Polymicrogyria
Polymicrogyria is a developmental malformation of the human brain characterized by an excessive number of small folds (gyri) on the surface of the brain. Either the whole surface or parts of the surface can be affected. Children suffer from a wide spectrum of issues from mild to severe
mental retardation, speech and swallowing problems and
seizures. Polymicrogyria is sometimes seen as part of a syndrome.
Causes are genetic, viral or due to lack of nutrition during gestation. With increased use of
imaging techniques polymicrogyria is becoming more widely diagnosed. Poor brain images or inadequate experience in interpreting images can lead to misdiagnosis as
Lissencephaly.
Polymicrogyria is a disorder of neuronal migration resulting in structurally abnormal cerebral hemispheres. The name Polymicrogyria broken down describes its characteristics "many small folds in the surface of the brain". It is also characterized by shallow sulci, a slightly thicker cortex, neuronal heterotopia and enlarged ventricles. When many of these small folds are packed tightly together, PMG may resemble
pachygyria (a few "thick folds" - a mild form of lissencephaly) in parts of the brain.
The difference between PMG and pachygyria/lissencephaly can be difficult to see on an MRI or CT scan, even for an experienced radiologist. The diagnosis of PMG is merely descriptive and is not a disease in itself nor does it describe the underlying etiology or cause of the brain malformation
Most children with Polymicrogyria, but not all, have some degree of global
developmental disabilities or delays, seizures, feeding difficulties, respiratory problems, motor dysfunction and mental retardation. It is difficult to make a predictable prognosis for children with the diagnosis of PMG because each child is unique in their presentation of this disorder.
Polymicrogyria, bilateral frontoparietal (genetic lesion)
