The identification of focal cortical dysgenesis by positron emission tomography (PET) in 5 of 13 children with cryptogenic infantile spasms is reported from the Departments of Neurology and Pediatrics and Division of Neurosurgery, UCLA School of Medicine, Los Angeles, CA. There was unilateral hypometabolism of cerebral glucose involving the parieto-occipito-temporal region. Neuropathological examination of resected tissue in four infants showed microscopic cortical dysplasia. The CT was normal in all infants and the MRI showed a subtle abnormality only in one. The EEG showed hypsarrhythmia and at times, a localized abnormality corresponding to areas of PET hypometabolism. PET may identify unsuspected focal cortical dysplasia in infants with cryptogenic spasms and resective surgery offers improved prognosis. 
COMMENT. Early studies showed that infantile spasms were cryptogenic in about 40% of patients  whereas more recent studies have demonstrated that this figure has diminished to 9-14%. The PET studies have uncovered further symptomatic cases previously not identified by CT and MRI. The same authors report lenticular nuclei hypermetabolism in 12 of 25 infants with spasms of cryptogenic or symptomatic types. They suggest that the lenticular nuclei may contribute to the pathogenesis of infantile spasms.