Clinical, radiologic, or CSF factors predicting development of multiple sclerosis (MS) after a first inflammatory demyelinating attack were identified in 117 children (56% <10 years, 34% <6 years) participating in a nationwide retrospective multicenter study in the Netherlands. A second MS-defining attack occurred in 43% of 54 children who presented with a monofocal clinically isolated syndrome (CIS), compared to 21% of 63 patients with a polyfocal CIS (p<0.006). Lesions considered typical of ADEM (basal ganglia and thalamic lesions and lesions >2 cm on MRI) occurred during PC1S, with or without encephalopathy. Children with PCIS had a preceding infection in 50%, fever in 42%, and seizures in 28%; they were not at greater risk of developing MS. Children with PCIS without encephalopathy progressed to MS more frequently than those with encephalopathy (ADEM). Risk factors for development of MS included elevated IgG index, oligoclonal CSF bands, 3 Barkhof MRI criteria (>9 lesions T2, infratentorial, juxtacortical, and >3 perivascular lesions), and KIDMUS supplemental MRI criteria (perpendicular to corpus callosum, thalamic/basal ganglia, and well-defined lesions). In children <10 years, Barkhof criteria had a higher sensitivity than KIDMUS criteria, but lower than in older children. Mean time to conversion to MS after a CIS was 17.7 months (range 2-75 months); after a PCIS attack, the mean time to MS diagnosis was 24 months (range 2-79 months). 
COMMENT. Barkhof and KIDMUS MRI criteria have a high specificity and are risk factors for conversion to MS in children with a first demyelinating attack, but their sensitivity is poor, especially at age <10 years. Over a mean period of observation of 54 months (range 5-201 months), 37 children (31%) developed MS. In this study children with initial monofocal symptoms were more likely to have MS (43%) compared to those with polyfocal features (21%). In contrast, 17% of children with an initial ADEM-like presentation were diagnosed with MS at follow-up.