berry aneurysm

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a sac formed by the localized dilatation of the wall of an artery, a vein, or the heart.
 Classification of aneurysms. All three tunica layers are involved in true aneurysms (fusiform and saccular). In false aneurysms, blood escapes between tunica layers and they separate. If the separation continues, a clot may form, resulting in a dissecting aneurysm. From Copstead and Banasik, 2000.
adj., adj aneurys´mal. The chief signs of an arterial aneurysm are the formation of a pulsating tumor, and often a bruit (aneurysmal bruit) heard over the swelling. Sometimes there are symptoms from pressure on contiguous parts.

The most common site for an arterial aneurysm is the abdominal aorta. A true aneurysm results from formation of a sac by the arterial wall with at least one unbroken layer. It is most often associated with atherosclerosis. A false aneurysm usually is caused by trauma. In this case, the wall of the blood vessel is ruptured and blood escapes into surrounding tissues and forms a clot. Because of pressure within the clot arising from the heart's contractions, the clot often pulsates against the examiner's hand as does a true aneurysm.

Although atherosclerosis is responsible for most arterial aneurysms, any injury to the middle or muscular layer of the arterial wall (tunica media) can predispose the vessel to stretching of the inner and outer layers of the artery and the formation of a sac. Other diseases that can lead to an aneurysm include syphilis, cystic medionecrosis, certain nonspecific inflammations, and congenital defects in the artery.

It is possible for a person to be unaware of a small aneurysm for years. About 80 per cent of all abdominal aneurysms are palpable and may be noticed on a routine physical examination. One should be particularly alert to the possibility of an aneurysm in persons with a history of cardiovascular disease, hypertension, or peripheral vascular disease.

Aneurysms tend to increase in size, presenting a problem of increasing pressure against adjacent tissues and organs and a danger of rupture. When an aneurysm ruptures, a critical situation ensues. The patient with a ruptured aortic aneurysm exhibits severe pain and blood loss, leading to shock. A ruptured cerebral aneurysm produces neurologic symptoms and can resemble the clinical picture of stroke syndrome.

Treatment of aneurysm depends on the vessel involved, size of the aneurysm, and general health status of the patient.
arteriosclerotic aneurysm an aneurysm arising in a large artery, most commonly the abdominal aorta, as a result of weakening of the wall in severe atherosclerosis; called also atherosclerotic aneurysm.
arteriovenous aneurysm an abnormal communication between an artery and a vein in which the blood flows directly into a neighboring vein or is carried into the vein by a connecting sac.
atherosclerotic aneurysm arteriosclerotic aneurysm.
bacterial aneurysm an infected aneurysm caused by bacteria.
berry aneurysm (brain aneurysm) a small saccular aneurysm of a cerebral artery, usually at the junction of vessels in the circle of Willis; such aneurysms frequently rupture, causing subarachnoid hemorrhage. Called also cerebral aneurysm.
cardiac aneurysm thinning and dilatation of a portion of the wall of the left ventricle, usually a consequence of myocardial infarction.
cerebral aneurysm berry aneurysm.
cirsoid aneurysm dilatation and tortuous lengthening of part of an artery; called also racemose aneurysm.
compound aneurysm one in which some of the layers of the wall of the vessel are ruptured and some merely dilated; called also mixed aneurysm.
dissecting aneurysm one resulting from hemorrhage that causes lengthwise splitting of the arterial wall, producing a tear in the inner wall (intima) and establishing communication with the lumen of the vessel. It usually affects the thoracic aorta (see aortic dissection) but can also occur in other large arteries. See illustration.
false aneurysm
one in which the entire wall is injured and the blood is contained by the surrounding tissues, with eventual formation of a sac communicating with the artery (or heart). See illustration.
fusiform aneurysm a spindle-shaped aneurysm; see illustration.
infected aneurysm one produced by growth of microorganisms (bacteria or fungi) in the vessel wall, or infection arising within a preexisting arteriosclerotic aneurysm.
mixed aneurysm compound aneurysm.
mycotic aneurysm an infected aneurysm caused by fungi.
racemose aneurysm cirsoid aneurysm.
saccular aneurysm (sacculated aneurysm) a saclike aneurysm; see illustration.
spurious aneurysm
false aneurysm (def. 1).
varicose aneurysm one formed by rupture of an aneurysm into a vein.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

ber·ry an·eu·rysm

a small saccular aneurysm of a cerebral artery that resembles the fruit; can rupture causing a subarachnoid hemorrhage.
Farlex Partner Medical Dictionary © Farlex 2012

berry aneurysm

A 0.2–0.5 cm saccular dilatation of arteries at the base of the brain, at or near the circle of Willis (95%) of BAs or at the vertebrobasilar arteries­ (5%), due to a developmental or congenital weakness in the medial muscle layer of the cerebral arteries. 30% of berry aneurysms are multiple, located at bifurcations, often anterior and appear in 1–2% of all autopsies; most berry aneurysms rupture at > 1 cm in diameter.

Risk of rupture
Linked to increased blood pressure (BP), which may be secondary to stress, due to acutely increased systemic BP—e.g., sexual intercourse, athletic competition.

Aortic coarctation, polycystic renal disease, collagen disorders (e.g., Ehlers-Danlos and Marfan syndromes), AV malformation and fibromuscular dysplasia.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

berry aneurysm

Neurology A 0.2-0.5 cm saccular dilation of arteries at the base of the brain, at or near the circle of Willis–95% of BAs or at the vertebrobasilar arteries–5%, due to a developmental or congenital weakness in the medial muscle layer of the cerebral arteries; 30% of BAs are multiple, located at bifurcations, often anterior and appear in 1-2% of all autopsies; most BAs rupture at > 1 cm in diameter. See Circle of Willis.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

ber·ry an·eu·rysm

(ber'ē an'yūr-izm)
Asmall saccular aneurysm of a cerebral artery that resembles a berry. Such aneurysms frequently rupture, causing subarachnoid hemorrhage.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

berry aneurysm

A berry-like swelling at the branching point of an artery under the brain, especially on the Circle of Willis, due to a congenital weakness, the rupture of which causes an often-fatal subarachnoid haemorrhage. Identified aneurysms may be treated by observation, surgical clipping or endovascular occlusion by detachable coils. Coiling appears to be safer in the case of ruptured aneurysms. (Sir James Berry, 1860–1946, Canadian surgeon).
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
Endovascular treatment has been confirmed as the treatment of choice for intracranial berry aneurysms. (1) While initial doubts on the part of microvascular neurosurgeons were addressed by the International Subarachnoid Aneurysm trials, the durability and long-term efficacy of coiled aneurysms have been questioned.
Histologically, there is degeneration of the internal elastic lamina and medial aplasia, as in intracranial berry aneurysms. (1,2) The carotidotympanic artery, a vestige of the embryonic hyoid artery, is a small branch that arises near the genu of the petrous ICA and passes superiorly through the stapes to supply the middle ear cavity.

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