Serial PET scans and MRIs were performed in 18 infants with West syndrome (WS) to determine the relation between cortical hypometabolism and delayed myelination in a study at Nagoya University School of Medicine, Japan. All 8 patients with symptomatic WS showed hypometabolism at onset, with persistence in 5 at 10 months, whereas only 4 of 10 patients with cryptogenic WS showed hypometabolism at onset and none at age 10 months. Localization of EEG abnormalities at 10 months correlated with the region of hypometabolism in only 2. MRI showed delayed myelination in 2 at onset of epilepsy and in 12 at 10 months. Delayed myelination at 10 months was correlated with hypometabolism. 
COMMENT. MRIs repeated at age 10 months may disclose delayed myelination in infants with WS. The delayed myelination is not always explained by ACTH therapy and may reflect the organic brain lesion causing the seizures.