Lissencephaly syndromes: clinical aspects.

We report clinical and neurophysiological findings in six children (three female, three male) with type I lissencephaly and three children (all female) with type II lissencephaly (Walker-Warburg syndrome). In type I lissencephaly the diagnosis is based only on electroencephalographic (EEG) signs, whereas in type II lissencephaly the diagnosis rests on clinical signs. In type I lissencephaly the EEG typically shows high alpha-beta activity, which is not seen in type II lissencephaly.