Arteriovenous malformation Health Dictionary

See DEFORMITIES.... malformation

The commonest deformity of the PALATE is cleft palate, which is a result of faulty embryonic development in which the two sides of the palate fail to fuse or only fuse in part. If the cleft extends the full length with bilateral clefts at the front of the MAXILLA, it may be accompanied by a cleft lip (also called hare-lip) and disruption in the development of the front teeth. About 1 in 500 babies is born with a cleft lip and 1 in 1,000 has a cleft palate. If the parents are affected, the risk is three times that of the normal population; if one child has a deformity, the risk for a subsequent child is higher. Associated abnormalities include tongue tie, malpositioning of the MANDIBLE and ?uid in the middle EAR.

Cleft palate and hare-lip should be recti?ed by operation, because both are a serious drawback to feeding in early life – while later, harelip is a great dis?gurement, and the voice may be affected. The lip may be dealt with at any time from the neonatal period to a few weeks, depending on the individual surgeon’s view of when the best result is likely to be achieved. Prior to operation, special techniques may be necessary to ensure adequate feeding such as the use of special teats in formula-fed babies. The closure of a large cleft in the palate is a more formidable operation and is better performed when the face has grown somewhat, perhaps at 6–12 months. The operations performed vary greatly in details, but all consist in paring the edges of the gap and drawing the soft parts together across it.

Further operations may be required over the years to improve the appearance of the nose and lip, to make sure that teeth are even, and to improve speech.

Parents of such children can obtain help and advice from the Cleft Lip and Palate Association (CLAPA).... palate, malformations of

An abnormal communication directly between an artery and a vein. An arteriovenous fistula may be present at birth or result from injury. A fistula can also be created surgically for easy access to the bloodstream in dialysis.... arteriovenous fistula

a congenital disorder in which there is distortion of the base of the skull with protrusion of the lower brainstem and parts of the cerebellum through the opening for the spinal cord at the base of the skull (see banana and lemon signs). It is associated commonly with *neural tube defects, *hydrocephalus, and a *syringomyelia. [J. Arnold (1835–1915) and H. Chiari (1851–1916), German pathologists]... arnold–chiari malformation

a thick-walled blood vessel that connects an arteriole directly with a venule, thus bypassing the capillaries. Arteriovenous anastomoses are commonly found in the skin of the lips, nose, ears, hands and feet; their muscular walls can constrict to reduce blood flow or dilate to allow blood through to these areas.... arteriovenous anastomosis

a direct communication between an artery and vein, without an intervening capillary bed. It can occur as a congenital abnormality or it may be acquired following injury or surgery. It may affect the limbs, lungs, or viscera and may be single or multiple. If the connection is large, the short-circuiting of blood may produce heart failure. Large isolated arteriovenous aneurysms may be closed surgically.... arteriovenous aneurysm