Abstracts

Rationale: Diffusion tensor imaging (DTI) has been applied to detect the white matter abnormalities in patients with focal epilepsies. However, there are few reports investigating the abnormalities in West syndrome (WS) by DTI. From the findings of FDG-PET and SPECT, it is supposed that abnormal interactions of cortical and subcortical structures may trigger the onset of spasms in WS. To investigate the abnormalities of these areas, we performed serial FDG-PET and DTI studies in patients with cryptogenic WS. Methods: Seven patients with newly diagnosed cryptogenic WS between June 2006 and September 2008 were prospectively studied. Interictal FDG-PET and DTI with a 3.0T magnetic resonance scanner were performed before adrenocorticotropic hormone (ACTH) therapy, and reexamined at 1 year of age or later. FDG-PET hypometabolism was evaluated by visual inspection. DTI was analyzed with free softwares; Volume-One v.1.72 and dTV.2SR. Regions of interests (ROIs) were placed in cerebral white matters, dentate nucleus, midbrain, lenticular nucleus, thalamus and corpus callosum. Apparent diffusion coefficient (ADC) in the each ROI was evaluated and compared with that of 13 controls. ADC abnormality was considered present if the ADC values were more than 10% high or low compared with those in age-matched controls. We also visualized uncinate fasciculus (UNC), corticospinal tract (CST), inferior longitudinal fasciculus (ILF) and commissural fibers from corpus callosum using tractography. The tract was considered abnormal when the tract was not visualized or the tract of one side was more than three times thinner than that of the opposite side. We could visualize both sides of these tracts equally in control cases. Results: Six of 7 patients were treated with ACTH, while 1 patient was not with ACTH because spasms disappeared with clonazepam. Seizures in all patients had been controlled by 1 year of age. The first PET showed unilateral cortical hypometabolism in 4 patients and bilateral hypometabolism in three. Two patients showed elevated ADC values in the regions consistent with the hypometabolic areas detected by PET. Three patients showed abnormalities on tractography. Right CST and ILF were thinner and bilateral UNC were not visualized in one patient. Left UNC was thinner in the second patient and left ILF and right UNC were thinner in the third patient. Focal hypometabolism remained at the second PET after initial treatments in 6 patients. Elevated ADC values and abnormalities on tractography disappeared in 2 patients at the second DTI scan. Conclusions: FDG-PET hypometabolism and DTI abnormalities were detected at the onset of cryptogenic WS. Abnormalities of ADC values and tractography tend to disappear after initial treatments. The reversible DTI abnormalities may suggest delayed maturation of white matters in cryptogenic WS.