Abstracts

Glucose transporter 1 deficiency syndrome (GLUT1DS) is well known but rare syndrome characterized by infantile onset epilepsy, mental retardation, abnormal eye movement, hypotonia, ataxia and dystonia. The seizure type evolution (complex partial seizures and generalized convulsions in infancy, absence seizures in childhood) and some fluctuation by fasting are diagnostic clues before confirmation of hypoglycorrhachia. In atypical cases the diagnosis is often difficult because spinal tap is not always easy to perform. Although some specific findings were reported on FDG-PET, none was reported on MRI until now. We found new specific MRI findings in GLUT1DS, which would be helpful for diagnosis. Serial cerebral MR imaging studies of 5 Japanese (3y - 7y) children with hypoglycorrhachia (CSF glucose [lt] 40mg/dl, glucose CSF/blood [lt] 0.4) were analyzed. Glucose uptake of patients[apos] RBC was decreased in 4 cases (definite GLUT1DS = group D) and normal in 1 case (probable GLUT1DS = group P). White matter lesions were observed in 3 cases (2 cases in Group D, 1 case in Group P). The case with severest clinical manifestations (group D) showed multiple asymmetric small ([lt]1cm) T2 hyperintensity lesions in subcortical white matter on FLAIR image. Those lesions were scattered over occipital, parietal and frontal lobes and showed increase in both number and size during follow-up period (7m, 3y and 5y). H-MRSpectroscopy of the lesions showed normal peaks of choline, creatine and N-acetyl aspartate. Multiple smaller subcortical white matter lesions were also observed in one case of group D (5y) and group P (3y). Multiple small subcortical lesions are supposed to be the results of long lasting moderate glucose deficiency in the brain tissue, since they located at the watershed regions of cerebral circulation without any accumulation of abnormal metabolites on MRS and are similar to lesions observed in some cases of glycogen storage diseases. The lesions are not only typical and highly observed (more than half cases, including probable case) in GLUT1DS, but also relate to clinical severity to some extent and sometimes expand with age. We conclude that the finding is specific to GLUT1DS and is helpful for screening before spinal tap examination and for assessment of the clinical severity. (Supported by Japan Epilepsy Research Foundation (2005).)