Definition

Dandy-Walker malformation is a congenital (present at birth) condition involving several abnormalities in the development of the brain. The malformation appears to result from destructive processes, such as inflammation or trauma, which block the circulation of cerebrospinal fluid (CSF) inside the head after the brain has been formed in the embryo.

Description

Dandy-Walker malformation was first described in 1914 by Drs. Dandy and Blackfan. The disorder typically includes the following abnormalities in brain structure:

Absence or incomplete formation of the vermis, the middle portion of the cerebellum, which is the part of the human brain that lies behind the two cerebral hemispheres.

Enlargement of the fourth ventricle, one of the human brain's four interconnected ventricles (inner cavities or chambers) that produce cerebrospinal fluid (CSF). In Dandy-Walker malformation, the CSF cannot circulate freely through the ventricles and the rest of the central nervous system (CNS), so it builds up inside the fourth ventricle and causes it to enlarge.

Cysts (sacs) containing CSF are formed in the posterior fossa, which is a hollow at the back of the skull that covers the cerebellum.

Absence or incomplete formation of the three foramina (small openings or holes) in the fourth ventricle.

In Dandy-Walker malformation, the CSF produced by the ventricles of the brain is not fully reabsorbed by the body; thus, the excess fluid accumulates in the fourth ventricle and the posterior fossa. As cysts in these areas grow, pressure from the fluid rises, producing a condition known as obstructive, or non-communicating, hydrocephalus (excess fluid on the brain). This type of hydrocephalus develops in 90% of children diagnosed with Dandy-Walker malformation. The size of the head may or may not be affected by pressure from the fluid.

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mesafoxx

Post edited by: mesafoxx, at: 02/24/2008 01:44

Post edited by: peetred, at: 02/24/2008 07:51