Researchers at the Hospital for Sick Children, University of Toronto and other centers in Canada used serial clinical and MRI examinations performed over a minimum of 24 months to retrospectively evaluate the 2010 and 2005 McDonald criteria for the diagnosis of pediatric multiple sclerosis (MS). Of 212 eligible participants, 34 experienced 2 or more clinical attacks of MS, 58 met the 2010 criteria, and 42 met 2005 McDonald criteria. Both the 2005 and 2010 criteria demonstrated high sensitivity (100%), specificity (86%), positive predictive value (76%), and negative predictive value (100%) for children older than 11 years with non-acute disseminated encephalomyelitis (ADEM) presentations. In younger children with a non-ADEM presentation, positive predictive value of the 2010 criteria was only 55%. None of the 50 children with ADEM met clinical criteria for MS, but 10 met 2010 and 4 met 2005 criteria. 
COMMENT. In the clinical criteria for MS, relapses must persist for a minimum of 24 hours, and attacks separated by >30 days. MRI allows demonstration of CNS lesions in space and time and simplifies the diagnosis of MS. Clinical evidence alone is sufficient if the patient presents with 2 or more attacks and 2 or more objective clinical lesions. With 2 attacks and 1 clinical lesion, diagnosis requires demonstration of dissemination in space by MRI. With 1 attack and 2 lesions, dissemination in time demonstrated by MRI is sufficient. With 1 attack and 1 clinical lesion, dissemination in space (DIS) and time may be demonstrated by 1 or more MRI-T2 lesions in 2 MS-typical regions. In patients with insidious neurological progression for 1 year, evidence for DIS may be based on 1 or more T2 lesions in periventricular, juxtacortical or infratentorial regions or spinal cord, and/or positive oligoclonal bands in CSF. 
These revisions are meant to simplify the diagnostic criteria, preserve their sensitivity and specificity, address their use across populations, and may allow earlier diagnosis. They accurately identify children older than 11 years at risk for MS relapses, but they are not ideal for younger children and are not suited for those with ADEM-like presentations.