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Arteriovenous malformation

 

 
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Arteriovenous malformation
 
 
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Arteriovenous malformation or AVM in the majority of cases is a congenital disorder
Congenital disorder

Congenital disorder involves defects in or damage to a developing fetus. It may be the result of Genetics abnormalities, the intrauterine environment, errors of morphogenesis, or a chromosomal abnormality....
 consisting of a connection between veins and arteries, this pathology is universally known because of its occurrence in the central nervous system, but can appear in any location.

The genetic transmission patterns of AVM, if any, are unknown. AVM is not generally thought to be an inherited disorder, unless in the context of a specific hereditary syndrome
Syndrome

In medicine and psychology, the term syndrome refers to the association of several clinically recognizable features, sign , symptoms , phenomena or characteristics that often occur together, so that the presence of one feature alerts the physician to the presence of the others....
.

toms of AVM vary according to the location of the malformation.






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Arteriovenous malformation or AVM in the majority of cases is a congenital disorder
Congenital disorder

Congenital disorder involves defects in or damage to a developing fetus. It may be the result of Genetics abnormalities, the intrauterine environment, errors of morphogenesis, or a chromosomal abnormality....
 consisting of a connection between veins and arteries, this pathology is universally known because of its occurrence in the central nervous system, but can appear in any location.

The genetic transmission patterns of AVM, if any, are unknown. AVM is not generally thought to be an inherited disorder, unless in the context of a specific hereditary syndrome
Syndrome

In medicine and psychology, the term syndrome refers to the association of several clinically recognizable features, sign , symptoms , phenomena or characteristics that often occur together, so that the presence of one feature alerts the physician to the presence of the others....
.

Signs and symptoms

Symptoms of AVM vary according to the location of the malformation. Roughly 88% AVM are asymptomatic; often the malformation is discovered as part of an autopsy
Autopsy

An autopsy, also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction, is a medical procedure that consists of a thorough examination of a Dead body to determine the cause and manner of death and to evaluate any disease or injury that may be present....
 or during treatment of an unrelated disorder (called in medicine an incidental finding), rarely its expansion or a micro-bleed from it, could cause epilepsy, deficit or elicit pain.

The most general symptoms include headache
Headache

In medicine a headache or wiktionary:cephalalgia is a symptom of a number of different conditions of the head and sometimes neck. Some of the causes are benign while others are medical emergencies....
 and epilepsy
Epilepsy

Epilepsy is a common chronic neurological disorder characterized by recurrent unprovoked seizure s. These seizures are transient signs and/or symptoms of abnormal, excessive or synchronous neuronal activity in the brain....
, with more specific symptoms occurring that normally depend on the location of the malformation and the individual. Other possible symptoms include:

  • Difficulties with movement or coordination, including muscle weakness
    Muscle weakness

    Muscle weakness is a direct term for the inability to exert force with one's muscles to the degree that would be expected given the individual's general physical fitness....
     and even paralysis
    Paralysis

    Paralysis is the complete loss of muscle function for one or more muscle groups. Paralysis can cause loss of feeling or loss of mobility in the affected area....
    ;
  • vertigo
    Vertigo (medical)

    Vertigo is a specific type of dizziness, a major symptom of a balance disorder. It is the sensation of spinning or swaying while the body is actually stationary with respect to the surroundings....
     (dizziness);
  • Difficulties of speech (dysarthria
    Dysarthria

    Dysarthria is a motor speech disorder resulting from Brain damage, characterised by poor articulation . Any of the speech subsystems can be affected....
    ) and communication, such as alogia
    Alogia

    In psychology, alogia , or poverty of speech, is a general lack of additional, unprompted content seen in normal Interpersonal communication....
    ;
  • Difficulties with everyday activities, such as apraxia
    Apraxia

    Apraxia is a neurological disorder characterized by loss of the ability to execute or carry out learned purposeful movements, despite having the desire and the physical ability to perform the movements....
    ;
  • Abnormal sensations (numbness, tingling, or spontaneous pain
    Pain

    Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm....
    );
  • Memory and thought-related problems, such as confusion
    ConFusion

    ConFusion is an annual science fiction convention organized by the Stilyagi Air Corps and its parent organization, the Ann Arbor Science Fiction Association....
    , dementia
    Dementia

    Dementia is the progressive decline in cognition due to damage or disease in the body beyond what might be expected from normal aging. Although dementia is far more common in the geriatric population, it may occur in any stage of adulthood....
     or hallucination
    Hallucination

    A hallucination, in the broadest sense, is a perception in the absence of a stimulus . In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid, substantial, and located in external objective space....
    s.

Pathophysiology

Arteries and veins are part of the human cardiovascular system
Circulatory system

The circulatory system is an organ that moves nutrients, gases, and wastes to and from cells to help fight diseases and help stabilize body temperature and pH to maintain homeostasis....
. Normally, the arteries in the vascular system carry oxygen-rich blood. Structurally, arteries divide and sub-divide repeatedly, eventually forming a sponge-like capillary bed. Blood moves through the capillaries, giving up oxygen and taking up waste products from the surrounding cells (CO2). Capillaries successively join together, one upon the other, to form veins that carry blood away. The heart acts to pump blood through arteries and uptake the venous blood.

If the capillary bed is thought of as a sponge, then an AVM is the rough equivalent of jamming a tangle of flexible soda straws
Drinking straw

A drinking straw is a short tube used for transferring a liquid - usually a drink from one location to another . The earliest drinking straws were hollow stems of grass, literally made of straw....
 from artery to vein through that sponge. On arteriogram films AVM formation often resemble a tangle of spaghetti
Spaghetti

Spaghetti is a long, thin, cylindrical pasta of Italy origin. A variety of pasta dishes are based on it, from spaghetti with cheese and pepper or garlic and oil to a spaghetti with tomato, meat, and other sauces....
 noodles. This tangle of blood vessels forms a relatively direct connection between high pressure arteries and low pressure veins.

The result is a collection of blood vessels with abnormal connections and no capillaries
Capillary

Capillaries are the smallest of a body's blood vessels, measuring 5-10 micrometre in diameter, which connect arterioles and venules, and enable the interchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissue s....
. This collection, often called a nidus, can be extremely fragile and prone to bleeding.

Diagnosis

AVMs can occur in various parts of the body

  • brain
    Human brain

    The human brain is the center of the human nervous system and is a highly complex organ. It has the same general structure as the brains of other mammals, but is over five times as large as the "average brain" of a mammal with the same body size....
    , causing a cerebral arteriovenous malformation
    Cerebral arteriovenous malformation

    Cerebral arteriovenous malformation is a malformed collection of blood vessels within the human brain, characterized by tangle of veins and artery....
  • spleen
    Spleen

    The spleen is an organ found in all vertebrate animals. In humans, the spleen is located in the abdomen of the body, where it functions in the destruction of redundant red blood cells, and holds a reservoir of blood....
  • lung
    Lung

    The lung is the essential respiration organ in air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located in the chest on either side of the heart....
  • kidney
    Kidney

    The kidneys are Organ that have numerous biological roles. Their primary role is to maintain the homeostasis balance of bodily fluids by filtering and secreting Metabolomics#Metabolitess and minerals from the blood and excreting them, along with water , as urine....
  • spinal cord
    Spinal cord

    The spinal cord is a long, thin, tubular bundle of neuron and glia that extends from the brain. The brain and spinal cord together make up the central nervous system....
  • liver
    Liver

    The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
  • intercostal space
    Intercostal space

    The intercostal space is the space between two ribs . Since there are 12 ribs on each side, there are 11 intercostal spaces....
  • iris
    Iris (anatomy)

    The iris is a membrane in the eye, responsible for controlling the amount of light reaching the retina. The iris consists of pigmented fibrovascular tissue known as a stroma of iris....
  • spermatic cord
    Spermatic cord

    The spermatic cord is the name given to the cord-like structure in males formed by the vas deferens and surrounding tissue that run from the abdomen down to each testicle....


AVMs may occur in isolation or as a part of another disease (e.g. Von Hippel-Lindau disease
Von Hippel-Lindau disease

Von Hippel-Lindau disease is a rare disease, autosomal dominant genetic condition in which hemangioblastomas are found in the cerebellum, spinal cord and retina....
 or hereditary hemorrhagic telangiectasia
Hereditary hemorrhagic telangiectasia

In medicine, hereditary hemorrhagic telangiectasia , also known as William Osler-Frederick Parkes Weber-Rendu syndrome, is an autosomal dominant genetic disorder that leads to blood vessel malformations....
).

This bleeding can be devastating, particularly in the brain. It can cause severe and often fatal stroke
Stroke

A stroke is the rapidly developing loss of brain function due to a disturbance in the blood supply to the brain. According to the National Stroke Association, a "stroke" occurs when a blood clot blocks and artery or a blood vessel breaks, interrupting blood flow to an area of the brain....
s. If detected before a stroke occurs, usually the arteries feeding blood into the nidus can be closed off, ensuring the safety of the patient.

Treatment

Treatment can be symptomatic, or it can involve surgery or radiation therapy. It can also be carried out via in interventinal radiography procedure using a glue
Glue

This is a list of various types of adhesive. Historically, the term "glue" only referred to protein colloids prepared from animal flesh. The meaning has been extended to refer to any fluid adhesive....
 to cut off the blood supply to the AVM.

Epidemiology

An estimated 300,000 Americans
United States

The United States of America is a Federal government constitutional republic comprising U.S. state and a federal district. The country is situated mostly in central North America, where its Contiguous United States and Washington, D.C., the Capital districts and territories, lie between the Pacific Ocean and Atlantic Oceans, Borders of the U...
 have AVMs, of which 12% (approximately 36,000) will exhibit symptoms that differ greatly in severity.

Society and culture

  • On December 13, 2006, Senator
    United States Senate

    The United States Senate is the upper house of the Bicameralism United States Congress, the lower house being the United States House of Representatives....
     Tim Johnson was diagnosed with AVM and treated at George Washington University
    George Washington University

    The George Washington University is a Private university, Mixed-sex education university located in Washington, D.C. The school was chartered on February 9, 1821 as The Columbian College in the District of Columbia by an Act of Congress and since that time has developed into a nonsectarian research institution....
     Hospital.


Cases in fiction

  • The plot of William Finn's
    William Finn

    William Alan Finn is an award-winning United States composer and lyricist, especially of musical theater....
     1998 Off-Broadway musical, A New Brain
    A New Brain

    A New Brain is a musical theater with music and lyrics by William Finn and book by Finn and James Lapine.The musical was first produced Off-Broadway at the Mitzi E....
    , revolves around the main character's battle with AVM.
  • The character Nate Fisher
    Nate Fisher

    Nate Fisher is a fictional character on the HBO television series Six Feet Under played by Peter Krause....
     on the HBO television show Six Feet Under suffers from AVM.
  • Patients with AVM appeared in an episode of the series House
    House (TV series)

    House, also known as House, M.D., is an American medical drama that debuted on the Fox Broadcasting Company network on November 16, 2004....
     entitled DNR, as well as in a fictional British medical show called Harley Street
    Harley Street (TV series)

    Harley Street was a 2008 Television in the United Kingdom medical drama shown on ITV.The series was made by Carnival Films and was set in Harley Street, London....
    .
  • The main character in Robert J. Sawyer
    Robert J. Sawyer

    Robert James Sawyer is a Canada science fiction writer, born in Ottawa in 1960 and now resident in Mississauga. He has published 18 novels, and his short fiction has appeared in Analog Science Fiction and Fact, Amazing Stories, On Spec, Nature, and numerous anthologies....
    's book Mindscan suffers from an AVM that is at risk of reducing him to a permanent vegetative state.


Research directions

Despite many years of research, the central question of whether to treat AVMs has not been answered. All treatments, whether involving surgery or drugs, have risks and side-effects. Therefore it might be better in some cases to avoid treatment altogether and simply accept a small risk of coming to harm from the AVM itself. This question is currently being addressed in clinical trials.

External links

  • from the DMOZ Open Directory.