What is lissencephaly?
A typical scan of a human’s brain will reveal
many complicated wrinkles, folds, and grooves. This is how the body packs a
large amount of brain tissue into a small space. The brain starts to fold
during fetal development.
But some babies develop a rare condition known
as lissencephaly. Their brains don’t fold properly and remain smooth. This
condition can affect a baby’s neural function and symptoms can be severe.
What are the symptoms of lissencephaly?
Babies born with lissencephaly may have an
abnormally small head, a condition known as microlissencephaly. But not all
babies with lissencephaly have this appearance. Other symptoms may include:
- difficulty feeding
- failure to thrive
- intellectual impairment
- malformed fingers, toes, or hands
- muscle spasms
- psychomotor impairment
- trouble swallowing
It’s possible to perform imaging scans on a
fetus as early as week 20 if one or both parents have a family history of
lissencephaly. But radiologists may wait until 23 weeks to perform any scans.
What causes lissencephaly?
Lissencephaly is often considered a genetic
condition, though sometimes a viral infection or poor blood flow to the fetus
may cause it. Scientists have identified
malformations in several genes as contributors to lissencephaly. But research
into these genes is ongoing. And mutations in these genes cause varying levels
of the disorder.
Lissencephaly develops when a fetus is 12 to
14 weeks old. During this time nerve cells begin to move to other areas of the
brain as it develops. But for fetuses with lissencephaly, the nerve cells don’t
The condition can occur on its own. But it’s
also associated with genetic conditions such as Miller-Dieker syndrome and
How is lissencephaly diagnosed?
If a baby experiences symptoms related to
incomplete brain development, a doctor may recommend an imaging scan to examine
the brain. This includes ultrasound, CT, or MRI scans. If lissencephaly is the
cause, a doctor will grade the disorder to the degree that the brain is
Brain smoothness is called agyria, and brain groove
thickening is called pachygyria. A grade 1 diagnosis means that a child has
generalized agyria, or that most of the brain is affected. This occurrence is
rare and results in the most severe symptoms and delays.
Most children affected have grade 3
lissencephaly. This results in thickening on the front and sides of the brain
and some agyria throughout the brain.
How is lissencephaly treated?
Lissencephaly can’t be reversed. Treatment
aims to support and comfort affected children. For example, children who have
difficulty feeding and swallowing may need a gastrostomy tube inserted into their
If a child experiences hydrocephalus, or an
excessive accumulation of cerebrospinal fluid, surgery that shunts fluid away
from the brain may be necessary.
A child may also need medications if they
experience seizures as a result of lissencephaly.
What is the outlook for someone with lissencephaly?
The outlook for a child with lissencephaly
depends on the condition’s severity. For example, severe cases may result in
the child failing to develop mentally beyond a three- to five-months old
Children with severe lissencephaly have a
life expectancy of about 10 years, according to the National Institute of Neurological Disorders and Stroke. Common causes of death include choking on foods or fluids (aspiration),
respiratory disease, or seizures. Children with mild lissencephaly can
experience near-normal development and brain function.