Abstract Details

A 9 year old girl with high functioning trisomy 21 presented with progressive encephalopathy. While initially interactive and playful, she developed decreased speech production, withdrawal from family, hallucinations, decreased appetite with increased oral secretions, diaphoresis, and urinary incontinence. Clinical changes correlated temporally to positive anti-TPO antibody and mild subclinical hypothyroidism. She previously had normal yearly thyroid studies, but no prior antibody testing. Brain imaging was normal and investigations for alternate etiologies to include infection, metabolic disease, or other antibodies associated with autoimmune encephalopathy were negative. Due to profound EEG slowing, thyroid antibodies, and acute neuropsychiatric changes, she was diagnosed with probable Hashimoto’s encephalopathy. She had minimal subjective improvement after 5 days of IV methylprednisolone and IVIG. Plasmapheresis induced rapid improvement to about 80% of her baseline (per parents), but she re-presented with the same progressive symptoms less than 2 months later. Rituximab and mycophenolate were initiated but failed to show benefit. Chronic plasmapheresis initially improved symptoms, but sustained improvement was not achieved. Seven months into her illness she was started on monthly tocilizumab infusions due to its use as a 3^rd line agent in autoimmune encephalitis. Within 3 months, her neuropsychiatric symptoms improved. She remained on monthly tocilizumab infusions and is now at her pre-DSDD baseline nine months later.