52 patients <18 years were diagnosed with autoimmune encephalitis, 10 (19.2%) of these were positive for TPO antibodies. Median age at disease onset was 14.5 years (range 6-18 years) with only 1 male patient being. Mental status (90%) and behavior changes (100%) were most common presentations, seizures were detected in only 1 patient. MRI (20%) and EEG (30%) abnormalities were uncommon, and only 1 patient had evidence of inflammation in cerebrospinal fluid (CSF). Autoimmune encephalitis and paraneoplastic antibody panels were negative besides 2 (20%) patients having concomitant Thyroglobulin (TG) antibodies. All patients needed additional IVIG after steroids treatment, 7(70%) patients received Rituximab and 3(30%) patients needed Plasmapheresis. All patients recovered at an average of 4.4 years follow up.

Encephalopathy associated with thyroid antibodies can be steroid unresponsive in the pediatric population. Further immune therapy, including plasmapheresis, should be considered in these patients, even in the absence of other para-clinical evidence of inflammation.