invasive In medicine, it describes a procedure that does not require inserting an instrument through the skin or into a body opening. In cancer, it describes disease that has not spread outside the tissue in which it began.

Non-isocentric treatment planning Non-isocentric treatment is a system of radiation in which beams originate from arbitrary points in the workspace and are delivered to the lesion. The result is an even concentration of radiation within the contours of the target or lesion. Non-isocentric radiation is offered exclusively with CyberKnife radiosurgery.

O

Oncolgy The study of Cancer

P

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

Paresis Weakness.

PET (Positron Emission Tomography) PET is an imaging technique that provides a picture of brain activity by measuring levels of injected glucose sugar labeled with a radioactive marker. Tissues that show increased uptake of the radioactive marker or radio-tracer are suspicious for tumor growth.

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.

Primary Brain Tumor A primary brain tumor originates from cells in the brain or surrounding tissue. This is in contrast to a malignant brain tumor that originates elsewhere in the body and spreads to the brain through the bloodstream.

Protocol An outline of care; a treatment plan.

R

Radiation Therapy A low dose of radiation commonly given over 10-35 treatments. This treatment has been utilized for many decades as a standard.

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. See stereotactic radiosurgery (SRS)

Recurrence The return of symptoms or the tumor itself.

Resection Surgical removal of a tumor.

Residual tumor Tumor remaining after surgery.

S

Sarcoma A cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.

Stereotactic Stereotactic is the term used to describe the means by which a target is imaged or identified in 3 dimensional space through a precise coordinate system with a high degree of accuracy.

Stereotactic radiosurgery (SRS) Stereotactic radiosurgery delivers a high dose of radiation, generally in 1-5 treatment fractions. Treatments greater than single fraction are referred to as hypo-fractionation (i.e., 2-5 fractions).

Stereotactic radiotherapy (SRT) Stereotactic radiotherapy delivers lower doses of focused radiation over a series of treatment sessions. Each treatment is called a fraction, therefore, this type of therapy is sometimes called “fractionated or hyper-fractionated” therapy. A bite block that fixes to the patient’s upper teeth or mask may be used in place of a head frame for head treatments.

Steroids Medications used to decrease swelling around tumors.

T

Tinnitus Buzzing or ringing in the ear.

Treatment planning The process by which doctors and physicists prepare a plan for treatment of a particular target. The amount of dose delivered as well as the location of dose distribution is determined during treatment planning. In addition, the 
dose limitations to the surrounding critical tissues are reviewed during this time for safety measures.

Trigeminal Neuralgia AKA tic douloureux, is a severe pain disorder that involves the trigeminal nerve (The main sensory nerve of the head and face, and the motor nerve of the muscles used in chewing. Also called fifth cranial nerve.) The pain is described as paroxysmal lancinating electric-like pain lasting a few seconds, often triggered by sensory stimuli, confined to the distribution of one or more branches of the trigeminal nerve.

Tumor An abnormal growth.

V

Vascular Relating to blood vessels.

Vascularity The blood supply of a tumor.

Vertigo Dizziness.

X

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

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