A study from Canada has defined features of spinal cord involvement that may help to diagnose children with myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD), multiple sclerosis (MS) or seronegative monophasic myelitis at the time of presentation.

The study included a total of 107 children, recruited from the multicenter Canadian Pediatric Demyelinating Disease Study. Of these, 40 had MOGAD, 21 had MS and 46 had seronegative myelitis. The median age at onset of disease was 11 years. These children presented with three months of an acquired demyelinating syndrome; 246 MRI scans showing spinal cord lesions were examined for the final analysis. Patients with poor-quality images and those who tested positive for anti-aquaporin 4 antibody were not included in the trial. Patients diagnosed with relapsing seronegative myelitis and nondemyelinating disease were also excluded. The clinical, serological and brain MRI findings were not disclosed to the reviewers. 

Published in the journal JAMA Network Open, the results showed that 75% children with MOGAD showed longitudinally extensive spinal cord lesions vis à vis 43% of children with seronegative myelitis, whereas only 5% of children with MS had these lesions on MRI. Axial gray matter T2-hyperintensity forming the H sign was seen in 63% children with MOGAD in comparison to 33% children with seronegative myelitis. None of the children with MS showed the H sign. In some children with MOGAD, the hyperintensity was restricted to the anterior horns (the snake-eyes sign).

The presence of leptomeningeal enhancement was highly indicative of MOGAD; 69% of children with MOGAD vs 26% with seronegative myelitis vs 7% with MS.

“Children with MOGAD were more likely to have complete lesion resolution on serial images (14 of 21 children [67%]) compared with those with MS (0 of 13 children).”

The diagnosis of MOGAD is based on the detection of antibodies to myelin oligodendrocyte glycoprotein (MOG). But these have to be tested “in proximity to incident demyelination” for reliable diagnosis.

This study has shown that features on MRI can help to differentiate pediatric MOGAD from MS and seronegative myelitis. Presence of longitudinally extensive spinal cord lesions, gray matter hyperintensity and leptomeningeal enhancement may be useful pointers to the diagnosis of MOGAD-associated myelitis in children aided by MOG-IgG testing. In children with MS, the leptomeningeal enhancement is rare and the H sign is also not seen.

Reference

1. Fadda G, et al. Comparison of spinal cord magnetic resonance imaging features among children with acquired demyelinating syndromes. JAMA Netw Open. 2021 Oct 1;4(10):e2128871. doi: 10.1001/jamanetworkopen.2021.28871.