Lissencephaly

What is lissencephaly?

Lissencephaly, which literally means “smooth brain,” is a rare brain malformation that is characterized by an absence or incomplete development of the ridges or convolutions of the outer region of the brain, causing the brain to appear unusually smooth. Lissencephaly can either occur as an isolated abnormality or in association with another underlying syndrome, including Miller-Dieker syndrome and Norman-Roberts syndrome.

What causes lissencephaly?

There may be various possible causes of lissencephaly if it does not occur as a complication of other conditions. Viral intrauterine infections or insufficient blood flow to the brain during fetal development could be to blame, but there are also genetic factors that have been implicated in cases of isolated lissencephaly. Specifically, mutations of the LIS1 gene, the XLIS gene, or the TUBA1A gene have all been identified as potential genetic causes for this disorder, as have alterations or deletions of a specific region on chromosome 17. These are of autosomal recessive or X-linked inheritance.

What are the symptoms of lissencephaly?

Infants with classic lissencephaly have a smaller-than-usual head circumference. The unusual smoothness of the brain also can cause seizures, severe or profound intellectual disability, feeding difficulties, failure to thrive, growth retardation, and impaired motor abilities. In addition to these, lissencephaly can also cause subtle facial changes, such as a relatively small jaw or slight indentation of the temples. If lissencephaly has occurred as a complication of a different underlying syndrome, additional complications will also occur, depending on the nature of the particular syndrome.

How is lissencephaly diagnosed?

In some cases of lissencephaly, the condition can be detected before birth using an amniocentesis or chorionic villus sampling (CVS). After birth, lissencephaly can be diagnosed or confirmed based on a thorough clinical evaluation and a variety of brain imaging studies, including the following:

• MRI scans and/or CT scans
• Electroencephalography (EEG)
• Chromosomal/DNA analysis

What are the available treatments for lissencephaly?

There is no cure currently available for lissencephaly, so treatment of the condition is symptomatic and supportive. Improving the intake of nutrients for children with feeding difficulties is vital, as is the administration of anticonvulsant drugs to help prevent, reduce, or control seizures. General therapies, whether speech, physical, or occupational, can also help manage other complications of lissencephaly.

Where can I find more information on lissencephaly?

• National Organization for Rare Disorders (NORD)
• NIH
• Healthline