Neurophysiological and neuroradiological features preceding infantile spasms

Neonatal EEG, cerebral evoked potentials, CT scan findings and their evolution were investigated in 42 neonates who eventually developed the West syndrome. In infants with perinatal hypoxia, the EEG displayed most often marked or maximal depression in the first week of life. The highly abnormal initial EEG improved progressively with time. The most frequent findings in early infancy was discontinuous tracing and persistent alternating tracing at 1-2 months, and absent sigma rhythms at 3-4 months. The VEP, AEP and CT scan also showed findings suggesting severe degree of brain damage. In infants with meningitis, the initial EEG was less depressed but the EEG abnormality persisted or worsened. In infants with prenatal causes the neonatal EEG was variable, ranging from a normal background EEG to specific abnormalities. The evolution of paroxysmal abnormalities was similar in all groups. There were no epileptiform discharges in early months. The appearance of hypsarrhythmia was preceded by focal and then multifocal spike or sharp wave discharges.