EEG and evoked potentials in a series of 21 patients with lissencephaly type I

Twenty-one Dutch patients were the subject of an extensive study into lissencephaly type I. One hundred and fourteen EEG's of these patients were studied. The EEG's were compared to 52 EEG's recorded from 21 patients with an atypical cortical dysplasia and to a control group consisting of 882 EEG's recorded from 823 patients for various reasons. The EEG's in the lissencephaly patients showed the following patterns significantly more often: (a) generalized fast activity (8-18/s) with an amplitude higher than 50 microV, (c) sharp- and slow-wave complexes with an amplitude higher than 500 microV, (d) an alternating pattern consisting of bursts of sharp waves alternating with periods of electrocerebral depression. Ninety-five percent of the lissencephaly patients showed pattern (a) or (c) or both compared to only 5% of the patients with an atypical cortical dysplasia and 0.4% in the controls. The SSEP's recorded in ten patients after stimulation of the median nerve were abnormal in all. EEG and evoked potentials appear to be valuable examinations in the (differential) diagnosis of lissencephaly type I.