Posted by CCF Neurology MD on October 16, 1997 at 16:22:51:

In Reply to: megalencephaly question posted by Janet on September 24, 1997 at 13:32:33:

: Hi,

I would like to know if any research has been done to find out what causes this. Also, does this cause developmental delays?

Thanks
Janet
Dear Janet, Megalencephaly results from an excessive amount of normal brain components, from an increase in individual cell types (most commonly the support cells also known as glial cells, or from an increase storage of metabolites. The brain may increase in size so that its weight may actually double. In a number of children with Megalencephaly they are of normal intelligence, otherwise of normal development, predominately male and with at least 39% of a family history of enlarged head, most commonly in the child's father family (in one study). In such families, transmission of the condition is most likely to be as an autosomal dominant trait (that is a child of a father with an enlarged head has a 50% chance of also having an enlarged head). However, other children who have megalencephaly will also have mental retardation, seizures, coordination problems and decrease muscle tone. These children will often have also an abnormal development of the skin. This disorder can present as a seperate disease or syndrome while other times it may be a component of another syndrome (e.g. neurofibramatosis I or von Recklinghausen Disease). This variation of megalencephaly can also be inherited as an autosomal dominant disorder. If you wish your child (I assume this is what the question is in relation to) to be evaluated for reassurance purposes, I would recommend you make an appointment at the CCF Department of Pediatric Neurology or a pediatric neurologists recommended by your family pediatrician. "This information is provided for general medical education purpose only. Please consult your physician for diagnostic and treatment options of your specific medical condition."