Term Glossary

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Abscess: An infected, inflamed area in the body where pus collects.

Amblyopia: Poor vision due to non-use of an eye caused by underdevelopment of the visual pathway to the brain.

Aneurysm: A weakened dilated blood vessel that is prone to rupture (hemorrhage).

Angiogram: A test/procedure used to examine blood vessels of an organ such as the brain or lung. A small tube(catheter) is inserted into a vein or artery. A dye is then injected which highlights all the blood vessels and high-speed x-ray pictures are taken.

Angioid Streaks: Lines resembling blood vessels.

Angiogenesis: Development of blood vessels.

Angioma: Any malformation made up of blood vessels. These could be veins or a combination of arteries and veins (arteriovenous malformations or AVMs).

Anticonvulsant: Any medication that counteracts seizures.

Arterial Blood Gases (ABG): As part of the testing for PAVMs, blood is taken from an artery in the wrist to measure the oxygen level.

Arteriogram: See angiogram

Arteriovenous Malformation: An abnormal, direct connection (like a short circuit)between an artery and a vein.

Asymptomatic: Having no obvious symptoms.

Autosomal Dominant: A genetic term describing a disorder that affects men and women equally and has a 50% chance to be passed to each of ones offspring.

AVM: see arteriovenous malformation.

Babinski’s Reflex: A reflex named after Professor Babinski. Stroking the sole of the foot should normally cause the big toe to point downwards. A babinski sign is when it points up instead, and the other toes fan out. Implies spasticity. A babinski reflex is considered normal in the immature nervous system, such as in a baby.

Bilateral: Both sides, as opposed to Unilateral (one side).

Biopsy: A small piece of body tissue is removed for microscopic examination.

Buphthalmos: Enlarged size of the eye. Caused by Glaucoma occurring in infancy.

CAT scan: (Computed Axial Tomography). An x-ray test of any organ that uses computer reconstruction of multiple images of sections. One example is a CAT Scan of the lungs, sometimes used in HHT to determine the lung AVMs.

Cataract: An opacity in the lens of the eye. May obstruct vision.

Catheter: A small plastic tube which is inserted into a vein.

Cautery: A small electric needle that is applied to burn tissue. This is sometimes used in HHT to treat telangiectases and control bleeding.

Cerebral: An adjective used to describe anything related to the brain.

Chromosome: Microscopic particles within the cells of our bodies that contain genes.

Coilembolization: A treatment for AVM. A stainless steel or platinum coil is placed in an AVM, through a catheter, to permanently block off blood flow to an AVM

Congenital: Present from the time of birth.

Contralateral: On the opposite side.

Convulsion: Seizure. Abnormal electrical discharge of the brain causing a motor, sensory, or behavioral disturbance.

Corpus Callosum: White matter tract connecting the left and right hemispheres (halves) of the brain.

Cutaneous Lesions: Skin lesions.

Cyanotic: The bluish tinge of the skin when the blood oxygen level is low.

Dermatologist: A doctor who specializes in the skin.

Diagnosis: The process of identifying a disease based on symptoms and signs.

Diffuse: Spread out in all directions, not localized.

Dye Laser/Pulsed Dye Laser: Emits a beam of light energy in the wavelength of the color red. Used in treating telangiectases on the skin.

Echo Bubble: An ultrasound test to detect AVMs in the lung. A Sterile salt-water solution is shaken to create micro bubbles and is then injected into an arm vein. Ultrasound images of the heart are recorded to see if these bubbles reach the left side of the heart (suggestive of lung AVMs).

Electrocautery: See cautery.

EEG/Electroencephalogram: A recording of brain electrical activity.

Embolism: An obstruction in a blood vessel, usually by a blood clot.

Embolization/Embolotherapy: A Treatment for AVMs. Some sort of device (usually a coil or plug) is placed using a catheter to block off the blood flow to an AVM.

Endoscopy: Examination of the hollow organs of the body by passing a camera on a tube into the organs (such as the stomach and bowels).

Endothelium: The inner layer of cells which line the blood vessels.

ENT: A doctor who specializes in the ears, nose and throat. Also called an otolaryngologist.

Epistaxis: Nosebleeds.

Focal Seizure: Seizure arising from one part of the brain.

Forme Fruste: An atypical form of a disease, a variation of the disease.

Frontal Lobe: Most forward lobe of the brain. Deals with higher cognitive function (i.e. planning, organizing, etc.). Contains the motor cortex.

Fistula: An abnormal passage or connection between two organs or blood vessels.

Gastroenterologist: A doctor who treats diseases of the gastrointestinal or digestive tract (the stomach, the small intestine, and the colon).

Generalized Seizure: Seizure affecting much of the brain and involving loss of consciousness or awareness.

Genes: The codes in our cells that transmit our inherited traits to our children. See hereditary.

Geneticist: A physician who treats patients with hereditary disease or a scientist who specializes in the study of genetics.

Genetic Counselor: A professional with a graduate degree in genetic counseling who specializes in genetic disorders, and their implications for an individual and his/her family.

Genome, The Human: A world initiative/project of the 90s designed to locate all the genes of the human body.

Glaucoma: Increased pressure in the eye causing damage. May lead to blindness if not treated.

Goniotomy: Surgical procedure for removing obstructions to the free flow of aqueous humor into the canal of Schlemm of the eye.

Hemangioma: Another type of blood vessel malformation that can occur in the brain or liver (different from AVMs) and not connected to HHT.

Hematemesis: Vomiting blood.

Hematocrit: A measurement of blood. A normal reading would be 36% - 46%.

Hemiparesis: A paralysis of one side of the body usually caused by a stroke.

Hemiplegia: Paralysis of one side of the body. Hemiparesis is milder, where there is weakness (not paralysis) of one side of the body.

Hemoglobin: The substance in the blood that carries oxygen from the lungs out to various parts of the body. A normal hemoglobin count would be about 12-15.

Hemoptysis: Coughing up blood.

Hemorrhagic: Heavy bleeding.

Hereditary: Transmitted from generation to generation by the genes.

HomonymousHemianopsia: Visual impairment or blind spot of one half of one’s visual field, for example left half of each visual field in each eye (not one eye).

Hormone: Naturally occurring chemical substance formed by the body and carried to another area where it has a specific effect, i.e., estrogen. Hormones can also be manufactured and administered.

Hypoxemia: A condition in which the amount of oxygen in the blood is reduced.

Intracranial: Located within the skull (including the brain).

Intracranial Calcification: Calcium deposits in the brain.

Intractable Seizures: Seizures that cannot be controlled.

Ipsilateral: On the same side (as opposed to Contralateral).

Ischemia: Local and temporary deficiency of blood supply due to obstruction of the circulation to a part.



LASER photo coagulation: Use of a LASER such as the YAG or Argon to treat telangiectasia in HHT.

LASER therapy: The acronym LASER stands for Light Amplification by Stimulated Emission of Radiation. A very intense beam of light is focused on the affected area. Used to treat telangiectases of the skin, GI tract, and nose.

Lesion: An abnormality in an organ of the body. An AVM is a type of lesion. See AVM.

Lobectomy: Operation to remove one lobe of the brain. There are four lobes on each side of the brain (Frontal Lobe, Temporal Lobe, Parietal Lobe, and Occipital Lobe).

MRA: (Magnetic Resonance Angiography) An MRI technique designed to view the major arteries of the brain.

MRI: (Magnetic Resonance Imaging) A scan of the brain (or other organ) which does not use radiation, but uses magnetic energy to determine the presence of AVMs, aneurysms, stroke and brain abscess.

Melena: Black stool due to bleeding in the stomach or the duodenum. Dark stool may also be caused by oral iron therapy.

Migraine: A type of headache often characterized by a preliminary change in vision (aura) followed by severe headaches. They are particularly common in patients with HHT and lung AVM(s).

Morbidity: To have significant symptoms or complications from a disease or a treatment.

Mucous Membrane: Also called the mucosa. The lining of the body cavities that connects with the outside air. For example, the lining of the nose or mouth.

Mutation: A change in the code of a gene, which can cause a genetic disorder.

Neurologist: A doctor who specializes in the brain and spinal cord.

Neurosurgeon: A doctor who does surgery of the brain and spinal cord.

Occipital Lobe: The lobe at the most posterior (back) part of the brain. Deals with vision.

Occlude: To close a passage.

Occult Blood: Blood that is present in the stool, but not visible to the eye (usually because it is digested and no longer red).

Occupational Therapist: A professional specialist in development of fine motor skills.

Ophthalmologist: A doctor who specializes in diseases of the eye.

Otolaryngologist: A doctor who specializes in diseases of the ear, nose and throat. Sometimes called an ENT doctor.

Parietal Lobe: Just in front of the Occiptal Lobe. Deals with sensory functions.

PAVM: Direct connections between the arteries and veins in the lung.

PET scan: A scan that looks at function, rather than structure of an organ, including the brain.

Physical Therapist: A professional specialist in development of gross motor skills and physical activities.

Placebo: A substance or medicine given to the patient, which has no medical action but which may make the patient feel better, i.e., The Placebo Effect.

Port Wine Stain: Characteristic birthmark of SWS. Usually on the face, but can extend to other parts of the body, particularly the neck and trunk. A port wine stain by itself does not necessarily constitute SWS.

Prognosis: Predicted outcome.

Prophylactic: Preventative.

Pulmonary: Used to describe anything pertaining to the lungs.


Radiologist: A doctor who specializes in the use of X-rays or other body imaging techniques. A radiologist who specializes in image-guided therapy is called an interventional radiologist.

Radiosurgery: See stereotactic radiation therapy.

Screening: Tests performed to determine the presence of an abnormality before it causes a problem. Used most often in HHT to refer to detection of lung and brain AVMs. See MRI, ECHO BUBBLE, CAT scan.

Seizure: Spontaneous firing in the brain to cause detectable change in the body. Seizures can be convulsive (such as grand mal) or non-convulsive (such as absence).

Septal Dermoplasty: A skin graft performed inside the nose to prevent nosebleeds.

Septum: The wall of cartilage that divides the nose into two sides.

Shunt: The passage of blood directly from an artery to a vein. A short circuit.

SPECT: (Single Photon Emission Computed Tomography) noninvasive imaging techniques that depicts altered brain blood flow.

Stereotactic Radiation Therapy: A metal frame is placed around the skull and x-ray is used to try to shrink an AVM of the brain. Focusing the x-ray avoids injury to the surrounding normal brain.

Stroke: Occurs when part of the brain is suddenly deprived of its blood supply, causing a reduction in oxygen. This leads to weakness, numbness, and sometimes loss of consciousness that lasts longer than 24 hours. Stroke symptoms may occur in an HHT patient either due to a hemorrhage from a brain AVM or due to a clot from a lung AVM. See also TIA.

Systemic: Affecting the entire body (as opposed to focal or local, which means affecting only one area of the body).

Temporal Lobe: The lobes on either side of the brain, slightly above and in front of the ears. Deals with emotions, memory, language.

Thrombosis: Blood clot.

TIA: (Transient Ischemic Attack) A neurological event with stroke-like symptoms that last less than 24 hours. See stroke.

Telangiectasia/Telangiectases: From the Greek words, telos (end), angeion (vessel) and ektasis (extension). An abnormal connection between small arteries and veins. These can be seen on the skin as red or purple spots. Could be described as a small AVM. See AVM.

Trabeculotomy: A type of glaucoma surgery to lower the pressure in a glaucomatous eye.

Unilateral: On one side.

Vascular: Related to blood vessels.



YAG Laser/Nd:YAG Laser: Refers to a laser emitting a beam composed of Neodymium, Yttrium, Aluminum and Garnet. Used to treat telangiectases of the GI tract and nose.