MOG AB positive disease presenting as Acute disseminated encephalomyelitis and unilateral optic neuritis phenotype in a 6-year-old boy: a case report

The autoantibodies against myelin oligodendrocyte glycoprotein (MOG-abs) are a well-recognized biomarker in acquired demyelinating syndromes. The diversity in clinical phenotypes and neuroimaging findings is still being understood in the paediatric population. The presenting clinical phenotype strongly depends on the age at onset. Acute disseminated encephalomyelitis (ADEM) and ADEM-like phenotypes are common in younger children, but optic neuritis (ON) is predominantly seen in females and in older children and or adults.

We present a 6.5-year-old boy who presented with rapid onset of worsening encephalopathy and was found to have the combination of ADEM with multiple T2/FLAIR high signal intensity areas involving the gray-white junction of both cerebral hemispheres, thalami, right basal ganglia, and brain stem. There was no spinal cord involvement. The imaging also detected unilateral longitudinally affected optic neuritis. His serum was positive for MOG-Abs but negative for Aquaporin 4 antibodies. His cerebrospinal fluid was negative for oligoclonal bands. He showed slow recovery following high dose methylprednisolone and five cycles of plasma exchange. Complete clinical recovery was achieved within twelve weeks of admission.

Conclusion

Contrary to the usual older age of MOG-ON, this case illustrates a unilateral ON detected on MRI in a six-year-old boy occurring in conjunction with a MOG-ab positive encephalomyelitis.