Seventeen term and near-term infants with hypoxic ischemic encephalopathy (HIE) were studied at Okazaki City Hospital and other centers in Japan to clarify the relationship between prolonged depression of the EEG and later development of West syndrome (WS). Group A, 4 patients with prolonged EEG depression over 21 days, and Group B, 13 with disappearance of EEG depression by 21 days of age, are compared. WS developed in all 4 infants in Group A, but only 1 of 13 in Group B. Abnormal irregular faster waves (irregular spiky beta or sharp theta) in 11 infants from both groups between 2 and 28 days of age were related to an adverse developmental outcome but not to West syndrome. Prolonged depression of EEG over 21 days of age in term infants with HIE is a predictor of later development of WS (sensitivity 0.80, specificity 1.0, pos predictive value of 1.0, neg predictive value 0.92). In comparison, MRI lesions in basal ganglia, thalamus, and white matter had a sensitivity of 0.80, specificity 0.92, pos predictive value of 0.80, and negative predictive value of 0.92. 
COMMENT. Watanabe and colleagues (1987, 2001) previously reported neonatal EEG abnormalities that preceded WS, but the predictive value of EEG depression was not established. The abnormal irregular faster waves, not significantly related to the later development of WS, were not precursors of hypsarrhythmia. Given the importance of early treatment of infantile spasms with ACTH for optimal benefit, the definition of a reliable pre-hypsarrhythmia pattern in the EEG of infants at risk of developing West syndrome should lead to more effective therapy and improved prognosis.
STXBP1 mutations account for one-third of cases of early infantile encephalopathy with suppression-burst pattern (Ohtahara syndrome) . Also, STXBP1 mutation should be considered as a possible cause of symptomatic West syndrome without known cause.