Positron emission tomography (PET) was used to determine local cerebral metabolic rates for glucose in 44 infants with spasms at the Departments of Neurology and Pediatrics, Division of Nuclear Medicine and Biophysics and the Brain Research Institute, University of California, Los Angeles, School of Medicine, CA. Ictal events were detected in the EEG in 10 studies during PET. The most consistent abnormality on PET was the symmetrical increase of relative cerebral metabolic rate for glucose in the lenticular nuclei and was apparent in 32 of the 44 infants. This relative hypermetabolism of the lenticular nuclei occurred with both cryptogenic or symptomatic spasms, and was not characterized by any specific EEG abnormality. Every infant with focal abnormalities on CT and/or MRI also had a focal abnormality on PET in the same location, but 17 of 28 infants with focal abnormalities on PET had no detectable focal abnormalities on CT and/or MRI. 
COMMENT. The lenticular nuclei may contribute to the mechanism of infantile spasms. A cortical-subcortical interaction is proposed in the pathophysiology of infantile spasms. A Commission on Pediatric Epilepsy of the International League Against Epilepsy, following a workshop on infantile spasms, has proposed that the term infantile spasms is too restrictive and the term “spasms” is preferable to designate a special type of epileptic seizure that involves the axial musculature-in flexion, extension or mixed- and that often occurs in clusters. They propose that this type of seizure should be listed in the International Classification of Epileptic Syndromes (Commission 1981) and not be confined to the International Classification of Epileptic Syndromes (Commission 1989).