Abstracts

Rationale: To determine how specific abnormal EEG findings found between 3 and 12 months correlate with clinical outcome on long term follow up Methods: This is a retrospective study of 358 infants who had at least one EEG in the first year of life and subsequent clinical assessment between ages 4 to 16 years. Clinical outcome parameters included epilepsy and neurologic outcome (intelligence, school performance, developmental milestones and neurological examination). Long term prognosis was classified into Normal when patients had normal clinical outcome parameters, Minor Sequelae when patients had mild abnormalities in clinical outcome parameters, Major Sequelae when patients had moderate to severe abnormalities in clinical outcome parameters, and Epilepsy when patients had seizures and were on medication Results: 66 had normal outcome, 39 had minor and 253 had major sequelae. 234 had epilepsy on follow up and 106 had not. 117/358 had major abnormal EEG background of which 90% had major sequelae and 75% had epilepsy. 98/358 had abnormal sleep potentials of which 91% had major sequelae and 80% had epilepsy. 175/358 had epileptiform discharges of which 85% had major sequelae and 80% had epilepsy. 60/358 had ictal epileptiform discharges of which 93% had major sequelae and 86.5% had epilepsy. 53/358 had hypsarrhythmia of which (90%) had major sequelae and 76.5% had epilepsy. 192/358 had moderate to severe abnormal overall EEG impression of which 85% had major sequelae and 79% had epilepsy Conclusions: Interictal epileptiform discharges, ictal epileptiform discharges and hypsarrhythmia in the first year were associated with major neurologic sequelae and with epilepsy. Abnormal EEG background and sleep potentials were associated with major neurologic sequelae but not definitely with epilepsy. 80 to 85% of children with a moderately to severely abnormal overall EEG impression in the first year were associated with major neurologic sequelae and/or epilepsy