Lissencephaly means “smooth brain.” The normal folds are missing or very shallow, so the surface looks almost flat. This rare change is usually spotted before birth or soon after delivery.

Head size may be smaller than expected at birth, but some babies start with a normal head that grows slowly, slipping down the growth chart by three to six months.

Muscle tone is often low at first. Infants feel floppy when lifted, and feeding can be weak, leading to long, sleepy feeds and slow weight gain.

Seizures commonly start in the first weeks of life. They may look like brief eye rolls, repetitive jerks, or long staring spells that are easy to miss if you’re not watching closely.

Development is delayed. Rolling, sitting, and head control arrive late or never fully appear. Many children need support to sit and use a wheelchair later.

Swallowing and saliva control can be hard. Drooling is frequent, and small coughs during feeds may signal that liquids are heading the wrong way.

Vision and hearing are often reduced. Eyes may cross or wander, and loud hand-claps might not trigger a startle.

Facial features can look similar across children: small jaw, thin upper lip, and a slightly flat nose bridge, giving a “smooth” face to match the smooth brain.