Researchers at Children’s Hospitals in Milan, Italy, determined the prognostic value of electroencephalographic patterns in 23 newborns with severe perinatal hypoxic-ischemic encephalopathy, treated with hypothermia. EEG monitoring was obtained within 48 hours after birth, and at follow-up at ages 1 week, 1 month, 3-6 months, and 1 year. EEG background activity was classified as follows: 1) inactive pattern; 2) severe low-voltage continuous pattern; 3) trace alternant-like, discontinuous pattern; and 4) monomorphic middle-voltage, continuous 30-100mcV activity, with poor spatial and sleep-state organization. Pattern 1 (inactive) in the first 48 hrs was associated with death or severe neurologic sequelae. Pattern 2 (low-voltage continuous) at age 1 week indicated a poor prognosis, and the persistence of EEG abnormalities in 67% patients at age 1 month was associated with a higher risk of neurologic sequelae. A normal EEG at age 1 month was associated with a favorable outcome at age 1 year. After 1 month of age, the EEG is less sensitive but more specific in prediction of outcome, due to the natural trend toward normalization with age. At age 1 year, 52% infants had normal neurologic examinations, 13% had minor sequelae, and 17% major sequelae; 17% had died within 1 month of age. 
COMMENT. These results confirm previous findings that background EEG abnormalities detected in newborns soon after hypoxic-ischemic encephalopathy are predictive of outcome, even in patients treated with hypothermia.