This ongoing study examines abnormalities of cerebral perfusion in a consecutive series of children with infantile spasms and correlates cerebral blood flow (CBF) abnormalities with electroencephalographic (EEG), neuroimaging, and pathologic findings. A consecutive series of children with infantile spasms, diagnosed by standard clinical and EEG criteria, had cerebral perfusion studies using 99Tc-HmPAO single photon emission computed tomography (SPECT), together with neuroimaging studies using computed tomography (CT) and/or magnetic resonance imaging (MRI), interpreted independently and correlated with surgical pathologic findings. Twenty children aged 2-13 months (mean 9.3 months) were studied over a 4-year period; 60% had symptomatic infantile spasms due to cerebral dysgenesis (33%), other congenital lesions (25%), tuberous sclerosis (17%), or other causes (25%), and the remaining patients were cryptogenic (40%). CBF abnormalities were present in 85%: multifocal decrease (40%), focal increase (25%), diffuse decrease (15%), and focal increase (10%), while the remaining 15% had normal cerebral blood flow. Focal cortical lesions may lead to infantile spasms, even in cryptogenic patients diagnosed by functional neuroimaging such as 99Tc-HmPAO SPECT. In selected patients, surgical excision of the cortical lesions leads to improved seizure control and possibly outcome. The localization and surgical excision of focal cortical lesions in infantile spasms required further investigation with functional and structural neuroimaging, EEG, and intraoperative electrocorticography.