Original articleThe perfusion defect seen with SPECT in West syndrome is not correlated with seizure prognosis or developmental outcome
Introduction
West syndrome is an age-dependent epileptic encephalopathy with multiple etiology and with diverse psychomotor outcome. It is classified as a generalized epileptic syndrome [1] because of the generalized EEG abnormalities and its bilateral clinical manifestations. There has been extensive work by many investigators about the pathophysiology of West syndrome, however it is still poorly understood [2], [3], [4], [5], [6]. Recent neuroimaging studies [7], [8], [9] indicate that cortical pathologic conditions play an important role in the pathophysiology of West syndrome. Based on the results of positron emission tomography (PET) studies, Chugani et al. proposed that the spasms result from interaction between focal or diffuse cortical abnormalities and subcortical structures [7].
Previous interictal single photon emission computed tomography (SPECT) studies of patients with West syndrome found focal or areal cortical hypoperfusion [10], [11], [12], [13] and, in a rare instance, focal cortical hyperperfusion [11]. We reported an ictal SPECT study of West syndrome, in which we found two clear patterns of ictal-hyperperfusion: cortical and subcortical [14]. Based on fluorodeoxyglucose (FDG)-PET studies, Chugani et al. reported that in addition to a focal cortical defect in the local cerebral rate of glucose metabolism, there was increased glucose metabolism in the brainstem and lenticular nuclei bilaterally in many of the patients studied [7]. Except for one report of normal perfusion in the basal ganglia, none of the previous interictal SPECT studies of West syndrome have mentioned any abnormality of the subcortical structures [11]. No SPECT studies have examined whether the cortical perfusion abnormality affects the seizure prognosis or developmental outcome. We evaluated the interictal SPECT findings of 40 infants with West syndrome, focusing on 26 cases who were followed for more than 2 years after the onset, to assess whether the cortical perfusion abnormality correlates with the prognosis of seizures or the developmental outcome.
Section snippets
Subjects
Forty infants (17 boys and 23 girls), diagnosed from typical tonic spasms and hypsarrhythmia as having West syndrome, took part in a SPECT study. The purpose of the study and the methods used were explained to the parents of each patient, and informed consent was obtained. All of the SPECT studies were performed on the initial admission to our hospital, when the patients had tonic spasms. The interval between the onset of spasms and the time of SPECT ranged from 0 to 20 months (mean 2.7±3.7
Interictal SPECT findings
Fifteen patients (38%) were classified as normal. Of these, 3 patients (mean age 6 months) had bilateral frontal hypoperfusion and seven patients (mean age 6.7 months) had relative hyperperfusion of the basal ganglia and occipital and sensorimotor areas bilaterally as well as hypoperfusion of the bilateral frontal areas. The remaining five patients (mean age 7.8 months) had essentially equal perfusion throughout the entire cortex and basal ganglia. Six out of 12 patients (50%) with cryptogenic
Discussion
In line with previous reports [10], [11], [12], localized cortical perfusion abnormalities were found in 24 of 40 patients with West syndrome, suggesting that a focal cortical lesion is closely related to the development of West syndrome. In addition, two of our patients had subcortical perfusion abnormalities. In a study of 44 patients with West syndrome, Chugani et al. reported that 32 had glucose hypermetabolism in the lenticular nuclei bilaterally and 21 had hypermetabolism in the
Acknowledgements
This study was supported in part by Grant-in-Aid from the Ministry of Education, Science and Culture, and from the National Center of Neurology and Psychiatry (NCNP) of the Ministry of Health and Welfare, Japan.
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