Defining and categorizing leukoencephalopathies of unknown origin: MR imaging approach

PURPOSE: To categorize leukoencephalopathies of unknown origin into a few m ajor groups by using magnetic resonance (MR) imaging criteria to facilitate further studies, and to assess the possibility of defining "new" (ie, unti l now unknown) disease entities within these major groups. MATERIALS AND METHODS: MR images of 92 patients (55 male, 37 female; mean a ge, 9.3 years) with a leukoencephalopathy were examined by using a scoring list of 68 items. Seven major categories were defined according to the pred ominant location of the white matter abnormalities. Statistical analysis wa s used to assess the validity of these seven categories. RESULTS: Statistical analysis results showed that the seven categories coul d be well distinguished by either using the defining variables initially ac cepted as inclusion criteria or selecting a few other variables found to ha ve discriminating value. The additional variables confirmed that the catego ries are essentially distinct and vary systematically with regard to items other than the inclusion criteria. The existence of two recently defined le ukoencephalopathies was confirmed, but no consistent evidence of other new disease entities could be provided. CONCLUSION: Establishing these seven categories helps in the interpretation of individual studies by demonstrating features that the patient has in co mmon with other patients, and it may facilitate further research on homogen eous subgroups of patients and allow pooling of data across multiple center s.