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A type of brain malformation


Updated May 13, 2014

The normal brain

The normal brain has many ridges and valleys

Photo © A.D.A.M.
The word lissencephaly comes from two Greek words: lissos, meaning "smooth," and enkaphalos, meaning "brain." If you look at a normal brain, the gray matter (cerebrum) has ridges and valleys in its surface. In lissencephaly, the brain surface is almost completely smooth. The physical structure of the brain did not develop correctly during pregnancy.


Researchers believe that there are several possible causes of lissencephaly. It may be caused by injury to the fetus during its development, such as from a viral infection or insufficient blood flow to the brain. Another cause may be a genetic mutation. Researchers have identified two genes associated with lissencephaly. One is on chromosome 17, named LIS1. The other is on the X chromosome, named XLIS or Doublecortin. Whether lissencephaly can be inherited is not yet clear.


Like other disorders, lissencephaly can occur in varying degrees. Generally, though, the child will have:
  • mental retardation
  • seizure disorder
  • difficulty swallowing and eating
  • difficulty controlling his/her muscles (ataxia)
  • stiffness or spasticity of arms and legs
  • slowed growth and developmental delays
  • a smaller than normal head (microcephaly)


It may not be apparent at birth that a child has lissencephaly, because outwardly the child may appear healthy and normal. Around ages 2 to 6 months, though, the parents will notice that the child is not developing normally. Seizures may start to occur, including a severe type called "infantile spasms." It may be difficult to get the seizures under control.

If lissencephaly is suspected based on the child's symptoms, magnetic resonance imaging (MRI) or computed tomography (CT scan) can look at the brain and confirm the diagnosis.


There is no way to reverse the effects of lissencephaly; however, some of the problems children with lissencephaly can develop, such as muscle contractures or pneumonia, may be prevented through good medical care and physical and occupational therapy. Each child can be assisted to reach his/her potential level of development.

Clinical trial needs participants

Children with lissencephaly are being sought for the Human Epilepsy Genetics--Neuronal Migration Disorders Study. The website states, "The purpose of this study is to identify genes responsible for epilepsy and disorders of human cognition." ClinicalTrials.gov has more information about the study.


"Lissencephaly." Index of Rare Diseases. 2002. National Organization for Rare Disorders. 24 Dec 2008

"NINDS Lissencephaly Information Page." Disorders A-Z. 29 Oct 2008. National Institute of Neurological Disorders and Stroke. 24 Dec 2008

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