SOMATOSENSORY-EVOKED POTENTIALS IN HEMIMEGALENCEPHALY AND LISSENCEPHALY - ANATOMO-FUNCTIONAL CORRELATIONS

Four patients with hemimegalencephaly and four with lissencephaly were studied by median nerve somatosensory evoked potentials. The peripher al conduction velocity and the conduction time between the brachial pl exus (Erb's point) and cervical cord were normal in both malformations . In hemimegalencephaly, the cortical components were absent on the ma lformed hemisphere but normal on the healthy side, whereas in lissence phaly an abnormal, prolonged N20 wave was recorded bilaterally. The di fference presumably relates to the absence of normal cortical laminati on in hemimegalencephaly and to the presence of a 'four-layered' corte x in lissencephaly.